Melanochromis vermivorus Trewavas 1935

Konings-Dudin, Gertrud, Konings, Adrianus F. & Stauffer, Jay R., 2009, Descriptions of three new species of Melanochromis (Teleostei: Cichlidae) and a redescription of M. vermivorus, Zootaxa 2076 (1), pp. 37-59 : 40-44

Melanochromis vermivorus Trewavas 1935

( Fig. 2a ; Table 1)

Melanochromis vermivorus Trewavas 1935:79

Non-type material examined. PSU 4550 , 16 , 53.0–76.0 mm SL and AMNH 246007 , 2 , 58.3–73.9 mm SL; Mala ẁi: Lake Mala ẁi: Nkudzi : 14° 9.772’ S, 35° 0.011’ E, Stauffer and Konings, 10 Oct. 2004 ; PSU 4554 , 22 , 53.0–76.0 mm SL; Mala ẁi: Lake Mala ẁi: Boadzulu Island : 14° 14.835’ S, 35° 8.572’ E, Stauffer and Konings, 21 Oct. 2004 .

Diagnosis. Melanochromis vermivorus is distinguished from its congeners that exhibit the reverse malefemale stripe coloration, except M. melanopterus , by the yellow-brown to dark brown ground color (which is cream white to bright yellow in the other species) and from M. melanopterus by a larger interorbital width (18.5–25.5 % vs. 16.6–20.6 % HL) and by a deeper head (80.5–99.4 % vs. 68.7–82.0 % HL).

Description. Morphometric ratios and meristic values appear in Table 1. Moderate elongate species (mean BD 32.5% SL) with greatest body depth at about base of fourth dorsal spine. Dorsal body profile gradually curving to caudal peduncle; ventral body profile slightly convex anteriorly and gradually curving upward along base of anal fin. Dorsal head profile straight between snout tip and interorbital, making 40–45° angle with body axis, then rounding to dorsal fin origin; eye (mean 31.6% HL) larger than depth preorbital and positioned in anterior half of head with posterior orbit margin lying on or slightly posterior of vertical median of head. Snout long with isognathous jaws and somewhat thickened lips; teeth on lower jaw in 3–4 rows with outer row bicuspid and inner rows tricuspid. Teeth of lower pharyngeal bone well spaced with a sharp cusp; teeth of posterior row slightly enlarged.

Dorsal fin with XVI–XVIII (mode XVII) spines and 7–9 (mode 8) soft rays. Anal fin with III spines and 7 or 8 (mode 7) soft rays. First 6–8 dorsal spines gradually increasing in length posteriorly with first spine less than 1/3 length of eighth spine; last 10 spines slightly increasing in length posteriorly with last spine longest; soft dorsal with rounded or subacuminate tip, third or fourth ray longest, not or about reaching base of caudal fin. Anal spines progressively increasing in length posteriorly; fourth or fifth ray longest, reaching to about base of caudal fin, slightly longer than dorsal in males. Caudal fin subtruncate to emarginate. Pelvic fin not reaching anal fin in females; reaching first to second anal spine in males. Pectoral fin rounded, paddle-shaped, short, reaching vertical through base of 10 th or 11 th dorsal spine.

Flank scales large, ctenoid; abrupt difference to small scales on breast and belly; cheek with 1–7 rows of small scales. Upper branch of lateral line with 19–29 pored scales; lower branch 8–11. Dorsal and anal fins scaleless; small scales over proximal half of caudal fin.

Coloration. Breeding males: head dark blue/black with two, faintly marked light blue interorbital bands; cheek and gular region blue/black; nape gray/blue. Body dark blue/black with distinct blue midlateral stripe and less distinct blue dorso-lateral stripe; dorsum gray/blue overlain with irregular black markings; caudal peduncle dark blue/black with blue midlateral stripe; belly and breast dark blue/black. Dorsal fin light blue with light blue lappets. Caudal fin dark blue/black membranes and light-blue rays; narrow yellow trailing edge. Anal fin black, with 1–4 orange/yellow ocelli and light blue ventral border. Pelvic fins black with light blue leading margin. Pectoral fins with gray/black rays and clear membranes.

Females: head yellow brown/dark brown with gray/brown gular region. Body yellow brown/dark brown with black midlateral and dorso-lateral stripe. Dorsal, caudal, and anal fins gray/brown with broad yellow/ light brown trailing edge. Pelvic fins brown with narrow white/light blue leading margin. Pectoral fins with brown rays and yellow-brown membranes.

Distribution and field observations. Melanochromis vermivorus is a rare occurrence in the shallow (<5 m deep) intermediate habitat at Nkhudzi, Mphande, and Boadzulu islands, but also, even less common, at deeper levels (10–15 m) at Makokola Reef ( Fig. 1 ). Males in breeding coloration are uncommon, and none were seen that defended a breeding territory. The species is attracted to disturbed sediment and appeared to have a mostly opportunistic feeding behavior (stomach analyses were not performed). In this respect, it resembles M. melanopterus with which it was never sympatric in our observations and collections. Its distribution lies south of Kanchedza Island in the southeastern arm of the lake, and it has never been found sympatric with M. heterochromis either.

Figures

FIGURE 1. Map of Lake Malaẁi with localities mentioned in the text.

FIGURE 2. Preserved specimens of: a. Melanochromis vermivorus from Nkhudzi (PSU 4550, 69.5 mm SL); b. Melanochromis heterochromis from Thumbi East Island (PSU 4548, 56.4 mm SL); c. Melanochromis melanopterus from Thumbi East Island (PSU 4547, 62.6 mm SL); d. the holotype of Melanochromis mellitus from Mumbo Island (AMNH 35387, 79.4 mm SL).