Cotylopus rubripinnis, Keith & Hoareau & Bosc, 2005

Keith, Philippe, Hoareau, Thierry & Bosc, Pierre, 2005, The genus Cotylopus (Teleostei: Gobioidei) endemic to the rivers of islands of the Indian Ocean with description of a new species from Mayotte (Comoros), Journal of Natural History 39 (17), pp. 1395-1405 : 1397-1403

Cotylopus rubripinnis n. sp.

( Figures 1 , 3 ; Tables I–IV)

Material examined

Nine specimens from Mayotte ( Comoros, Indian Ocean), size range 28.9–47.5 mm SL.

Holotype: MNHN 2004-0560 , female (49.4 mm SL); Koualé river , Mayotte, 3 November 2003, G. Marquet, P. Valade, E. Feunteun, P. Bosc, and T. Hoareau coll. Paratypes: MNHN 2004-0561 , four males, four females (28.9–47.5 mm SL), Koualé river , Mayotte, 3 November 2003, G. Marquet, P. Valade, E. Feunteun, P. Bosc, and T. Hoareau coll.

Diagnosis

Slender body, lateral scales 37–51, transverse back series 6–11, transverse forward series 6–10, zigzag series 13–16. Pectoral fins orange to red, dorsal and caudal fin orange to red with black rays; a black band on upper edge of caudal fin. Posterior part of body yellowish to reddish.

Description

Body elongate, slightly compressed between second dorsal and anal fins, and caudal peduncle, becoming slightly cylindrical, and then slightly depressed anterior to first dorsal fin. Mouth inferior and slightly oblique, jaws not protractile. Opercle and preopercle without spines and edges smooth. First dorsal fin free from second dorsal fin with six spines; second dorsal fin with one spine and 9–10 rays; anal fin with one spine and 10 rays; pectoral fin rays 15–16, and slightly rounded along posterior margin; pelvic fin I, 5, fifth rays of each fin joined together their entire length to form a cup-like disk strongly adherent to belly between all five rays. Caudal fin usually with 15 branched rays, rounded along posterior margin. Lateral scales 37–51. Predorsal scales 0, transverse back series 6–11, transverse forward series 6–10 and zigzag series 13–16. Cutaneous sensory papillae orientated transversely, each papilla in a shallow depression. Scales sexually dimorphic with males having more ctenoid scales than female: scales laterally cycloid on the first third of body and ctenoid on the posterior two-thirds for female and mostly ctenoid for male. Head, nape, belly, pectoral base, and usually one-third of anterior part naked. Upper jaw with 11– 16 large trilobic teeth in curved bands with a gap at the symphysis. Teeth point posteriorly with one or two rows of replacement teeth protruding through gum before primary row. Lower jaw with a single row of small conical teeth (four to six). Upper lip broad, smooth along edge, lacking cleft. Gill opening restricted to pectoral base; isthmus broad extending ventrally to pectoral base. Anterior nostril in short tube, posterior nostril without tube; cephalic sensory pore system in adults mainly A, B, C, D, F, K, L, N and O, some juveniles also with H ( Figure 1 ), all paired except for D which is singular; oculoscapular canal is not divided into posterior and anterior canals. Second dorsal, anal and caudal fins slender in males. Males with urogenital papilla triangular in appearance with distal tip rounded ( Figure 2a ). Females with bulbous urogenital papilla ( Figure 2b ).

Colour in life ( Figure 3 )

Background of body grey or bluish in anterior part and reddish to yellowish in posterior part. All scales with dusky spot posteriorly. Belly whitish to bluish. Back of head grey to reddish brown; cheek and opercle sometimes with grey to brown streaking. First dorsal fin with orange to reddish membrane and dusky spines. Second dorsal fin with rays and spine dusky, and a black margin; membrane orange to reddish. Caudal fin generally yellowish in females, orange to reddish in males with some parts of rays dusky; upper margin with a blackish band. Anal fin with dusky rays, membrane slightly cream, distally with a blackish margin. Pectoral fin yellowish to reddish.

Colour in preservation

Background of body grey to yellowish; mid-laterally a thin dusky line or band. All scales with dusky spot posteriorly; dorsum generally evenly dusky from nape to upper caudal peduncle; belly yellowish. Background of head grey to brown; cheek and opercle sometimes with dusky streaking. Snout and upper lip anteriorly dusky; head yellowish ventrally. First dorsal fin with spines dusky. Second dorsal fin with rays and spine dusky, a black margin and a greyish membrane. Caudal fin generally greyish with dusky rays, upper margin with blackish band. Anal fin with dusky rays, membrane slightly cream, distally with a blackish margin. Pectoral fin greyish; pelvic disk generally without pigment.

Ecology

Cotylopus rubripinnis is reported from a swift clear high gradient and well-oxygenated freshwater stream (Koualé river), where it feeds on algae. The substrate may be entirely rocky with little or no gravel (depth 0.3–0.6 m).

Distribution

Cotylopus rubripinnis is actually only known from Mayotte island ( Comoros, Indian Ocean). It seems very rare.

Affinities

C otylopus rubripinnis differs from C otylopus acutipinnis in having fewer scales in lateral series 37–51 versus 48–63, fewer scales in transverse back series 6–11 versus 7–24, fewer scales in transverse forward series 6–10 versus 10–34, and fewer scales in zigzag series 13–16 versus 15–26. It differs also in having more ctenoid scales laterally, colours of the fins in living fish reddish versus dusky, posterior part of the body yellowish to reddish versus grey to brown, and the body and fins more elongated.

Etymology

The new species is named rubripinnis from ruber which means red in latin and pinna for fin, with reference to red dorsal, caudal and pectoral fins.

Figures

Figure 1. Diagrammatic illustration of head in Cotylopus rubripinnis. (a) Dorsal view; (b) lateral view; (c) ventral view.

Figure 2. Diagrammatic illustration of urogenital papilla in Cotylopus rubripinnis. (a) Male; (b) female. 1, Anus; 2, urogenital papilla; 3, anal fin.

Figure 3. Cotylopus rubripinnis n. sp., MNHN 2004-0561 (live specimen), Koualé river, Mayotte, 3 November 2003, G. Marquet, P. Valade, E. Feunteun, P. Bosc, and T. Hoareau coll. (photograph: P. Bosc).