Metriaclima xanthos, Ciccotto, Patrick J., Konings, Adrianus & Stauffer, Jay R., 2011

Ciccotto, Patrick J., Konings, Adrianus & Stauffer, Jay R., 2011, Descriptions of five new species in the genus Metriaclima (Teleostei: Cichlidae) from Lake Malaŵi, Africa, Zootaxa 2738, pp. 1-25 : 11-14

Metriaclima xanthos , new species

Fig. 5A –C; Table 4

Metriaclima sp. " aurora lumbaulo": Konings, 2001: 155.

Holotype. PSU 4494, 44.3 mm SL; Mozambique: Lake Malaŵi: Lumbaulo, 11° 54.024' S, 34° 54.307' E; A.F. Konings & J.R. Stauffer, 19 Feb 2002.

Paratypes. PSU 4495, 4; 44.6–49.3 mm SL; data as for holotype.

Diagnosis. A moderately-sloped head and bicuspid teeth in the outer row of the jaws place this species in Metriaclima . The brown and blue/gray alternating lateral bars in conjunction with the yellow dorsal and dark anal fin of breeding males distinguish M. xanthos from males of all other members of Metriaclima . Female M. xanthos are yellow/brown, usually more yellow than females of any other member of the Aurora group, but not all female M. xanthos can be distinguished according to the color pattern. Metriaclima xanthos is further distinguished from M. aurora males from the Mbweca and Tumbi Point populations that are similar but lack dark pigment in the anal fin, and from the neighboring M. glaucos by the lower jaw length, which is longer in M. xanthos (mean 35.4, range 34.6–36.7 % HL) than in M. aurora (mean 31.2, range 28.4–33.5 % HL) and in M. glaucos (mean 30.8, range 28.8–32.8 % HL).

Description. Morphometric and meristic data in Table 4 . Dorsal snout profile slightly concave to straight; mouth cleft at slightly downward angle; jaws isognathous. Teeth on dentary in 2 or 3 rows, on premaxilla in 2 or 3 rows; outer row teeth typically bicuspid anteriorly and unicuspid posteriorly, inner rows tricuspid, innermost row unicuspid; lower pharyngeal jaw with numerous slender teeth with teeth in posterior row slightly larger. Portion of upper dental arcade normally visible in closed mouth. Tips of teeth in premaxilla and dentary in V-shaped line with anteriormost in upper and lower jaw furthest apart and not touching in closed mouth. Lateral scales ctenoid.

Lateral body coloration of breeding male blue/gray with 6 or 7 brown bars below dorsal fin, yellow ventrally, yellow caudal peduncle with flecks of blue. Head gray with 2 blue/gray interorbital bars; ventral third of operculum yellow with gray opercular spot; gular region yellow. Dorsal fin yellow with blue lappets. Caudal-fin rays yellow with blue membranes. Anal fin dark gray/brown with light blue distal edge and 4 orange ocelli. Leading edge of pelvic fin white, first ray brown, remainder yellow. Pectoral fin clear.

Female yellow/brown laterally with 5 faint brown bars, yellow breast, and white belly. Head orange/brown; gular region yellow; gray/black opercular spot. Dorsal fin yellow/brown with orange lappets. Caudal-fin rays orange with brown membrane. Anal fin orange with 1–4 small yellow ocelli. Pelvic fin orange. Pectoral fin clear.

Remarks. We compared the minimum polygon clusters formed by plotting the second sheared principal component of the morphometric data against the first principal component of the meristic data for Metriaclima aurora , M. glaucos , and M. xanthos ( Fig. 6 ). Size accounted for 90.9% of the observed variance and the second principal component accounted for 2.4%. Variables with the highest loadings on the sheared second principal components were horizontal eye diameter (0.59), vertical eye diameter (0.55), and snout length (-0.28). The first principal component of the meristic data accounted for 14.3% of the total variance. Variables with the highest loadings on the first principal component were tooth rows on lower jaw (0.34), tooth rows on upper jaw (0.32), and dorsal spines Metriaclima xanthos

n=5

(0.24). The minimum polygon clusters formed by M. aurora and M. glaucos did not overlap. Metriaclima aurora had a larger horizontal eye diameter (mean 37.0) and vertical eye diameter (mean 36.8) than M. glaucos (mean 33.7 for horizontal and vertical eye diameters). Metriaclima xanthos was intermediate between these two species, however a MANOVA in conjunction with a Hotelling-Lawley trace demonstrated that the three minimum polygon clusters were significantly (p<0.05) different.

Distribution. Metriaclima xanthos was only collected at Lumbaulo, Mozambique, and is not known to occur elsewhere ( Fig. 1 ).

Etymology. The specific epithet, xanthos , is Greek for yellow, in reference to the yellow belly and dorsal fin of breeding males. It is treated as a noun in apposition.

Figures

FIGURE 1. Map of Lake MalaŴi showing the locations of species discussed throughout the text.

FIGURE 6. Plot of the first principal component of the meristic data (PC 1) and the sheared second principal component of the morphometric data (PC 2) of Metriaclima aurora (●, Likoma Island; x, Mara Point; ․, Mbweca; +, Tumbi Point; Ο, N’kolongwe), M. xanthos (˔), and M. glaucos (□).

FIGURE 5. A. Metriaclima xanthos, holotype, PSU 4494, 44.3 mm SL; Mozambique: Lake MalaŴi: Lumbaulo. B. M. xanthos, male in habitat at Lumbaulo, Mozambique; approx. 70 mm SL; not preserved. C. M. xanthos, female in habitat at Lumbaulo, Mozambique; approx. 50 mm SL; not preserved.

Tables

TABLE 4. Morphometric and meristic values of Metriaclima xanthos from Lumbaulo. Mean and range include holotype.

Standard length, mm Head length, mm	holotype 44.3 13.9	mean 45.7 14.7	range 44.3–49.3 13.9–15.6
Percentage of standard length Head length Snout to dorsal Snout to pelvic Greatest body depth Caudal peduncle length	31.4 35.4 36.4 33.9 13.2	32.2 34.7 36.9 33.0 14.2	31.4–32.8 32.4–36.5 36.1–37.4 30.8–35.1 12.8–15.3
Least caudal peduncle depth Dorsal-fin base length Anterior dorsal to anterior anal Anterior dorsal to posterior anal Posterior dorsal to anterior anal Posterior dorsal to posterior anal	11.4 62.8 52.6 65.6 30.3 15.9	11.9 61.6 51.3 64.1 29.8 15.4	11.4–12.4 58.6–63.9 49.6–53.1 62.2–65.6 28.3–31.1 14.8–16.7
Anterior dorsal to pelvic-fin origin Posterior dorsal to pelvic-fin origin Percentage of head length Horizontal eye diameter Vertical eye diameter Snout length	37.2 60.7 36.8 33.7 27.5	35.9 57.8 37.1 35.9 26.2	33.3–37.4 55.3–60.7 36.7–37.6 33.7–37.1 24.1–27.5
Postorbital head length Preorbital depth Lower-jaw length Cheek depth	43.7 21.4 34.6 20.1	40.0 20.9 35.4 20.8	38.4–43.7 19.2–21.7 34.6–36.7 18.7–22.6
Head depth Meristics	92.2	87.8 mode	80.8–92.2 range
Dorsal-fin spines Dorsal-fin rays Anal-fin spines Anal-fin rays Pelvic-fin rays Pectoral-fin rays	17 9 3 9 5 13	17 8, 9 3 8 5 14	17–18 8–10 3–3 8–9 5–5 13–14
Lateral line scales Pored scales posterior to lateral line Cheek scales Gill rakers on first ceratobranchial Gill rakers on first epibranchial Teeth in outer row of left lower jaw	29 0 4 12 3 21	29, 31 1, 2 4 11, 12 3 21	29–32 0–2 3–5 11–13 2–3 15–23
Teeth rows on upper jaw Teeth rows on lower jaw	3 3	3 2	2–3 2–3