Aphyosemion mandoroense, Van Der Zee & Walsh & Boukaka Mikembi & Jonker & Alexandre & Sonnenberg, 2018

Van Der Zee, Jouke R., Walsh, Gina, Boukaka Mikembi, Valdie N., Jonker, Michiel N., Alexandre, Marco P. & Sonnenberg, Rainer, 2018, Three new endemic Aphyosemion species (Cyprinodontiformes: Nothobranchiidae) from the Massif du Chaillu in the upper Louessé River system, Republic of the Congo, Zootaxa 4369 (1), pp. 63-92 : 76-79

Aphyosemion mandoroense , new species

( Figs 10–11 ; Table 6)

Holotype. AMNH 263405 , male, 34.0 mm SL, Republic of the Congo, Mandoro River, swamp forest flood benches, tributary of the Louessé River, Niari River drainage (2°25'27" S, 12°53’19" E), collection locality OS9, field label M311, collected by G. Walsh, M. Alexandre & V. Boukaka Mikembi, 11 November 2013.

Paratypes. AMNH 262592, 1 male, 37.1 mm SL, collected with the holotype; AMNH 262591, 2 males, 24.3– 26.8 mm SL, Republic of the Congo, Mandoro River, recently flooded swamp forest flood bench, field code OS2, field label M298, G. Walsh, M. Alexandre & V. Boukaka Mikembi, 26 November 2013; AMNH 262590, 3 males 24.3–26.4 mm SL and 1 female, 37.5 mm SL, Republic of the Congo, about 1.5 km south of the village of Lisoukou (10 km south of Mayoko) on the road R1 to Mossendjo, Leyou River, tributary of the Mandoro River, tributary of the Louessé River, Niari River drainage, field code M27, field labels M268 & M274, G. Walsh, M. Alexandre & V. Boukaka Mikembi, 22 October 2013; AMNH 262593, 2 males, not measured, Republic of the Congo, tributary of Mandoro River, field code M21S, G. Walsh, M. Alexandre &, V. Boukaka Mikembi, 18 October 2013.

Diagnosis. ( Figs 10–11 , Table 6) Males of ‘ A ’. mandoroense are distinguished from all other Aphyosemion s.l. species by the lack of red pigmentation on its fins, except for the posterior margin of the dorsal fin in some specimens. DNA data ( Fig. 4 ) and male colour pattern place it into the ‘ A ’. coeleste group.

‘ Aphyosemion ’ mandoroense can be distinguished by its diagnostic male colouration pattern from all other species of the ‘ A ’. coeleste group by the nearly complete absence of red in unpaired fins, versus red margins or submarginal stripes in all other species except ‘ A ’. ocellatum, which shows faint red areas in the unpaired fin centre of some individuals. The new species is distinguished from all other species except ‘ A ’. ocellatum and ‘ A ’. passaroi by its dark grey to black margins of unpaired fins. It is distinguished from ‘ A ’. passaroi by the nearly complete absence of red in fins, blue side and opercule versus basal broad red stripe in anal fin and orange to brownish or pinkish side and opercule.

‘ Aphyosemion ’ mandoroense is distinguished from the ‘ A ’. ocellatum populations with blue sides by the three or four rows of red dots on anterior side, the light blue opercule versus a dark red blotch posterior to operculum, and yellow or orange operculum, and from those with a more brownish to orange body colour by the blue side colour, absence of dark red blotch posterior to operculum and blue operculum. ‘ Aphyosemion ’ ocellatum in addition has darker and broader fin margins on pelvic, anal, dorsal, and upper and lower caudal fin.

The superficially most similar ‘ A ’. citrineipinnis and ‘ A ’. ocellatum also have a reduced red pigmentation on fins, but usually at least traces of a red stripe at the base of the anal fin is present. Base of anal fin in ‘ A ’. citrineipinnis blue, central to distal part yellow versus completely yellow in ‘ A ’. mandoroense . Unpaired fin margins in ‘ A ’. mandoroense dark grey to black versus no or very narrow dark fin margin in ‘ A ’. citrineipinnis. Many ‘ A ’. citrineipinnis populations usually show a prominent "wound mark", a group of dark red scales just behind the operculum, that is always absent in ‘ A ’. mandoroense , which shows three or four rows of red dots on the anterior side above the pelvic fin. The operculum is light blue in ‘ A ’. mandoroense versus yellow to orange in ‘ A ’. citrineipinnis. In ‘ A ’. mandoroense , the yellow colour of the caudal fin is extended in the dorsal and ventral edge of the caudal peduncle, versus no yellow on caudal peduncle in ‘ A ’. citrineipinnis. In ‘ A ’. mandoroense , the dorsal fin inserts more posteriorly than in ‘ A ’. citrineipinnis (D/A = 1/10–11 versus 1/ 7 –8).

Description. See Figures 10–11 for general appearance and colour pattern and Table 6 for morphometric data of type series. Largest observed specimen in type series 37.1 mm standard length. Strong sexual dimorphism, adult males more colourful than females and have larger unpaired fins.

Dorsal profile straight or slightly convex, greatest body depth at base of pelvic fin, ventral profile slightly convex. Caudal peduncle dorsally and ventrally slightly concave. Snout rounded, mouth directed upwards, lower jaw longer then upper jaw, posterior end of rictus at level of dorsal third of eye.

Frontal neuromasts in two separate grooves, pre-opercular, pre- and post-orbital system with tubular canals. Two rather wide supra-orbital grooves (13.9–15.0 % of inter-orbital width, Table 6) with three neuromasts each.

Teeth on jaws unicuspid, outer row large and inward curved, inner teeth smaller and more irregularly placed. Scales cycloid, body completely scaled except ventral head surface. Frontal squamation of G-type. No scales on dorsal and anal fin base, two to three scale rows on caudal fin base, two scale rows beneath the eye; scales on mid longitudinal series 31–32; transverse series of scales before dorsal fin nine; circumpeduncular scale row 14. All unpaired fins rounded in males, no elongated rays at the caudal fin edges; caudal fin posterior margin rounded. Number of dorsal fin rays 11–12, anal fin rays 16–17; first dorsal fin ray above anal fin ray 10–11. Pectoral fin just reaching pelvic fin, pelvic fin not reaching anal fin.

Live colouration. Males ( Fig. 10 ). Side of body and operculum light blue. Lips and throat bright lemon to yellow. Dorsal side yellow brown, ventrally yellow. Majority of scales on anterior, approximately dorsal half of side with small red spot forming up to four rather regular horizontal lines, posterior scales with faint reddish margin forming weak reticulated pattern. Three red streaks on operculum typical for Aphyosemion s.l. (Van der Zee 2002) reduced or absent. All fins bright yellow. Dorsal fin with narrow grey margin, becoming red on tip and posterior four fin rays. Caudal fin with broad grey posterior margin, anal fin with narrow dark grey margin. Iris greyish with some metallic blue areas, central part surrounding black pupil has narrow yellowish to whitish ring.

Females ( Fig. 11 ). Body light brown to grey-brownish, dorsally darker and ventrally light brown, with golden hue dorsally. Pre-operculum light, sometimes almost whitish, operculum with many melanophores. Lips and sometimes chin yellow. Scales on sides, especially along the anterior lateral line, with a dark border, forming a reticulated pattern. Most scales on dorsal half of sides with a very small red dot at the transition of two scales.

Dorsal fin hyaline with numerous red dots, in some female’s dorsal fin with narrow dark edge, last four fin rays with red edge. Anal fin hyaline, unspotted, sometimes with red hue. Caudal hyaline, unspotted, membrane between the first three to four dorsal and ventral fin rays red. Pelvic and pectoral fins hyaline, unspotted.

After 3 months in 70 % ethanol. Males. Side and dorsal grey with sharp transition to unpigmented light ventral anterior to the anal fin. Head dorsally dark grey with a sharp transition to whitish ventrally on head and throat. Lips grey. All fins except caudal fin hyaline, unspotted. Caudal fin hyaline with broad dark grey posterior edge and dark blotch at base; inter-radial membrane of centre four to five fin rays with dark spots.

Females. Side grey with gradual transition to light grey ventrally. No sharp transition of dark dorsal and light ventral of head as in males. All scales with a dark margin, most pronounced along lateral line. Pectoral fins hyaline, all other fins with many very small dark spots on inter-radial membrane. Dorsal fin with red spots, anal and caudal fin unspotted. Caudal fin with red markings at dorsal and ventral insertion.

Distribution and habitat. ‘ Aphyosemion ’ mandoroense is currently only known from the tributaries of the upper Mandoro River (Louessé basin) in south-western Congo, where it occurs sympatric and sometimes syntopic with ‘ A ’. coeleste or ‘ A ’. cryptum , new species. In the Leyou River it occurs syntopic with ‘ A ’. coeleste and ‘ A ’. cyanoflavum .

Etymology. The species is named after the Mandoro River, a tributary of the Louessé River in the southern Massif du Chaillu in the Republic of the Congo.

Figures

FIGURE 4. Phylogenetic results of the cytochrome b data for the ‘A’. coeleste group. Bayesian analyses (BA): numbers at nodes represent posterior probability values for both analyses (NST2/NST6). All trees are rooted with M.cameronense (CAM 262). Sample abbreviations are given in Table 1.

FIGURE 10. ‘Aphyosemion’ mandoroense, male, 34.0 mm SL, holotype, AMNH 263405.

FIGURE 11. ‘Aphyosemion’ mandoroense, female, 37.5 mm SL, paratype, AMNH 262590.