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A description of Apistogramma species-groups


In 1990 I gave a talk at the 15th annual weekend convention of the Northeast Council of Aquarium Societies entitled "Description, Distribution and a Proposed Phylogeny of Apistogramma Species-Groups". Later, I wrote an article under the same title for the Colorado Aquarist (Wise, 1990). It proved very popular and many other aquarium society journals reprinted it. Due to the amount of new information on species of Apistogramma that became available over the next ten years, I updated the paper in 2002. It was published on the web site of the Apistogramma Study Group. During the past two decades, still more data on Apistogramma species from both scientists and hobbyists have been published. These include genetic phylogenetic discoveries (Miller & Schliewen 2005; Ready et al. 2006; Tougard et al. 2017; da Costa et al. 2019; Estivals et al. 2020) that were not available until just a few years ago. New species and collecting locality data for both described and undescribed species have greatly expanded. All of this new data make it possible to have an even better understanding of the Apistogramma species-groups, their patterns of distribution, and seemingly how the many different species of Apistogramma arose from one another.
At this time, it is generally accepted that there are approximately 100 scientifically described species of Apistogramma. Over 400 additional undescribed species/forms have been reported in hobby-oriented literature, on web sites, internet forums or social media. Some of these undescribed species/forms, however, may be only geographic variants of already known species. Nevertheless, I feel confident in saying that at least 500 different species of Apistogramma are distributed throughout the many river systems in tropical South America east of the Andes.
With so many different species, it is virtually impossible to make a positive identification without some means of breaking the genus down into manageable parts.


History

     With ever more species being discovered, and the potential for the number to expand dramatically, it early became obvious that the genus Apistogramma needed to be broken down into various species-groupings in order to more easily identify individual species. Meinken (1962) originally erected species groups based on different eye diameters and nose lengths. Although others thought that this was an artificial grouping (e.g. Goldstein, 1970), Meinken's groupings remained the basis for identifying Apistogramma for almost 20 years. Kullander (1980) proposed a more natural grouping of the genus, based on many more shared characteristics. He listed seven species-groups and several species that were then not assignable to species-groups. Schmettkamp (1982) was the first to recognize that most species-groups had a regional pattern of distribution. He proposed nine species-groups plus additional, non-assignable, species. Koslowski (1985) originally published the list of species-groups that most apistophiles have used for the past 30+ years. He also subdivided some species-groups, calling these divisions "complexes". He originally had seven groups and nine complexes, plus species not assigned to any of these. Koslowski (2002) expanded the number to 13 species-groups and 16 complexes. In their preliminary genetic studies, Miller & Schliewen (2005) largely confirmed Koslowski’s groupings and recognized 13 groups and ten complexes split into four basal lineages. Römer (2006a, b) published a computer generated statistical analysis of the genus. His groupings rarely coincide with those of other authors. This may have been due to an insufficient number of characteristics used in the program. I personally find them confusing and often contradictory, therefore I do not use his groupings. In this paper, I base most of my groupings on the works of Koslowski (2002) and Stawikowski (2005), which includes the preliminary genetic findings of Miller & Schliewen (2005). I recognize 16 species-groups, 24 species-complexes, plus several unaffiliated species, in four distinct lineages with two sublineages. These are:



    A.-regani-Lineage
      A.-regani-Group
          A.-kullanderi-Complex
          A.-sp.-"Xingu"-Complex
          A.-caetei -Complex
          A.-resticulosa-Complex
          A.-commbrae-Complex
          Apistogrammoides
          A.-borellii-Complex
          A.-regani-Complex
          A.-sp.-"Angle-patch"-Complex
          A.-eunotus-Complex

                A.-eunotus-Subcomplex
                A.-cruzi-Subcomplex
                A.-ortegai-Subcomplex

     A.-alacrina-Group
          A.-alacrina-Complex
          A.-sp.-"Mitu"-Complex

     A.-macmasteri-Group
          A.-hongsloi-Complex
          A.-macmasteri-Complex

                A.-macmasteri-Subcomplex
                A.-hoignei-Subcomplex


    A.-pertensis-Lineage

         A.-steindachneri-Group
         A. wapisana
         A.-pertensis-Group
              A.-pertensis-Complex
              A.-velifera-Complex
         A.-iniridae-Group


    A.-trifasciata-Lineage
      A.-trifasciata-Sublineage      
       Ancestral A.-trifasciata-
lineage species

       A.-brevis-Group
       A.-sp.-"D10"-Group
       A.-cacatuoides-Group
       A.-nijsseni-Group
       A.-norberti-Group
       A.-atahualpa-Group
            A.-atahualpa-Complex
            A.-barlowi-Complex

       A.-trifasciata-Group
     A.-agassizii-Sublineage
       A.-gibbiceps-Group
       A.-bitaeniata-Group
            A.-paucisquamis-Complex
            A.-bitaeniata-Complex

       A.-agassizii-Group
            A.-pulchra-Complex
            A.-agassizii-Complex

                  A.-agassizii-Subcomplex
                  A.-agassizii-Broad-Black-
Caudal-Seam-Subcomplex

                  A.-agassizii-Netz / Net-
Subcomplex


   A.-diplotaenia-Lineage
        A.-diplotaenia-Group


           Taeniacara
















































(All entries of this table are links. If you want to look at a particular group, complex etc., you may simply click on the respective entry)


     The increase in the number of species-group/complexes is mostly due to the discoveries of new species/forms that are related to species not previously assignable to already existing groups or complexes. Some of these groupings are speculative, due to the lack of precise distribution data as well as little to no meristic or genetic data for the scientifically undescribed species.

     Identification of the species-groups listed here is based primarily on the black markings shared by all of the species within an individual species-group. Other features, such as the shape of the body and the dorsal and caudal fins of males, are also useful but aren't as reliable. These are all readily visible on live fish and make them more useful for hobbyists. Other features, such as the skeletal and pharyngeal teeth structure, are equally valuable but are not readily seen on living fish. Breeding behavior and aggressive display behavior are generally similar within a species-group. The number of sensory pores found on the head is another feature that is very valuable. These pores can be used to separate the genus into three major blocks. I consider those species-groups with a full compliment of 4 infraorbital and 5 dental pores to be the more primitive or "ancestral" groups. Those that have reduced infraorbital and dental pore counts are considered members of more "advanced" species-groups. The "advanced" species-groups can be further subdivided by reductions in dental pores. Pore reduction, however, might also be seen in dwarf species where the reduced number of pores is caused by the small size of the fish. These pores usually cannot be seen without magnification, thus this feature is difficult to use on live specimens.

Cephalic Pores

dp = dental pores (two pores on the other side of the head are not visible from this side);
ip = infraorbital pores; aap = anguloarticular pores.


     The shape of the fins and body can also be used to separate ancestral from advanced species, but are not totally reliable. Apistogramma males with tails that are round to oval, truncate (squared-off), or exhibit slight extensions at the top and bottom of the tail (double tipped) are often ancestral species. Those with caudal fin extensions placed closer to the middle of the fin's edge (lyrate) or spade-shaped are always members of advanced species-groups. Likewise, Apistogramma males with even dorsal fins that show very little or no serrations and possess at best minor dorsal fin extension are typically ancestral forms. Those with "fancy" dorsal fins, that have extremely long anterior dorsal spines and lappets, or sail-like fins, are almost always advanced species. With regard to body shape, ancestral forms tend to be more deep-bodied and more laterally compressed. Advanced forms commonly are elongate and less compressed. Pronounced sexual dimorphism is more commonly seen in advanced species, as is the tendency toward polygamy.
One important thing to remember, however, is that while ancestral species cannot exhibit advanced characteristics, advanced species can - and frequently do - exhibit "retrograde" ancestral features.



DESCRIPTION

     To properly recognize the important diagnostic features used for the identification of Apistogramma species, it is important to know how to locate the dark markings and other diagnostic features on these fish. The most important dark markings are shown on the following figures:


Primary Dark Markings

1. Preorbital (Nose) Stripe, which extends from the eye to the tip of the snout.

Primary Dark Markings

Primary Dark Markings

2. Supraorbital (Forehead) Stripe, which extends from the eye to the back of the forehead.

3. Suborbital (Cheek) Stripe, which extends downward from the eye, usually to the edge of the gill cover.

4. Postorbital Stripe, a narrow extension of the lateral band from the back of the eye to the back of the gill cover.

5. Vertical Bars, seven (rarely eight or six) evenly spaced bars that extend from the dorsal edge to the ventral edge of the body. These bars vary in width and intensity depending on the species and the mood of the individual fish.

6. Lateral Band, a broad horizontal band that extends along the mid-line of the flanks, from the posterior edge of the gill cover to the base of the caudal fin. In some species it extends into the caudal fin. The lateral band can break up into a row of spots on many apisto species. These spots are typically equal in width or slightly wider than the lateral band. The number of spots, depending on species and mood, can vary from seven (rarely eight) to zero; five to seven is more typical.

7. Caudal Spot, a blotch on the base of the caudal peduncle posterior of Bar 7. This spot can vary in size and shape depending on the species. On some species it is part of the lateral band that extends into the caudal fin.

8. Lateral Spot, develops at the intersection of Bar 3 and the lateral band. When in a series of flank spots, it is typically the largest. Certain groups of species don’t show a lateral spot.


Secondary Dark Markings

9. Flank Patch, a blotch seen on Bar 3 that extends well above the lateral band. It is much taller and wider than a lateral spot.

10. Abdominal Stripes, form as dark horizontal stripes on the abdomen below the lateral band. These stripes can be continuous and even, wavy, or even as a series of closely spaced blotches.

Habitat

Secondary Dark Markings

11. Abdominal Streaks, form slightly diagonal vertical stripes on the abdomen below the lateral band. These are usually formed by dark pigment on the front or rear edge of scales, so they are not typically continuous.

12. Abdominal Bands, develop from part of the vertical bars, but appear only below the lateral band.

13. Anal Blotch, dark pigment visible only around anus.

14. Ventral Stripe, a dark stripe that extends along the ventral edge of the head and/or body. It is variable in length, where it can appear anywhere between the lower lip and the anus.

15. Dorsal Spots, form from darkening of the dorsal part of the vertical bars. The dorsal spots can spread into the base of the dorsal fin on some species.

16. Pectoral Blotch, forms from dark pigmentation around the insertion of the pectoral fins.

17. Postorbital Blotch, forms from darkening of part of Bar 1, immediately behind the posterior edge of the gill cover.

18. Caudal Patch, a dark patch on the caudal peduncle formed from part of Bar 7 and the caudal spot.

19. Caudal Fin Markings, patterns of dark markings on the caudal fin. Caudal fins can be hyaline/clear, have a series of rows of spots and/or horizontal stripes, or rings of color around the outer margin.

     Primarily using dark markings and assisted by cephalic pores, finnage, body shape, and behavioral characteristics, it's possible to describe the species-groups. As in my previous articles on the subject, this caveat applies: Since this isn't a scientific paper and I don't have a "professional reputation" to protect, I'm allowing myself more license in suggesting relationships than would a professional taxonomist!




Apistogramma-regani-Lineage

     All members of the A.-regani-lineage are distinguished by having a complete set of 4 infraorbital and 5 dental pores. In addition, members of the A.-regani- lineage do not show a lateral spot on vertical Bar 3. Most species show a lateral band that breaks into flank spots, but none shows a more distinct lateral spot. Most show a caudal spot clearly separated from the lateral band. The caudal fins of males are typically round to squared off, but some have short extensions at the top and bottom of a squared off fin. The A.-regani-lineage includes the A.-regani-, A.-alacrina-, and A.-macmasteri-groups. The unassigned species Apistogramma borellii and Apistogrammoides pucallpaensis are also considered part of the A.-regani-lineage.


Apistogramma-regani-Group

     Species of the A.-regani-group exhibit many plesiomorphic (primitive) features. Most show very little sexual dimorphism and tend to be for the most part casually polygamous. This means that the male does not expend extraordinary time & energy acquiring and maintaining a large territory with several female territories in it. If his territory has several females in it, however, he will breed with them all.

     Morphologically, A.-regani-group species are characterized by their relatively deep bodies, low and even dorsal fins (1), typically round caudal fins (2), often showing vertical flank bars (3), and lack a lateral spot on the lateral band (4). As would be expected, the A.-regani-group represents an ancestral group with a complete set of four infraorbital pores below each eye and five dental pores along the lower jaw.

     The Apistogramma-regani-group is the most widely distributed of the Apistogramma species-groups. They can be found in most tributaries of the Amazon Basin. They are also found in coastal streams entering the Atlantic Ocean from eastern Venezuela to the Rio Parnaiba of eastern Brazil. They also can be found in the Paraguay-Paraná Basin of southeastern Brazil to northeastern Argentina. There are presently over 30 scientifically described and more than 70 undescribed species within the group, including Apistogrammoides pucallpaensis. With so many species it's not surprising that the Apistogramma-regani-group has been subdivided into ten complexes and even includes species that are not assignable to any of the complexes.



Apistogramma-kullanderi-Complex

     The A.-kullanderi-complex is composed of moderately large to very large (up to 5 in./12.5 cm TL) species closely related to species of the A.-sp.-"Xingu"-complex. They share the same robust, moderately deep body seen on populations of A. sp. "Xingu". The most conspicuous differences between species of the A.-kullanderi-complex and the A.-sp.-"Xingu"-complex are seen in the dark markings on the females. The vertical bars (1) show extremely irregular borders, something extremely rare in other Apistogramma species. Females also show a large black gullar area (2) extending from the lower lip to the vent.

     Presently all known members of the A.-kullanderi-complex occur in the upper Rio Xingu except A. sp. "Peixoto", which occurs in nearby tributaries of the upper Rio Tapajós. There are presently three scientifically described and one undescribed species in the complex. I consider species of the A.-kullanderi-complex to be closest to the ancestral form of the genus Apistogramma. They show many pleisiomorphic features also seen in the rhabdotus-group of the genus Gymnogeophagus, which Kullander (1998) considers phylogenetically a sibling/sister-genus of Apistogramma. Among these are size, sexual dimorphism, and the bar pattern on females. Their ranges are separated by the Brazilian Highlands. The A.-kullanderi-complex occurs along the northern periphery of this highland, while the rhabdotus-group is found on the southern side of the highland.

to the species / forms p.t. in the A.-kullanderi-complex.


Apistogramma-sp.-"Xingu"-Complex

     The species of the A.-sp.-"Xingu"-complex are small to moderate in size (<2¾ in./ 7 cm TL). They show a mix of features seen on both the A.-caetei- and A.-regani-complexes. They have slender to moderately deep bodies and males have low to moderately high dorsal fins with even spines. The deeper bodied species have a moderately broad lateral band; the slender bodied species have a narrower band. Unlike on A.-caetei-complex species, the lateral band has even top and bottom borders (1) and it becomes gradually broader toward the posterior (2). It ends in front of a caudal spot, as on A.-regani-complex species, but the area between the end of the band and the caudal spot (3) is not as bright as seen on the A.-regani-complex species. The caudal spot on A.-sp.-"Xingu"-complex species tends to be small and either round or square (4). The caudal spot on A.-regani-complex species tends to be larger and more oval or vertically oriented. The caudal fin is round, usually with rows of fine stripes. There are five, possibly more, undescribed species in the A.-sp.-"Xingu"-complex.

     Most species of the complex are found in the middle to lower Rio Xingu. One species occurs in the lower Rio Tapajós. The species A. sp. "Itaparaná", reported to be from the Rio Purus, appears to be a population of A. sp. "Chao" from the Rio Xingu and most likely doesn’t actually occur in the Rio Purus.
There are no scientifically described species within the complex, which presently includes at least seven undescribed species.

to the species / forms p.t. in the A.-sp.-"Xingu"-complex.


Apistogramma-caetei-Complex

     The A.-caetei-complex is an assemblage of medium sized species (<3 in./7.5 cm) with a relatively robust body. They are characterized by having abdominal streaks (1) that form thin diagonal bars below a narrow zigzag lateral band (2) and a pattern of vertical rows of spots over the entire caudal fin (3) on males. The lateral band ends in Bar 7 in front of a caudal spot. Part of Bar 7 is darker just below the lateral band. This makes the lateral band appear to have a downward, right angle break (4) just in front of the caudal spot. Presently there is only one, but possibly three other scientifically described and at least six undescribed species that can be assigned to the complex.

     Species in the A.-caetei-complex are known to occur in Atlantic coastal streams from the Rio Parnaiba, northward to Ilha de Marajó at the mouth of the Amazon, and into to Brazilian state of Amapá near Macapá. Species are also found in tributaries of the Rio Tocantins system of eastern Brazil. Another is questionably believed to originate from the upper Rio Paraguay.

to the species / forms p.t. in the A.-caetei-complex.


Apistogramma-resticulosa-Complex

     The A.-resticulosa-complex is composed of a group of relatively small species (<2¾ in./7 cm). In addition to the standard A.-regani-group features, these species exhibit a narrow zigzag lateral band (1), a series of faint, poorly defined, abdominal streaks in the form of vertical dashes below the lateral band (2). These characteristics are similar to features seen on members of the A.-caetei-complex. The body, however, is not as robust as that of A.-caetei-complex species and the lateral band doesn’t show the downward break at Bar 7. There are faint stripes toward the center or only on the posterior part of the caudal fin (3) and the body usually shows a blue sheen on males.

     Presently there are two, possibly four, scientifically described species and another dozen or more undescribed species/forms within the complex.
The species of the A.-resticulosa-complex are almost all found south of the main channel of the Amazon. Their distribution includes the Bolivian Amazon and extreme southeastern Peru and southwestern Brazil, which are extensions of the Bolivian Amazon drainage. From this locus, they are distributed down the Rio Madeira, eastward into the lower parts of the southern tributaries of the Amazon, and down to the Ilha de Marajó at the mouth of the Amazon.

to the species / forms p.t. in the A.-resticulosa-complex.


Apistogramma-commbrae-Complex

     The species of the A.-commbrae-complex appear to be offshoots of the A.-resticulosa-complex. Members of both complexes show many similarities. The A.-commbrae-complex is comprised of a group of mostly small species (<2¾ in./7 cm). Members show most of the characteristics found on all species of the A.-resticulosa-complex, although the abdominal streaks seen on the A.-resticulosa-complex are modified into horizontal abdominal stripes (1) on some species in the A.-commbrae-complex. One feature that separates the species of the A.-commbrae-complex from those of the A.-resticulosa-complex is a distinctive caudal blotch (2). This blotch is formed from the caudal spot that has merged with a highly pigmented part of Bar 7.

     The A.-commbrae-complex includes four scientifically described species. Some geographic populations of these species possibly are separate undescribed species.
All are found in the Bolivian Amazon and Rio Paraguay system.

to the species / forms p.t. in the A.-commbrae-complex.


Apistogrammoides-Complex

     The genus Apistogrammoides, which contains only one species – Apistogrammoides pucallpaensis, is genetically part of the A.-regani-lineage and probably more closely related to a deep-bodied member of the A.-commbra-complex, like A. linkei. Therefore, it can be considered a complex within the A.-regani-group. It differs from other A.-regani-group species by not showing a distinct caudal spot. Instead, Apistogrammoides shows a vertical band at the base of the caudal fin that joins to a narrow more even edged lateral band, where they form a "T" shaped pattern (1). The anal fin has 7-8 anal spines (2) – twice the number seen on species of Apistogramma.

     Apistogrammoides pucallpaensis is distributed throughout the Peruvian Amazon – from tributaries of the middle Río Ucayali to the Colombian Amazon around Leticia.



Apistogramma-borellii-Complex

     Apistogramma borellii is a non-allied species from the Río Paraguay drainage. It is characterized by its small size (<2¼ in/6 cm), deep and laterally compressed body, high sail-like dorsal fin (1), and round to very slightly spade-shape tail (2). A zigzag lateral band is usually visible only on the posterior half of the body (3). Flank bars are only visible when under stress. A bright blue colored body is typical of males. The infraorbital pores in A. borellii are reduced to three, an advanced species characteristic. On the other hand, the anguloarticular canals are usually missing entirely, something found only in one other Apistogramma species, A. trifasciata, also found in the Río Paraguay. Perhaps reduction in sensory pores may be related to subtle differences found in the environment of the Río Paraguay, although it may also be a chance mutation like that which occurred in the A.-pertensis-group. In many respects A. borellii appears to be a deeper bodied, higher finned, offshoot of the A.-macmasteri-group.

     Only one other form might be a member of this group. This is Apistogramma sp. "Río Paraguay III" (Mayland & Bork, 1997a, b). It looks much like a slender, low dorsal finned A. borellii. It was found only once and nothing is known of its natural habitat. Apistogramma sp. "Río Paraguay III" was found in a shipment of A. borellii from the upper Río Paraguay. There is a good possibility that it is only an aberrant A. borellii.

     Apistogramma borellii is distributed throughout much of the Río Paraguay/Paraná drainage, from the southern Mato Grosso of southern Brazil to the city of Corrientes in northern Argentina. It also occurs in tributaries of the Río Uruguay in Uruguay. It has the southern-most distribution of any species of Apistogramma, extending even into subtropical South America. As such it is more cold tolerant than most Apistogramma species.

to the species / forms p.t. in the A.-borellii-complex.


Apistogramma-regani-Complex

     Species in the A.-regani-complex comprise an assemblage of mostly medium sized (<3 in./7.5 cm), deep bodied and laterally compressed fish characterized by seven conspicuous vertical bars running the entire height of the body (1). These bars are chiefly visible on juveniles and females. In addition, all species in the A.-regani-complex are characterized by having a very pale zone that separates the lateral band from the caudal spot (2).
There are at present five scientifically described and at least 11 undescribed species placed within the complex.

     Species of the A.-regani-complex are widely distributed throughout the Amazon drainage. The locus of the complex appears to be centered in streams along the middle and lower Amazon. Other species are also found in the upper Purus, and Juruá drainages of southwestern Brazil, the upper Negro of northern Brazil and southeastern Colombia, and in the lower Ucayali of Peru. Species are also found in Atlantic coastal streams from north of the Amazon to the Guyana/Venezuela border.

to the species / forms p.t. in the A.-regani-complex.


Apistogramma-sp.-"Winkelfleck/Angle-patch"-Complex

     The species of the A.-sp.-"Winkelfleck"-complex show features similar to those of the A.-regani- and A.-sp.-"Xingu"-complexes. These fish are moderately large (<3 in./7.5 cm) and have a deep and highly laterally compressed body. Males have low, even dorsal fins. The cross-striped caudal fin is noticeably small in comparison to the size of the fish (1). The most diagnostic characteristic is the pattern of its vertical bars that show during aggressive display. The bars extend diagonally backwards on the abdomen (2). Only two forms are presently known.

     The A.-sp.-"Winkelfleck"-complex occurs in tributaries of the Río Nanay (Peru) and in southern tributaries of the Amazon between the Río Orosa in Peru and Leticia, Colombia.

to the species / forms p.t. in the A.-sp.-"Winkelfleck/Angle-patch"-complex.


Apistogramma-eunotus-Complex

     The species of the A.-eunotus-complex are all moderately large (<3½ in/9 cm). Their deeper, laterally compressed bodies  (1) distinguish them from most members of the A.-regani-complex. The species also show greater sexual dimorphism than seen that in other A.-regani-group complexes. The caudal fin shape is usually round but some species can develop a truncate fin with no, one, or even two short caudal extensions. All have a fairly broad lateral band, usually with even borders  (2), separated from a distinct caudal spot. The area between the lateral band and caudal spot is not pale like that seen on regani-complex fish.

     There are seven scientifically described species and at least another 30 undescribed forms in the complex. This does not include two scientifically described and several undescribed species that show attributes of both the A.-eunotus- and A.-regani-complexes.
All of the species within the A.-eunotus-complex occur in the Río Amazonas drainage of Peru and Colombia, plus one in the neighboring Rio Jutai (Brazil) and Río Putumayo drainage in Colombia.
Based on secondary features, mostly dark markings, the A.-eunotus-complex can be split into three subcomplexes.



Apistogramma-eunotus-Subcomplex

     In addition to features seen on all species in the A.-eunotus-complex, the species of the A.-eunotus-subcomplex are characterized by a comparatively higher, even to slightly serrated, dorsal fin (1). Males commonly possess round tails, colored orange in parts. Some species can develop one or two caudal fin extensions. An orange spot at the insertion of the pectoral fin is characteristic of this subcomplex (2). Many, but not all species of the A.-eunotus-subcomplex develop one or more split vertical bars on the posterior half of the flanks when in threat display. These splits are formed from scales that become light colored in the 5th, 6th and rarely 7th vertical bars below the lateral band (3). Split vertical bars are not unique to this A.-eunotus-subcomplex species. It is also seen on some species of the A.-steindachneri- and A.-cacatuoides-groups as well as a couple of other A.-regani-group species. On these species, however, the split bars are more extensive, ranging from the 4thto the 7th vertical bars.

     There are two scientifically described and at least ten undescribed species/forms within the subcomplex.
The A.-eunotus-subcomplex is distributed exclusively in the Peruvian and Colombian Amazon and Rio Jutai in western Brazil.

to the species / forms p.t. in the A.-eunotus-subcomplex.


Apistogramma-cruzi-Subcomplex

     The species of the A.-cruzi-subcomplex are similar to A.-eunotus- subcomplex species. They, however, are distinguished by their lack of split vertical bars. The dorsal fin on males is lower and rarely shows serrated spines (1). The posterior tip of the soft dorsal fin is typically longer, too (2). Males in many populations develop a more oval to truncate shaped caudal fin, often with two short caudal extensions. All show well-developed abdominal stripes (3).

     There presently are three scientifically described species and more than 15 undescribed species/forms in the subcomplex.
The A.-cruzi-subcomplex is distributed in tributaries of the extreme western Amazon system. Representative of the subcomplex occur in the lower Río Ucayali in Peru, the Río Napo system of Peru and Ecuador, the Río Putumayo system in Peru and Colombia, and Río Caquetá system in Colombia.

to the species / forms p.t. in the A.-cruzi-subcomplex.


Apistogramma-ortegai-Subcomplex

     Very few characteristics separate members of the A.-ortegai-subcomplex from those of the A.-cruzi-subcomplex. They could easily be considered to be just one subcomplex. They are identical in body shape and fin development. Abdominal stripes in the A.-ortegai-subcomplex are usually present, but not as prominent as on A.-cruzi-subcomplex species. Species in the A.-ortegai-subcomplex are often more colorful. Species of the A.-ortegai-subcomplex can be easily separated from those of the A.-cruzi-subcomplex by one feature. The A.-ortegai-subcomplex species develop a caudal blotch from the caudal spot and part of the 7th vertical bar (1), similar to that of the A.-commbra-complex.

     The A.-ortegai-subcomplex presently includes two scientifically described species and possibly as many as five undescribed species.
Species of the A.-ortegai-subcomplex are known only from northern tributaries of the Peruvian Amazon between the Río Napo and the Río Ampiyacu.

to the species / forms p.t. in the A.-ortegai-Subcomplex.



Apistogramma-alacrina-group

     The species of A.-alacrina-group show features that indicate that they may form a bridge between species of the A.-macmasteri-group and those of the A.-eunotus-complex. Most are medium to moderately large in size (2¼ - 3½ in./6 - 8 cm TL). Their fairly broad lateral band has two rows of alternating light and dark scales. The rows of dark scales are offset so that they form a zipper-like band (1). This band is more similar to the zigzag lateral band seen on members of the A.-macmasteri-group than the even bordered lateral band of A.-eunotus-complex species. The tail of the male is round to very slightly squared off. The dorsal fin is low and even (2) on males, unlike the high and serrated dorsal seen on males of the A.-macmasteri-group. In this respect, it is more similar to that of males of the A.-cruzi-subcomplex. Females of the A.-alacrina-group exhibit the yellow with black checkered brood pattern characteristic of both the A.-macmasteri-group and A.-cruzi –subcomplex. Like females of the A.-cruzi-subcomplex, females of most A.-alacrina-group species do not develop a black ventral stripe typical for females of the A.-macmasteri-group. Instead, females develop only an anal blotch. A pectoral blotch is sometimes part of the female’s brood dress. The males, like males of A.-macmasteri-group species, are highly polygamous.
This is an ancestral species-group, with four infraorbital and five dental pores.
The A.-alacrina-group can be separated into 2 species-complexes based on differences in size, finnage, and some dark markings.

     There is one scientifically described species (A. alacrina) and possibly ten or more undescribed species in the group.
The A.-alacrina-group is distributed in northeastern Ecuador and southeastern Colombia. Species are found in tributaries of both the Orinoco and Amazon.



Apistogramma-alacrina-Complex

     The species of the A.-alacrina-complex are distinguished from species of the A.-sp.-"Mitu"-complex by having larger (2¾ – 3½ in./7 – 8 cm TL), more robust bodies (1). Males are visibly larger than females. The soft parts of the dorsal and anal fins are more extended, the dorsal extending almost to the posterior of the caudal fin (2). Almost all females in brood dress show a prominent dark blotch below and often above the pectoral fin insertion  (3).

     The A.-alacrina-complex has one scientifically described and at least eight undescribed species.
Species of the complex are distributed in upper tributaries of the Amazon and Orinoco rivers in northeastern Ecuador and southeastern Colombia.

to the species / forms p.t. in the A.-alacrina-complex.


Apistogramma-sp.-"Mitu"-Complex

     The A.-sp.-"Mitu"-complex species appear to represent forms in the A.-alacrina-group that have adapted to habitats in streams with a higher rate of flow than those of the A.-alacrina-complex. They are distinguished from A.-alacrina-complex species not only by their smaller size (2¼ - 2¾ in. / 6 - 7 cm TL) but by their more slender body form (1) and slightly larger caudal fin  (2) in proportion to body depth. A.-sp.-"Mitu"-complex species also show less elongated soft rays on the dorsal and anal fins (3). These features appear to be adaptations to waters with a higher rate of flow.
Sexual dimorphism in body size and finnage is less conspicuous than that in A.-alacrina-complex species.
A.-sp.-"Mitu"-complex species also show some differences in some of their dark markings. Unlike almost all species of the A.-alacrina-complex, the species of the A.-sp.-"Mitu"-complex do not show a lower pectoral spot and the upper one is very small when visible and does not extend above the pectoral insertion (4), which it does on many A.-alacrina-complex species. The lateral band, when visually continuous, often appears narrower between the last two bars on the caudal peduncle or even shows a small gap at this position. When the lateral band appears as a row of spots, this gap is often noticeably larger than the others (5).

     There are at least 2, possibly more, species in the A.-sp.-"Mitu"-complex.
All are found in the middle and upper Río Vaupés and the Río Inirida systems of Colombia

to the species / forms p.t. in the A.-sp.-"Mitu"-complex.


Apistogramma-macmasteri-Group

     The A.-macmasteri-group is closely related to the A.-regani-group. It replaces the A.-regani-group in the Orinoco Basin. It is characterized by medium to moderately large (2¾ – 3¼ in. / 7 – 8 cm TL), robust-bodied, sexually dimorphic species. Males have moderately to highly extended, serrated, dorsal fin lappets (1). Caudal fins are round to truncate with rare double tipped extensions. The lateral band typically forms a zigzag or ladder like pattern or is broken into a series of spots (2). Dorsal spots are usually visible along the insertion of the dorsal fin (3). Brooding females exhibit an intense golden yellow body with a checkerboard pattern of black dorsal and lateral spots. Most brooding females have a ventral stripe that extends somewhere between the chin to the vent, or at least a dark spot at the insertion of the ventral fins.
All species in the A.-macmasteri-group have the ancestral four infraorbital and five dental pores.
Presently there are ten scientifically described and many more undescribed species in the group. Many of the forms may be geographic color variants but they also include some that are distinct species. More distribution data and taxonomic/genetic studies are needed to clarify this question.

     The species of the A.-macmasteri-group are found, with one exception, exclusively within the drainage of the Río Orinoco. They are distributed from its headwaters in the foothills of Andes, in the Guiana Highlands in Colombia and Venezuela, and all the way to the delta of the Río Orinoco on the Caribean coast of Venezuela.
The species of the A.-macmasteri-group can be divided into two complexes, based on the design of the lateral band and other color markings. The A.-macmasteri-complex can be further divided into two subcomplexes based mostly on body shape and dark markings.



Apistogramma-hongsloi-Complex

     Males of the A.-hongsloi-complex can be recognized by a ladder/lattice-like lateral band  (1), a broad horizontal band, either red or black, on the ventral part of the flanks along the insertion of the anal fin (2), and usually a bright red patch that hides the caudal spot (3). The lateral band is typically very broad with lighter centers and dark edges on the scales. This forms the ladder-like pattern. This pattern is more pronounced in the areas between the vertical bars. Wild forms of the A.-hongsloi-complex all show a round caudal fin.

     At present there are two scientifically described and at least four undescribed species within the the A.-hongsloi-complex.
All known forms in the complex, except for one possible form, occur in the lower parts of Orinoco tributaries in Colombia and Venezuela. The lone one, occurs in the middle Río Vaupés, a Colombian tributary of the Rio Negro/Amazon system. They are found together with A.-macmasteri-complex species only in the Río Caura, Río Vichada and Río Guarrojo.

to the species / forms p.t. in the A.-hongsloi-complex.


Apistogramma-macmasteri-Complex

     In contrast to the A.-hongsloi-complex, species of the A.-macmasteri-complex develop a zigzag lateral band (1). With rare exceptions, brooding females show no ventral stripe. Males show an upper and lower red and/or black caudal fin borders (2). The tail can be round to squared-off/truncate, some with one or two short extensions.

     The A.-macmasteri-complex is found in tributaries of the Orinoco above areas that contain A.-hongsloi-complex forms. Exceptions are A. guttata from the delta of the Orinoco, and A. pedunculata from the Río Caura.
The A.-macmasteri-complex can be split into two subcomplexes based mostly on body shape and dark marking around the head.


Apistogramma-macmasteri-Subcomplex

     The A.-macmasteri-subcomplex is composed of species that tend to differ from species of the A.-hoignei-subcomplex by exhibiting a slightly more slender or elongate body shape (1), mostly due to having a slightly longer and narrower caudal peduncle. The caudal fin of males is round in younger specimens but it commonly develops a squared off or double-tipped posterior margin in more mature specimens (2). The top and bottom edges of the caudal fin are commonly bordered in red (3). In some wild forms and many domestic strains most of the caudal fin can be red or orange. The head shows fewer and paler dark spots compared to forms of the A.-hoignei-subcomplex (4). Brooding females commonly exhibit a chest blotch (5), but with few exceptions show no markings on throat and chin.

     At present there are two described species, possibly three if one includes A. guttata, and possibly 20 or more undescribed forms in the A.-macmasteri-subcomplex.
They are primarily distributed in the upper reaches of tributaries of the Río Orinoco in Colombia.

to the species / forms p.t. in the A.-macmasteri-subcomplex.


Apistogramma-hoignei-Subcomplex

     The A.-hoignei-subcomplex is composed of species that tend to differ from species of the A.-macmasteri-subcomplex by exhibiting a slightly deeper body shape, mostly due to appearing to have a slightly shorter and deeper caudal peduncle (1). Fin shape is similar to that of species of the A.-macmasteri-subcomplex, but they often show a black edge at the top and bottom of the caudal fin that is bordered interiorly by red (2). The head area shows more, larger and usually darker spots compared to forms of the A.-macmasteri-subcomplex  (3). The males commonly show metallic bluish/greenish lips  (4) and sometimes a metallic bluish/greenish area that covers the posterior edge of the caudal spot (5). Males also commonly exhibit a row of dark spots in the upper third of each hard dorsal spine lappet that is bordered above by light metallic tips (6). These color patterns are rarely seen in A.-macmasteri-subcomplex males. Brooding females usually show distinct black markings on throat and chin (7).

     Presently there are at least five described species, possibly six if one includes A. guttata, and at least four undescribed forms in the A.-hoignei-subcomplex. They are primarily distributed in the lower reaches of tributaries of the Río Orinoco, closer to its main channel, in Colombia and Venezuela.

to the species / forms p.t. in the A.-hoignei-subcomplex.


Apistogramma-pertensis-Lineage

     Based on the genetic studies of Miller & Schliewen (2005), the A.-pertensis-lineage is composed of the A.-steindachneri-group and its sister taxon, A. wapisana, plus the A.-pertensis-group and its sister taxa, the A.-iniridae-group. Unlike the A.-regani-lineage, species in the A.-pertensis-lineage show a pronounced lateral spot. A similar lateral spot is seen on most forms in “advanced” species-groups, but these species typically show a reduction of cephalic pores. Species in the A.-pertensis-lineage, however, – with the exception of A. wapisana and forms in the A.-iniridae-group – almost always show a complete series of cephalic pores like species in the A.-regani-lineage.


Apistogramma wapisana

     Apistogramma wapisana is an unusually tiny species (< 1½ in./3.5 cm) showing a mix of features exhibited by the A.-steindachneri- and A.-pertensis-groups. Like members of the A.-steindachneri-group, it shows a large flank patch (1) that extends above a narrow lateral band (2). The body shape is elongate and slightly fusiform, like that of members of the A.-pertensis-group, but the dorsal fin is very low (3). It shows a reduced number of infraorbital pores, but this is more likely due to its tiny size than being an advanced form.
It is notable for being one the few Apistogramma species having reversed sexual dimorphism, where the males are slightly smaller than the females. Also unusual is its breeding behavior in which, unlike in most Apistogramma species, the male A. wapisana initiates courtship.

     The distribution of Apistogramma wapisana occurs in the Rio Branco and middle Rio Negro. Its distribution, like its physical features, are intermediate between the primary loci of the A.-steindachneri-group (Guyana, Surinam, Rio Negro) and the A.-pertensis-group (middle to lower Amazon).




Apistogramma-steindachneri-Group

     The A.-steindachneri-group is comprised of medium to large species (< 3¾ in/9 cm) with moderately deep, laterally compressed, bodies that show minor sexual dimorphism. Males are casually polygamous. If there are several females and only one male, the male will spawn with each female. If, however, there are two fairly equal males and if there are at least two females and enough room for each male to hold a territory, each male will form part of a breeding pair. There usually won't be a dominant male servicing all of the females. Males are noticeably larger than their female counterpart. They can have moderately extended dorsal fin lappets that can be even to very slightly serrated (1). The males' caudal fins can be round, truncate, or double-tipped. Vertical bars and the lateral band are usually visible only on frightened or stressed individuals. During aggressive display, some of the posterior vertical bars appear as split narrow vertical bands. A large flank patch (2) situated on or immediately above the narrow, rarely visible, lateral band (3) is characteristic of A.-steindachneri-group species. This group is "ancestral", possessing four infraorbital and five dental pores.

     There are presently three scientifically described and at least two, possibly four undescribed species in the A.-steindachneri-group.
The A.-steindachneri-group shows a continuous distribution from Guyana and Suriname down the Rio Branco and south into the mouth of the Rio Negro. Species are also found in the Rio Tefé and Rio Madeira systems.

to the species / forms p.t. in the A.-steindachneri-group.


Apistogramma-pertensis-Group

     The Apistogramma-pertensis-group is comprised of a series of tiny to medium-sized (1½ - 3.5 in./4 – 7.5 cm), elongate, slightly fusiform, species that generally lack much pigmentation on the anterior dorsal fin rays (1). In males, most or all of the dorsal fin lappets commonly extend well above the fin rays and are fused together into a sail-like filament (2). The lateral band is narrow (3) and ends in front of a caudal spot. Male caudal fins are round, lyrate, spade or even three-lobed shaped and covered by rows of spots. Vertical bars are only visible on stressed fish. Other than the height of the dorsal fin on males there is little sexual dimorphism and for the most part the species are preferentially monogamous.

     There are six scientifically described and at least six undescribed species in the A.-pertensis-group, which is split into two complexes.
Distribution of the A.-pertensis-group includes tributaries of the Amazon between the Rio Tapajós (lower Amazon) and the Rio Tefé (middle Amazon/Solimðes), the entire Rio Negro drainage, and adjoining areas of the upper and middle Río Orinoco.



Apistogramma-pertensis-Complex

     Besides the characteristics found on all members of the A.-pertensis-group, males of the Apistogramma-pertensis-complex species all have round to modified oval-shaped tails. Apistogramma sp. "Erdfresser/Earth-eater" is atypical in that it has a lyrate or three-lobed tail and A. sp. "Schwanzzipfel/Tail-point" has a lyrate tale that eventually becomes spade shaped. A.-pertensis-complex species typically show no black pigmentation on the flanks except for the lateral band and lateral spot (1). The dorsal fin usually has the first 3 spines separated from a sail like fin (2). Most scientifically described species have the ancestral four infraorbital pores and five dental pores, although some species show only 3 infraorbital pores.

     This species-complex occurs in the Orinoco and Rio Negro drainage, with populations "flushed" into areas of the middle Amazon.

to the species / forms p.t. in the A.-pertensis-complex.


Apistogramma-velifera-Complex

     The species of the A.-velifera-complex show characteristics of both the A.-pertensis-group and its sibling, the A.-iniridae-group. The lateral band is fairly broad for a A.-pertensis-group species, more like that seen on A.-iniridae-group species (1). They, however, show the separate caudal spot of the A.-pertensis-group (2). The caudal fin on males is either a modified oval or lyrate, also like that seen on most species of the A.-iniridae-group. The dorsal fin of males can exhibit characteristics of either the A.-pertensis-complex or A.-iniridae-group. On A. velifera, for example, the dorsal fin lappets on males are all fused into a sail like filament - except for the first dorsal spine (3). On A. sp. "Putzer" all of the spines are fused together like that seen on A.-iniridae-group males.
Interestingly, the infraorbital pore count is variable on species of this complex. Some specimens will have a full set of four pores, while other specimens of the same species will show a reduction to three. Some specimens have even been found to have four pores on one side and three on the other!
The A.-velifera-complex appears to form a ‘bridge’ between the A.-pertensis- and A.-iniridae-groups.

     The A.-velifera-complex occurs from the upper Rio Negro, in Brazil to the middle Río Orinoco, in Colombia and Venezuela, including the Casiquiare Channel which connects the two river systems together.

to the species / forms p.t. in the A.-velifera-complex.


Apistogramma-iniridae-Group

     Other than the features characteristic to members of the A.-pertensis-group, the A.-iniridae-group species usually show two or more rows of spots below the lateral band (1). Some species also exhibit several dark diagonal bars below the lateral band on their posterior flanks  (2). The lateral band extends into the tail, with no caudal spot  (3). All of the dorsal fin lappets are fused together to form a sail-like dorsal fin (4). All have lyrate tails except A. iniridae (oval) and A. sp. "Içana" (lyrate or spade shaped). In A. iniridae only rare specimens develop extensions on some caudal fin rays. All species in the A.-iniridae-group normally possess three infraorbital pores - an advanced feature. Species of the A.-iniridae-group are notable among the A.-pertensis-lineage for showing this reduced number of infraorbitals. This is an advanced trait typically seen only on members of the A.-trifasciata- and A.-diplotaenia-lineages and some unusual species previously noted. The reduction of infraorbital pores might have occurred independently in the A.-iniridae-group or the A.-iniridae-group might be the ancestor of these two lineages.

     Presently there are four scientifically described and at least seven undescribed species in the group.
The species of the A.-iniridae-group are known to occur only in the upper Rio Negro of Brazil and closely associated tributaries of the upper Río Orinoco of Colombia and Venezuela. In this respect, they have a distribution pattern similar to that of the A.-velifera-complex.

to the species / forms p.t. in the A.-iniridae-group.



Apistogramma-trifasciata-Lineage

     Based on the preliminary genetic studies of Miller & Schliewen (2005), the members of Koslowski’s (2002) A.-trifasciata-lineage and A.-agassizii-lineage form a monophyletic unit separate from other lineages. In what follows, I will use the name A.-trifasciata-lineage for this unit. It contains much of what in the past I called advanced species-groups. The species-groups within the A.-trifasciata-lineage contain species that typically possess a reduced number of infraorbital pores (3 instead of the normal 4). Compared to species belonging to other lineages, most species within the A.-trifasciata-lineage show other advanced traits like more elongated, less laterally compressed bodies, males with ornate dorsal and caudal fins, and a behavioral display involving frontal rather than lateral threat display. It should be noted that not all of the species will show these traits. Some show retrograde ancestral traits, too.
The A.-trifasciata-lineage is composed of nine species-groups. Seven of the species-groups have species with a complete set of dental pores. These form the A.-trifasciata-sublineage. The other two species-groups belong to the A.-agassizii-sublineage in which the species exhibit a reduced number of dental pores (4 instead of the normal 5). The A. trifasciata-lineage appears to be distributed, for the most part, around the periphery of the Amazon Basin, along the main channel of the Amazon (probably a more recent event), and in the Río Paraguay system. It appears that a species similar to A. arua is the source from which all members/species of the A.-trifasciata-lineage originated.



Apistogramma-trifasciata-Sublineage

     As mentioned above, the A.-trifasciata-lineage can be subdivided into two sublineages based on one distinctive characteristic: the number of dental pores typically exhibited by the species. While the A.-trifasciata-sublineage species typically exhibit only 3 infraorbital pores, they also possess five dental pores, typical of that of other lineages. The A.-agassizii-sublineage species typically show not only reduced infraorbital pores, but also a reduction of dental pores from five to four.
While checking the pores on preserved fish is easily done, it is more difficult on live specimens. However, the following other features can usually be used to separate species of the two sublineages. Species of the A.-trifasciata-sublineage are usually, but not always, visually more robust, deeper-bodied, and laterally compressed fish (1). In this respect they have a body shape more typical of the A.-steindachneri-group. Males of most, but not all, A.-trifasciata-sublineage species possess moderately high, serrated dorsal fins (2), while most, but not all, A.-agassizii-sublineage species show a low and even dorsal fin profile, or at most extended spines on the anterior-most part. Although neither feature is entirely diagnostic for the A.-trifasciata- or A.-agassizii-sublineage, they will indicate the most likely sublineage to which a species might belong.

     The A.-trifasciata-sublineage has seven species-groups that include two species-complexes, plus several unassigned species that are considered relic ancestors of the A.-trifasciata-lineage. Species of the A.-trifasciata-sublineage are found throughout the range of the A.-trifasciata-lineage.



Apistogramma arua and other relic ancestral A.-trifasciata-lineage species

     Apistogramma arua, A. salpinction, A. cf. salpinction (Itapeaçu) and A. sp. "Doppelfleck" are medium to moderately large
2½ - 31/8 in./6.5 – 8cm species. Only A. arua has been studied to any extent. The other three, however, show some features that indicate they might be related. They do not appear to belong to a distinct species-group. Instead, they show features found in several A.-trifasciata-lineage species-groups. Apistogramma arua, for example, exhibits a net-like pattern on the flanks (1) similar to that of the A.-brevis-group and a pattern of black markings roughly similar to that of the species found in the A.-trifasciata-group.  (2). The dark markings of A. salpinction resemble more those of the A.-cacatuoides-group. The body shape and finnage of all three species are similar to that of the A.-cacatuoides-group (3). It is possible that these three species represent relic species of the ancestral A.-trifasciata-lineage species.

     All four of the species occur in the Amazon Basin between the Rio Madeira and Rio Tapajós system, a location that is on the far eastern periphery of the range of the trifasciata-lineage.

to the Ancestral Apistogramma-trifasciata-Lineage species.


Apistogramma-brevis-Group

     Species of the A.-brevis-group are composed of tiny to moderately large (1½ - 3 in./3.5 – 7.5 cm) species. They are characterized by having moderately deep, slightly laterally compressed bodies. Except for two species, males of Apistogramma-brevis-group species have highly serrated dorsal fins (1). The caudal fin is crossed by rows of fine spots at least in the central part (2). The ventral fins are unusually short and blunt for males (3). On the flanks, the posterior edge of the scales are dark and form a net-like pattern (4).

     The A.-brevis-group presently includes four scientifically described plus five undescribed species. It is endemic to the upper Rio Negro of Brazil and Colombia and upper Río Orinoco of Colombia and Venezuela.

to the species / forms p.t. in the A.-brevis-group.


Apistogramma-sp.-"D10"-Group

     The Apistogramma-sp.-"D10"-group is composed of species that are hard to define as a species-group because they show few unique distinguishing features. They do show some plesiomorphs (features shared from a common ancestor) in which they differ from other groups. As such, the group is comprised of medium to large (2¾ - 3½ in./6.5 – 10 cm TL) species characterized by having moderately elongate, relatively deep and laterally compressed (twice as high as wide) bodies, especially in larger males. Depending on the species, males exhibit dorsal fins that vary from moderately low and even to high and highly serrated. Males, and even females of some species, develop long tips on the dorsal, anal and ventral fins (1). The caudal fin is quite variable in form and markings. It can be round to double-tipped and show either no markings or be crossed by rows of spots. The broad and always zigzag bordered lateral band (2). can be either separate from the caudal spot or attached to it only narrowly. The caudal spot is generally rounded and about the same height as the lateral band, but can expand vertically in aggressive or stressed individuals. Species show a well-developed lateral spot the same height as the lateral band (3). A series of vertical abdominal streaks, that vary in intensity depending on mood, occur below the lateral band (4). The head is proportionally slightly larger than that of typical Apistogramma (5). This is most likely a result of being mouthbrooding species.
At first glance, species of the A.-sp.-"D10"-group resemble species of the A.-macmasteri-group of the A.-regani-lineage. This is most likely due to evolutionary convergence since they live in similar biotopes. They differ, however, by having a conspicuous lateral spot and normally only 3 infraorbital pores. These features are characteristics of species belonging to the A.-trifasciata-lineage. They actually appear to be most closely related to species of the A.-brevis-group. The A.-sp.-"D10"-group differs from species of the A.-brevis-group by having extended ventral fin tips, which are short and blunt on the males of the A.-brevis-group, and lack the net-like pattern seen on the flanks of A.-brevis-group species.
Behaviorally, the A.-sp.-"D10"-group also differs from the display behavior of A.-brevis-group species. The A.-brevis-group species, in frontal display, drop the lower jaw and open the mouth wide. Species of the A.-sp.-"D10"-group, in frontal display, keep the mouth closed or only slightly open. One species even lays on its side in frontal display. In some species the males will court the female in a vertical, tail-standing position. At least two of the species in the A.-sp.-"D10"-group are delayed, larvophylic mouthbrooders. Eggs are hung in a cave in typical Apistogramma fashion. Once the eggs hatch the female places the larvae in her mouth where she holds them, except when she is feeding, until the fry become freeswimming. In this respect the breeding behavior resembles that of species in the A.-barlowi-complex.

     The A.-sp.-"D10"-group presently includes three undescribed species.
The group is known only from the upper Rio Vaupés and middle Río Caquetá of Colombia.

to the species / forms p.t. in the A.-sp.-"D10"-group.


Apistogramma-cacatuoides-group

     The members of the A.-cacatuoides-group are medium to large (2½ - 3½ in/6.5 – 8 cm) species. Males are characterized by their robust but slightly elongate and laterally compressed bodies, enlarged lips (1), extended anterior dorsal fin lappets (except A. staecki)  (2), and usually lyrate caudal fins (3). All species in the group show a moderately wide lateral band that either extends into the base of the caudal fin or ends in front of a distinct caudal spot. On species without a caudal spot, the lateral band often narrows noticeably in the posterior caudal peduncle and then widens again at the base of the caudal fin. This narrow part of the lateral band often fades away and forms a ‘pseudo caudal spot’ (4). Like all groups in the A.-trifasciata-lineage, all species of the A.-cacatuoides-group exhibit a reduced number of infraorbital pores. The males tend to be highly polygamous.

     Presently the A.-cacatuoides-group has six, probably more, scientifically described species and at least eight, probably more, undescribed species. Apistogramma cacatuoides very likely is a superspecies. Many of the different populations of A. cacatuoides most likely will be found to be separate species after further genetic testing.
The A.-cacatuoides-group is distributed along the outer fringes of the southern and western Amazon Basin in Bolivia, Peru, Colombia and extreme western Brazil. It appears that it migrated from the Peruvian Amazon comparatively recently down the main channel of the Amazon as far east as Santarém, Brazil.

to the species / forms p.t. in the A.-cacatuoides-group.


Apistogramma-nijsseni-Group

     Species of the A.-nijsseni-group are characterized as moderately large (3 in./7.5 cm) species with robust, moderately deep and laterally compressed bodies. The head is relatively large with strongly developed jaws and thick lips (1) . The species have dark brachiostegial membranes (2) that, when spread wide in frontal display, give the head an even larger appearance. On males, the shape of the dorsal fin ranges from low and even to high and deeply serrated. The tips of the soft parts of both the dorsal and anal fins are short and relatively blunt (3). Most females develop a brood dress with large dark patches on the gill covers, flanks or abdomen, and caudal peduncle (4). Males can show this pattern, too, but it is often hidden under a blue body sheen. The lateral band almost never is visible except in juvenile species. The caudal fin is typically round on both sexes, but some species have broadly double-tipped caudals on one or both sexes. Both sexes of many species develop a red/orange band around the outer margin of the caudal fin (5), except for species with lyrate tails. These usually show the red/orange color only on the upper and lower margins of the tail.

     The distribution of the A.-nijsseni-group occurs in isolated blackwater tributaries of the Río Marañon, Río Ucayali, Río Nanay, Río Napo, and Río Caquetá of Peru, Ecuador and Colombia, which drain to ancient Napo Superfan. Presently, there are nine scientifically described species and three undescribed species within the group.

to the species / forms p.t. in the A.-nijsseni-group.


Apistogramma-norberti-group

     The species of the A.-norberti-group are moderately large (3 in/7.5 cm TL) robust species that show a mix of characteristics found in the A.-nijsseni-, A.-cacatuoides- and A.-atahualpa-groups. They exhibit a body form similar, but deeper/higher backed, than that of species in the A.-cacatuoides-group. The finnage is similar to that of species found in the A.-atahualpa-group, and frontal display is similar to that seen in the A.-nijsseni-group. The head is deeper than that seen on species of the A.-cacatuoides-group  (1), and more similar to that seen on some species of the A.-atahualpa-group. To a greater degree than those of the A.-atahualpa-group and more like the A.-cacatuoides-group, A.-norberti-group species show enlarged, usually orange to red lips, on males  (2). The dorsal fin of males exhibits extensions more like those seen in the A.-atahualpa-group. The anterior part has moderately high lappets and the remainder is lower and slightly serrated (3). Most but not all specimens of both sexes display a large dark patch on the soft part of the dorsal fin (4). Very few other species exhibit such a patch. The ventral fins develop tips that are similar to those seen on the A.-atahualpa-group, but shorter than those typical of the A.-cacatuoides-group. The caudal fin, which is crossed by vertical rows of spots, can be round or double-tipped like those seen on species of the A.-atahualpa-group. The lateral band is broader than that seen on the A.-cacatuoides- and A.-atahualpa-group (5). The lateral spot at times appear as a light spot on the dark lateral band, similar to that seen on some species in the closely related A.-cacatuoides-, A.-atahualpa- and A.-nijsseni- groups. In certain moods the lateral spot expands above the lateral band a short distance, forming a small flank patch (6). There are 3 rows of wavy abdominal stripes (7) below the lateral band, similar to those seen on species of the A.-cacatuoides-group. In aggressive frontal display, males of the A.-norberti-group expand the brachiostegial membrane, like species of the A.-nijsseni-group (8).

     Presently, there are only two recognized species in the A.-norberti-group – one scientifically described and one undescribed. They display a disjunct pattern of distribution. Apistogramma norberti occurs in the lower Río Ucayali drainage (Río Tahuayo and Río Tamshiyacu), while the undescribed A. cf. norberti (Lyretail) is found in streams entering the Amazon near Leticia, Colombia.

to the species / forms p.t. in the A.-norberti-group.


Apistogramma-atahualpa-Group

     The species of the A.-atahualpa-group are large (> 3½ in./8 cm), robust species. They probably arose from a A.-cacatuoides-group species. The shape of the body, dark markings, and finnage are very similar to those of species in the A.-cacatuoides-group. The head (1) is noticeably deeper than that seen on A.-cacatuoides-group species. The lips are not as enlarged (2). The ventral fins of A.-atahualpa-group males develop extended tips that are shorter than those of the A.-cacatuoides- and A.-nijsseni-group  (3).
I propose two species-complexes in the A.-atahualpa-group, separated mostly on the length of the head. The enlarged head size in the A.-barlowi-complex is probably a recent adaptation toward primitive mouthbrooding.

     At present the A.-atahualpa-group includes four scientifically described species and at least one that is undescribed.
All of the species in the group are known to occur in tributaries of the western Amazon of Peru, Colombia and western Brazil that drain the ancient Napo Superfan region.All of the species in the group are known to occur in tributaries of the Peruvian and the nearby Colombian Amazon that drain the ancient Napo Superfan region.



Apistogramma-atahualpa-Complex

     The body of A.-atahualpa-complex species are large (3½ in./8 cm), moderately elongated and slightly laterally compressed. The dorsal fin develops highly extended anterior dorsal fin lappets  (1). Soft parts of the dorsal and anal fins of males have pointed tips but are not greatly extended (2). The caudal fin is either round or double-tipped, either clear or patterned with rows of fine spots. The species show a caudal spot that at times is joined to the lateral band by a thin dark stripe (3).

     There are presently two described species in the A.-atahualpa-complex. Four other forms are known, but two of these are probably geographic populations of the two described species.
All members of the A.-atahualpa-complex are found in blackwater tributaries of the Río Nanay between Iquitos and Nauta, Peru, the Río Tapiche on the opposite side of the Amazon, and the Río Galvez.

to the species / forms p.t. in the A.-atahualpa-complex.


Apistogramma-barlowi-Complex

     The species of the A.-barlowi-complex are very similar to those of the A.-atahualpa-complex in body size, shape and finnage. Their large body (> 3½ in./8 cm) is moderately elongated but less laterally compressed than that of species in the A.-brevis-group. Males have extended anterior dorsal fin lappets (1) and a double tipped caudal fin, part of which shows spot-rows (2). One unique feature seen on A.-barlowi-complex species is the unusually large head  (3). The head is approximately one-third of the body’s standard length. This latter feature is probably a modification toward mouthbrooding. Species in the A.-barlowi-complex show a tendency at times to be delayed larvophylic mouthbrooders. At other times they breed in a typical Apistogramma fashion. Environmental factors (substrate, spawning sites, fry predators, etc.) seem to influence which breeding mode is used.

     Presently the A.-barlowi-complex is composed of two scientifically described species and four still undescribed species.
Its distribution is found in northern tributaries of the Amazon between the mouth of the Río Napo in Peru and the Rio Jutai(?) in western Brazil.

to the species / forms p.t. in the A.-barlowi-complex.


Apistogramma-trifasciata-Group

     The A.-trifasciata-group species in many respects look much like miniature versions of A.-cacatuoides-complex species. Members of the A.-trifasciata-group are characterized by the combination of having a small (<2½ in/6.5 cm), moderately elongate and compressed body, extended anterior dorsal fin lappets (1), long ventral fins  (2) on males, and a round caudal fin (3). The lateral band is broad in the caudal peduncle, but narrows toward the head (4). Males are highly territorial and polygamous.

     I personally believe that the A.-trifasciata-group is an offshoot of the A.-cacatuoides-group. It has similarities to A. staecki, a member of the A.-cacatuoides-group. Behaviorally, A.-trifasciata-group species are much more like A.-cacatuoides-group species in that they are very territorial and highly polygamous. Their extended, separate, anterior dorsal fin lappets are common to it and species of the A.-cacatuoides-group. Geographically, the A.-trifasciata-group originates in areas that overlap those of the A.-cacatuoides-group.

     The A.-trifasciata-group has two scientifically described species. It is possible that A. trifasciata represents a superspecies, composed of several separate but similar looking species.
The A.-trifasciata-group is distributed in the Rio Paraguay/Paraná drainages of Brazil, Paraguay, and Argentina and tributaries of the Rio Mamoré/Guaporé system of Bolivia and Brazil.

to the species / forms p.t. in the A.-trifasciata-group.


Apistogramma-agassizii-Sublineage

     The A.-agassizii-sublineage is part of the A.-trifasciata-lineage. Like species of the A.-trifasciata-lineage, the species of the A.-agassizii-sublineage typically show advanced traits like infraorbital pores reduced to three, elongated, less laterally compressed bodies, males with ornate dorsal and caudal fins, a distinct lateral spot, and a behavioral display involving frontal rather than lateral threat display. In addition to these traits, they all show the number of dental pores reduced from five to four. The males also show the "A. agassizii lip spot". This spot is a metallic blue patch situated on the lower part of the upper lip near the corner of the mouth.

     The A.-agassizii-sublineage has three species-groups. The species of the sublineage probably originated in the middle Amazon region of Brazil. The seemingly more primitive species are now found in the upper reaches of Rio Negro and Rio Madeira. From there they migrated west into the Peruvian Amazon and east into the lower Amazon and Rio Tocantins.



Apistogramma-gibbiceps-Group

     The species of the A.-gibbiceps-group are medium size fish (<3 in/7.5 cm) characterized by their elongate, almost fusiform, body shape. The dorsal fin on males can be low and even to slightly serrated, with moderate to high extensions on two of the three anteriormost dorsal spines (1). With the exception of A. elizabethae, the body shows narrow or broad, slightly diagonal, abdominal bars/stripes that extend across most of the lower flanks below a prominent lateral band  (2). Males possess a lyrate caudal fin with (with the exception of A. sp. "Maravilha") a pattern of longitudinal stripes  (3). On some species, the middle rays of the lyretail lengthen to produce a spade/lance-shaped fin. Like all species in the sublineage, species within this species-group all have only three infraorbital pores and four dental pores. The "A. agassizii lip spot" is usually very small and indistinct.

     There are three scientifically described, and one undescribed species in the A.-gibbiceps-group.
With the discovery of A. sp. "Maravilha", a species that shows features intermediate between A. elizabethae and A. gibbiceps, Apistogramma elizabethae is now included in the A.-gibbiceps-group. Previously A. elizabethae was an outlier and many authors consider A. elizabethae the most primitive form of the A.-agassizii-sublineage. There is another possible form similar to A. elizabethae that was pictured in a Japanese aquarium magazine several decades ago. It conforms to A. elizabethae in all respects except that the dorsal fin shows no extended spines. Instead, the dorsal fin is low and even, similar to that of A. agassizii. Since similar specimens have not been found, it is possible that the fish was a specimen of A. elizabethae with a damaged dorsal fin.

     All species in the A.-gibbiceps-group are found in tributaries of the Rio Negro in Brazil and Colombia, as well as tributaries of the Rio Branco in Brazil and Guyana.

to the species / forms p.t. in the A.-gibbiceps-group.


Apistogramma-bitaeniata-Group

     Species of the A.-bitaeniata-group include medium (2¾ in./7 cm) to moderately large (3½ in./8.5 cm) species with an elongate, moderately fusiform body. Males of most species show double-tipped to lyrate caudal fins. The dorsal fin shows even, serrated or elongated anterior lappets. The ventral fin tips are long (1), and the flanks show one to three broad abdominal bands (2) below a broad lateral band.
The A.-bitaeniata-group is split into two species-complexes based on shape of the dorsal fin, number of abdominal stripes, and species distribution.

     The A.-bitaeniata-group is restricted to black water drainages, mostly near the main channel of the upper and middle Amazon in Peru, Colombia, and Brazil as well as throughout the Rio Negro drainage of Brazil.



Apistogramma-bitaeniata-Complex

     The A.-bitaeniata-complex is characterized by having traits similar to those of the A.-paucisquamis-complex. Where almost all species of the A.-paucisquamis-complex show two or more prominent abdominal stripes below the lateral band, species of the A.-bitaeniata-complex typically exhibit one prominent abdominal stripe immediately below the lateral band plus one or two fainter stripes or two or more horizontal rows of spots (1). The dorsal fin on males typically shows highly extended anterior spines (2). Most species also show a double tipped caudal fin (3). The exception to this is A. sp. "Caño de la Libertad", which shows a moderately high serrated dorsal and round caudal, with a very faint second abdominal stripe. It appears to be a form intermediate between the two species complexes.

     There are two scientifically described species. Apistogramma bitaeniata, however, could be considered a superspecies composed of many forms that appear similar but are actually separate species. Presently there are up to seven undescribed species in the complex, not including the various forms of A. bitaeniata.
The species of the A.-bitaeniata-complex are found in black water drainages, mostly near the main channel of the Amazon, from tributaries of the Río Marañon in Peru, the Río Caquetá/Japurá of Colombia/Brazil, and as far east as the Rio Tapajós in Brazil.

to the species / forms p.t. in the A.-bitaeniata-complex.


Apistogramma-paucisquamis-Complex

     The A.-paucisquamis-complex is characterized by the traits common to the A.-bitaeniata-group, except that all show two or three abdominal bands, never only one (1), a dorsal fin on males that is low and even to slightly serrated (2), and typically a lyrate
caudal fin (3).

     There are two scientifically described and three undescribed species presently in the complex.
The species of the A.-paucisquamis-complex are found only in tributaries of the Rio Negro in Brazil.

to the species / forms p.t. in the A.-paucisquamis-complex.


Apistogramma-agassizii-Group

     The A.-agassizii-group is comprised of a number of moderately large (<4 in./10 cm), moderately elongate species with a broad lateral band (1), a prominent lateral spot  (2), and dark head stripes (3). The caudal fin of males is either round or spade/lance shaped. The dorsal fin is low and even  (4). They are polygamous species. Like all other species-group in the A.-agassizii-sublineage, the member species have only three infraorbital and four dental pores.

     The A.-agassizii-group presently has three scientifically described and possibly more than a dozen undescribed species split into two complexes.
The A.-agassizii-group is distributed throughout most of the Amazon basin. Most occur close to the main channel of the Amazon. Other more distant ranges include much of the Rio Madeira/Purus and Rio Negro systems, as well as the lower Rio Tocantins and some Atlantic coastal streams immediately south of the mouth of the Amazon Delta.



Apistogramma-pulchra-Complex

     All species of the A.-pulchra-complex possess a round caudal fin (1) and low even dorsal fin on both sexes. The caudal pattern on males is typically formed from concentric rows of spots  (2). The outer margin of the caudal fin might show some color, but not the multiple submarginal bands seen on members of the A.-agassizii-complex. The flanks of the body are crossed by a broad lateral band and scales on the body typically show dark edges that present a net-like appearance.

     The A.-pulchra-complex is found in mostly blackwater biotopes of the Rio Branco (Rio Negro system), Rio Uatumã, and Rio Madeira systems of Brazil. Where species of the A.-pulchra- and A.-agassizii-complexes are found close together, the A.-pulchra-complex species seem to occur in the less hospitable locations. It is possible that A.-agassizii-complex species outcompeted A.-pulchra-complex species for the more desirable biotopes.

to the species / forms p.t. in the A.-pulchra-complex.


Apistogramma-agassizii-Complex

     Species in the A.-agassizii-complex possess a spade-shape caudal fin (1) and low, even, dorsal fin. Some populations show a very faint abdominal band below the lateral band, especially on females. This abdominal band, however, is never as distinct as those on members of the A.-bitaeniata-group.
The caudal fins of males display two or more colored submarginal bands  (2). The interior of the caudal fin can show irregular markings, but almost never show even rows of spots typically visible on most species of the A.-pulchra-complex.

     Presently, the A.-agassizii-complex includes only one scientifically described species.
Apistogramma agassizii however represents a superspecies with dozens of similar-looking forms that are separate species. Estivals et al. (2020) have already recognized three distinct species previously considered to be A. agassizii (sensu lato), based on genetic data. These species are, at present, still scientifically undescribed.
Besides the multiple forms commonly recognized as A. agassizii, there are presently at least one - and up to five - scientifically undescribed species within the agassizii-complex that are divided into three subcomplexes.

The agassizii-complex has a very wide distribution. It is found in the Rio Negro, Rio Madeira/Purus of Brazil, the Río Amazonas of Peru and Colombia, and the Brazilian Solimðes/Amazon/Rio Tocantins as far east as Belem, plus coastal streams along the Atlantic near the Amazon Delta.

to the species / forms p.t. in the A.-agassizii-complex.


Apistogramma-agassizii-Subcomplex

     Species of the agassizii-subcomplex are distinguished from species of the Broad-Black-Caudal-Seam-subcomplex by the pattern on the caudal fin and from the Netz-subcomplex by the pattern seen on the flanks. Apistogramma-agassizii-subcomplex males typically have a spade/lance-shaped caudal pattern of a narrow dark caudal margin, broader light-colored submarginal band and an interior dark band that is typically wider than that of the dark outer band  (1). This pattern is also seen on males of the Netz-subcomplex.
The agassizii-subcomplex differs visibly from that of the Netz-subcomplex by not exhibiting the net-like pattern seen on the flanks of Netz-subcomplex males. At most, agassizii-subcomplex males will show dark margins only on parts of the edges of the scales of the
flanks  (2).

     Presently there is only one scientifically described species (A. agassizii) in the agassizii-subcomplex. However, there are three additional but scientifically unnamed species recognized by their genetic variance. Besides these four species, there are at least 10 other forms/populations within the agassizii-subcomplex that are most likely separate species.

The A.-agassizii-subcomplex species occur exclusively in the upper Amazon of Peru, Colombia, and Brazil. Forms are found from the lower Río Ucayali and Río Marañon in Peru down to the Colombian Amazon and then downstream in the Rio Solimões in Brazil to the Rio Negro.

to the species / forms p.t. in the A.-agassizii-subcomplex.


Apistogramma-agassizii-Broad-Black-Caudal-Seam-Subcomplex

     Species of the A.-agassizii-Broad-Black-Caudal-Seam (BBCS) - subcomplex exhibits minor, but visible differences to those of the species of the other two subcomplexes. When compared to forms in the agassizii- and Netz-subcomplexes, males of the BBCS-subcomplex appear to have a slightly more slender/elongate (1) body shape.
Except for older, more well-developed, males, the dorsal and anal fin tips are not as long as on species of the other two subcomplexes. Males typically also have a more blunt spade/lance-shaped caudal fin.  (2).
The scale pattern on flanks of males is similar to that of males of the agassizii-subcomplex. The feature that distinguishes males of the BBCS-subcomplex is the pattern of bands in the caudal fin. The pattern is composed of a broad dark caudal margin, broad light-colored submarginal band and an interior dark band that is noticeably narrower than that of the dark outer band  (3).

     At present there are no scientifically described species in the BCCS-subcomplex. There are at least 8 forms and several color variants that are members of the subcomplex. Whether or not these color variants are distinct forms or populations of other forms requires further study.

The BBCS-subcomplex are known only from right bank (southern) tributaries of the lower Amazon, east of the Rio Purus to the mouth of the Amazon and rivers entering the Atlantic Ocean near Belém, Brazil.

to the species / forms p.t. in the A.-agassizii-Broad-Black-Caudal-Seam-Subcomplex.


Apistogramma-agassizii-Netz / Net-Subcomplex

      The forms of the A.-agassizii-Netz-subcomplex closely resemble those of the A.-agassizii-subcomplex with only minor differences. In body shape they are more robust than those of the BBCS-subcomplex and also often appear heavier than forms in the A.-agassizii-subcomplex (1).
Mature males develop long tips on the dorsal, anal and caudal fins (2).
The most diagnostic feature of the Netz-subcomplex, however, is the net-like pattern on the flanks of males. This pattern is formed by dark edges that border the anterior edge of each scale, which join the dark edges of scales above and below (3).

     Like species in the BCCS-subcomplex, at present there are no scientifically described species in the Netz-subcomplex. There are at least 7 undescribed forms that are recognized.

The Netz-subcomplex forms all occur in left bank (northern) tributaries of the Amazon from the Rio Negro almost to the mouth of the Amazon.

to the species / forms p.t. in the A.-agassizii-Netz / Net-Subcomplex.


Apistogramma-diplotaenia-Lineage

     In spite of the fact that species of the A.-diplotaenia-lineage have many characteristics in common with members of the A.-agassizii-group, genetic studies of Miller and Schliewen (2005) indicate that the A.-diplotaenia-group is not closely related to other species-groups and possibly represents a separate lineage within the genus.
The species all have infraorbital pores reduced to three and dental pores reduced to four.

     Species of the A.-diplotaenia-lineage are found only in tributaries of the middle and upper Rio Negro and the upper Río Orinoco of Brazil, Colombia, and Venezuela.



Apistogramma-diplotaenia-Group

     The species of the A.-diplotaenia-group are moderately small (<2¼ in./6 cm) fish with elongate, nearly fusiform bodies. The dorsal fin on males is low and even to very slightly serrated (1). The caudal fin is round to slightly spade/lance shape (2). The unique diagnostic feature of these species is the "double lateral band" (3). The lateral band is extremely broad over most of the length of the body. A pale row of scales develops along the central section of this lateral band. This makes the band appear as a double band.

     Presently there are two scientifically described species in the species-group.
The species of the A.-diplotaenia-group are found only in tributaries of the middle and upper Rio Negro and the upper Río Orinoco.

to the species / forms p.t. in the A.-diplotaenia-group.


Taeniacara

     The genus Taeniacara also shows many physical similarities to species of the A.-agassizii-sublineage. These include an even more elongated body with a broad lateral band  (1) and lance/spade-shape caudal fin (2) on males. In many ways it looks much like A. elizabethae with a low dorsal fin (3).It shows a significant reduction in cephalic pores compared with species of Apistogramma.
Genetic studies by Miller and Schliewen (2005) indicate that Taeniacara is not closely related to any Apistogramma species-group. It appears that it arose from a common ancestor with Apistogramma.

     Presently the genus is considered to be monotypic, the only species being Taeniacara candidi. Considering the highly disjunct distribution of this species, in the Rio Negro and southern side of the Amazon, it is likely that the species will eventually be recognized as being two or more separate species.
Taeniacara is distributed in the middle Amazon drainage between Manaus and Santarém and in the lower and middle Rio Negro of Brazil.



Conclusion

     There are now close to 500 recognized species and forms of Apistogramma. With so many different species it is virtually impossible to easily identify different species. I find that I can reduce the number of possible species I need to consider significantly by first determining to which of the species-groups it belongs. I consider these species-groups more as descriptive aids than representing true phylogenetic clades. Still it is likely that these species-groups are monophyletic for the most part. Please do not consider these descriptions as absolute truth. I am sure that changes will be needed as more data becomes available – as is apparent from earlier editions of this article. I am always interested in the opinions of other Apistogramma enthusiasts. Only through continued discussion can we more accurately understand the many species of Apistogramma and their place within the genus.


Acknowlegement

     An article of this size and breadth cannot be accomplished without the help of more people than I can acknowlege individually. Still, I want to thank all of the ichthyologists and hobbyists whose information on species and collecting locations was needed for this article. I especially wish to thank Tom Christoffersen and Frank Hättich for their help critiquing and proofreading the article. Without their help this article would not be as complete as it is. Thank you Tom and Frank.


References Cited

da Costa, Gideão Wagner Werneck Félix, Marcelo de Bello Cio, Thomas Liehr, Eliana Feldberg, Luiz Antonio Carlos Bertollo and Wagner Franco Molina. 2019. Extensive Chromosomal Reorganization in Apistogramma Fishes (Cichlidae, Cichlinae) Fits the Complex Evolutionary Diversification of the Genus. Internat. J. Molecular Sciences 20: 4077.

Estivals, Guillain, Fabrice Duponchelle, Uwe Römer, Carmen Garcís-Dávia, Etienne Airola, Margot Deléglise and Jean?François Renno. 2020. The Amazonian dwarf cichlid Apistogramma agassizii (Steindachner, 1875) is a geographic mosaic of potentially tens of species: Conservation implications. Aquatic Conservation: Marine and Freshwater Systems. John Wiley & Sons Ltd.

Goldstein, R. J. 1970. Cichlid Notes. T.F.H. Mag. 18(12): 78-81.

Koslowski, Ingo. 1985. Die Buntbarsche der Neuen Weld — Zwergcichliden. Essen. Reimer Hobbing GmbH. 192 pp.

Koslowski, Ingo. 2002. Die Buntbarsche Amerikas. Band 2: Apistogramma & Co. Verlag Eugen Ulmer GmbH & Co. Stuttgart. 318p.

Kullander, S. O. 1980. A taxonomical study of the genus Apistogramma Regan, with a revision of Brazilian and Peruvian species (Teleostei: Percoidei: Cichlidae). 152 pp. Bonn. Zool. Monogr. 14.

Meinken, Hermann. 1962. Ein neue Apistogramma-Art aus dem mittleren Amazonas-Gebiet, zugleich mit dem Versuch einer Übersicht über die Gattung (Pisces, Percoidea, Cichlidae). Senk. biol. 43(2): 137-143.

Miller, Michael & Ulrich Schliewen. 2005. The molecular phylogeny of the genus Apistogramma – a working hypothesis. In Stawikowski, Rainer (ed). Südamerikanische Zwergcichliden/South American Dwarf Cichlid. DATZ Sonderheft/Special Pub. Eugen Ulmer KG, Stuttgart. p 22-25.

Ready, J. S., I. Sampaio, H. Schneider, C. Vinson, T. Dos Santos, & G. F. Turner. 2006. Colour forms of Amazonian cichlid fish represent reproductively isolated species. J. Evol. Biol. 19(4): 1139-1148.

Römer, Uwe. 2006a. Cichlid Atlas. Volume 2: Natural History of South American Dwarf Cichlids Part 2. Mergus Verlag GmbH. Melle. 1319p.

Römer, Uwe. 2006b. Cichliden Atlas. Band 2: Naturgeschichte der Zwergbuntbarsche Südamerikas Teil 2. Mergus Verlag GmbH. Melle. 1319p.

Schmettkamp, Werner. 1982. Die Zwergcichliden Südamerikas. Landbuch-Verlag GmbH, Hannover. 176 p.

Tougard, Christelle, Carmen R. García Dávila, Uwe Römer, Fabrice Duponchelle, Frédérique Cerqueira, Emmanuel Paradis, Bruno Guinand, Carlos Angulo Chávez, Vanessa Salas, Sophie Quérouil, Susana Sirvas, Jean-François Renno. 2017. Tempo and rates of diversification in the South American cichlid genus Apistogramma (Teleostei: Perciformes: Cichlidae). PLoS ONE 12(9): e0182618. Published online 2017 Sep 5.

Wise, Mike. 1990. Description, Distribution, and a proposed phylogeny of Apistogramma species-groups. The Apisto-gram 9(1) (#33): 4-10.

Wise, Mike. 2002. Description, Distribution, and a proposed phylogeny of Apistogramma species-groups revisited. Apistogramma Study Group web site: http://www.apisto.com/phylo/phylobody.html (Site now closed)

Mike Wise, October, 2021.