Nemacheilus paucimaculatus, Bohlen & Šlechtová, 2011

Bohlen, Jörg & Šlechtová, Vendula, 2011, Nemacheilus Paucimaculatus, A New Species Of Loach From The Southern Malay Peninsula (Teleostei: Nemacheilidae), Raffles Bulletin of Zoology 59 (2), pp. 201-204 : 201-203

Nemacheilus paucimaculatus , new species

( Fig. 1 , 2 , 3 )

Material examined. – Holotype: ZRC 52361, 47.1 mm SL, Malaysia: Johor, tributary of Segamat River upstream of Segamat , 02º28'47"N 103º05'13"E, coll. J. Bohlen & V. Šlechtová, 4 Mar. 2006.

Paratypes: CMK 22255, 1 ex., 43.0 mm SL ; IAPG A1742-1743 , 2 ex., 37.4–43.7 mm SL, locality data as for holotype . ZRC 2063 , 35 ex., 28.7–52.4 mm SL, Malaysia: Negeri Sembilan, Sungai Jelai, 14 th mile along road from Tampin to Kuala Pilah , about 2°37'N 102°16'E, coll. M. Dali & C. K. Quek, 29 Apr. 1967 .

Additional material: ZRC 489 , 5 ex., 46.9–61.5 mm SL, Malaysia: Selangor, Ulu Langat, Dusun Tua , about 3°08'N 101°50'E, coll. J. I. Furtado, 6 Nov.1963 .

Diagnosis. – Nemacheilus paucimaculatus is distinguished from all congeners except N. arenicolus by its colour pattern of 8–10 dark brown dorsal saddles and 8–10 dark brown blotches, each larger than eye, along the lateral midline (vs. 10–19 blotches, a stripe or a marbled pattern in other species). It is distinguished from N. arenicolus by the presence of a dark blotch on the first rays of the dorsal fin (vs. absence) and the presence of scales on the whole body (vs. restricted to few rows along lateral line in the anterior part of body).

Description. – General body shape as in Figs. 1 , 2 . Morphometric data as in Table 1. A moderately sized

nemacheiline loach, largest known size 61.5 mm SL. Body elongate, anterior part only slightly compressed; caudal peduncle compressed; head slightly compressed. Body slender, maximum body depth at origin of dorsal fin. Caudal peduncle elongate, its height 1.3–1.9 times in its length and 1.4–1.9 times in body depth at dorsal-fin origin. No adipose crest on dorsal or ventral midline of caudal peduncle. Axillary pelvic lobe present and free.

Dorsal fin with 4 simple and 9½, rarely 10½ branched rays. Distal margin of dorsal fin straight. Anal fin with 3 simple and 5½ branched rays, not reaching caudal-fin base. Caudal fin with 9+7 (three out of 30 counted specimens), 9+8 (26 specimens) or 10+8 (one specimen) branched rays, deeply forked, lobes pointed and of same length. Pelvic fin with 8 rays; origin under last unbranched or first branched dorsalfin ray; reaching slightly beyond half of distance to anal-fin origin; not reaching anus, which is situated about one eye diameter in front of anal fin. Pectoral fin with 11 or 12 rays, reaching slightly behind half of distance between bases of pectoral and pelvic fins.

Body completely covered with scales except between base of pectoral fins. Complete lateral line with 90–102 pores. Cephalic lateral line system with 5 supraorbital, 4+11 infraorbital, 9 pre-operculo-mandibular and 3 supratemporal pores.

Anterior nostril pierced in front side of a flap-like tube, with low anterior rim. Mouth gape arched, about twice as wide as long ( Fig. 3 ). Lips and barbels covered with unculi. Processus dentiformis present. Lips moderately thick; upper lip without median incision; 5–9 deep furrows in median part, papillae on remaining parts of lip. Lower lip with a small median interruption and 3–5 furrows on each side. Inner rostral barbel reaching behind corner of mouth, outer rostral and maxillary barbels reaching behind vertical through posterior rim of eye.

Sexual dimorphism. – Males with finger-shaped suborbital flap under the eye and thickened first branched pectoral-fin ray. Smallest male specimen with enlarged suborbital flap 36.9 mm SL.

Coloration. – In 70% ethanol: Ground colour light yellow, lighter on ventral side than on dorsal side. Dorsal half of

head light grey, ventral half light yellow. A row of 8–10 dark brown blotches along lateral midline of body. In a few specimens blotches vertically elongated. Blotches usually as large as, or larger than eye and of same width or wider than interspaces. A thin black line sometimes visible along lateral midline in the porsterior part of the body. Eight to ten dark brown saddles, wider than interspaces present along dorsal midline; saddles frequently ventrally elongated and conjoined with lateral blotches. Black spot at base of caudal fin surrounded by a whitish area. Head with following dark grey markings: dorsal blotch in front of nape, band between eyes and band between nostrils. Indistinct band from the snout to about two-thirds of distance to eye and horizontal band on opercle present on sides of head. Small black spot on anterior part of dorsal fin close to base, usually smaller than pupil and located between third unbranched to first branched ray. First branching point of branched dorsal-fin rays with pigmentation; resulting in a faint dark row of spots about midway along dorsal fin. In few specimens, second row of pigmented zones appears along second branching point of branched dorsal-fin rays. Dark grey pigment along uppermost and lowermost branched caudal-fin ray and first branched pectoral-fin ray. All other fins hyaline.

Distribution. – Known currently from three localities in the basins of Muar and Langat in Johor, Selangor and Negeri Sembilan in southern Peninsular Malaysia.

Etymology. – The name is derived from the Latin prefix ‘ pauci’, meaning ‘having few’ and the Latin ‘macula’, meaning ‘blotches’, referring to the comparably low number of lateral and dorsal blotches.

Figures

Fig. 1. Nemacheilus paucimaculatus, ZRC 52361, holotype, 47.1 mm SL, Malaysia: Johor, tributary of River Segamat.

Fig. 2. Nemacheilus paucimaculatus, A, B ZRC 52361, holotype, 47.1 mm SL, Malaysia: Johor, tributary of River Segamat; C CMK 22255, 43.0 mm SL, same data as A; D ZRC 2063, 52.4 mm SL, Malaysia: Negeri Sembilan, Sungai Jelai; E ZRC 2063, 44.4 mm SL, same data as D.

Fig. 3. Nemacheilus paucimaculatus, ZRC 52361, holotype, 47.1 mm SL; mouth, ventral view (scale bar = 5 mm).