Nanochromis sabinae, Anton Lamboj, 2005

Anton Lamboj, 2005, Nanochromis sabinae, a new cichlid species (Teleostei, Cichlidae) from the Upper Congo River area and Northeast Gabon., Zootaxa 827, pp. 1-11 : 2-9

Nanochromis sabinae , new species

(Figs. 1-4)

Nanochromis sp. “Makoua” - Lamboj 2004, 164; Nanochromis sp. “Genema” - Linke & Staeck, 2002, 115, 125, 126; - Lamboj 2004, 164; Nanochromis sp. Linke & Staeck, 2002, 115; Nanochromis sp. aus Makoua , Sawatzky, 1996; Nanochromis sp. “Bamanja-Gelbwangen” , Freyhof, 1996

Holotype. NMW 94839, male, 50.4 mm SL; Congo, (Brazzaville): Loubi River, tributary of the Likoula River (Congo system), SW of Makoua, nearby the village of Lengui; 0° 0' S, 15° 38' E, R Sawatzky, Mar 1996.

Paratypes. NMW 94840, 1 male, 1 female, 52.1+38.6 mm SL, same as holotype . - AMNH AMNH 235651-2 1 male, 1 female, 48.2+37.4 mm SL, same as holotype . - MRAC 20479-20481, 2 males, 1 undet, 21.9-30.2 mm SL, Congo Français: Riv. Sangha . - MRAC 2396-044-P-0196-0197, 2 males, 52.5+32.5 mm SL, Congo (Brazzaville): Ruisseau pres d'Olombo, route de l'ouest, 3 km avant la Komo, J. Huber, Jul 1978 . - MRAC 96-044-P-0198-0199, 2 undet., 16.0+20.6 mm SL, Congo (Brazzaville): mares 50 km N d´Obouya, pres du pont sur la Vouma, J. Huber, Jul/ Aug 1978 . - MRAC 096-044- P-0200-0201, 2 undet., 13.2+16.0 mm SL, Congo (Brazzaville): apres le bac de Makoua, dans les mares de la foret Nionde, J. Huber, Jul/ Aug 1978 . - MRAC 96-044-P-0202, 1 undet., 28.2 mm SL, Congo (Brazzaville): petit ruisseau 3 km E de Louenk, J. Huber, Jul/ Aug 1978 . - - MNHN 1930-60, 1 male, 3 females, 33.5-46.2 mm SL, Gabon: Liboumba, (Ogowe system) Baudon, 1930 .

In addition 10 pairs of descendents of the material collected by Sawatzky (F3-F5) were used for behavioural observations, but not included in the anatomical or type series.

Diagnosis. A species of Nanochromis with the following combination of characters: Body moderately elongated, steep and rounded front profile, snout rounded, caudal fin rounded. One tubular infraorbital bone. Nape and opercle scaled, cheek with 1 or 2 scale rows, at least on the posterior part. Females with a few, silvery colored scales around the genital papilla. A black longitudinal body stripe, not extended into the caudal fin.

Description. Measurements and meristic counts for holotype and 13 paratypes in Table 1.

Sexual dimorphism and dichromatism well-developed. First ray of pelvic fin longest in both sexes, but always more produced in males than in females. Tips of pelvic fin not reaching origin of anal fin in either sex. Caudal fin rounded. Caudal peduncle short, from slightly longer than deep to slightly deeper than long.

Osteology and dentition. Infraorbital bones series with lachrymal and one tubular element; lachrymal with four openings of laterosensory system. 24-25 vertebrae, of which are 13-14 abdominal and 11 caudal.

Premaxilla and dentary with 2-3 rows of unicuspid teeth. Anteriorly in the lower jaw a few teeth orientated posteriorly, not buccally. Lower pharyngeal bone triangular, with teeth shouldered unicuspid (lateral parts of the bone) or asymmetric bicuspid (central field).

Gill rakers on first gill arch. Six-9 tuberculate gill rakers on ceratobranchial, 3-7 pointed gill rakers on epibranchial. Well developed hanging pad on roof of the pharynx.

Scales. Cycloid, 1-2 rows of scales on cheek, often only on the posterior edge; 3-4 horizontal rows on operculum. Dark spot on outer edge of opercle unscaled. Chest-scales normally absent, no scales or a few dispersed scales between pectoral and pelvic fin. A single aberrant specimen ( MRAC 96-044-P-0202) with small, deeply embedded scales on chest and 5 scale-rows between pectoral and pelvic fin.

Upper lateral line always with some non-pored scales in the row separated from dorsal-fin base anteriorly by 3 scales, at the 8th pored scale by ½-1 scales, at last pored scale by 0-½ scales. End of upper lateral line never overlapping lower lateral line.

About ¼ -1/3 of caudal fin covered with scales; other fins unscaled.

Coloration. Live specimens of both sexes (Figs. 2-4): Head and body middle brown to reddish brown. Dark scaleless spot on the outer edge of opercle, only poorly visible in some behavioural situations. Lips orange to brown. Dark longitudinal stripe sometimes visible on sides (in stressed, submissive, breeding and guarding individuals), at about height of lower lateral line, from posterior edge of the eye to end of caudal peduncle, but not extending into caudal fin. Dark bar from the anterior edge of the eye to the middle of upper lip. Body darker dorsally than rest of body, in extremely stressed individuals 7 black blotches below dorsal fin base visible. Upper edge of eye red.

Male specific coloration. Posterior half of dorsal fin with white margin, followed by a thin red submargin in some specimens. Dorsal fin pale reddish brown anteriorly, orange to reddish brown posteriorly, often with some small reddish and pale blue maculae in soft parts. Caudal fin clear to hyaline, with 6-8 rows of red to reddish-brown and pale blue maculae, normally pale or absent on lower edge. Posterior half of upper edge of fin with thin white margin and broader red submargin in some individuals. Anal fin bluish to violet, with some rows of red and pale blue maculae and dark violet to black outer edge. Anterior edge of pelvic fins whitish, other parts of fin pale reddish to pale violet. Pectoral clear to pale orange.

Body scales with greyish margins.

Opercle, throat, ventral parts of the flanks and chest rosy to orange.

Female specific coloration. Dorsal fin with thin black to grey margin, followed by a white to silvery submargin. Rest of fin with orange to red coloration, with pale blotches and/or small black spots in soft parts of some individuals. Caudal fin with pale orange to red coloration, more intensive in upper parts, without patterns or marks. Anal fin clear to slightly yellow. Pectoral fin pale yellow to pale orange. Pelvic fin with whitish anterior edge, rest of fin pale orange to violet. Lachrymal, cheeks, opercles orange to red. Flanks and belly region, from the posterior edge of the origin of the pectoral fin to origin of the anal fin, up to about mid-body or higher in some individuals, pale rosy to dark rosy or violet in ripe females. A silvery genital spot, covering about 2-3 scales on each side around genital papilla. Dorsum of ripe females often with orange flush.

Juveniles of both sexes exhibit a pattern of unregular dark spots on mid-brown coloration, up to a size of about 10 mm. With increasing size, sex-specific coloration is seen.

Preserved specimens (Fig. 1): General coloration of both sexes: Head and body brown, darker dorsally. Cheek, throat, pre-pelvic and pre-pectoral regions of flanks and chest pale light brown. Upper lips, forehead, lachrymal region dark to black, same with dorsal-fin base. Dark spot on outer edge of opercle. A dark longitudinal stripe visible in some individuals, reaching from posterior edge of eye to end of caudal peduncle, but not extending into the caudal fin.

Male specific coloration. Dorsal fin dusky to dark brown anteriorly, pale to clear posteriorly, with numerous dark spots in soft parts. Caudal fin pale to clear, with 6-8 vertical rows of dark spots, more intensive distally, lower, outer edge of fin without spotting. Anal fin anteriorly dusky to dark, dark outer edge and pale to clear posteriorly, with rows of dark spots. Pelvic and pectoral fin pale to clear.

Female specific coloration. Belly dark to black. Dorsal fin with dark base, and dark outer edge, with pale regions between. Some dark spots in dorsal soft in some specimens. Caudal fin, anal fin, pelvic and pectoral fins pale to clear, with some disperse, very small and dusky dots in some individuals.

Breeding behaviour. In aquaria, a monogamous, pair bonding, cave spawner. The eggs are normally guarded by the female, with no participation of the male. Hatching occurs after three day post-spawn. Wrigglers are normally hung on the roof of the cave. Juveniles are swimming free 8-9 days post-spawn, guarded by both parents for a duration of about 5-6 weeks. Breeding and guarding individuals of both sexes exhibit a pale, unspectacular coloration, with a dark, longitudinal stripe visible in most cases.

Distribution (Fig. 5, 6). Congo (Brazzaville), central regions west of the Upper Congo River and in the northwestern parts of Gabon; according to aquarist literature (e.g. Linke & Staeck, 2002; Freyhof 1996) the species also seems to occur in most northern parts of the Democratic Republic of the Congo (around the towns of Genema and Bamanya (Riv. Bondele)).

Type locality (Loubi River, fig.6) is a small river, with maximum depth of c. 1.20 m, 2-3 m wide, within a forested region, with many trees and bushes around. Water dark red-brown, with conductivity of 40 µS, pH of 4,0 and temperature of 24° (edge)-25 °C (middle of water) (R. Sawatzky, pers. comm.).

Etymology. Dedicated to my daughter Sabina Lamboj.

Comparisons. Nanochromis sabinae differs from N. concortus , N. minor , N. nudiceps , N. parilus , N. splendens and N. transvestitus in the presence of a scaled nape and cheeks and a less elevated upper lateral line, with only the last few scales contiguous with the dorsal-fin base.

It differs from N. dimidiatus and N. squamiceps in tendencies to: (a) a shorter head length (23.4-32.8 % SL vs. 27.8-35.5 % SL and 30.7-34.0 % HL), greater head depth (57.5-71.2 % HL vs. 54.2-63.6 % HL and 55.2-63.5 % HL) and a greater preorbital length (13.7-19.7 % HL vs. 12.0-16.3 % HL and 12.7-17.7 % HL), what results in a more robust and rounded forehead and snout profile; (b) a shorter caudal peduncle (11.5-16.0 % SL vs. 13.4-17.3 % SL and 12.9-17.3 % SL) and (c) a higher number of gill rakers on the first arch (11-15 vs. 10-13 and 10-14). It also differs from both species in general coloration patterns and in the few silvery scales around the genital papilla in females, vs. no silvery scales in females of N. dimidiatus and a broad band of silvery scales from the genital region up to mid-body in females of N. squamiceps , and a dark longitudinal stripe not extended into the caudal fin vs. extended into the caudal fin in both congeners. Additionally, it differs from N. dimidiatus in a tendency to a higher count for the total lateral line (25-31 scales vs. 23-27 scales) and in the thin white margin and red submargin on the posterior half of the upper edge of the male caudal fin, which is absent in N. dimidiatus .

Nanochromis sabinae presents all characteristics of Greenwood´s (1987) first group of Nanochromis which possibly is, following Greenwood, the less derived group. Therefore, within the genus, a closer relationship of the new species to N. dimidiatus and N. squamiceps is suggested.

An interesting fact is the distribution of the new species in the Congo system as well as in the Ogowe system (Liboumba), what could indicate some connections - at least in past decades - between the reaches of both river systems.