Lepidocephalus pahangensis ( de Beaufort, 1933 )

Deein, Gridsada, Tangjitjaroen, Weerapongse & Page, Lawrence M., 2014, A revision of the spirit loaches, genus Lepidocephalus (Cypriniformes, Cobitidae), Zootaxa 3779 (3), pp. 341-352 : 348

Lepidocephalus pahangensis ( de Beaufort, 1933)

Pahang Spirit Loach

( Fig. 1D )

Acanthophthalmus pahangensis de Beaufort, 1933:31 . Type locality: off Mentakab, Pahang, Pahang River, Malay Peninsula. Holotype ZRC 490; see Hora (1941:55–56) and Alfred (1970:70).

Diagnosis. A species of Lepidocephalus that is readily distinguishable ( Fig. 1 , Table 1 ) from all other species of Lepidocephalus by the absence of scales on top of the head. It is further distinguished from L. spectrum by the presence of eyes and dark pigment on the body, and absence of tubules along the lateral line; from L. pallens by having the dorsal-fin origin well behind (vs. over) the pelvic-fin origin (predorsal length 68.2 vs. 59.9% SL); from L. nanensis by having large papillae on the lips ( Fig. 3B ); and from L. macrochir by having a longer head (21.8 vs. 16.6–18.8% SL). Although counts for L. pahangensis are available only for the holotype, it differs from all other species in having 4 (vs. 5–6) branched anal-fin rays, and from all except L. spectrum in having 9 (vs. 8) branched dorsal-fin rays.

Description. Body deep, slab-sided; greatest depth 17.0% SL. Head narrow, length 21.8% SL. Eye small, in dorsal half of head in shallow depression above bifid suborbital spine. Origin of dorsal fin behind origin of pelvic fin. Small axillary lobe on pelvic fin. Large fleshy lobe at origin of pectoral fin.

No scales on top of head; scales present on cheek and opercle; body completely covered with minute, partially embedded scales. Lateral line complete, 174 pores along lateral line, 6 pores on caudal fin; no tubules on lateral line. Mouth horseshoe-shaped; lips with large papillae on outer surfaces; upper lip without indentation; lower lip with median indentation on lower edge ( Fig. 3B ). Two pairs of rostral barbels; inner pair reaching to corner of mouth, outer pair reaching past corner of mouth; one pair of maxillary barbels, reaching approximately to vertical at posterior end of groove containing suborbital spine. Large flap on anterior nostril. Dorsal rays iii,9; pectoral rays 11; pelvic rays 7; anal rays ii,4; upper branched caudal rays 7; lower branched caudal rays 7. Pectoral fin falcate with 2 nd ray longer than other rays (15.6% SL), but not thickened. Pelvic fin small, 6.4% SL.

Coloration. Described as being uniformly colored (presumably pinkish gray-brown as in L. nanensis ) by de Beaufort (1933).

Distribution. Known only from the type locality, the Pahang River at Mentakab, Peninsular Malaysia ( Fig. 2 ).

Remarks. In the original description of Acanthophthalmus pahangensis, de Beaufort (1933) described the head as scaleless. The holotype has no scales on top of the head, but has scales on the cheeks and opercles. It seems likely that de Beaufort was referring only to the top of the head in his description, as scales are readily apparent on the cheek and opercle. Hora (1941) examined the holotype and found scales “on the head in the region below and behind the eyes.” Oddly, Hora included a drawing of the head and anterior body of the holotype that differs from his verbal description in showing scales on top of the head as well as on the cheek and opercle. De Beaufort was correct in originally noting the absence of scales on top of the head.

Figures

FIGURE 1. Species of Lepidocephalus. (A) L. nanensis, holotype, NIFI 4388, 72.0 mm SL, Nan River, Thailand; (B) L. macrochir, syntype, BMNH 1866.5.2.55, 77.7 mm SL, Sumatra or Java; (C) L. pallens, holotype, RMNH 7783, 41.9 mm SL; (D) L. pahangensis, holotype, ZRC 490, 35.8 mm SL; (E) L. spectrum, paratype, USNM 230267, 49.2 mm SL, Kalimantan. Photos A, C, D and E by Z. Randall; B by M. Sabaj Perez.

FIGURE 2. Distribution of specimens of Lepidocephalus examined.

FIGURE 3. Mouths of Lepidocephalus. (A) L. nanensis, holotype, NIFI 4388, 72.0 mm SL, Nan River, Thailand; (B) L. pahangensis, holotype, ZRC 490, 35.8 mm SL; (C) L. spectrum, paratype, USNM 230267, 49.2 mm SL, Kalimantan. Photos by Z. Randall.