Bathyclarias atribranchus is among the least known of the endemic deep-water clariid catfishes of Lake Malawi. Greenwood (1961) described it (as Dinotopterus atribranchus) from a single specimen of 39 cm (15.4 inches) standard length. It has never been illustrated, so far as I know.

This species of Bathyclarias lives on the bottom at depths greater than 70 meters (FishBase). According to Eccles (1992), it feeds on worms.

B. atribranchus can be distinguished from the other species of Bathyclarias by possessing all the following characters (Greenwood, 1961: 230):

1. Gill rakers short, length of longest gill raker (on outer arch) divided by length of longest gill filament = 0.3-0.6 (0.3 in the unique holotype, a probable adult of 39 cm SL);
2. Barbels rounded in cross section, smooth and simple;
3. Body smooth, not pitted; and
4. Gills and suprabranchial cavity black.

In the same 1961 paper, Greenwood synonymized the genus Bathyclarias, which Jackson (1959) had created for the deep-water clariids of Lake Malawi, with Dinotopterus, previously limited to the single Lake Tanganyika species D. cunningtoni. Greenwood examined the anatomical features that Jackson (who did not mention Dinotopterus) had used to define Bathyclarias. These features include the degree of reduction of the suprabranchial organ (an accessory breathing organ that supplements the gill filaments in typical, shallow-water clariids), the arrangement of the superficial skull bones, and the lateral placement of the eyes on the head, so that the eyeballs protrude from the head outline when viewed from above or below. Greenwood also examined variation in the development of an adipose dorsal fin, and other features. He concluded, "If all these characters are considered, there seem to be no anatomical grounds for recognizing two genera..." and treated all the deep-water Malawi endemics as species of Dinotopterus.

Just recently, however, Anseaume & Teugels (1999) re-examined Greenwood's action, and revalidated Bathyclarias as a genus distinct from Dinotopterus. They found that the two genera can be distinguished by a number of characters from morphometrics (proportions), overall morphology, and osteology (study of the bones). As for the latter, Anseaume & Teugels (1999: 415) conclude:

...the two genera can be distinguished by the position of the suprapraeopercular, the position and shape of fontanelles [gaps between the bones on top of the skull], the shape of the mesethmoid and the latero-ethmoid, and the shape of the parieto-suproccipital process. The number of underlying elongated neural spines of the adipose fin and the smaller fin size in Bathyclarias distinguish them unambiguously.

Last Update: 17 October 1999 Web Author: M. K. Oliver, Ph.D. Copyright © 1997-2021 by M. K. Oliver, Ph.D. - ALL RIGHTS RESERVED