Metriaclima melissa, Stauffer & Konings, 2023

Stauffer, Jay R. & Konings, Adrianus F., 2023, Description of a geographically variable elongate rock-dwelling cichlid (Cichliformes: Cichlidae) from Lake Malaŵi, Africa, Zootaxa 5296 (2), pp. 265-274 : 267-273

Metriaclima melissa sp. nov.

Figures 2–4

Pseudotropheus elongatus ‘bee’ Ribbink et al. (1983)

Pseudotropheus sp. ‘elongatus chailosi’ Konings (1989)

Pseudotropheus sp. ‘elongatus chewere’ Konings (1989)

Type material

Holotype. PSU 13377 ( Fig. 2 ), adult male, 60.2 mm, S 10° 23.77’ E 034° 15.250’, Chitande Island , Lake Malawi , Malawi, Africa, 17 Jan. 2007, A. F. Konings & J. R. Stauffer, Jr.

Paratypes. PSU 2240 , 25 specimens 51.1–71.9 mm SL; data as for holotype .

Non-type material. S 10° 26.477’ E 034° 16.233’, Mbuyu , Lake Malaŵi , Malaŵi, Africa, 21 Jan. 2007, A. F. Konings & J. R. Stauffer, Jr. PSU 2260 , 19 specimens 48.2–65.9 mm SL, S 10° 22.022’ E 034° 14.551’; Chewere , Lake Malaŵi , Malaŵi, Africa 18 Jan. 2007, A. F. Konings & J. R. Stauffer, Jr. PSU 2178 , 22 specimens 49.9–72.9 mm SL.

Diagnosis

The presence of bicuspid teeth in the outer row of both the upper and lower jaws, a swollen ethmo-vomer bloc that is angled between 40–54º with the parasphenoid ( Fig. 3 ), jaws that are about isognathic, and its feeding method (see field observations below) place this species in Metriaclima . The black dorsal and ventral margins of the caudal fin distinguish M. melissa from other Metriaclima except for M. flavifemina , M. nigrodorsalis , M. usiyae , M. ngarae , and M. gallireyae . The 8–10 bars on the flank of M. flavifemina and M. nigrodorsalis distinguish M. melissa which has 5–7 bars. M. melissa has distinct dark bars on the flank while such bars are absent in M. usisyae and is further distinguished from this species by a shallower body (28.9–31.7 vs. 35.2–40.3 %SL) and a shorter snout (25.3–30.6 vs. 32.0–37.6 %HL). A shallower body depth distinguishes M. melissa (13.7–19.8 %SL) from M. ngarae (37.1–40.1 %SL) and M. gallireyae (34.9–43.3 %SL).

Description

Morphometric and meristic data in Table 1 . Small-sized mbuna, with greatest body depth at about 6 th and 7 th dorsal-fin spine. Dorsal body profile with gradual curve downward posterior 8 th dorsal-fin spine; ventral body profile nearly straight between pelvic fins and base of anal fin with slight upward line from anal fin to caudal fin. Dorsal head profile with continuous curve between interorbital and dorsal-fin origin.

Mouth wide with both upper and lower jaw broadly rounded. Teeth in upper and lower jaws in 3 rows with only outer row extending onto lateral arm, premaxilla, and dentary; teeth in outer row bicuspid anteriorly becoming unicuspid in main lateroposterior dentigerous area; inner rows tricuspid or unicuspid in innermost row. Dorsal fin with XVI or XVIII (mode XVII) spines and 8–10 (mode 9) rays. Anal fin with III spines and 8–9 (mode 8) rays. First 5–6 dorsal-fin spines gradually longer posteriorly. Anal fin spines progressively longer posteriorly; 4 th or 5 th anal-fin ray longest. Caudal fin weakly emarginate, covered with 2–4 rows of minute scales. Length of pectoral fin to 12–13 th dorsal-fin spine. Flank scales ctenoid with abrupt change to small scales on breast and belly; 31–33 lateral-line scales with 1–2 pored scales posterior to hypural plate; cheek with 4 rows of scales.

Coloration; population at Chitande Island. Head of male black with two light blue interorbital bars ( Fig. 4 ); blue opercle spot with blue highlights; yellow gular with melanophores. Flank bright yellow; five dark brown/black bars followed by two fainter bars; breast black; belly gray; caudal peduncle yellow. Dorsal fin with yellow lappets; spinous portion dorsal fin dark brown/black with 2–3 yellow patches; posterior half rayed portion yellow/brown with blue spots. Dorsal and ventral three rays and membranes of caudal fin black with thin white upper and light blue lower margin; interior rays black with yellow and blue membranes. Anal fin dark gray to black with narrow light blue margin, gray/light blue posterior 5 th ray with 1–3 yellow/orange ocelli; Pectoral fin clear. Pelvic fin black with light blue leading edge.

Head of female brown with white and green highlights on opercle; gular brown. Flank light brown with blue bordered scales; brown breast; light brown belly. Dorsal fin light brown with black submarginal band; white to yellow lappets. Dorsal and ventral two rays of caudal fin black; interior rays brown with clear membranes. Anal fin with broad black band distally and clear/gray proximally with 1–3 small yellow ocelli; Pectoral fin with gray rays and clear membranes. Spine and first ray of pelvic fin black with white leading edge; remainder clear.

Population at Mbuyu. Head of male gray/green with two blue interorbital bars ( Fig. 5A ); dorsal ¼ of preopercle and opercle light blue; light blue opercle spot with light blue highlights; yellow gular with melanophores. Ventral third flank yellow/brown anterior to anal fin; dorsal flank light blue with 6–7 gray bars; caudal peduncle light blue/yellow; breast brown; belly light gray; yellow spot posterior base pectoral. Dorsal fin yellow with brown bar extensions sometimes covering entire spinous part; with thin light blue submarginal band and yellow lappets; posterior five rays yellow with blue membranes. Dorsal and ventral two rays and membranes of caudal fin black; interior rays yellow with clear membranes. Anal fin proximally gray fading to black with 2–4 yellow/orange ocelli. Pectoral fin clear. Pelvic fin with white leading edge, brown/yellow anteriorly to clear posteriorly.

Head of female gray/brown; two light gray interorbital bars; gular light gray; black opercle spot with green highlights. Scales on upper 2/3 rd flank light brown with light blue border; ventral 1/3 rd light brown; 5–6 gray rays extending 2/3 rd of body; light gray breast and belly. Dorsal fin gray with yellow marks on membranes and yellow lappets. Dorsal and ventral two rays of caudal fin black; interior rays yellow with blue membranes. Anal fin gray/ brown with 1–2 small yellow ocelli. Pectoral fin clear. Spine and first ray of pelvic fin black; remainder brown to clear.

Population at Chewere. Head of male black/brown with black gular; light blue patches on opercle and preopercle ( Fig. 5B ). Flank light blue with five broad black bars laterally but united on both dorsal and ventral part flank with 4–5 light blue ovals mid-flank between bars; caudal peduncle light blue with ventral quarter black continuous with ventral black margin caudal fin; breast dark brown/black with brown belly. Dorsal fin black/dark brown with blue/ white lappets over spinous portion and yellow/brown lappets over rayed portion; posterior five rays yellow with blue membranes. Dorsal 2–3 rays and ventral 3–5 rays and membranes of caudal fin black; interior rays yellow/brown with light blue membranes with brown spots; upper and lower edge caudal light blue. Anal fin black anteriorly to brown posteriorly with posterior three rays yellow with blue membranes; 1–3 yellow ocelli. Pectoral fin with gray rays and clear membranes. Pelvic fin with light blue leading edge, black rays, and clear membranes.

Head of female brown. Flank beige/light blue with five gray bars; ventral 1/3 rd gray; caudal peduncle gray ( Fig. 5D ). Dorsal fin gray with black submarginal bar and white/yellow lappets. Dorsal and ventral two rays of caudal fin black; interior rays brown with clear membranes and brown spots. Anal fin dark brown with 1–2 brown ocelli. Pectoral fins clear. Spine and first ray of pelvic fin black with white leading edge; remainder clear.

Distribution

The type material of Metriaclima melissa was collected from Chitande Island (S 10° 23.77’ E 034° 15.250’), on submerged reefs near Mbuyu (S 10° 26.477’ E 034° 16.233’) and near Chewere (S 10° 22.022’ E 034° 14.551’), Lake Malaŵi, Malaŵi, Africa. The species was also encountered on a reef in Chilumba Bay (S 10° 25.844’ E 034° 15.738’), at Katale Island (S 10° 27.312’ E 34° 17.143’), and at Chirwa Island (S 10° 27.789’ E 034° 16.536’) ( Fig. 5C ).

Field observations

Metriaclima melissa occurs in an intermediate habitat which consists of a mixture of rocks and sand at a depth of 5– 40 m. Non-breeding individuals normally occurred in the shallower part of the range. It feeds from plankton and from Aufwuchs on the rocks in the habitat. Individuals of all populations have been observed combing algae from the Aufwuchs in a manner typical of Metriaclima species ( Konings & Stauffer 2006), i.e., perpendicular to the substrate. Juveniles and non-breeding female occur in small groups while feeding from the algal matrix on the rocks. Males are territorial and usually occur in deeper (10–30 m) areas that comprise mostly of sand with some scattered rocks. They defend a spawning site burrowed alongside or beneath a, usually isolated, rock. Mouthbrooding females hide in the rockier part of the habitat and usually are solitary. Fry-guarding females have not been encountered and the brood is probably abandoned once expelled from the female’s mouth.

Etymology. The specific epithet melissa , the Greek word for bee, is a noun in apposition and it alludes to the bee-like coloration of adult males at the type locality, Chitande Island.

Remarks

When the morphometric and meristic data for the three populations of M. melissa were compared, the first principal components (size) explained 77.4% of the observed variance, and the sheared second principal component explained 4.3%. Variables that had the highest loadings on the sheared second principal components were premaxillary pedicel length (0.77), distance between the posterior anal fin and the dorsal caudal fin (-0.34), and the preorbital depth (0.24). The first principal components of the meristic data explained 20.0% of the variance. Variables with the highest loading on the first principal components of the meristic data were dorsal-fin rays (0.42), anal-fin rays (0.39), and number of rows of cheek scales (0.36). A plot of the second sheared principal component of the morphometric data and the first principal component of the meristic data ( Fig. 6 ) showed that the clusters of the three populations examined largely overlapped.

Figures

FIGURE 2. Metriaclima melissa. Holotype, PSU 13377, adult male, 60.1 mm SL, S 10° 23.77’ E 034° 15.250’, Chitande Island, Lake Malaŵi, Malaŵi, Africa.

FIGURE 3. Skull of Metriaclima melissa from Chitande Island (A), Mbuyu (B), and Chewere (C) showing the swollen rostral tip of the ethmo-vomerine bloc and its angle with the parasphenoid.

FIGURE 4. A male Metriaclima melissa at the type locality Chitande Island, Lake Malaŵi, Malaŵi, Africa.

FIGURE 5. A male Metriaclima melissa at Mbuyu (A), at Chewere (B), and at Chirwa Island (C). A female M. melissa at Chewere (D), Lake Malaŵi, Malaŵi, Africa.

FIGURE 6. Plot of the second sheared principal components of the morphometric data (SHRD PC2) of the morphometric data and the first principal components of the meristic data (PC1) for three populations of Metriaclima melissa (blue: Chitande o; red: Mbuyu +; and green: Chewere x).