Metriaclima sciasma, 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 : 14-17

Metriaclima sciasma , new species

Fig. 7A –C; Table 5

Pseudotropheus sp. "kingsizei north": Konings 2001: 159.

Metriaclima sp. " aurora north": Konings 2007: 177.

Holotype. PSU 4490, 63.8 mm SL; Tanzania: Lake Malaŵi: Magunga, 10° 19.344' S, 34° 34.849' E; T.D. Kocher, A.F. Konings, & J.R. Stauffer, 11 Feb 2005.

Paratypes. PSU 4491, 17; UMBC 16, 1; AMNH 246002, 2; 48.4–71.2 mm SL; data as for holotype. — PSU 4492, 20; 46.9–66.9 mm SL; Tanzania: Lake Malaŵi: Ngwazi, 10° 10.490' S, 34° 32.927' E; T.D. Kocher, A.F. Konings, & J.R. Stauffer, 10 Feb 2005. — PSU 4493, 20; 53.6–68.5 mm SL; Tanzania: Lake Malaŵi: Makonde, 9° 56.862' S, 34° 27.296' E; T.D. Kocher, A.F. Konings, & J.R. Stauffer, 8 Feb 2005.

Diagnosis. A moderately-sloped head and bicuspid teeth in the outer row of the jaws place this species in Metriaclima . A black pelvic fin, a dark-blue cheek and preorbital area, and a blue dorsal fin without a black submarginal band in breeding males and the light-brown colored females that have yellow fin-margins distinguish M. sciasma from all other members of Metriaclima . Breeding males of M. sciasma are distinguished from those of some populations of M. zebra by the presence of a single interorbital bar (2 in M. zebra ) and by black pigment on the anterior membranes of the anal fin. Female M. sciasma cannot reliably be distinguished from those of most other members of the Aurora group, but differ from those of M. aurora by more vertical bars below the dorsal fin (7–10 vs. 6).

Description. Morphometric and meristic data in Table 5 . Dorsal snout profile slightly concave to straight; mouth cleft with slightly downward angle; jaws isognathous. Teeth on dentary in two to three rows, on premaxilla in two to four 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 separate in closed mouth. Lateral scales ctenoid.

Lateral body coloration of breeding males blue dorsally with 7–10 gray bars, white ventrally, and blue/gray caudal peduncle. Preorbital, cheek, and operculum dark blue/gray; blue opercular spot; gray/blue gular region; premaxillary and maxillary blue/gray; blue/gray interorbital bar. Dorsal fin blue with light-blue lappets. Caudal fin with gray rays and blue membranes. Anal fin blue/gray with 2–7 yellow ocelli. Pelvic fin black with white leading edge. Pectoral fin clear.

all Magunga Makonde Ngwazi Females brown dorsally and gray/white ventrally. Head brown with blue highlights on operculum and grey/ green opercular spot; white gular region. Dorsal and anal fins yellow/brown. Proximal third of caudal fin dark brown, distal third light brown/yellow, membranes with faint blue spots. Pelvic fin with white leading edge, first 2 rays and membranes yellow/brown with remaining clear. Pectoral fin clear.

Distribution. Metriaclima sciasma has an extensive distribution north of the Ruhuhu River in the northeastern part of Lake Malaŵi ( Fig. 1 ). The river and the sandy shores south of Mbamba Bay form a geographic barrier between M. sciasma and the other members of the Aurora group.

Etymology. The specific epithet, sciasma , is Greek for shadow, in reference to the black pelvic fins of 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 7. A. Metriaclima sciasma, holotype, PSU 4490, 63.8 mm SL; Tanzania: Lake MalaŴi: Magunga. B. M. sciasma, male in habitat at Magunga, Tanzania; approx. 60 mm SL; not preserved. C. M. sciasma, female in habitat at Magunga, Tanzania; approx. 50 mm SL; not preserved.

Tables

TABLE 5. Morphometric and meristic values of Metriaclima sciasma from Magunga, Makonde, and Ngwazi. Holotype from Magunga.

Standard length, mm Head length, mm Percentage of standard length	holotype 63.8 18.7	mean 60.9 18.3	n=21 range 48.4–71.2 14.8–21.0	n=20 range 53.6–68.5 16.5–21.1	n=20 range 46.9–66.9 14.4–20.6
Head length Snout to dorsal Snout to pelvic Greatest body depth	29.4 30.4 38.6 31.4	30.1 31.1 37.8 31.8	28.7–31.8 29.3–33.6 35.6–39.7 29.1–34.3	29.0–31.9 29.9–33.1 37.0–43.4 30.5–34.1	29.0–31.4 30.0–33.1 34.6–38.4 29.6–33.7
Caudal peduncle length Least caudal peduncle depth	15.2 12.4	14.5 11.8	13.7–15.9 10.7–12.4	12.4–16.2 11.1–12.3	12.9–16.5 11.3–13.1
Dorsal-fin base length Anterior dorsal to anterior anal Anterior dorsal to posterior anal Posterior dorsal to anterior anal Posterior dorsal to posterior anal Anterior dorsal to pelvic-fin origin	63.5 51.6 65.3 31.0 15.6 35.6	61.7 51.1 64.2 29.7 14.8 35.3	59.6–63.7 47.7–53.8 62.3–66.7 27.7–32.3 13.7–15.6 31.0–38.3	59.0–63.6 49.3–54.3 61.8–66.7 26.9–30.7 14.1–15.9 34.0–38.0	58.9–65.5 48.8–53.6 60.6–66.9 27.0–32.1 13.4–15.7 32.8–38.0
Posterior dorsal to pelvic-fin origin Percentage of head length Horizontal eye diameter Vertical eye diameter Snout length Postorbital head length	56.8 33.9 32.7 26.9 41.5	57.3 33.8 33.7 26.3 41.0	54.6–60.7 31.4–37.1 31.9–36.6 22.8–28.1 39.2–42.6	53.3–58.6 30.9–35.1 30.9–35.1 23.0–31.5 38.8–43.1	56.1–60.5 30.4–36.8 31.5–37.1 23.8–28.1 38.7–43.3
Preorbital depth Lower-jaw length Cheek depth Head depth	23.7 33.2 26.4 93.5	21.4 34.3 24.5 90.8	18.3–24.6 31.6–35.9 20.2–28.8 80.8–101.6	16.6–28.9 30.7–36.0 20.9–27.8 86.0–96.8	18.0–23.5 32.7–36.9 18.6–28.7 81.9–93.7
Meristics Dorsal-fin spines	17	mode 17	range 16–18	range 16–18	range 17–19
Dorsal-fin rays Anal-fin spines Anal-fin rays Pelvic-fin rays Pectoral-fin rays Lateral line scales	9 3 8 5 14 29	9 3 8 5 14 30	8–10 3–3 7–9 5–5 14–15 29–31	8–9 3–3 7–8 5–5 14–15 28–30	8–10 3–3 7–9 5–5 13–15 29–31
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 Teeth rows on upper jaw	2 5 12 3 19 3	2 5 12 3 17 3	0–3 4–6 11–13 3–4 13–21 2–3	0–2 3–6 10–13 2–4 14–23 2–3	0–2 3–6 11–14 2–4 12–22 2–4
Teeth rows on lower jaw	3	3	2–3	2–3	2–3