In 1990 I gave a talk on the "Description, Distribution and a Proposed Phylogeny of Apistogramma Species-Groups" at the 15^th annual weekend workshop of the Northeast Council of Aquarium Societies. Later, I published an expanded paper by the same title in the Colorado Aquarist (Wise, 1990). It proved very popular and has been reprinted in many aquarium society journals. Since then much has changed. A lot of new information on species of Apistogramma has become available, both scientific and hobby oriented. More species have been scientifically described and even more new undescribed species are being found by hobbyist/collectors. Collecting data for both described and undescribed species have been greatly expanded. All of this new information has made it possible to get a better understanding of what makes a species-group, how it is distributed, and how the many different species of Apistogramma arose from one another.

At this time there are 52 scientifically described species of Apistogramma. At least 90 additional undescribed species have been reported in hobby oriented literature. Some of these undescribed species, however, are geographic variants of other known species. Nevertheless I feel confident in saying that at least 100 different species of Apistogramma are distributed throughout most of the tropical drainages of South America east of the Andes.

With so many presently known species, and the potential for the number to expand dramatically, it's obvious why the genus Apistogramma has been broken down into various species-groups. Meinken (1962) 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 7 species-groups and several species that were then not assignable to species-groups. Schmettkamp (1982) was the first to recognize that each species-group had a regional distribution. He proposed 9 species-groups plus extra, unassignable, species. Koslowski (1985b) originally published the list of species-groups most apistophiles use today. He also subdivided some species-groups calling these divisions "complexes".

All of these authors use the term "complex" to refer to a series of species derived from a single ancestral species (monophyletic). Kullander and Koslowski, however, both recognize the possibility that some of their groups may not be monophyletic but appear closely related only because of convergent evolutionary forces at work. Koslowski's "complexes" are sub-groupings of species within a species-group that share a greater number of external features in common. The complexes listed in this article, unlike those used by the other authors, are descriptive only and are not based on any presumed monophyly. Don't confuse them with the monophyletic complexes used by other authors.

Presently, I can recognize 13 species-group with 14 complexes within the groups. These are:

A. regani-group	A. pertensis-group	A. gibbiceps-group
A. commbrae-complex	A. pertensis-complex	A. gibbiceps-complex
A. caetei-complex	A. iniridae-complex	A. personata-complex
A. regani-complex	A. sp. Balzfleck-group	A. cacatuoides-group
A. resticulosa-complex	A. diplotaenia-group	A. cacatuoides-complex
A. eunotus-complex	A. agassizii-group	A. nijsseni-complex
A. sp. Rotpunkt-group	A. elizabethae-complex	A. trifasciata-group
A. macmasteri-group	A. bitaeniata-complex
A. steindachneri-group	A. agassizii-complex
A. borellii-group

Some of these are speculative at best due to the lack of precise distribution data as well as little to no meristic data for the scientifically undescribed species.

Identification of the species-groups listed here is based primarily on the dark markings shared by all the species within the group. Other features such as the shape of the body and dorsal and caudal finnage of males are also useful but aren't as reliable. These are all readily visible on live fish and make them very useful to hobbyists. Other features, such as the number of gill rakers, are equally valuable but are not easily discerned on living fish. Breeding behavior and aggressive display tactics are generally similar within a species-group. Another feature that is very valuable is the number of sensory pores found below each eye. These pores separate the genus into two major blocks. I consider those species-groups with a full compliment of four infraorbital pores to be the more primitive or "ancestral" groups. Those that have reduced cephalic pore counts - typically three, but possibly fewer - are members of the more "advanced" species-groups. These infraorbital pores usually can't be seen without magnification, thus this feature will be difficult to determine on live specimens.

Finnage and body shape can also be used to separate ancestral from advanced species, but isn't 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 usually 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 are typically ancestral forms. Those with "fancy" dorsals, having extremely long anterior dorsal spines and lappets or sail-like finnage, are 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 to slightly fusiform in shape. One important thing to remember, though, is that while ancestral species can't exhibit advanced characteristics, advanced species can and frequently do exhibit "retrograde" ancestral features.

 

DESCRIPTION

Using primarily dark markings and assisted by finnage, body shape, and behavioral characteristics it's possible to describe the following species-groups. As in my previous paper 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 true taxonomist!

 

Apistogramma regani-group

The regani-group is considered by most specialist to be the most primitive in the genus. Species exhibit very little sexual dimorphism and tend to be for the most part casually monogamous. 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 "service" them all. Morphologically, regani-group species are characterized by their relatively deep bodies, low and even dorsal fins, round caudal fins, usually prominent vertical flank bars, and in particular, the lack of a lateral spot on the lateral band. As would be expected, the regani-group is an ancestral species-group with a complete set of four infraorbital pores below each eye.

The regani-group is the most widely distributed of the Apistogramma species-groups. They can be found in most tributaries of the Brazilian Amazon south of the river itself, as well as the Peruvian and Bolivian Amazon. They're also found in coastal streams entering the Atlantic Ocean from eastern Venezuela to the Rio Parnaiba of eastern Brazil and have spread to northern Brazilian Amazon tributaries east of Manaus. They also can be found in the Paraguay-Paraná system and associated parts of the Mato Grosso from southeastern Brazil to northeastern Argentina. There are presently 16 scientifically described species within the group and at least 11 undescribed species. With so may species it's not surprising that the regani-group has been subdivided into five complexes.

 

Apistogramma commbrae-complex

The species of the commbrae-complex are considered to be the most primitive of the regani-group as well as the genus. Besides the characteristics found on all species of the regani-group, all commbrae-complex species possess a distinctive rhomboid caudal peduncle patch. This patch is made up of the typical caudal peduncle spot that has merged with a highly pigmented Bar 7. The three known species belonging to the commbrae-complex are found in the Bolivian Amazon and Rio Paraguay system.

 

Apistogramma caetei-complex

The caetei-complex is an assemblage of medium sized species with a fairly robust build. They're also characterized by having diagonal bars below the lateral band and bands over the entire caudal fin. There are presently two scientifically described and at least three undescribed species in the complex.

Species in the 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. Species are also found in tributaries of the Rio Tocantins and Rio Topajós of eastern Brazil. Another is questionably believed to originate from the upper Rio Paraguay.

 

Apistogramma regani-complex

Species in the regani-complex comprise an assemblage of medium sized, deep bodied, fish characterized by seven conspicuous vertical bars running the entire height of the body. These bars are particularly visible on juveniles and females. There are four scientifically described and at least three undescribed species presently placed within the complex.

Species of the regani-complex are distributed in streams along the middle and lower Amazon all the way to its mouth. Species are also found along the Atlantic coast north of the Amazon to the Guyana/Venezuela border. One species is also found in the upper Rio Madeira drainage, and others in the Peruvian Amazon.

 

Apistogramma resticulosa-complex

The resticulosa-complex is comprised of a group of relatively small species. In addition to the standard regani-group features, these species exhibit a narrow zigzag lateral band, a series of faint, poorly defined, vertical dashes below the lateral band, faint stripes toward the center or only in the posterior part of the caudal fin, and usually a blue body sheen in males. Presently there are three scientifically described and at least six undescribed species within the complex.

The species of the 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 Rios Xingú, Tapajós and Tocantins, eastward to the Ilha de Marajó at the mouth of the Amazon.

 

Apistogramma eunotus-complex

The species of the eunotus-complex are all moderately large, deep bodied, fish with fairly broad lateral bands and moderately high, even to slightly serrated, dorsal fins. Males commonly possess orange colored tail fins. An orange spot at the insertion of the pectoral fin is characteristic of the complex. There are three scientifically described and at least three undescribed species within the complex.

The eunotus-complex is distributed exclusively in the Peruvian Amazon and nearby drainages of northeastern Ecuador, southeastern Colombia, and extreme western Brazil.

 

Apistogramma sp. Rotpunkt-Group

The species of Rotpunkt-group may form a bridge between species of the macmasteri-group and those of the eunotus-complex. Females of this group exhibit the yellow with black checkered brood patterncharacteristic of the macmasteri-group but do not show a black ventral stripe or patch. The males, like macmasteri-group species, are highly polygamous but are more like members of the eunotus-complex in appearance. They are moderately large with slightly extended, non-serrated, dorsal fins. The broad lateral band has two rows of alternating light and dark scales. The dark scale rows are offset so that the black scales form a zipper like band. The tails are round to very slightly squared off. This is an ancestral species-group, having four infraorbital pores. There are at least three species in the group, all scientifically undescribed.

The Rotpunkt-group is distributed in tributaries of both the Orinoco and Amazon in southeastern Colombia.

 

Apistogramma macmasteri-group

The macmasteri-group is closely related to the regani-group. It's characterized by large, robust-bodied, sexually dimorphic species. Males have moderately to highly extended, serrated, dorsal fin lappets. Caudal fins are round to truncate with rare double tipped extensions. The lateral band typically forms a zigzag like pattern or is broken into a series of spots. Brooding females exhibit an intense golden yellow body checkerboarded with black dorsal and lateral spots. Most brooding females have a ventral stripe that extends from the chin to the vent, or at least a dark spot at the insertion of the ventral fins. All species in the macmasteri-group have the ancestral four infraorbital pores. Presently there are five scientifically described and at least two, possibly more, undescribed species in the group. There are many geographic color variants that may or may not be distinct species. More distribution data are needed to clarify this problem.

The species of the macmasteri-group are found exclusively within the drainage of the Rio Orinoco and associated parts of the upper Rio Negro. In the Rio Orinoco they are distributed from its headwaters in Colombia and Venezuela all the way to its mouth on the Caribbean coast of Venezuela.

 

Apistogramma steindachneri-group

Another offshoot of the regani-group, the steindachneri-group is comprised of medium to large species with moderately deep, laterally compressed, bodies showing 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 won't be a dominant male servicing all the females. Males are noticeably larger than their female counterpart, can have moderately extended dorsal fin lappets that may be even to very slightly serrated, and caudal fins that are round, truncate, or double-tipped. Vertical bars and the lateral band are usually visible only on frightened or stressed individuals. A large flank patch situated on or above the lateral band is characteristic of steindachneri-group species. This group is "ancestral", possessing four infraorbital pores. There are three known species in the group, all scientifically described.

There are presently three scientifically described and one, possibly more, undescribed species in the steindachneri-group. It 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.

 

Apistogramma borellii-group

Apistogramma borellii is a non-allied species from the Rio Paraguay drainage. It's characterized by its small size, deep body, high but even dorsal fin, and round to very slightly spade-shape tail. A zigzag lateral band is usually visible only on the posterior half of the body. 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 canal is usually missing entirely, something found only in one other Apistogramma species, A. trifasciata, also found in the Rio Paraguay. Perhaps reduction in sensory pores may be related to subtle differences found in the environment of the Rio Paraguay, although it may also be a chance mutation like that which occurred in the pertensis-group. In many respects A. borellii appears to be a deeper bodied, higher finned, offshoot of the resticulosa-complex.

Only one other species might be a member of this group. This is Apistogramma sp. Rio Paraguay III (Mayland & Bork, 1997a, b). It looks much like a slender, low dorsal finned, A. borellii. The female displays a brood dress more like A. borellii than that of members of the resticulosa-complex females. They show no black markings on the flanks. Still, it may be a member of the resticulosa-complex. More information is needed to be certain. The only other species that might conceivably be closely related to A. borellii is the Peruvian species Apistogrammoides pucallpaensis.

Apistogramma borellii is distributed throughout much of the Rio Paraguay/Paraná drainage, from the southernmost Mato Grosso of southern Brazil to the city of Corrientes in northern Argentina. It has the southern-most distribution of any species of Apistogramma, extending even into subtropical South America. As such it's more cold tolerant than most Apistogramma species. Apistogramma sp. Paraguay III is collected with A. borellii in the upper Rio Paraguay.

 

Apistogramma pertensis-group

The pertensis-group is comprised of a series of elongate, slightly fusiform, species that generally lack much pigmentation on the anterior dorsal fin rays. In males the dorsal fin lappets extend well above the fin rays and are fused together into a sail-like filament. Male caudal fins are typically spotted and either round or lyrate. Flank bars are only visible on stressed fish. There is little sexual dimorphism and for the most part they're strictly monogamous. There are four scientifically described and at least seven undescribed species in the pertensis-group which is split into two complexes. The pertensis-group is unique among the Apistogramma species-groups in that it has both ancestral and advanced forms in it.

Distribution of the pertensis-group includes the entire Rio Negro drainage, adjoining areas of the upper Rio Orinoco, and lower Amazon.

 

Apistogramma pertensis-complex

Besides the characteristics found on all members of the pertensis-group, the pertensis-complex species all have round to modified oval-shaped tails and no black pigmentation on the flanks except for the lateral band. All scientifically described species have the ancestral four infraorbital pores.

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

 

Apistogramma iniridae-complex

Other than the features characteristic to all members of the pertensis-group, the iniridae-complex species usually exhibit several dark diagonal bars below the lateral band on their posterior flanks. The lateral band extends into the tail, with no caudal pedunlce spot. All have lyrate tails except A. iniridae. In this species only occasional specimens develop caudal fin ray extensions. All members of the iniridae-complex possess three infraorbital pores - an advanced feature.

All species of the iniridae-complex are known to occur only in the upper Rio Negro of Brazil and closely associated tributaries of the upper Rio Orinoco of Colombia and Venezuela.

 

Apistogramma sp. Balzfleck-group

I am proposing the Balzfleck-group based on features exhibited by several undescribed species: A. sp. Balzfleck (Koslowski, 1985a), A. sp. Weißsaum (Windisch, 1991), A. sp. Tiquié (Römer, 1995), A. sp. Pimental (Glaser & Glaser, 1996), A. sp. Orangesaum (Mayland & Bork, 1997), A. sp. Minima (Zenner, 1998), and possibly A. sp. Felsen/Rock and A. sp. affin. pertensis (both in Glaser & Glaser, 1996). These diminutive species rarely exceed 3.5 cm (1_ in.) in length. They are moderately elongate and slightly fusiform, lack most pigmentation on the anterior dorsal fin rays, where known tend to be strictly monogamous, and display almost no sexual dimorphism (although the females are, atypically, slightly larger than the males). Some of these characteristics are seen in members of the Apistogramma pertensis-group. Their low, even, dorsal fins, round caudal fins, narrow lateral band, and their large prominent flank patch show affinities with the steindachneri-group. Where known, the Balzfleck-group species have their infraorbital pores reduced to three, making them members of an advanced species-group.

Other than A. sp. Tiquié, which is from the Rio Uaupés (upper Rio Negro) and A. sp. Weißsaum, from the Rio Uraricuera (upper Rio Branco), no precise distribution for the Balzfleck-group is known. Apistogramma sp. Pimental is reported to come from the Rio Pimental (a river not listed in any of the atlases I've checked). All shipments of it have originated from exporters in Manaus. Other than A. sp. Balzfleck, which is a clear water species, all of the others are definitely a black water species. From this scant information I speculate that the Balzfleck-group occurs in the upper Rio Negro and the Rio Branco in northern Brazil - where both pertensis- and steindachneri-group species are known to occur.

The Balzfleck-group appears to have features intermediate between the steindachneri-group and the pertensis-group. Being an advanced species-group, it's unlikely that it could form a bridge between two species-groups containing ancestral species. Without additional collections and distribution data, however, all of this must remain only speculation.

 

Apistogramma diplotaenia-group

I am proposing the diplotaenia-group based on the unique features of A. diplotaenia and two other little-known species, A. sp. Gabelband/Fork-band (in Glaser & Glaser, 1996) and A. sp. Mabó/Miua/Uambé (Yamazaki, et al., 1997). Apistogramma diplotaenia is an advanced species possessing three infraorbital pores. The same is postulated for the others but isn't known for certain. All are small, elongate, and slightly fusiform species in which the males possess low, even, dorsal fins and round to slightly spade-shape caudal fins. The feature most diagnostic in this species-group is the presence of a broad double band running all or most of the length of the body. When Kullander (1987) described A. diplotaenia, he postulated that the lower band was derived from abdominal bars like those found on members of the iniridae-complex. Without additional data he wouldn't speculate on where A. diplotaenia should be placed among the Apistogramma species-groups.

Apistogramma diplotaenia is known to be distributed throughout the Rio Negro drainage and into the upper Rio Orinoco. The distribution of A. sp. Gabelband isn't known but all imports of this species have come from Manaus, a locus for fish coming out of the Rio Negro. Apisotgramma sp. Mabó/Miua/Uambé comes from the rivers of the same name. These are tributaries of the Rio Negro.

 

Apistogramma agassizii-group

The agassizii-group comprises a number of moderately elongate species with a broad lateral band, a prominent lateral spot, and dark head stripes. They are polygamous species. It's an advanced species-group with member species having only three infraorbital pores. The agassizii-group has affinities to, and probably split from, the iniridae-complex. Kullander (1980) suggested that the species A. gephyra was a bridge species linking the agassizii-group to the pertensis-group. Since then additional taxonomic and behavioral studies show that A. gephyra is an advanced form with behavioral traits very similar to A. agassizii. Apistogramma gephyra should be considered a member of the agassizii-group. The agassizii-group has seven scientifically described and at least three, possibly more, undescribed species split into three complexes.

The agassizii-group is distributed throughout most of the northern and western Amazon basin. Anomalous populations of the agassizii-group appear to have been "flushed" into the lower Amazon. With such a wide distribution, it's not surprising that it can be subdivided into three complexes.

 

Apistogramma elizabethae-complex

Species of the elizabethae-complex are characterized by having lyrate tail fins with one or more abdominal bands below the lateral band. The single abdominal band on A. elizabethae is commonly very faint to invisible. Most have low, even, dorsal fins, although A. elizabethae has highly extended anterior lappets. This complex shows more traits in common with species of the iniridae-complex than the following two and thus may be considered the most primitive of the three complexes.

All members of the elizabethae-complex originate in the Rio Negro.

 

Apistogramma bitaeniata-complex

Species of the bitaeniata-complex have double-tipped truncate to lyrate caudal fins, serrated or anteriorly elongated dorsal fin lappets, and a broad abdominal band below the lateral band. Apistogramma bitaeniata, A. sp. affin. bitaeniata, and A. sp. Orangeflossen (which may be a hybrid) are the only members in this complex. They exhibit a close affinity to the elizabethae-complex.

Apistogramma bitaeniata is restricted to black water drainages in Peru and Brazil near Leticia, Colombia, and Lago Tefé, Brazil. Apistogramma sp. affin. bitaeniata is known only from two specimens found as contaminants in a shipment of Corydoras pygmaeus from Peru. Apistogramma sp. Orangeflossen is known only from the original specimens of unknown origin and their domestic offspring.

 

Apistogramma agassizii-complex

Species in this complex possess round to spade-shape tails with low, even, dorsal fins.

The agassizii-complex has a very wide distribution. It is found in the Rio Negro, Rio Madeira, Peruvian Amazon, and the Brazilian Amazon as far east as Belem.

 

Apistogramma gibbiceps-group

Another probable offshoot of the pertensis-group is the gibbiceps-group. Like the agassizii-group, the gibbiceps-group is closely aligned with the iniridae-complex. The gibbiceps-group is characterized by broad diagonal abdominal bars which extend across most of the lower flanks below a broad, prominent, lateral band. Males possess lyrate caudal fins. Species within this group all have only three infraorbital pores. There are presently three scientifically described and possibly two undescribed species in the gibbiceps-group. Still, it can be divided into two species-complexes.

All species in this group are found in the upper and middle Rio Negro, as well as nearby tributaries of the Rio Orinoco, and in the lower to middle Rio Branco.

 

Apistogramma gibbiceps-complex

The gibbiceps-complex exhibits a very close affinity to members of the iniridae-complex. Beside features typical of all members of the gibbiceps-group, species of the gibbiceps-complex are characterized by their elongate, almost fusiform, body and low dorsal fin. Only one scientifically described species and possibly one undescribed species belong to this species-complex.

Members of the gibbiceps-complex are reported from the middle Rio Negro and the Rio Branco of northern Brazil.

 

Apistogramma personata-complex

Besides features characteristic of all members of the gibbiceps-group, the personata-complex is recognized by being composed of large, moderately elongate and laterally compressed, species possessing highly extended dorsal fin lappets and slightly enlarged lips in males. The abdominal bars can be prominent to virtually non-existent. Many features held in common with species of the Apistogramma cacatuoides-complex indicate that there is an affinity between the personata-complex and the cacatuoides-group. There are presently two scientifically described and one undescribed species within the personata-complex.

All members of the personata-complex come from the Rio Uaupés (Brazil)/Rio Vaupés (Colombia) system of the upper Rio Negro and tributaries of the Rio Orinoco as far north as Puerto Ayacucho, Venezuela.

 

Apistogramma cacatuoides-group

The cacatuoides-group species are characterized by their robust but slightly elongate bodies, enlarged lips, extended anterior dorsal fin lappets, and usually lyrate caudal fins. All species exhibit a reduced number of infraorbital pores. The males are highly polygamous. The cacatuoides-group has seven scientifically described and at least one undescribed species divided into two complexes.

The cacatuoides-group probably arose from the gibbiceps-group as seen in the bridge species A. sp. Breitbinden. This undescribed species from the upper Rio Negro/upper Rio Orinoco is morphologically very closely related to A. personata a robust member of the gibbiceps-group. Among the characteristics shared by the two species-groups are the extended anterior dorsal fin lappets, lyrate tail, and similar dark markings in brooding females particularly in the head region.

The cacatuoides-group is distributed along the outer fringes of the Amazon Basin in Peru, Ecuador, Bolivia, and extreme western Brazil.

 

Apistogramma cacatuoides-complex

In addition to the characteristics typical of all cacatuoides-group species listed above, species of the cacatuoides-complex also posses prominent lateral bands and zigzag abdominal stripes. In species originating in the Bolivian Amazon the abdominal stripes may be reduced to a series of dark smudges on the edges of scales.

Members of this complex are usually associated with white or clear water habitats in the Peruvian and Bolivian Amazon, and the Rio Juruá of western Brazil.

 

Apistogramma nijsseni-complex

Besides the features typical of all members of the cacatuoides-group, the nijsseni-complex is characterized by the absence of a lateral band (in adults), and, in brooding females, an expansion of the lateral spot and suborbital stripe. Males exhibit light and dark bands bordering the posterior margin of the caudal fin.

Species of the nijsseni-complex are associated with black water habitats in the Andean foothills of Peru, Ecuador and Colombia.

Apistogramma norberti and A. atahualpa display characteristics intermediate between the cacatuoides- and nijsseni-complexes.

 

Apistogramma trifasciata-group

The trifasciata-group species in many respects look much like miniature versions of cacatuoides-complex species. Members of the trifasciata-group are characterized by the combination of having a small moderately elongate and compressed body, extended anterior dorsal fin lappets and ventral fins (males), and round caudal fin. They are advanced species with a reduced number of cephalic pores. Males are highly territorial and polygamous.

The trifasciata-group is distributed in the Rio Paraguay/Paraná drainages of Brazil, Paraguay, and Argentina and the Rio Guaporé/Mamoré system of Bolivia and Brazil.

I personally believe that the trifasciata-group is an offshoot of the cacatuoides-complex. It has similarities to A. staecki, a questionable but defensible member of the cacatuoides-complex. Behaviorally, A. trifasciata is much more like cacatuoides-complex species in that it's a highly territorial, polygamous species. Its reduced infraorbital pore count and extended, separate, anterior dorsal fin lappets are common to it and the cacatuoides-complex.. Geographically, it originates in areas (Bolivian Amazon and Rio Paraguay) neighboring that of the cacatuoides-complex.

 

DISTRIBUTION

In tropical South America the principal cause of endemism, particularly for small fish, is the large number of hydrologic barriers that occur. A hydrologic barrier is a water course that prevents the free migration of fish from one area to another. These can be things like wide, deep, river channels, falls and rapids, and possibly even variations in water chemistry and temperature. Apistogramma species typically inhabit the shorelines of small streams, lakes, pools, flooded forests, and floating meadows. In these locations they are typically found hiding among snags, leaf litter, and where available aquatic and bog plants. They are never found in the open main channel of major rivers. Their small size prevents them from readily crossing major channels without some kind of assistance.

Apistogramma species with extensive distributions of over 500 km (300 mi.) are anomalies, and such species are typically highly adaptable in their habitats. Apistogramma agassizii is a perfect example. This species is found in many of the smaller tributaries near the main channel of the Amazon River. It has been collected over a 5,000 km (3000 mi.) stretch, from the lower Rio Ucayali in northern Peru to around Belem on the lower Amazon of eastern Brazil. Such an anomalous distribution pattern appears almost impossible for such a small species, but is readily explainable if one looks at the actual distribution pattern of this fish. Apistogramma agassizii has an extremely linear distribution pattern. It's rarely found more than a 100 km (60 mi.) upstream from the main channel of the Amazon. Such a distribution would indicate that over the centuries this fish has been transported (flushed) from it original habitats in the Peruvian Amazon downstream to its present locations, most probably in floods occurring during the rainy season. The most likely mode of transportation would be hitching rides among the roots and branches of uprooted trees and brush, or in patches of floating meadow ripped from the banks of streams by flood waters. Apistogramma agassizii is a highly adaptable fish almost exclusively inhabiting white or clear water environments. Most other Apistogramma species with distribution patterns over 500 km (300 mi.) in length are also found to be white or clear water species and their distribution patterns are also quite linear.

Black water species are typically highly endemic, probably due to their water chemistry requirements. Black water habitats, streams in particular, are usually not extensive. Exceptions to this, of course, can be found. The best known would be the Rio Negro drainage and most of its northern and western tributaries. In the Rio Negro drainage several species do have a fairly wide distribution, but only Apistogramma gephyra and Apistogramma pertensis have succeeded in expanding beyond the black water environment into clear water streams and lakes entering the lower Amazon.

 

PROPOSED PHYLOGENY

The following is my proposed phylogeny of the Apistogramma species-groups. As I said previously, since this isn't a scientific paper I'm allowing myself much more license in suggesting relationships than would a true taxonomist!

The genus Apistogramma appears to have an extensive history, probably arising from its geophagine ancestors prior to the Pleistocene Epoch, over two million years ago. As such, the genus would have been subjected to multiple events of periodic contraction of the Amazon rain forests caused by ice ages in the Northern Hemisphere. These great ice ages trapped sizable quantities of water in their extensive glacial ice sheets, which in turn caused the lowering of sea level by at least 100 meters (330 ft.) and drying of areas not directly affected by glaciers. During periods of maximum glaciation in the Northern Hemisphere, the Amazon basin dried out, becoming vast grasslands. The rain forest receded to areas where the orographic effects caused by mountains and highlands still provided enough rainfall to supply their needs. Interestingly these areas, called "refugia" (see Haffer, 1974 and Lynch, 1988), also are the loci for most of the Apistogramma species-groups. During interglacial periods large areas of the northern ice sheets melted, releasing water, and in turn expanded the rain forests to cover the Amazon basin.

During the contractions of the rain forests, populations of ancestral Apistogramma species were separated from each other for considerable periods of time, allowing them to evolve into very different species-groups. During interglacial periods these species-groups would expand and colonize newly available areas. The expansion and contraction of the Amazon rain forest must have occurred several times, since there were at least three periods of continental glaciation in the North American part of the Northern Hemisphere during the Pleistocene. The expansion and contraction of the rain forests explain why species-group are so varied and why they tend to exhibit well defined regional distributions.

The ancestral Apistogramma species probably were casually monogamous, with little sexual dimorphism - similar to those in the commbrae-complex of the regani-group. The ancestral forms probably originated in the Mato Grosso region like A. commbrae. From this ancestral group of species the commbrae-complex and the other complexes of the regani-group radiated outward. The caetei-complex moved northeastward to the Atlantic coastal streams of Brazil. The regani-complex moved in a arcuate route starting in the middle Amazon drainages south of the main channel around Manaus. It eventually "jumped" this hydrologic barrier, migrated down both sides of the lower Amazon, and then moved northward into the Guianas - something the caetei-complex has yet been able to do.. One species may have migrated southward where if gave rise to A. pleurotaenia in the Rio Paraguay. The resticulosa-complex migrated west, into the Bolivian Amazon. From there they moved north into the middle and lower Brazilian Amazon, primarily south of the main channel. One or more resticulosa-complex species radiated outward, south and west. From these arose A. borellii in the Rio Paraguay and Apistogrammoides pucallpaensis in the Peruvian Amazon. The ancestors of the eunotus-complex are probably derived from the regani-complex. They moved west from the middle Amazon into the Peruvian Amazon and adjacent areas.

The Rotpunkt- and macmasteri-groups arose from eunotus-complex species. The Rotpunkt-group possibly forms an intermediate bridge between the other two. The Rotpunkt-group originated somewhere in the northern foothills of the Peruvian Amazon. At some time their home streams were pirated away from the Amazon drainage and incorporated into the Rio Orinoco drainage where they possibly gave rise to the macmasteri-group. From there the macmasteri-group spread northeastward all the way to the mouth of the Orinoco, and now is invading the upper Rio Negro.

The steindachneri-group arose from a regani-complex species inhabiting areas of the middle Amazon, possibly the Rio Madeira. From here they jumped the Amazon and migrated up the Rio Negro and eventually entering Guyana and Suriname.

The Balzfleck-group is problematic in its phylogenetic placement. In many respects it represents a group of bridge species between the steindachneri-group and the pertensis-group. The reduced number of infraorbital pores, however, indicates that it's an advanced species-group. Such a group is unlikely to bridge two species groups which both exhibit ancestral forms. Perhaps the Balzfleck-group is merely a dead-end offshoot of either the steindachneri- or pertensis-group. Until more taxonomic and geographic data are available the phylogenetic placement of the Balzfleck-group must remain speculative.

The pertensis-group evolved from either the steindachneri-group, Balzfleck-group, or the regani-complex in the middle reaches of the Rio Negro. The pertensis-group is unique in that it has one ancestral and one advanced species-complex. The ancestral forms belong to the pertensis-complex, are mostly found in the middle to lower Rio Negro, and the middle to lower Amazon. The advanced species, belong to the iniridae-complex, are distributed in the upper Rio Negro and adjacent area in the Rio Orinoco drainage.

The diplotaenia-group probably arose from an A. iniridae-like species somewhere in the Rio Negro and is now distributed throughout its drainage. It also shows some affinity to the elizabethae-complex and may be a bridge-group between the iniridae-complex and agassizii-group.

The agassizii-group also arose from the iniridae-complex. There is a question of how the agassizii-complex, which appears to have originated from a fish coming from the upper Rio Negro, arrived in the Peruvian Amazon. It's possible that the agassiziii-group separated from the iniridae-complex prior to a glacial period when the Amazon rain forest was expansive. During a dry, glacial, period ancestors of the agassizii- and bitaeniata-complexes may have migrated northwest into the Napo rain forest refuge. During a later interglacial epoch this area may have been pirated by the Peruvian Amazon. The elizabethae-complex remained in the Rio Negro drainage. Somewhere in its travels down the Amazon the agassizii-complex probably gave rise to Taeniacara candidi.

An iniridae-complex species also gave rise to the gibbiceps-group in the middle Rio Negro where the slender gibbiceps-complex species still exist. Later, the more robustly built personata-complex species migrated up the Rio Negro and more recently into the adjacent parts of the Rio Orinoco.

One of the early personata-complex species probably migrated westward with the ancestors of the agassizii- and bitaeniata-complexes, where it gave rise to the cacatuoides-group. The cacatuoides-complex of the cacatuoides-group was able to adapt to varied environments and extended its range southeast into the Bolivian Amazon where it gave rise to the trifasciata-group. The trifasciata-group eventually migrated into the Rio Paraguay/Paraná system. The members of the nijsseni-complex found niches primarily in black water upland streams of Peru and Ecuador. This adaptation to black water environments has restricted the nijsseni-complex species to highly localized habitats.

As I stated in the original paper, this is not "etched in stone". Many more species will undoubtedly be discovered that will refine and modify the family tree (Fig. 1). For now this is how I see it, but I'd love to hear constructive criticisms of this paper. Constructive criticism can only lead to a better understanding of this fascinating genus of dwarf cichlid.

 

REFERENCES CITED

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

Haffer, J. 1974. Avian speciation in tropical South America. Nuttall Ornithol. Club, Cambridge. (14): 1-380.

Koslowski, Ingo. 1985a. Die Balzfleck-Apistogramma, ein Kuriosum unter den Zwergbuntbarschen Südamerikas. D.A.T.Z. 38(3): 102-105.

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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.

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Mayland, H. J. and Dieter Bork. 1997a Zwerg Buntbarsche. Landbuch Verlag, Hannover, Germany. 208pp.

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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.

Römer, Uwe. 1995. Uaupes. Aqua Geõgraphia. 11(1): 6-27.

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Zenner, Lothar. 1998. A dwarf among dwarfs, Apistogramma sp. "Minima". Aqualog News No. 16: 4.