Pelvicachromis silviae, Lamboj, 2013

Lamboj, Anton, 2013, A new dwarf cichlid (Perciformes) from Nigeria, Cybium 37 (3), pp. 149-157 : 152-154

Pelvicachromis silviae , new species ( Figs 1, 2 )

Holotype. - NMW 95243 , male, 47.8 mm SL; Nigeria, Niger River system, river Uwerum, near village of Ughelli , app. 5°30’N, 5°59’E, Delta State, coll. E. Ajih, Feb. 2009.

Paratypes. - NMW 95244 , 2 males, 3 females, 35.7- 41.5 mm SL, same as holotype . MRAC 91-067 -P-0549, female, 43.9mm SL, Nigeria: Niger River system, Okoso Creek, 5°08’N- 6°23’E, coll. C.B.Powell, Jul. 1991 . MRAC B2-22 -P-1-2, 1 male, 1 female, 33.3 + 43.9mm SL, same as holotype .

Diagnosis

A species of Pelvicachromis , distinguished from congeners by a combination of characters as follows: Differs from P. subocellatus in somewhat greater body depth (37.4- 43.0% SL vs. 34.5-41.6%, mean 39.2 vs. 37.3%), shorter snout length (20.4-28.1% HL vs. 23.4-30.9%, mean 24.9 vs. 26.7%), greater eye orbit diameter (31.3-35.7% HL vs. 28.9-32.9%, mean 33.0 vs. 30.5%), greater lower jaw length (30.9-38.5% HL vs. 25.4-35.3%, mean 35.1 vs. 30.9%), lesser scales between pelvic and pectoral fin (3-5 vs. 5-6), in males in lappet-like elongation of some rays of caudal fin (vs. no such elongation) and in females in greenish and yellow coloured parts on dorsal parts of body, situated over red belly region (vs. silver coloured scales around red belly region). Differs from P. sacrimontis Paulo, 1977 in greater body depth (37.4-43.0% SL vs. 29.0-36.5%, mean 39.2 vs. 33.3%), greater head length (33.2-36.9% SL vs. 27.0-32.0%, mean 35.4 vs. 28.9%), greater caudal peduncle depth (15.8- 17.5% SL vs. 14.0-15.3%, mean 16.8 vs. 14.7%), shorter snout length (20.4-28.1% HL vs. 26.2-38.7%, mean 24.9 vs. 32.3%), greater postorbital distance (40.4-45.7% HL vs. 31.7-41.8%, mean 42.1 vs. 37.0%), shorter interorbital dis- 43.0% SL vs. 33.6-37.6%, mean 39.2 vs. 35.9%),

greater head length (33.2-36.9% SL vs. 31.5-33.0%, mean 35.4 vs. 32.2%), greater caudal peduncle length (15.8-17.5% SL vs. 9.4-12.2%, mean 16.8 vs. 10.7%), higher number of pored scales of lateral line (26-28 vs. 24-26). Differs from P. taeniatus (Boulenger, 1901) in greater body depth (37.4-43.0% SL vs. 29.9-36.4%, mean 39.2 vs. 34.6%), greater head length (33.2-36.9% SL vs. 28.4-33.8%, mean 35.4 vs. 31.4%), greater pre-anal distance (66.2-69.8% SL vs. 62.8-66.7%, mean 68.3 vs. 65.6%), greater prepelvic distance (37.9-44.3% SL vs. 36.0-37.5%, mean 39.8 vs. 36.9%), shorter preorbital distance (16.3-17.3% HL vs. 18.6-21.1%, mean 16.9 vs. 20.2%), fewer spines in dorsal fin (14-16 vs. 17-18). Differs from P. kribensis (Boulenger, 1911) (revalidation Lamboj et al., under review) in greater body depth 37.4-43.0% SL vs. 30.4-37.3%, mean 39.2 vs. 33.2%), greater prepelvic distance (37.9-44.3% SL vs. 32.5-37.7%, mean 39.8 vs. 35.1%), shorter preorbital distance (16.3-17.3% HL vs. 17.0-22.3%, mean 16.9 vs. 19.1%), lesser spines in dorsal fin (14-16 vs. 17-18). Differs from P. sp. aff. taeniatus “Wouri“ in greater body depth (37.4-43.0% SL vs. 28.7-35.1%, mean 39.2 vs. 32.3%), greater prepelvic distance (37.9-44.3% SL vs. 33.4-39.5%, mean 39.8 vs. 36.5%), greater eye orbit diameter (31.3-35.7%SL vs. 22.6-32.5%, mean 33.0 vs. 28.6%), more slender caudal peduncle (caudal peduncle length 73.2-85.3% of caudal peduncle depth vs. 93.9-124.6%, mean 78.1 vs. 106.0%), fewer spines in dorsal fin (14-16 vs. 17-18).

Differs from P. humilis (Boulenger, 1916) , P.

rubrolabiatus Lamboj, 2004 and P. signatus Lamboj ,

2004 in absence of 7-8 vertical bars on body, visible in several behavioural situations, in three infraorbital bones vs. two, in greater body depth (37.4-43.0% SL head profile slightly rounded. Dorsal profile curving gently downward along length of dorsal fin base. Ventral profile gently rounded in males and non-ripe females, more rounded in ripe females. Sexual dimorphism and dichromatism well developed. First ray of pelvic fin always longest in males, tip of pelvic fin reaching anterior base of anal fin or beyond. In females, first ray of the pelvic fin shorter or of equal length to second ray. Caudal fin mostly rounded in both sexes, but with some elongated rays in upper portion in males, forming a small lappet. Some rays in posterior parts of dorsal and anal fins pronounced, but always much longer in males. Adult males usually 15-25% larger in TL than females.

Osteology and dentition. Infraorbital series with lachrymal and three additional tubular bones, with a distinct gap between second and third (dermosphenotic) tubular infraorbital. Lachrymal with four laterosensory pores.

Premaxilla with 2 rows, dentary with 2 or 3 rows of regularly set unicuspid teeth. Anteriorly in lower jaw a few teeth are slightly rotated and point inward.

Gill rakers on first gill arch. Seven to 10 tuberculate gill rakers on ceratobranchials, 5-6 pointed gill rakers on epibranchials. Well-developed hanging pad on roof of the pharynx.

Figures

Figure 2 (right). - Coloration patterns of P. silviae for both sexes in different behavioural situations, in comparison with P. subocellatus from Lower Congo, Moanda region.All specimens imported for ornamental fish trade, not preserved, not measured. A: Female of P. silviae; B: Female of P. subocellatus, both in normal coloration, possessing the two lateral bands; C: Female of P. silviae; D: Female of P. subocellatus in normal coloration without lateral bands; E: Female of P. silviae; F: Female of P. subocellatus in courting display; G: Male of P. silviae; H: Male of P. subocellatus; I: Male of P. silviae guarding fry, notice the pattern of diffuse vertical bars from dorsum to midbody; J: Juveniles of P. silvae with an age of about 2 weeks, before getting adult coloration.