Sarotherodon lamprechti, Neumann, Dirk, Stiassny, Melanie L. J. & Schliewen, Ulrich K., 2011

Neumann, Dirk, Stiassny, Melanie L. J. & Schliewen, Ulrich K., 2011, Two new sympatric Sarotherodon species (Pisces: Cichlidae) endemic to Lake Ejagham, Cameroon, west-central Africa, with comments on the Sarotherodon galilaeus species complex, Zootaxa 2765, pp. 1-20 : 10-16

Sarotherodon lamprechti , sp. nov.

Figures 5 , 7–9 ; Table 3

Holotype. ZSM 29929, male 98.61 mm SL; Cameroon: South-West Prov.: Lake Ejagham, (Cross river basin), Manyu Subdivision; 5° 45' N / 8° 59' E; February-March 1993, U. K. Schliewen. Paratypes. Total of 47 specimens, 26.3–104.9 mm SL; same data as holotype. AMNH 233728 (2, ex ZSM 29931), 96.0– 104.9 mm SL. MRAC 2004-04-P-3-4 (2, ex ZSM 29930), 92.6–94.6 mm SL. ZSM 29930 (5 now 3), 83.2–104.9 mm SL. ZSM 29931 (3 now 1), 101.0 mm SL. ZSM 29932 (3), 95.1–104.8 mm SL. ZSM 29933 (6), juveniles 26.3–50.2 mm SL. ZSM 29934 (21), 85.6–103.1 mm SL. ZSM 39716 (1), juvenile, 89.36 mm SL. ZSM 39717 (1), 57.73 mm SL. ZSM 39718 (7), 88.68–103.22 mm SL.

Non-type material. AMNH 216150 (10, 1 C&S), 78.4–106.0 mm SL; Cameroon: South-West Prov.: Lake Ejagham, (Cross River basin); February 1985, W.J. Dominey. AMNH 216153 (15, 2 C&S), 75.4–95.0 mm SL; same data. AMNH 217743 (1 C&S), 56.7 mm SL; same data.

Diagnosis. Sarotherodon lamprechti is distinguished from all congeners by a lack of scales over the pectoralfin base. Further distinguished from its sympatric sibling species, S. knauerae , and other S. galilaeus populations, by a combination of a prognathous lower jaw and an elongate ventral keel on the lower pharyngeal jaw. It also differs from the sympatric S. knauerae in a lower gill raker number (20–25, mode 22 vs. 24–30, mode 28), longer pelvic fins reaching to (females), or beyond (males), first anal fin-spine (vs. not reaching beyond anus), from S. knauerae and other S. galilaeus populations and subspecies by long pectorals reaching the last anal fin-spine (vs. ending either in front of or at first anal fin-spine). Upper lip large and prominent (ULL 22.5–28.4 % HL vs. 19.1– 25.4 % HL in S. knauerae , 19.3–23.6 % HL in neighbouring riverine S. galilaeus , 18.9–24.2 % HL in S. g. borkuanus and 6.9–12.3 % HL in S. g. multifasciatus ). Differs from S. g. sanagaensis in lower preorbital depth (16.3–25.2 % SL vs. 25.0–27.8 % HL) and from S. g. boulengeri in lower body depth (36.3–40.4 % SL vs. 44.5– 50.0 % SL). Finally differs from phenotypically similar S. caroli and S. linnellii in lower gill raker number (20–25 mode, 22 vs. 18–20, mode 19 and 15–18, mode 18), and from other Barombi Mbo Sarotherodon in higher number of dorsal fin-rays (13–15, mode 14 vs. 10–12, mode 11).

Description. Based on the holotype and 47 paratypes. For morphometric and meristic data refer to Table 3, for general appearance see Figs. 7 A&B and 9A&B. Head large, conspicuously prognathous lower jaw, and prominent fleshy upper lips. Head profile straight, sharply convex behind nape to dorsal fin; ventral head profile straight to ventral rim of opercle. Greatest body depth in front of pectoral fin insertion. Caudal peduncle elongate, longer than deep.

Squamation. Three scale rows on cheek, large scales along outer rim of opercle, with a few small scales scattered loosely over rest of gill cover. Cycloid chest scales do not cover base of pectoral fin, which is naked ( Fig. 5 B). Inter-pelvic area densely covered with minute scales, approximately half size of chest scales. Smaller scales on ventral part of belly, lateral belly scales grading gradually towards lateral flank scales. Upper branch of lateral line ascending to spiny dorsal fin and separated from it by 3 or 4 scale rows, ending 1 or 2 scale rows below fin, separated from lower lateral line by two scale rows, lower lateral line beginning in front of first anal spine and extending onto caudal fin (mean of two pored scales on caudal). Basal third of caudal fin finely scaled.

Fins. Dorsal fin XV or XVI (mode XV) spines, 12–14 (mode 14) branched rays. Anal fin III spines, 10–12 (mode 11) branched rays. Dorsal fin shallow, spines increasing in length to 5th, following spines of equal length. Dorsal-fin lappets ending at tip of spines (females) or a little produced (males). Rayed dorsal and anal fins rounded, extending a little beyond caudal-fin base. Pelvic fin spine about two thirds as long as first branched ray, fin pointed but not produced, reaching or almost reaching anus. Pectoral fin pointed, branched rays increasing in length to 5th then gradually decreasing in length, fin reaches well beyond last anal spine in most specimens. Caudal fin truncated and deeper than long.

Gill rakers. Total rakers on first arch, 20–25 (mode 22). Rakers stout, compressed (not slender and elongate as in most S. galilaeus populations), first 10 on lower branch small and stout, becoming more elongate towards angle of arch, epibranchial rakers strongly decreasing in size towards last.

Jaws and dentition. Lower jaw prognathous with 53–106 (mean 92) slender- necked bicuspid outer row teeth on upper and 26–62 (mean 52) on lower jaw. Towards angle of jaws teeth with reduced minor cusps or fully unicuspid, upper half of outer row teeth with free necks. One to two rows of tricuspid inner teeth, deeply embedded in soft tissue on both jaws. Lower pharyngeal bone gracile, ventral keel elongate, more than twice length of dentigerous area ( Fig. 8 B). Dentigerous area densely covered with extremely slender unicuspid teeth. Second pharyngobranchial not greatly inflated, moderately vacuolated, bearing two or three robust unicuspid teeth on posterior face ( Fig. 8 D).

Colour in life ( Fig. 9 A–F). Males: Base body colour golden with golden iridescence on flanks and head, but not on nape towards dorsal fin or laterally along dorsal fin base. Nuptial males dusky blackish ventrally, blotchy dark brown above lateral line and along dorsal fin base, belly black except for light coloured anus and genital papilla. Head black ventrally, upper lip, ethmoidal area, dorsal head surface, nape and upper parts of preorbital and pre- and postopercle orbit metallic golden-green. Nine or ten thin vertical stripes present in juveniles and subadults, retained in nuptial males sometimes as irregular black blotches, which may extend onto belly. Iris brown with narrow golden inner rim. Dorsal fin reddish turning dark brown in nuptial males. Caudal fin golden-reddish proximally, dusky greyish distally.

Females: Overall colouration golden-grey, with golden iridescence over flanks. Belly white, anus and genital papilla in mature females extruded and white. Adult females sometimes with eight or nine thin lateral stripes extending from lateral line to dorsal fin base, ending in small dark grey or black irregular blotches over 2 or 3 scale rows below dorsal fin. If visible, last stripe on caudal peduncle broader and more prominent than lateral flank stripes, if not then overall colouration black, opercular blotch with blue iridescence, rest of opercle greenishgolden. Head below orbit in some females dusky grey black, but not as intensively so as in males, otherwise golden-greenish. Upper lip metallic golden-green. Iris as in males. Dorsal fin with distinct light grey blotches, forming more or less regular diagonal stripes, distally with black margin. Fin membranes red-brownish, colouration becoming more distinct caudally. Caudal fin yellowish-golden medially, becoming transparent distally. Anal fin reddish-brown, pelvic fin-spine with golden iridescence. Colour in preservation ( Fig. 7 A&B). Males: Body brown to dark greyish brown dorsally, upper lip dark brown, lower lip dark brown anteriorly, ventral and laterally light brown. Interorbital brown, becoming darker towards nape and in front of dorsal fin. Cheek brown, dorsal gill cover translucent brown, opercular blotch prominent. Branchiostegal membranes, interopercle, ventral part of preopercle, and opercle light brownish beige. Six or seven black, sometimes broad, lateral blotches, often merging into a single fine line above lower lateral line. Dorsal fin membrane light brown, spinous fin lappets dark brown to blackish, no markings in rayed fin. “ Tilapia spot” not present in adult males. Caudal fin membranes brownish beige, darkening proximally in some specimens. Anal fin beige, darkening near fin base, some males displaying a broad dark brown to blackish band near fin base. Pelvic fins beige brown with prominent dark brown pigmentation becoming denser along spines and towards free fin tips. Pectoral fins beige brownish and translucent, pectoral finbase darkly pigmented. Sexually mature males with dark brown body colouration while belly and produced starkly white anus. Upper lip dark brown, anterior rim of lower lip dark brown, brown or grey towards ventral border; interorbital area, nape and predorsal dark brownish black. Branchiostegal membranes dark brown to black anteriorly, interopercle, ventral preopercle and opercle dark brown.

Females: Overall colouration brown. Upper lip brown, darker anteriorly; lower lip beige. Interorbital and nape brown, darkening towards dorsal fin insertion. Cheek brownish grey, opercle translucent with prominent opercular blotch; lower part of opercle beige. Branchiostegal membranes pale beige with darker pigmentation anteriorly. If present, vertical bars reduced to broad lateral blotches over four to six lateral scales. Chest light beige; belly creamy white, black peritoneum visible; lateral belly with brownish hue, ventrally between inter-pelvic region and anus white. Dorsal fin membrane beige to greyish, finely pigmented; spines brownish; lappets dark brown distally. Caudal fin brownish-beige, darker proximally. Anal fin beige and finely pigmented, brownish near fin base. Pelvic fins beige, pectoral fins beige-brownish and translucent, pectoral fin-base slightly pigmented. Distribution and Ecology. Sarotherodon lamprechti is a pelagic phytoplanctivore, endemic to Lake Ejagham in the Cross River drainage ( Republic of Cameroon). It is common in large swarms in open water, or on the lake bottom in deeper zones during the main breeding season (August/September). Nuptial males excavate shallow pits with narrow rims over sand (“bowers”) ( Fig. 9 E), which serve as courtship territories and spawning sites. Bower diameter ranges from 16–47 cm; larger bowers appear to be more common in deeper sandy areas (3–9 m deep) where the majority of bowers are concentrated often in close proximity. Neighbouring males often engage in agonistic interactions between bowers. Only rarely, and only in shallow water less than 3 m deep, males in full nuptial colouration can be observed without bowers, but over natural depressions above fallen trees or flat stones ( Fig. 9 A&C). According to field observations, S. lamprechti is a female mouth-brooder. Etymology. Named for Jürg Lamprecht (1941–2000), who worked for his PhD on haplotilapiine cichlids, and who supported UKS as a mentor, teacher and friend at the Max-Planck-Institut (Seewiesen), and DN as a teacher.

Figures

FIGURE 5. Anterior squamation, A. Sarotherodon knauerae, B. Sarotherodon lamprechti.

FIGURE 7. Sarotherodon lamprechti. A. ZSM 29929, female, 98.61 mm SL (holotype). B ZSM 39718, male, 91.86 mm SL (paratype).

FIGURE 8. Lower pharyngeal jaw in ventral and dorsal view, A. Sarotherodon knauerae, B. Sarotherodon lamprechti. Upper pharyngeal jaw, left side in ventral view, C. Sarotherodon knauerae, D. Sarotherodon lamprechti, E. Sarotherodon galilaeus (Lower Niger). Abbreviations: Ep 1 – 4, epibranchials 1 – 4, Pb 2 – 3, pharyngobranchials 2 – 3, Pb 3 tp, toothplate of Pb 3, UP 4, fourth upper pharyngeal toothplate. Double headed arrows indicate width of Pb 2. Pharyngeal bones scaled proportionately for comparison (A. vs. B.) and (C. vs. D. vs. E.).

FIGURE 9. Sarotherodon lamprechti in natural colouration. A. Male in full nuptial colouration, courting above crotch in shallow water. B. Breeding female. C. Courting in-shore pair (male left, female right). D. Female in nuptial colouration (background courting male). E. Male above sand pit in deeper water. F. Swarm of surface feeding juveniles.