Nimbapanchax, Sonnenberg, Rainer & Busch, Eckhard, 2009

Sonnenberg, Rainer & Busch, Eckhard, 2009, Description of a new genus and two new species of killifish (Cyprinodontiformes: Nothobranchiidae) from West Africa, with a discussion of the taxonomic status of Aphyosemion maeseni Poll, 1941, Zootaxa 2294, pp. 1-22 : 8-10

Nimbapanchax , new genus

Type species. Nimbapanchax leucopterygius , new species, by original designation.

Diagnosis. In addition to their genetic distinctness, the species of this new genus differ from A. guineense by several morphological characters. In Nimbapanchax the frontal squamation is usually of the G-type, which might be the plesiomorphic state in Nothobranchiidae , versus the exceptional E-type in A. guineense ( Scheel 1968; Wildekamp 1993). However, Huber (1978) reported an E-type pattern for some individuals of Diapteron georgiae and Raddaella kunzi and we found in N. melanopterygius , new species, several individuals with an E-type pattern and in one case one of the E-scales is covered by the G-scale and the other one is above the G-scale.

We found in Nimbapanchax a slightly lower mean number of scales along the lateral line than in Archiaphyosemion (see Tables 3–5 ); however, Daget (1954) gives the range from 30–34 scales so the upper number found in Nimbapanchax overlaps with the lowest in Archiaphyosemion . Nimbapanchax can also be diagnosed by lower numbers of transverse scales (8–10 vs. 11–12) and circumpeduncular scales (12–14 vs. 15–17) without overlapping ranges ( Tables 3–5 ).

Nimbapanchax usually has lower vertebrae counts as Archiaphyosemion (vertebrae with pleural ribs 13– 14, vertebrae with haemal spines 14–16 [total numbers 27–30] vs. 14–15 + 16–17 [total numbers 30– 31])( Table 5 ). Overlap in total vertebrae numbers is currently only known between N. leucopterygius new species (29–30) and A. guineense (30–31), the remaining Nimbapanchax species have counts between 27–29 vertebrae.

The color pattern in the male caudal fin consists mostly of dark blotches or dots, stripes, if present, only short in posterior part versus contrasting light and dark stripes, usually from root of caudal to posterior fin margin between or along fin rays and no dots or blotches in A. guineense . Adult Nimbapanchax species do not reach, according the literature and own observations, the maximum total length of adult A. guineense (60 mm vs. 65 mm, Wildekamp & Van der Zee 2003).

Holotype Paratypes 3 mean Paratypes Ƥ mean all Types mean all Types range all Types SD Both Nimbapanchax and Archiaphyosemion are separated from the related Callopanchax and Scriptaphyosemion by the combination of the following characters: lower dorsal and anal fin counts as Callopanchax (D: 11–15, A: 14–18 [ Archiaphyosemion ], D: 8–14, A: 13–18 [ Nimbapanchax ] vs. D: 14–23, A: 17–20 in Callopanchax [data from Wildekamp & Van der Zee 2003]), origin of dorsal fin posterior to origin of anal fin versus origin of dorsal and anal fin nearly at the same level in Callopanchax ; body brown to reddish brown, in males with metallic blue to blue-greenish on sides, only rarely red pigmentation (mainly in some populations of A. guineense , in N. petersi and N. viridis ) and no red submarginal stripes in dorsal and upper caudal fin versus an intensive blue or green background on side in males with red lines, dots or blotches and red submarginal stripes in all unpaired fins in Scriptaphyosemion , except for a red margin on anal fin instead of a red submarginal stripe in some populations.

Included species. Nimbapanchax jeanpoli ( Berkenkamp & Etzel, 1979) , N. leucopterygius new species, N. melanopterygius new species, N. petersi ( Sauvage, 1882) , and N. viridis ( Ladiges & Roloff, 1973) .

Distribution. With the exception of N. petersi , which inhabits the coastal plain in southeastern Ivory Coast and southwestern Ghana, all remaining species are found around the Mount Nimba region in southeastern Guinea, northern Liberia, and western Ivory Coast in the upper region of the coastal rivers drainage systems (Mano to Sassandra Rivers) ( Fig. 1 ) ( Berkenkamp & Etzel 1979; Etzel 1974a, b, 1992, 1993; Huber 1982, 2000; Paugy et al. 1990; Teugels et al. 1988; Wildekamp & Van der Zee 2003).

Etymology. Named after the Mount Nimba region, around which most of the included species are found, in combination with Panchax Valenciennes in Cuvier and Valenciennes, 1846, a junior synonym of Aplocheilus McClelland, 1839 , an aplocheiloid genus, often used in the last century for several African species as common name. Gender masculine.

Remarks. We erect Nimbapanchax as new genus to include all former Archiaphyosemion species except the type species of Archiaphyosemion Radda, 1977 , A. guineense ( Daget, 1954) , because the molecular data, supported by morphology, indicate that the latter is only distantly related to the species included in the new genus. The monophyly of Archiaphyosemion in the current usage is not supported and the former ' Roloffia ' group is represented in the molecular genetic data by four distinct lineages where Archiaphyosemion is the sister group to Scriptaphyosemion and Callopanchax , and Nimbapanchax probably the sister group to a clade formed by these three genera.

Figures

FIGURE 1. Distribution map of Archiaphyosemion and Nimbapanchax: A. guineense collections are indicated by a grey circle, N. petersi by a black circle, N. jeanpoli by a grey square, N. viridis by a black square, N. leucopterygius by a grey triangle, and N. melanopterygius by a black triangle. The actual species distribution will in fact be broader based on records not associated with vouchered specimens.