Pangio lidi, Hadiaty, Renny Kurnia & Kottelat, Maurice, 2009

Hadiaty, Renny Kurnia & Kottelat, Maurice, 2009, Pangio lidi, a new species of loach from eastern Borneo, Indonesia (Teleostei: Cobitidae), Zootaxa 2171, pp. 65-68 : 65-68

Pangio lidi , new species

( Figs. 1–2 )

Holotype. MZB 16528, 67.2 mm SL; Indonesia: Kalimantan Timur: Mahakam basin, Ulu Belayan, Sungai Petung Kanan (0°32'06"N 116°10'55"E); D. Wowor & R. K. Hadiaty, 6 June 2008.

Paratype. CMK 20805, 57.2 mm SL; same data as holotype.

Diagnosis. Pangio lidi belongs to the P. anguillaris group, which is diagnosed by its slender body (depth at dorsal-fin origin 14-21 times in SL; 61-71 total vertebrae) and a plain brown body. It is distinguished from all other species of this group by the absence of pelvic fins and fewer vertebrae (41–42 + 17–18 = 59, vs. total 61–71). Further, it has the origin of the anal fin under the base of the dorsal fin (vs. behind in P. bitaimac ), 7+7 branched caudal-fin rays (vs. 6+ 6 in P. d o r i a e), no scales on the cheek (vs. present in P. d o r i a e), and the tube of the anterior nostril developed into a nasal barbel (vs. not developed into a nasal barbel in P. anguillaris ).

Description. General body shape and appearance are shown in Figure 1 . The specimens are strongly arched, so that measurements are difficult to duplicate. Morphometric data of the holotype (listed first) and paratype are given here only with indicative value: total length 73.2, 61.8 mm (108.9, 108.0 % SL); head length 11.0, 12.4 % SL; predorsal length 72.5, 72.6 % SL; preanal length 74.0, 77.6 % SL; body depth at dorsal-fin origin 4.6, 4.7 % SL; length of caudal peduncle 19.9, 19.6% SL; depth of caudal peduncle 3.1, 3.0 % SL (6.4, 6.5 times in its length); body width 3.1, 3.5 % SL; length of pectoral fin 3.4, 4.9 % SL; snout length 3.6, 4.2 % SL, 32.4, 33.8 % HL; eye diameter 0.7, 1.0 % SL, 6.8, 8.5 % HL; interorbital width 1.8, 2.1 % SL, 16.2, 16.9 % HL.

Dorsal fin with 2 rudimentary, 1 simple, 6 branched and 1 unbranched rays, last 2 articulating on same pterygiophore; first pterygiophore inserted behind neural spine of vertebrae 39 or 41. Pectoral fin with 6 or 7 rays. Both specimens probably females as pectoral fins not curled upwards, and second pectoral-fin ray not thicker than other rays. Pelvic fin and pelvic girdle missing (confirmed from radiograph). Anal fin inserted at some distance behind anus, origin under base of first branched dorsal-fin ray, with 2 rudimentary, 1 simple, 5 branched and 1 unbranched rays, last two articulating on same pterygiophore; first pterygiophore inserted behind hemal spine of vertebrae 41 or 42. Caudal fin truncate to very slightly emarginate, with 8+8 principal rays (7+7 branched).

Body apparently entirely scaled, scales deeply embedded. Head naked. Suborbital spine bifid, outer branch straight, inner branch slightly curved, longer and stronger than outer one. Three pairs of barbels, one rostral, one maxillary and one at angle of mouth, reaching slightly behind eye. Lower lip interrupted medially, each half with an slightly thickened inner lobe, tip of lobe rounded; margin of membrane connecting lobe and barbel at corner of mouth entire, not fringed, without notches. Anterior nostril at tip of a short tube, posterior edge elongated into a nasal barbel reaching eye; tubular part about ¼ to 1 / 5 of total length of nasal barbel.

Vertebrae: 41+18=59, 42+17=59.

Coloration. Preserved specimens: Head and body greyish brown, with a few darker dots (each dot being a dark greyish to black scale) forming a faint gray stripe along dorsal midline. A dark brown to blackish midlateral stripe from upper extremity of gill opening to middle of caudal-fin base, widened at posterior extremity. Median 5 rays of caudal fin with black edges, interradial membranes between these rays grey, resulting in a short stripe continuing midlateral stripe. Base of these rays black, forming together a triangular spot. Base of other rays brown, resulting in a vertical mark at base of fin, separated from midlateral stripe by a short gap. Unbranched principal caudal-fin rays dark brown. Other fins hyaline.

In life ( Fig. 2 ): green-brown to bronze colour, whitish or pinkish towards belly. Head pale brown on top, greyish below with gills distinct through opercle and making a conspicuous dark pink patch.

Distribution and habitat. The species is presently known only from the type locality in the lower Mahakam drainage, in eastern Borneo. Sungai Petung Kanan is about 5 m wide, 0.5–1.0 m deep, fast current, gravel substrate with some sandy shores and a few stones, clear water, pH about 5. Pagio lidi was collected in an area with slow countercurrent, under large trees, among leaf litter. The stream flows through an open area, in secondary forest.

Etymology. Lidi is the Indonesian word for the rachis (stalk) of the coconut leaf, a reference to the slender and elongate shape of this fish. A noun in apposition.

Remarks. Pangio lidi is distinguished from all other species of the P. anguillaris species group by the absence of the pelvic fins and pelvic girdle. It is further distinguished from P. doriae ( Perugia, 1892) by having 7+7 branched caudal-fin rays (vs. 6+6), no scales on the cheek (vs. present), and fewer vertebrae (41–42 + 17–18 = 59, vs. 46–49 + 15–18 = 62–67).

Pangio lidi differs from P. anguillaris ( Vaillant, 1902) by having the anterior nostril modified into a nasal barbel (vs. nostril at tip of a short tube), and fewer vertebrae (41–42 + 17–18 = 59, vs. 50–52 + 19–20 = 69–71; Kottelat & Lim 1993: 246).

Pangio lidi differs from P. bitaimac Tan & Kottelat (2009) by having the origin of the anal fin under the base of the dorsal fin (vs. behind in P. bitaimac ), the nasal barbel reaching the eye (vs. at tip of a short tube), fewer vertebrae (41–42 + 17–18 = 59, vs. 46–49 + 14–17 = 61–64; Tan & Kottelat 2009), a more slender body (depth at dorsal origin 21–22 times in SL, vs. about 17), and the colour pattern at the base of the caudal fin (black coloration restricted to the interradial membranes between the 5 median rays, extending onto most of membrane, resulting in a short stripe continuing the stripe on caudal peduncle, vs. black pigments on proximal area of all interradial membranes, resulting in a vertically elongated blotch).

Pangio lumbriciformis Britz & Maclaine, 2007 (from Myanmar) possibly also belongs to the P. anguillaris group. It shares the dark grey to black stripe on median caudal-fin rays. Pangio lidi differs from P. lumbriciformis in having more vertebrae (41–42 + 17–18 = 59, vs. 40–41 + 13–15 = 54–56).

Figures

FIGURE 1. Pangio lidi; Indonesia: Kalimantan Timur: Sungai Petung Kanan. a, MZB 16528, holotype, 67.2 mm SL; b, CMK 20805, paratype, 57.2 mm SL.

FIGURE 2. Pangio lidi, holotype, MZB 16528, 67.2 mm SL; Indonesia: Kalimantan Timur: Sungai Petung Kanan.