Taxonomy of Cichlids

Introduction

Cichlids are large family of fish called Cichlidae in the order Perciformes.
Cichlids are members of a group known as the Labroidei along with the wrasses Labridae, damselfish ,Pomacentridae, and surfperches Embiotocidae.
This family is both large and diverse.
At least 1,300 species have been scientifically described, making it one of the largest vertebrate families.
New species are discovered annually, and many species remain undescribed.
The actual number of species is therefore unknown, with estimates varying between 1,300 and 3,000.

Taxonomy

Kullander (1998) recognizes eight subfamilies of cichlids:

• Astronotinae
• Cichlasomatinae
• Cichlinae
• Etroplinae
• Geophaginae
• Heterochromidinae
• Pseudocrenilabrinae
• Retroculinae

Cichlid taxonomy is still debated, and classification of genera cannot yet be definitively given.
A comprehensive system of assigning species to monophyletic genera is still lacking, and there is not complete agreement on what genera should be recognized in this family.

One problem that transformed cichlid taxonomy is related to dentition, which had been used as a classifying characteristic.
In many cichlids, tooth shape changes with age, due to wear, and cannot be relied upon.
Genome sequencing and other technologies transformed cichlid taxonomy.

As an example of the classification problems, Kullander placed the African genus Heterochromis phylogenetically within neo tropical cichlids, although later papers concluded otherwise.
Other problems center upon the identity of the common ancestor for the Lake Victoria super flock, and the ancestral lineages of Tanganyikan cichlids.

When classification are done on the basis of morphology and compared with classification based of genetic analysis, we find differences between the two approaches.

However there is a consensus that the Cichlidae as a family is monophyletic, that is all cichlids arose from a common ancestor.

Astronotinae

Astronotus ocellatus : Oscar cichlid
Image Credit: Hayath Mohammad

Astronotinae is a subfamily of cichlids from South America, where they are found in the Amazon, Orinoco, Parana and Paraguay river basins, and various rivers in the Guiana's.
The subfamily includes three genera, each with two species.

Cichlasomatinae

Andinoacara Rivulatus
Image Credit: Alf Stalsbergi

Cichlasomatinae is a subfamily of cichlid fishes.
It includes all cichlids native to islands in the :

• Caribbean (Cuba and Hispaniola),
• USA (southern Texas),
• Mexico and Central America,
• and many of the cichlids from South America excluding those belonging to other cichlid subfamilies.

The subfamily Cichlasomatinae is often divided into two tribes:

• Cichlasomatin.
• Heroini.

Cichlinae

Cichla_temensis : A Member of Cichlinae family
Image Credit: Wikipedia

Cichlinae is a subfamily of South American fishes in the cichlid family.
They are predatory and relatively elongated in shape.
Of the three genera in the subfamily, some species of Cichla reach almost 1 met re (3.3 ft) in length, making them by far the largest cichlids of the Americas, and among the largest cichlids anywhere.
In contrast, Teleocichla are among the smallest cichlids of the Americas, a nd most species only reach around 6 centimeters (2.4 in) in length.

Etroplinae

Etroplus suratensis
Image Credit: Beta M

Etroplinae is a subfamily in the cichlid family of fishes.
The subfamily includes two genera:

• Etroplus: which are the only cichlids native to India and Sri Lanka.
• Paretroplus from Madagascar,(other genera native to this island are in the subfamilies Paratilapiinae and Ptychochrominae).

Geophaginae

Geophagus Iporangensis
Image Credit: Hayath M

Geophaginae is a subfamily of cichlid fishes from South America.
They are found as far west as the Andes and as far south as northern Argentina.
A single species, Geophagus crassilabris is from southernmost Central America.
Very roughly, the subfamily can be divided into two subgroups based on appearance and to some extent behavior (from a phylogenetic point of view this grouping is not correct, however)

1. Dwarf cichlids:
   which do not surpass 10 centimetres (3.9 in) in length, they are represented by following genera:
   • Apistogramma
   • Biotoecus
   • Crenicara
   • Dicrossus
   • Mazarunia
   • Microgeophagus
   • Taeniacara.
2. Earth eaters:
   A range of medium-small to fairly large cichlids, where many species have a habit of picking up large mouthfuls or earth or sand, they are represented by following genera:
   
   • Acarichthys
   • Biotodoma
   • Geophagus
   • Gymnogeophagus
   • Satanoperca (the superficially similar Retroculus are sometimes also called earth eaters, but are members of another subfamily).
   • Heterochromidinae

Heterochromis multidens is a species of cichlid endemic to the Congo River Basin in Central Africa.
It can reach a length of 29.5 centimetres (11.6 in)TL.
This species is likely more closely related to cichlids from the Americas rather than other African cichlids.
It is currently the only known member of its genus and tribe.

Pseudocrenilabrinae

Cyphotilapia frontosa
Image Credit: Wikipedia

The Pseudocrenilabrinae is a subfamily in the cichlid family of fishes which includes all the Middle Eastern and African cichlids with the exception of the unusual Heterochromis multidens and the Malagasy species.

Some authors have recognized additional African subfamilies,
e.g. the Tilapiinae of Hoedeman (1947),
Tylochrominae of Poll (1986),
Heterochrominae of Kullander (1998) or Boulengerochrominae of Tawil (2001)

Cichlids of the greater East African lakes like the Mbuna in the Lake Malawi, and v arious species from Lake Victoria and Lake Tanganyika belong to this subfamily.
The Pseudocrenilabrinae tribes Haplochromini and Tilapiini are widespread in Africa; t he others are more localized, particularly in the East African Rift lakes.

Ptychochrominae

ParetroplusMaromandia
Image Credit: Paul Loiselle

Ptychochrominae is a subfamily in the cichlid family of fish.
They are restricted to lakes and rivers in Madagascar, and the majority are threatened.
Most cichlid genera native to Madagascar are included in this subfamily except for Paretroplus subfamily Etroplinae) and Paratilapia (sometimes included in Ptychochrominae, but likely belongs in its own subfamily).

Retroculinae

The subfamily Retroculinae has a single genus Retroculus.
These cichlids are native to tropical South America.
They are superficially similar to Geophagus.