The Congo Project

2. Featured Fish
Labeo fulakariensis Tshibwabwa et al. 2006

Labeo fulakariensis

Labeo greenii (above) and Labeo reidi (below)

Collection localities for Labeo fulakariensis

A. papillate versus B. plicate lips

In 2006 Sinaseli Tshibwabwa and colleagues described a new species of the cyprinid genus Labeo from the lower Congo River. The species was named Labeo fulakariensis in reference to the Foulakari River at the confluence of which most of the type series was collected. Subsequent collecting in the lower Congo has revealed that this species has a relatively widespread distribution along the main river channel and is by no means restricted to the vicinity of the Foulakari. The species appears to be quite common among collections made along the river's course, but like many of the other Labeo species in the lower Congo, Labeo fulakariensis appears to be most often collected in the vicinity of rocks and rocky outcrops. No specimens have yet been collected in Pool Malebo, nor in the middle Congo above the Pool.

Morphologically Labeo fulakariensis appears most similar to two other Congolese species, Labeo greenii and Labeo reidi, all three are species with plicate versus papillate lips (see figure below) and all possess a well-marked, large blackish spot on the caudal peduncle near the base of the caudal fin. As can be seen from the accompanying photographs Labeo fulakariensis can readily be distinguished from these other species. It is distinguished from Labeo greenii, the species with which it appears most morphologically similar, by dorsal fin shape (concave in Labeo fulakariensis versus falcate in Labeo greenii) and by the lack of the deep transverse furrow and upwardly directed fleshy anterior appendage that are present in Labeo greenii. Also Labeo greenii appears to be a more slender-bodied species than Labeo fulakariensis. Labeo fulakariensis differs from Labeo reidi, a species also found in the middle and upper Congo River but not present in the lower Congo region, by the possession of small hidden maxillary barbels (these are larger and visible externally in Labeo reidi), smaller superodorsally positioned eyes (eyes larger, and laterally positioned in Labeo reidi), as well as by the number of scale rows around the caudal peduncle (16 in Labeo fulakariensis versus 17-20 in Labeo reidi).

Prior to the study of Tshibwabwa et al this species had been confused with the morphologically similar Labeo greenii. We have yet to collect any specimens of Labeo greenii in the lower Congo and, although a thorough examination of material housed in museum collections has yet to be undertaken, it appears that Labeo fulakariensis is found only in the lower Congo River and is replaced by Labeo greenii, in the middle and upper Congo River.

1. Featured Fish
Brycinus comptus (Roberts and Stewart, 1976)

Brycinus comptus

Brycinus imberi

Black Spot

Predorsal

Brycinus comptus is a relatively small alestid fish that is abundant throughout the Lower Congo River and beyond. Roberts and Stewart (1976) were the first to recognize that what had previously been considered to be Alestes (=Brycinus) imberi in the Lower Congo was in fact two morphologically similar species; Brycinus imberi and a second taxon, which they formally described under the name of Alestes comptus. They designated a specimen from Inga on the Lower Congo River as the holotype, and a specimen from Bangui on the Ubangi River as a paratype for Brycinus comptus.

In the course of our work in the Lower Congo we have collected large numbers of Brycinus comptus, and most often have collected Brycinus imberi in the same nets, in other words the two species appear to occur sympatrically throughout the Lower Congo River. Elsewhere we have collected Brycinus comptus from the Kasai River. The precise distribution of this fish is hard to discern at present as it has been confused with Brycinus imberi in most museum collections. It would seem however, that the species is quite widespread in the Congo River. A thorough review of museum holdings of "Brycinus imberi" will be necessary to delimit the range of Brycinus comptus in the Congo.

Morphological differences between Brycinus comptus and B. imberi, although not striking, are readily apparent and consistent. In addition to the features noted by Roberts and Stewart in their original description, the two species are easily distinguished by the size and position of the black spot on the caudal peduncle; in Brycinus comptus this spot is smaller than in Brycinus imberi, and it does not extend to the level of the adipose fin as it does in Brycinus imberi. Additionally, Brycinus comptus has slightly smaller scales, and a count of 9-10 predorsal scales vs. 7-8 in Brycinus imberi.