Hylopanchax leki, 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 : 40-42

Hylopanchax leki , new species

( Figs. 6–8 , Table 1 )

Holotype. ZSM 40764 (ex ZSM 29615), male, 26.6 mm SL, Democratic Republic of Congo, Province Bandundu, stream at Lompolé and Yaka (02° 34' S, 20° 14' E), U. Schliewen, 28–29 July 2002.

Paratypes. ZSM 40765 (ex ZSM 29615), 4 males and 5 females, 21.9–29.0 mm, collected with the holotype.

Diagnosis. Placed in Hylopanchax based on the diagnostic characters given above. Distinguished from all other Hylopanchax species except for Hylopanchax ndeko , new species, by the position of the dorsal fin (D/A = 8– 10 versus D/A = 11–14), the number of dorsal fin rays (11–13 versus 6–9), the number of pectoral fin rays (11 –13 versus 8–10), the number of transversal scales (19–20 versus 15 or 16) by its deep body (29.2–35.5 % SL versus 16.3–25.6 % SL), by the low caudal peduncle ratio (1.2–1.7 versus 1.6–2.4), and by having 2 or 3 rows of scales underneath the eye versus 1 row of scales. Longer dorsal spines of vertebrae at mid-body versus short dorsal spines with lower length differences between mid-body and anterior or posterior spines. Distinguished from Hylopanchax ndeko , new species, by having fewer scales in the longitudinal series (mode 22, range 21–23 versus mode 25 and 24–26), prominent lobes of the supra-temporal neuromast system and male colour pattern ( Figs. 6 & 7 ). Snout, lower jaw, and anterior part of throat dark orange versus yellow snout and lower jaw and white throat in H. ndeko , new species; flanks just below dorsal fin with orange shine versus purple shine, dorsal and anal fin dark orange versus yellow anal and dorsal fin with a red distal submarginal stripe and a nearly transparent margin, white edged caudal fin olive brown with orange shine versus white edged blue caudal fin.

Description. See Figures 6 and 7 for general appearance and Table 1 for morphometric and meristic data of the type series. A large and deep Hylopanchax species, laterally strongly compressed; dorsal profile convex, slightly concave at nape; greatest body depth between pelvic and anal fin; ventral profile convex from head to end of anal fin; snout rounded, mouth directed upwards; lower jaw longer then upper jaw; on both jaws an outer row of larger, slightly curved conical teeth, 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, covering a great part of the groove; pre-opercular neuromast system with 5 pores; lobes of supra-temporal neuromast system very prominent, even visible with the naked eye. A µCT scan of two specimens showed the following characters: total number of 30 vertebrae, hypurals fused to one hypural plate, ten caudal fin rays attached to hypural plate, posterior neural and hemal spines flattened, the top of the latter fused to hypural plate ( Fig. 8 ). Scales cycloid, body completely scaled except ventral head surface, two to three rows of scales underneath the eye, frontal squamation of G-type, no scales on dorsal and anal fin base, scales on mid longitudinal series 21–23. Number of dorsal fin rays 11–13, anal fin rays 18–20, caudal fin rays 24–27, pelvic fin rays 6, pectoral fin rays 11–13. First dorsal fin ray above anal fin ray 8–10.

Colouration. Live specimens. Males ( Fig. 6 ). Back olive brown changing to orange below dorsal fin, flanks silverish with light green shine, changing to white on ventral side, snout and lower jaw orange. Flanks with four to five rows of scales anteriorly edged with black crescent shaped markings. Median fins and pelvic fins orange. Caudal fin with posterior white edge. Pectoral fins translucent. Narrow black band along base of anal fin. Urogenital papilla black.

Females. No information on live colouration available.

Preserved in ethanol. Males ( Fig. 7 ). Back brown, flanks light brown, ventrally edged with a band of black pigmentation, ventral side below this band whitish. Snout dark brown. Black pigmentation on flanks and anal fin as in live specimens. Pectoral fins translucent, all other fins greyish, caudal fin with posterior white edge.

Females ( Fig. 7 ). As males, less black pigmentation on flanks, black band at base of anal fin hardly visible, urogenital opening round, edged with small black spots.

Distribution. Hylopanchax leki is currently only known from the type locality, a small shady stream at Lompolé at the right bank of the Lokoro River, Salonga National Park, central Congo basin ( Fig. 1 ). Syntopic species: Barbus sp. aff. hulstaerti/papilio, Aphyosemion sp. and Congochromis cf. sabinae .

Etymology. The species name “ leki ” is the Lingala word for the “smaller or younger sibling”, referring to the fact that the species is the slightly smaller one of the sibling species pair described herein, the larger being Hylopanchax ndeko , new species of the left bank of the Lokoro river. 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 6. Male of Hylopanchax leki, photographed shortly after capture, stream between Lompolé and Yaka, Province Bandundu, Democratic Republic of Congo. Photographed by U. Schliewen, 28 July 2002.

FIGURE 7. Hylopanchax leki, male holotype (top), ZSM 40764, 26.6 mm SL, female paratype (bottom), ZSM 40765, 23.0 mm SL.

FIGURE 8. CT scan of Hylopanchax leki, non paratype, ZSM 49745, 22.2 mm SL.

Tables

TABLE 1. Morphometrics and meristics of Hylopanchax leki, new species, for 5 males (♂) and 5 females (♀). Morphometrics as percentage of standard length (SL). Standard length in mm. Abbreviations: TL = total length, BD = body depth, HL = head length, ED = eye diameter, IO = inter-orbital space, PD = pre-dorsal length, PA = pre-anal length, PP = pre-pelvic length, CL = caudal peduncle length, CH = caudal peduncle height, CR = caudal peduncle ratio, AB = anal fin base length, DB = dorsal fin base length, LS = number of longitudinal scales, TS = number of transversal scales, D = number of dorsal fin rays, A = number of anal fin rays, D / A = position of first dorsal fin ray relative to the opposite anal fin ray, C = number of caudal fin rays, P = number of pectoral fin rays.

Holotype ♂ TL 32.4	Paratype ♂ 35.4	Paratype ♂ 33.8	Paratype ♂ 34.6	Paratype ♂ 27.8	Paratype ♀ 35.9	Paratype ♀ 31.5	Paratype ♀ 28.3	Paratype ♀ 29.0	Paratype ♀ 27.8
SL 26.6 BD 30.5 HL 22.6	29.0 35.5 22.8	28.3 34.3 22.6	27.9 32.3 23.3	22.1 32.1 26.2	28.4 29.2 22.5	25.5 30.2 22.7	22.5 33.8 25.8	23.0 32.6 25.2	21.9 31.5 25.6
ED 8.3 IO 10.9 PD 63.1	9.3 11.7 63.4	9.2 11.7 61.8	9.0 11.1 65.2	11.3 12.7 64.7	8.5 12.0 65.8	9.8 11.4 65.0	11.1 12.4 65.3	11.3 12.2 65.2	14.2 12.8 65.2
PA 51.1 PP 37.2 CL 18.8	51.0 37.6 19.7	53.3 37.8 19.8	50.9 38.4 19.0	52.0 38.5 19.0	60.6 40.5 21.5	56.1 39.2 23.1	53.8 39.1 20.9	57.8 42.2 18.7	52.9 29.3 19.6
CH 14.7 CR 1.3 AB 27.8	14.8 1.3 26.2	14.8 1.3 26.9	14.7 1.3 29.7	15.4 1.2 26.7	14.0 1.6 18.7	13.7 1.7 20.4	15.1 1.4 24.0	14.8 1.2 24.3	15.5 1.3 25.1
DB 21.4 LS 22 TS 20	20.3 21 19	17.7 22 19	20.4 22 19	19.5 23 20	22.2 23 20	16.5 21 20	16.0 21 19	15.6 22 20	17.8 22 20
D 13 A 19 D/A 8	13 20 10	? 18 9	12 19 10	12 18 9	13 19 9	12 18 9	12 19 9	11 20 10	13 20 9
C 26 P 12	26 12	25 11	25 12	25 12	27 13	25 13	26 13	24 13	26 13