Aphyosemion rubrogaster Chirio, Legros & Agnèse, 2018

Agnèse, Jean-François, Chirio, Laurent, Legros, Olivier, Oslisly, Richard & Bhé, Hervé Mvé, 2018, Unexpected discovery of six new species of Aphyosemion (Cyprinodontiformes, Aplocheilidae) in the Wonga-Wongué Presidential Reserve in Gabon, European Journal of Taxonomy 471, pp. 1-28 : 21-24

Aphyosemion rubrogaster Chirio, Legros & Agnèse sp. nov.

urn:lsid:zoobank.org:act:1778A417-0D05-4C16-BE75-00B6DE36398C

Fig. 6 E–H, Table 8

Etymology

The specific epithet refers to the colour of the ventral region of this species (red).

Material examined

Holotype

GABON: adult ♁, 25.2 mm SL (31.3 mm TL), bridge on Niengé River , 0.65524 S, 9.57355 E, 61 m a.s.l., field reference code CHRSP6 - Niengué, 4 Jul. 2014, Laurent Chirio leg. ( MRAC 2016-019 -P-93). Paratypes

GABON: 12 ♁♁, 3 ♀♀, 16.1–23.5 mm SL, same collection data as for holotype ( MRAC 2016-019- P-94-108); 13 ♁♁, 18.9–26.6 mm SL, upper Alowé River, 0.70581 S, 9.47592 E, 48 m a.s.l., field reference code CHRSP 6-Alowé, 4 Mar. 2016, Laurent Chirio leg. ( MRAC 2016-019-P-109-121).

Differential diagnosis

Differs from all other species in A. alpha group through combination of following features: head with very intense reddish colour, flanks bluish-orange, ventral region orange (vs never same colour pattern). Distinguished from all other species of Chromaphyosemion by an alpha-shaped mark on pre- and postopercular region (vs no alpha-shaped mark, only some red macules).

Colouration of live males ( Fig. 6E )

FLANKS AND VENTER. Flanks orange and bluish with two often visible dark lateral stripes, four lines of red dots from opercle to caudal peduncle. Ventral region orange, region between end of the anal fin and caudal peduncle is intense orange. Dorsal region brown and bluish, with two rows of paradorsal copper scales from the operculum to caudal peduncle with two lines of carmine red dots.

HEAD. Very intense red, premaxilla reddish, mandible reddish with black lower lips, reddish supraorbital region, reddish infraorbital region with black macule, postorbital region bluish-grey with black macule, orange pre-opercle with two black macules, orange opercle with one black macule; black macules on pre- and post-opercular regions, revealing alpha-shaped mark.

FINS. Dorsal fin orange, blue on posterobasal portion of fin, with rows of carmine red dots between rays, carmine red streaks on distal and posterobasal portions of fin. Orange acumen on apex. Anal fin orange, with blue zone near submarginal band, regular, red submarginal band, blue marginal band and orange acumen. No punctuation. Caudal fin blue, orange on upper and lower lobes, with some red dots on median region, very long red streaks on median region and in upper and lower lobes, irregular, red submarginal band, blue marginal band and orange acumens. Pelvic fins orange with no punctuation, blue zone near submarginal band, submarginal red band, blue marginal band. Pectoral fins with orange reflections.

Colouration of live females ( Fig. 6F )

FLANKS AND VENTER. Flanks pale beige, four lines of red dots from opercle to caudal peduncle, two dark lateral stripes, venter pale beige, white on basal portion. Two rows of paradorsal brown scales in dorsal region from operculum to caudal peduncle with red dots.

HEAD. Premaxilla brown, mandible yellow-orange with black lower lips, with brown supraorbital region, white infraorbital region with black macule, white postorbital region with one black macule, pale blue pre-opercle, orange opercle with two macules.

FINS. Dorsal fin yellow-green, orange on distal portion, with rows of carmine red dots between rays. Anal fin translucent, orange zone on distal portion, blue on edge. Caudal fin translucent, orange on ventral portion of fin, red dots on dorsal portion of the fin near caudal peduncle. Pelvic fins translucent with orange reflection, blue reflection on edges. Pectoral fins translucent.

Colouration of ethanol-preserved males and females ( Fig. 6 G–H)

FLANKS AND VENTER. Flanks of males grey with four lines of red dots, venter whitish. Two rows of paradorsal red scales in grey dorsal region, the operculum to caudal peduncle, with two visible greyish lateral stripes. Flanks of females beige with two grey lateral stripes, four lines of red dots from opercle to caudal peduncle, incomplete near the peduncle; venter yellowish, with two grey lateral stripes. Two rows of paradorsal red scales in brown dorsal region, from operculum to caudal peduncle.

HEAD. Male with whitish mandible with black lower lips (Alowé specimens: orange below mandible), infraorbital region with one red macule, orange pre-opercular region and opercle region, and opercle with two small black macules. Head of female with black lower lips, infraorbital region with red macule, orange opercle.

FINS. Dorsal fin of male light orange with red dots and some red streaks on edge. Anal fin orange with red submarginal band. Caudal fin orange on median portion, with red streaks on upper portion, and red submarginal band. Dorsal fin of female whitish, rows of red dots between rays. Anal fin whitish, with no red dots. Caudal fin whitish, with some red dots on upper portion, red streaks on edge.

Distribution and habitat

This species has been found at two localities, one in the Niengé River ( Table 1 , Fig. 1 ) flowing towards Lake Gomé, itself flowing into the lower Ogooué River, and one in the Alowé River, flowing towards Lake Alombié, also flowing into the lower Ogooué River. The species has never been found elsewhere and seems to be endemic to this part of the lower Ogooué hydrographic basin. The habitat of this species differs quite significantly from that of the five other species: all specimens were found in 3 to 5 metre wide rivers with fast running water, and sandy bottoms with no aquatic vegetation. They were hidden in tree roots along the riverbanks, or under dead leaves at the mouth of small secondary brooks, but they were not found in the small brooks themselves. This species was found in syntopy with an undescribed species of Aphyosemion and an undescribed species of Plataplochilus .

Figures

Fig. 6. A–D. Aphyosemion aurantiacum Chirio, Legros & Agnèse sp. nov. A. Adult, ♁, from locality 12, not preserved. Photo O. Buisson. B. Adult, ♀, from locality 12, not preserved. Photo O. Buisson. C. Holotype, adult, ♁, from Wézé Spring (MRAC 2016-019-P-64). D. Paratype, adult, ♀, from Wézé Spring (MRAC 2016-019-P-65-73). E–H. A. rubrogaster Chirio, Legros & Agnèse sp. nov. E. Adult, ♁, from locality 16, not preserved. Photo O. Buisson. F. Adult, ♀, from locality 16, not preserved. Photo O. Buisson. G. Holotype, adult, ♁, from the Niengé River (MRAC 2016-019-P-93). H. Paratype, adult, ♀, from the Niengé River (MRAC 2016-019-P-94-108).

Fig. 1. Collecting sites of the different populations. Black circles: Aphyosemion alpha Huber, 1998; Black triangles: A. flavocyaneum Chirio, Legros & Agnèse sp. nov.; red triangle: A. flammulatum Chirio, Legros & Agnèse sp. nov.; yellow triangles: A. barakoniense Chirio, Legros & Agnèse sp. nov.; red circles: A. pusillum Chirio, Legros & Agnèse sp. nov.; yellow circles: A. rubrogaster Chirio, Legros & Agnèse sp. nov.; red squares: A. aurantiacum Chirio, Legros & Agnèse sp. nov.