Hylopanchax moke, Van Der Zee, Jouke R., Sonnenberg, Rainer & Schliewen, Ulrich K., 2013

Van Der Zee, Jouke R., Sonnenberg, Rainer & Schliewen, Ulrich K., 2013, Description of three new species of Hylopanchax Poll & Lambert, 1965 from the central Congo Basin (Cyprinodontiformes: Poeciliidae: Procatopodini) with a redefinition of the genus, Zootaxa 3701 (1), pp. 35-53 : 46-50

Hylopanchax moke , new species

( Figs. 12–14 , Table 3)

Holotype. ZSM 40768 (ex ZSM 29750), male, 20.8 mm SL, Democratic Republic of Congo, Bandundu Province, streams and small rivers around Lui Kotale (02° 45' S, 20° 22' E), U. Schliewen, 23–27 July 2002.

Paratypes. ZSM 40767 (ex ZSM 29750), 1 male and 2 females, 17.3–21.1 mm SL, collected with the holotype; ZSM 41386 (ex ZSM 29737, [25, now 24]), 1 female, streams and rivers around Lui Kotale, U. Schliewen 23–27 July 2002; MRAC 102524 –533, 5 males and 5 females, 17.3–20.2 mm SL, Democratic Republic of Congo, fôret marécageuse de la Lotende, Liombo, terr. de Bikoro, G. Marlier (I.R.S.A.C.), 6 October 1955. The geographic coordinates given for the MRAC paratypes were not correct, since they are located in Lake Tumba. G. Boden (RMCA) did some research and found a village Liombo just east of Bikoro (right bank of Lake Tumba) on the left bank of an unnamed river (ca. 0° 46’ S, 18° 10’ E). It is assumed that this is indeed the locality where the paratypes were collected.

Non-type. AMNH 252241, 1 specimen of undetermined sex, Democratic Republic of Congo, Baupanda Bomsito, small creek near Monkoto, not in Salonga National Park (1° 45' 00.31'' S, 20° 41' 36.72” E), R. Monsembula, 28 May 2010 (only studied from digital photographs).

Diagnosis. Placed in Hylopanchax based on the diagnostic characters given above for the genus. Distinguished from all other Hylopanchax species by its extreme slender body (body depth in % of SL: 16.3–20.0 versus 20.8– 35.5 in other Hylopanchax species [ Fig. 15 ]), and small size of mature specimens (max. SL 21.2 mm). Back almost straight and almost no difference in body depth between pectoral fin and anal fin versus convex back and greatest body depth always between pelvic and anal fin in other species.

Description. See Figures 12 and 13 for general appearance and Table 3 for morphometric and meristic data of the type series. A very small Hylopanchax species, moderately laterally compressed. Dorsal profile almost straight to slightly convex. Body depth almost the same between pectorial and anal fin; ventral profile slightly convex from head to end of anal fin; snout very short and straight in dorsal view, mouth directed upwards, lower jaw longer then upper jaw; on both jaws small slightly curved conical teeth, the outer row larger, inner teeth row more irregular arranged with smaller teeth; symphysis forming a ridge on lower and less on upper jaw; branchiostegal appendages present in adult males. Frontal or nasal neuromasts not present, one pre-orbital neuromast in short shallow open groove; post-orbital and supra-orbital neuromast system provided with large neuromasts and large lobes, preopercular neuromast system with 5 pores. A µCT scan of three specimens showed the following characters: a total number of 31 vertebrae, hypurals fused to one hypural plate, ten caudal fin rays attached to hypural plate, posterior neural and hemal spines thickened ( Fig. 14 ). Scales cycloid, body completely scaled except ventral head surface, one row of scales underneath the eye, frontal squamation of G-type, no scales on dorsal and anal fin base, scales on mid longitudinal series 23–26. Number of dorsal fin rays 6 or 7, anal fin rays 15–17, caudal fin rays 20–24, pelvic fin rays 6, pectoral fin rays 8–10. First dorsal fin ray above anal fin ray 11–14.

Colouration. Live specimens. Males ( Fig. 12 ). Back greyish brown, becoming gradually lighter towards ventral side. Flanks with two to three rows of scales anteriorly edged with black crescent shaped markings. Third (ventral) row sometimes vague or missing. Median fins yellowish with broad transparent blue margin, pelvic fin yellowish, pectoral fins translucent. Anal fin with broad dark outer edge and narrow black band at base. Urogenital papilla black.

Females. Body colour as males. All fins translucent.

Preserved in ethanol. Males ( Fig. 13 ). Brownish, body and anal fin pigmentation as in live specimens, all other fins translucent.

Females ( Fig. 13 ). Body and fins as in males.

Distribution. Hylopanchax moke is known from the western part of the central Congo Basin (“Cuvette”) between the Tshuapa and Kasai Rivers, Bandundu Province, Democratic Republic of Congo ( Fig. 1 ). It was found in calmer parts of larger forest streams.

Etymology. The species name “ moké ” is the Lingala word for “very small”, referring to the minute size of this species. A noun in apposition.

Figures

FIGURE 1. Collection point map of Hylopanchax based on specimens and data from the collections of the AMNH, ANSP, CAS, CUMV, MNHN, MRAC, SMF, ZFMK, and ZSM. Additional data are from Huber (2007) and R. Numrich (pers. comm.). Type localities are indicated by a capital T and numbered: T 1 = H. stictopleuron, T 2 = H. silvestris, T 3 = H. leki, T 4 = H. ndeko, T 5 = H. moke. Collection points of Hylopanchax species are indicated by the following symbols: olive circle = H. stictopleuron, light grey circle = H. silvestris, red square = H. leki, blue square = H. ndeko, light green triangle = H. moke, dark green triangle = H. sp. aff. moke, dark grey circle = H. sp. Cameroon, black circle = H. sp. Gabon, yellow square = H. sp. Odzala, pink circle = Hylopanchax collection, specimens not studied.

FIGURE 12. Male of Hylopanchax moke, male from a commercial import of ornamental fish into the USA in 2011. Photographed by Tony Terceira.

FIGURE 13. Hylopanchax moke, male holotype (top), ZSM 40768, 20.8 mm SL, female paratype (bottom), ZSM 40767, 19.6 mm SL.

FIGURE 14. CT scan of Hylopanchax moke, male holotype, ZSM 29750, 20.8 mm SL.

FIGURE 15. Comparison of body depth in % SL of H. moke and similar sized small specimens of other Hylopanchax species.