Aphyosemion pusillum 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 : 18-19

Aphyosemion pusillum Chirio, Legros & Agnèse sp. nov.

urn:lsid:zoobank.org:act:529ADFCC-1E00-4715-A157-1281E749DE48

Fig. 5 E–F, Table 6

Etymology

The specific epithet refers to the small size of this species.

Material examined

Holotype

GABON: adult ♁, 28.5 mm SL (33.8 mm TL), bridge on Okoyo River , 0.55590 S, 9.21322 E, 10 m a.s.l., field reference code CHRSP4 - Okoyo, 1 Mar. 2016, Laurent Chirio leg. ( MRAC 2016-019 -P-57).

Paratypes

GABON: 2 ♁♁, 24.5–24.8 mm SL, same collection data as for holotype ( MRAC 2016-019-P-58-59); 4 ♁♁, 20.6–23 mm SL, bridge on Pembé River, 0.61282 S, 9.15650 E, 5 m a.s.l., field reference code CHRSP 4-Pembé, 1 Mar. 2016, Laurent Chirio leg. ( MRAC 2016-019-P-60-63).

Differential diagnosis

Distinguished from all other species in A. alpha group by two delimited orange zones on body: orange portion on opercle and orange portion above pelvics fins (vs no orange portion) with beige ventral region (vs yellow-orange, white bluish or orange), anal fin orange, blue near basal portion and near submarginal red band, no punctuation (vs never a similar colour pattern). Distinguished from all other species of Chromaphyosemion by alpha-shaped mark on pre- and postopercular region, especially visible on preserved specimens (vs no alpha-shaped mark, only some red macules).

Colouration of live males ( Fig. 5E )

FLANKS AND VENTER. Flanks beige with two dark lateral stripes, two lines of small red dots from opercle to caudal peduncle. Ventral region beige with some blue iridescent scales between end of anal fin and caudal peduncle, orange portion above pelvics fins. Dorsal region light brown, two rows of paradorsal copper scales from operculum to caudal peduncle with two lines of red dots.

HEAD. Beige with premaxilla brown, mandible yellow orange with black lower lips, brown supraorbital region, beige infraorbital region with black macule, postorbital region beige with one black macule, beige preopercle with one black macule, opercle yellow orange in background with orange zone with four black macules; black macules on pre- and postopercular region reveal incomplete alpha-shaped mark.

FINS. Dorsal fin orange, yellowish on edge of fin, blue on posterobasal portion of fin, rows of carmine red dots between rays, red streaks on edge of fin, orange acumen on apex. Anal fin orange, blue near basal portion of fin and near submarginal band, regular red submarginal band, yellow green marginal band, small orange acumen. No punctuation. Caudal fin blue with beginning of upper and lower lobes light orange, red dots on upper part of fin, long red streaks on upper and median regions, red regular submarginal band, blue marginal band, orange acumens. Pelvic fins orange without punctuation, blue near submarginal band, submarginal red band and yellow green marginal band. Pectoral fins translucent.

Colouration of live females

Unknown

Character N HT Min Max Mean SD D 7 10 9 12 10.43 0.98 A 7 11 11 14 12.29 1.11 D/A 7 0 0 2 1.43 0.98 26.14 L.L. 7 27 (+2) 24 (+2) 27 (+3) 1.21 (+0.49) (+2.29) pDor 7 13 13 15 13.57 0.79 TRAV 7 8 7 8 7.43 0.53 S.L. 7 28.5 20.6 28.5 23.59 2.68 T.L. (%) 7 119 114 122 117.72 2.6 P.D. (%) 7 56 56 61 58.08 2.52 P.A (%) 7 65 57 65 60.48 2.99 P.V.(%) 7 52 43 52 47.3 3.19 Ht (%) 7 21 13 21 16.63 2.44 dcp (%) 7 11 7 13 10.29 1.84 Hd (%) 7 27 27 36 30.27 3.15 I.O. (%) 7 14 12 15 13.91 1.16 Eye (%) 7 6 6 9 7.53 0.99

Colouration of ethanol preserved males ( Fig. 5F )

FLANKS AND VENTER. Grey with three incomplete lines of red dots, venter beige with orange portion, white lower part, two grey lateral stripes. Two rows of paradorsal red scales in grey dorsal region from operculum to caudal peduncle.

HEAD. White mandible with black lower lips, white infraorbital region with black macule, white preopercular region, orange opercle; one dark macule in postopercular region.

FINS. Dorsal fin grey with rows of grey dots between rays. Anal fin with grey area on basal portion. Caudal fin grey with some red streaks on upper lobe, red dots in median portion.

Colouration of preserved females

Unknown.

Distribution and habitat

This small species has been found at only two localities in the Okoyo and Pembé Basins ( Table 1 , Fig. 1 ) and never elsewhere. The species seems to be endemic to these two small, coastal hydrographic basins, situated just north of the Wézé drainage. In the Okoyo Basin, A. pusillum Chirio, Legros & Agnèse sp. nov. was found out of the main course of the river, in small, muddy streams less than 1 m wide. In the Pembé Basin, it was found directly in the course of this small river, hidden among dead leaves and water plants, in quiet places. This species was found in syntopy with an undescribed species of Aphyosemion , two undescribed species of Epiplatys and an undescribed species of Plataplochilus .

Figures

Fig. 5. A–D. Aphyosemion barakoniense Chirio, Legros & Agnèse sp. nov. A. Adult, ♁, from locality 7, not preserved. B. Adult, ♀ from locality 7, not preserved. C. Holotype, adult, ♁, from the lower Barakonié River (MRAC 2016-019-P-19). D. Paratype, adult, ♀, from the lower Barakonié River (MRAC 2016-019-P-20-36). E–F. A. pusillum Chirio, Legros & Agnèse sp. nov. E. Adult, ♁, from locality 10, not preserved. F. Holotype, adult, ♁, from the Okoyo River (MRAC 2016-019-P-57).

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.