Saturday 14 April 2018

Trematocranus pachychilus: A new species of Cichlid Fish from Lake Malaŵi.

The Cichlids are an extremely successful group of freshwater Perciform Fish (Perches), found in North, Central and South America, as well as the Caribbean, the Middle East, South Asia and, most notably Africa, where the group reaches its highest diversity. Over 800 species have been described from Lake Malaŵi alone, which is more species of freshwater fish than have been described from the entire Northern Hemisphere and slightly over 1% of every vertebrate species ever described. The genus Trematocranus currently contains three species, all endemic to Lake Malaŵi. These are fairly large Fish, reaching about 250 mm in length, typically having a spotted pattern, with several rows of teeth on their pharyngeal plates.

In a paper published in the journal ZooKeys on 14 March 2018, Katrien Dierickx and Mark Hanssens of Ichthyology at the Royal Museum for Central Africa, Bosco Rusuwa of the Department of Biology at the University of Malawi, and Jos Snoeks, also of Ichthyology at the Royal Museum for Central Africa, and of the Laboratory of Biodiversity and evolutionary genomics at Leuven University, describe a new species of Trematocranus from Jafua Bay on the Mozambique shore of Lake Malaŵi.

The new species is named Trematocranus pachychilus, meaning 'thick-lip', in reference to the lips of this species, which are notably thicker than those of other members of the genus. The species is described from three specimens caught in 1998 and stored in alcohol at the Royal Museum for Central Africa. These range from 117.7 to 154.6 mm in length, and have lost their original colouration. They are deep bodied and laterally flattened, with teeth sharp and pointed at the front of the mouth and flat and rounded at the back; the rear teeth of the outer rows are bicusped, while the inner row are unicusped, though in larger specimens there are more bicusped teeth.

Trematocranus pachychilus, preserved specimen, adult male, 154.6 mm SL, Lake Malawi, Jafua Bay. Dierickx et al. (2018).

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