Trematocranus pachychilus, a new endemic cichlid from Lake Malawi (Teleostei, Cichlidae).

Katrien Dierickx,Jos Snoeks,Bosco Rusuwa,Mark Hanssens

doi:10.3897/zookeys.743.22814

Abstract

A new species of Trematocranus, T. pachychilus sp. n., is described from Lake Malawi. So far, it has only been found at Jafua Bay, Mozambique. It can easily be distinguished from T. labifer by its molariform pharyngeal dentition. A morphometric study, including 24 measurements and 15 counts, was done to compare the new species with T. microstoma and T. placodon. Trematocranus pachychilus is characterised by its thick lips. This species further differs from T. microstoma by its bicuspid (vs. unicuspid) outer oral teeth, wide (vs. small) pharyngeal bone, and its head shape. It resembles T. placodon, from which it can be distinguished by its straight to concave head profile (vs. rounded), less-developed pharyngeal bones (vs. hypertrophied), and the presence of small to minute teeth on the lateral parts of the dentigerous area on the lower pharyngeal bone. A key to the species of Trematocranus is provided.

Highlights

Lake Malawi, like most other African Rift lakes, is home to a large number of endemic cichlids, that in each lake radiated into many genera and species in a very short period
In subsequent comparative analyses of T. pachychilus with T. placodon and T. microstoma separately, the new species was found clearly distinct from the two others
A Principal component analysis (PCA) on the log-transformed measurements including T. pachychilus and T. microstoma resulted in a separation on the third principal axis (Fig. 1)

Summary

Introduction

Lake Malawi, like most other African Rift lakes, is home to a large number of endemic cichlids, that in each lake radiated into many genera and species in a very short period. Some sources estimate that there are more than 800 species of cichlids in Lake Malawi. The endemic genus Trematocranus Trewavas, 1935, currently includes three valid species: T. microstoma Trewavas, 1935, T. labifer (Trewavas, 1935), and T. placodon (Regan, 1922) (Eccles and Trewavas 1989). These fish can grow to sizes of 250 mm TL (Maréchal 1991). The teeth are placed in 3 - 8 inner teeth series in the lower oral jaw and the outer teeth are long and recurved, either bicuspid or simple (Eccles and Trewavas 1989)

Methods

Results

Discussion

Conclusion