The Identity of Pseudotropheus Elongatus, with the Description of P. Longior from Mbamba Bay, Tanzania, and Notes on Genyochromis Mento (Teleostei: Cichlidae)

97 Ichthyol. Explor. Freshwaters, Vol. 7, No.2, pp. 97-110,12 figs.,1 tab., September 1996 © 1996 by Verlag Dr. Friedrich Pfeil, Miinchen, FRG- ISSN 0936-9902 The identity of Pseudotropheus elongatus, with the description of P. longior from Mbamba Bay, Tanzania, and notes on Genyochromis mento (Teleostei: Cichlidae) Lothar Seegers * Although Pseudotropheus elongatus was originally described from Mbamba Bay, Tanzania, a species of the P. elongatus-complex from Nkhata Bay, Malawi, has been considered to be the typical P. elongatus. Collections from Mbamba Bay revealed that at least two elongate Pseudotropheus species co-occur. The two extant syntypes of P. elongatus belong to the two species from Mbamba Bay. The specimen pictured by Fryer (1956) is selected as lectotype. The other species is described here as P. longior, new species. A third elongate cichlid, frequent at Mbamba Bay, is Genyochromis menta; some observations on this fish are included. 1956 beschrieb Fryer Pseudotropheus elongatus von Mbamba Bay, Tanzania, wahrend in der Literatur bisher eine Form aus dem P. elongatus-Komplex von Nkhata Bay, Malawi, als P. elongatus im Sinne der Typen angesehen wurde. In Mbamba Bay gibt es zwei gestreckte Pseudotropheus-Arten. Die beiden existierenden Syntypen gehoren unterschiedlichen Taxa an, namlich jeweils einer der beiden bei Mbamba Bay vorkommenden gestreckten Pseudotropheus-Arten. Als Lectotypus fur P. elongatus wurde das Exemplar festgelegt, das von Fryer (1956) abgebildet wurde. Die andere Pseudotropheus-Art wird hier als Pseudotropheus longior n. sp. beschrieben. Eine dritte gestreckte Cichlidenart, die in Mbamba Bay haufig vorkommt, ist Genyochromis menta Trewavas, 1935. Zu dieser Art werden einige Beobachtungen mitgeteilt. Introduction the exceptions of Fryer and Staeck, the collec tions of the present author are the first from this In modern times, with few exceptions (Fryer, part of the lake since those of Fulleborn. 1956; Staeck, 1976), systematic research on the Ribbink et al. (1983) and others showed that fishes of Lake Malawi has been done mostly in many cichlids of Lake Malawi, especially the the Malawian waters. Since the time of Fulleborn 'mbuna' (Chitonga name for a group of rock at the end of the last century (not 1925-26 as frequenting cichlids defined by Ribbink et al., suggested by Konings, 1994: 24; see Paepke & 1983), very often are restricted to a limited area, Seegers, 1995) there has been only very limited sometimes not more than a few kilometers of research in the Tanzanian waters of Lake Nyassa rocky shore or a little island. It would be inter (as the lake is widely called in Tanzania). With esting, therefore, to know if there are species in * Grenzstraf5e 47 b, D-46535 Dinslaken, Germany. Ichthyol. Explor. Freshwaters, Vol. 7, No.2 98 Fig. 1. The type locality ofPseudotropheus elongatus andP .longior south ofMbamba Bay. To the left of the sandy shore is Chinyangi Point; Mbamba Bay is situated behind that landmark. In the foreground some rocks whereP. elongatus and P. longior were collected. the Tanzanian waters of the lake which are dif lateral view shows the highest point of the body ferent from those known from the Malawian at the origin of the dorsal fin. From this point shores and to determine their distribution. the body gets more and more slender to reach Unfortunately, there is a serious misunder the least depth at the caudal peduncle. The draw standing about the identity of P. elongatus. Not ing of Fryer does not show such a gentle de only Ribbink et al. (1983: 189), but all authors in crease of the body depth, but in his fish the the scientific and aquarium literature (Staeck, greatest body depth is near the end of the pelvic 1988: 83; Stauffer, 1988; Konings, 1989) consider fins (at about the middle of the body). Finally, a fish from Nkhata Bay as P. elongatus in the the fins disagree, especially the dorsal fin which sense of the types. is much deeper in the drawing of Fryer and has Fryer (1956) described four 'mbunas': Pseu a different shape, and the caudal fin, which has dotropheus minutus, P. elongatus, P. fuscoides and a concave margin in Fryer's drawing, whereas Labidochromis caeruleus. While the drawings of the margin of the caudal fin in Ribbink et al. is P. minutus and L. caeruleus coincide with the liv not concave but truncate or slightly convex and ing fish, this is not the case with P. elongatus. much more rounded. In conclusion either the First of all, the forehead is much too curved and drawing in Fryer (1956) is very crude (which the mouth is large and slightly subterminal. The contradicts the accuracy of the drawings of at lips are much thicker than those shown in the least P. minutus and L. caeruleus), or the illus drawing in Ribbink et al. (1983: 183). The diam trated species is not identical with the F. elongatus eter of the eye is strikingly large. Moreover, the of subsequent authors including Ribbink et al. body is rather deep in relation to its length. The (1983). drawing of P. elongatus in Ribbink et al. (1983) in Seegers: Pseudotropheus elongatus and P. longior 99 Because of all these contradictions, it was 64). Collections were made at some rocks at the desirable to collect at the type locality of P. elon northern end of the bay where the road to Liuli gatus and to compare that material with the types. leaves the village and from about 1,000 m south In fact, the text in Fryer (1956: 85) is not of the landspit of Chinyangi-Point which is situ unequivocal: 'Occurrence: The three specimens ated in the south of Mbamba Bay. Further collec of this species from which the above description tions were made at Maunyuni Rocks, located was prepared were collected at Mbamba Bay on approximately 700 m off shore to the west of the eastern shore of the lake. Three juvenile Chinyangi Point and from a small bay with a specimens have also been collected on the west rocky shore at the western side of Ngkuyo Is ern shore, at Nkata Bay'. Following of numer land, a small island about 6 km southeast of ous discussions with colleagues, I interpret the Mbamba Bay. Most of the material was collected first sentence as a designation of syntypes ac south of Chinyangi Point and at Maunyuni Rocks. cording to ICZN art. 72 (a) (i), (b) (i) and espe Live fishes were taken to Germany and used for cially (vi). The 'three juvenile specimens' which color notes, photography or behavioral studies. 'have also been collected' in my opinion are Standard length (SL) is used throughout. mentioned separately from those from which External counts and measurements widely fol the description was prepared. This 'separate low Barel et al. (1977). Scales in the lateral line mention of the latter expressly excludes them series are counted as described in Trewavas from the type series.' [ICZN art. 72 (b) (vi)]. In (1983: 39). All counts and measurements were this interpretation, the type locality of the made on the left side of the fish where possible. syntypes used in the original description is The material is deposited in the Natural Mbamba Bay; the Nkhata Bay specimens thus History Museum, London (BMNH) and the cannot be regarded as types. If, however, the text Zoologisches Museum der Humboldt Uni is interpreted as not excluding of the Nkhata Bay versitat, Berlin (ZMB). specimens, then these specimens would also belong to the syntype series and both localities would constitute the type locality. Beside from Pseudotropheus elongatus Fryer these technical and theoretical discussions the (Figs. 2a, 3a, 4a, 5, 6) fact is that Fryer deposited only two syntypes of P. elongatus from Mbamba Bay in a museum; Material examined. BMNH 1956.9.4:1 (Fig. 3 top, Nkhata Bay specimens never were deposited as 4 top), lectotype (present designation), male (?) types or non-types (see below). 65.9 mm SL; 76.4 mm TL; Mbamba Bay, L. Nyasa, Ribbink et al. (1983) were able to show that Tanzania; G. Fryer. - BMNH 1995.8.15:1-5, there are several populations in Lake Malawi 5 spms., 74.9-95.2 mm SL; Tanzania, Lake Nyassa which resemble P. elongatus from Nkhata Bay, or Malawi, about 1,000 m south of Chinyangi Malawi. Ribbink et al. (1983) recognize 24 differ Point, south of Mbamba Bay (TZ 90/117); col ent populations or even species. Since their lected alive April1990, preserved December 1990; publication, some of these populations have been B. Kilian & L. Seegers. - BMNH 1995.8.15: 6-8, formally described (Stauffer, 1988). The species 3 spms., 41.7-56.9 mm SL; same data, preserved to which these populations are compared is in the field.- ZMB 32.558,5 spms., 59.3-70.3 mm P. elongatus Fryer, 1956. It is the purpose of this SL; same data, preserved in the field. paper to redescribe this basic form to avoid further confusion. Diagnosis. A rock-dwelling cichlid ('mbuna') of the genus Pseudotropheus which is morpho logically similar to the relatively short and com Material and methods pact species of the P. elongatus complex as de fined by Ribbink et al. (1983). It is distinguished Fishes were collected by chasing them into a from most species of this complex by the com monofilament net (10m x 1m x 0.4cm mesh size) bination of the following characters: its deep and removed with a hand net at Mbamba Bay, and short body (body depth 27.7-31.4% SL), the Tanzania, in April, 1990. Mbamba Bay consists convex forehead profile and the coloration con of a shallow sandy beach, but is surrounded by sisting of 7-8 blue vertical bars on a dark brown rocky shores (Fig.

Load more