(Fig. 2)

Tilapia livingstonii Boulenger 1899

Pseudotropheus williamsi (non-Günther).— Regan 1922 Pseudotropheus livingstonii, Trewavas 1935.— Konings 2007 Pseudotropheus elegans (non-Trewavas).— Ribbink et al. 1983 Metriaclima livingstonii.— Stauffer et al. 1997

Material examined. Pseudotropheus livingstonii BMNH 1863.11.12.22, holotype, 55.7 mm SL, Zambesi Expedition, Lake Malaŵi; PSU 4925, 19, 64.3–114.4 mm SL, Cape Maclear, 14º05’ S, 34º54’E, Lake Malaŵi.

Diagnosis. Pseudotropheus livingstonii is distinguished from all other members currently in Pseudotropheus (Konings 2007), except P. crabro, P. demasoni, and P. saulosi, by the presence of five or fewer vertical bars below the dorsal fin. Most Pseudotropheus species either have no bars or have greater than five below the dorsal fin. Pseudotropheus livingstonii is distinguished from P. crabro, P. demasoni, and P. s au l os i by a pale yellow to hyaline dorsal fin vs. dorsal fin heavily pigmented with black.

Description. Principal morphometric ratios and meristics for holotype and for specimens from population at Cape Maclear in Table 1. Medium-sized to large mbuna, ovoid body (mean BD 31.4% SL) with greatest depth between fourth to sixth dorsal spine. Dorsal body profile with gradual curve downward posteriorly, more pronounced towards caudal peduncle; ventral body profile almost straight between pelvic fins and base of anal fin with upward taper to caudal peduncle. Dorsal head profile rounded, with smooth curve between interorbital and dorsal-fin origin; horizontal eye diameter (mean 32.0% HL) greater than preorbital depth (mean 19.6% HL); eye (along horizontal axis) in center of head; snout straight to slightly concave in some individuals; isognathous jaws; tooth bands with 4–5 rows in upper jaw and 3–5 rows in lower; rows continuous through symphyses; teeth in anterior outer row bicuspid with posterior lateral teeth primarily unicuspid, teeth in inner rows tricuspid.

......continued on the next page Dorsal fin XVII–XIX (mode XVIII) and 9–10 (mode 9). Anal fin III and 8–9 (mode 8). First 4–5 dorsal-fin spines gradually longer posteriorly; fourth spine about 2 times length of first spine; last 13 spines slightly longer posteriorly; last spine longest, about 3 times length of first spine; rayed portion of dorsal fin with subacuminate (females) to pointed (males) tip, third or fourth ray longest, to approximately ¼ length of caudal fin in females and approximately ¾ length of caudal fin in males. Anal-fin spines progressively longer posteriorly; third or fourth anal-fin ray longest, ½ length caudal fin in both sexes; 0–3 small yellow spots on posterior part of anal fin in females and 0–6 yellow spots on posterior part of anal fin in males. Caudal fin subtruncate to slightly emarginate. Pelvic fin to first or second spine of anal fin. Pectoral fin moderately long and wing-shaped with upper pointed tip, length to vertical line through base of 12th or 14th dorsal-fin spine. Flank scales ctenoid with abrupt transition to small scales on breast; 32–35 lateral-line scales; cheek with 3–4 (mode 4) rows of small scales; caudal fin with tiny scales to ¼ length; no scales on other fins. Gill rakers on first ceratobranchial 9–12 (mode 11).

Recently captured fish with dark brown head, white gular region with gray blotches; black spot on opercle with reflected blue highlights. Laterally brown with 4 dark brown bars from dorsal fin to belly. Caudal fin with yellow rays and clear membranes. Anal fin brown anteriorly to first or second ray, hyaline posteriorly; 0–6 yellow ocelli in rayed portion. Pectoral fins with yellow rays and clear membranes. Pelvic fins black anteriorly, hyaline posteriorly. Female coloration similar to male, not as vivid.