A new catfish from Sierra Leone Gordon Jon Howes Zoology Department, British Museum (Natural History), Cromwell Road, London SW7 5BD A collection of freshwater fishes from Sierra Leone made by Dr A. I. Payne contained three specimens of a previously undescribed dwarf catfish. At first sight these small fishes (33-5-36 mm SL) were thought to be the juveniles of a Synodontis species, but closer examination showed many significant differences. Furthermore, dissection of two specimens revealed that they were adult females, having ripe ovaries. In overall morphology the new catfish appears closer to members of the Mochokidae sensu lato than to those of any other siluroid family, (see p. 168). The possibility that these fishes belonged to the dwarf mochokid genus Microsynodontis was dispelled when comparisons were made with species of that genus. MOCHOKIELLA gen. nov. Fishes of a small size with a shallow body (depth 25-5-27-9 of SL). Head broad (almost equal to its length) with dorsal profile sloped, snout rounded, ethmoid with narrow rostral process. Nostrils widely separated, the posterior situated midway between the anterior nostril and the orbital rim. Anterior nostril tubular. Mouth small, lower lip developed only at the corners of the mouth. Premaxillary teeth short and conical, in a broad patch. Dentary teeth like those on the premaxilla, set in a broad semi-crescentic band. Vomerine teeth absent. One pair of maxillary and two pairs of mandibular barbels. The maxillary barbel long, reaching to the tip of the cleithral process. Outer mandibular barbel extending to halfway along the cleithral process, the inner reaching to the base of the pectoral spine. The outer barbel bears 3 long branches, or sub-barbels, and the inner has 4 (number constant in all specimens). The nuchal shield is well-developed, slightly rugose. There are 3 nuchal plates, the 3rd paired, divided by the 1st and 2nd dorsal fin spines. The cleithral process is narrowly triangular, extending to a line level with the edge of the 3rd nuchal plate. Eye supero-lateral without free orbital rim. Pectoral spine strong, almost reaching the origin of the pelvic fin, its anterior margin bears 23 serrations, the posterior margin 8-9 strong 'teeth'. The longest ray of the pelvic fin reaches to the origin of the anal fin. Anal fin base short, as long as the caudal peduncle. Adipose fin deep and long based, equal to its distance from the last dorsal fin ray. Caudal fin long and forked. Branchiostegal rays 6. Gill opening extending to the base of the pectoral fin spine; branchiostegal membrane forming a fold across the ventral surface of the head. Gill-rakers small, 6 on 1st ceratobranchial. Lateral line pores prominent, interrupted. Mochokiella is distinguished from all other African siluroids by a combination of characters including small adult size, uni-lateral branching of the mandibular barbels, supero-lateral position of the eye, bands of villiform jaw teeth, elongate humeral process, paired 3rd nuchal plate and distinctive colouration (see below). Type species: Mochokiella paynei sp. nov (Fig. 1) HOLOTYPE. An adult female, 33-5 mm SL BMNH 1979.8.22:1 collected from Kassawe Forest Reserve, Sierra Leone by Dr A. I. Payne, for whom the species is named. DESCRIPTION. Based on the holotype and two paratypes, BMNH 1979.8.22:2-3, 35-5 & 36 mm SL. Characters given here amplify the preceding generic description. The proportions given below are shown as percentages of the standard length except for nos Bull. Br. Mus. nat. Hist. (Zool.) 38 (3) : 165-1 70 Issued 29 May 1980 165
BioStor
