Hylopanchax ndeko, 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 : 43-46

Hylopanchax ndeko , new species

( Figs. 9–11 , Table 2 )

Holotype. ZSM 29745, male, 28.2 mm, Democratic Republic of Congo, Bandundu Province, Lokoro River drainage, Salonga National Park, Lui Kotale (02° 45' S, 20° 22' E), U. Schliewen, 23–27 August 2002.

Paratypes. ZSM 29766 (ex ZSM 29745), 8 males and 1 female, 16.8–30.0 mm SL, collected with the holotype.

Diagnosis. Placed in Hylopanchax based on the diagnostic characters given above. Distinguished from all other Hylopanchax species except for Hylopanchax leki by the position of the insertion of the dorsal fin (D/A = 8– 11 versus D/A = 11–14), the number of dorsal fin rays (12–14 versus 6–9), the number of pectoral fin rays (12 –13 versus 8–10), the number of transversal scales (18–22 versus 15 or 16), by its deep body (24.3–34.3 % SL versus 16.3–25.6 % SL), by the low caudal peduncle ratio (1.2–1.5 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 leki by having more scales in the longitudinal line (mode 25, range 24–26 versus mode 22 and 21–23) and male colour pattern ( Figs. 6 & 9 ). Snout and lower jaw yellow versus dark orange snout and lower jaw in H. ndeko ; dorsal and anal fin yellow with red distal edges versus dark orange anal and dorsal fin.

Description. See Figures 9 and 10 for general appearance and Table 2 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. 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 ( Fig. 11 ). Scales cycloid, body completely scaled except ventral head surface, 2 or 3 rows of scales underneath the eye, frontal squamation of G-type, no scales on dorsal and anal fin base, scales on mid longitudinal series 24–26. Number of dorsal fin rays 12–14, anal fin rays 18–21, caudal fin rays 24–26, pelvic fin rays 6, pectoral fin rays 12 or 13. First dorsal fin ray above anal fin ray 8–10.

Colouration. Live specimens. Males ( Fig. 9 ). Back olive brown, flanks silverish with blue shine, changing to white on ventral side, snout and lower jaw yellow. Throat white. Flanks with four to five rows of scales anteriorly edged with black crescent shaped markings. Dorsal and anal fins yellow with red edge, pelvic fins yellow with red margin. Caudal fin blue with posterior white edge. Pectoral fins translucent. Narrow black band at base of anal fin. Urogenital papilla black.

Females. No information on live colouration available.

Preserved in ethanol. Males ( Fig. 10 ). 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.10 ). As males, less black pigmentation on flanks, black band at base of anal fin hardly visible, urogenital papilla round, edged with small black spots.

Distribution. Hylopanchax ndeko is currently only known from the type locality. It is found in small shady streams and rivers around Lui Kotale at the left bank of the Lokoro River, southwestern Salonga National Park area, central Congo basin. Syntopic species: Barbus sp. aff. hulstaerti/papilio, Aphyosemion sp. and Congochromis cf. sabinae .

Etymology. The species name “ ndeko ” is the Lingala word for “sibling”, referring to the fact that the species is closely related to Hylopanchax leki of the right bank of the Lokoro river. A noun in apposition.

Figures

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 9. Male of Hylopanchax ndeko, photographed shortly after capture, stream at Lui Kotale, Province Bandundu, Democratic Republic of Congo. Photographed by U. Schliewen, 26 August 2002.

FIGURE 10. Hylopanchax ndeko, male holotype (top), ZSM 29745, 28.2 mm SL, female paratype (below), ZSM 29766, 23.0 mm SL.

FIGURE 11. CT scan of Hylopanchax ndeko, male paratype, ZSM 29766, 30.0 mm SL.

Tables

TABLE 2. Morphometrics and meristics of Hylopanchax ndeko, new species, for 9 males (♂) and 1 female (♀). Morphometrics as percentage of standard length. Standard length in mm. For abbreviations see Table 1.

Holotype Paratype ♂ ♂ TL 35.4 36.5	Paratype ♂ 36.2	Paratype ♂ 34.6	Paratype ♂ 28.0	Paratype ♂ 25.8	Paratype ♂ 22.5	Paratype ♂ 20.7	Paratype ♂ 20.5	Paratype ♀ 28.8
SL 28.2 30.0 BD 32.2 34.3 HL 24.5 22.3	30.0 32.0 23.0	27.5 31.6 24.7	22.1 28.0 24.4	20.3 29.5 23.6	17.7 29.4 24.9	16.8 25.6 20.8	18.9 24.3 22.2	23.0 28.7 24.3
ED 8.9 9.7 IO 11.0 10.3 PD 64.5 64.7	9.0 10.3 61.0	9.5 10.9 62.9	10.0 11.8 64.3	10.8 11.3 66.0	10.7 11.9 65.5	10.1 11.9 62.5	11.1 10.6 66.1	11.3 11.7 67.8
PA 49.3 48.3 PP 33.7 33.7 CL 19.5 20.3	49.0 35.0 18.7	50.9 39.3 18.2	56.1 38.9 18.6	51.2 36.0 17.7	50.3 36.2 19.2	47.6 31.5 20.8	52.9 35.4 19.0	49.4 36.1 16.5
CH 15.2 15.0 CR 1.3 1.4 AB 30.5 29.3	14.7 1.4 30.7	13.8 1.3 28.0	14.0 1.3 28.0	14.8 1.2 29.1	13.6 1.4 28.2	13.0 1.5 24.4	12.2 1.5 24.7	13.9 1.2 24.0
DB 21.6 20.3 LS 24 25 TS 22 21	19.7 26 22	20.4 25 21	18.1 25 21	17.3 26 20	18.6 25 20	17.2? 18	17.9? 20	17.4 24?
D 12 14 A 19 20 D/A 8 9	13 19 9	12 18 10	13 19 9	12 18 10	12 21 11	12 19 9	13 18 9	12 19 10
C 25 26 P 13 13	26 13	25 13	25 12	25 12	24 12	25 12	26 12	25 12