Thursday,15 November 2018, 1 : 50 AM

Ptychochromis:Cichlid Genus

PtychochromisLoisellei
Ptychochromis loisellei
Image Credit: Wikipedia

Introduction



Ptychochromis is a genus of cichlids endemic to rivers and lakes in Madagascar.
These are restricted to lakes and rivers in Madagascar, and the majority are threatened.


Taxonomy

The genus was described by Steindachner in 1880.
However an exhaustive study was made by John S Sparks and Smith in 2004.
They considered 21 morphological features considered analysis of 4 gene fragments.


Description

Stiassny and Sparks described the genus in details in a paper in 2006.

Some of the major features of this genus are:

  • Configuration of median frontal pores:
    All cichlids have sensory pores around central sensory line on their head,these are either grouped around the middle or can be set apart.
    The sensory pores of cichlids belonging to genus Ptychochromis are setup very far apart.

  • Tooth Form:
    All cichlids in this genus have bicuspid teeth ( having two points).
    These are set in a bilateral symmetrical shape in the jaw.

  • Anterior Dorsal fin
    There is well developed pro current spur on the first dorsal fin.
    This feature is also found in South American genus Gymnogeophagus.

  • Supra neural shape: The supra neural bone is in shape of inverted L.
    This feature is more marked in first supra neural bone, the second supra neural bone is more recurved in shape.

  • Anal Spines : The first anal spine is extremely short while succeeding two spines are long and more or less same in length.

  • Ctenoid Scales : Ptychochromis have ctenoid scales.
    Ctenoid scales have small spine like projections at one side of scale called cteni.
    They have weak cteni, although two species P. insolitus and P.inornatus have extremely developed cteni.


Distribution & Habitat:

Cichlids of genus Ptychochromis were widely distributed in fresh waters throughout much of northwestern, southwestern,and eastern Madagascar .
However, recent surverys indicate that populations throughout the island, especially in the south western and north western regions, have become increasingly rare and highly restricted.
Some populations like those of south western Onilahy drainage population,may have become extinct .