Amblyceps carinatum, Ng, 2005

Ng, Heok Hee, 2005, Amblyceps Carinatum, A New Species Of Hillstream Catfish From Myanmar (Teleostei: Amblycipitidae), Raffles Bulletin of Zoology 53 (2), pp. 243-249 : 243-245

Amblyceps carinatum , new species

( Fig. 1 )

Material examined. – Holotype - UMMZ 245588 , 34.7 mm SL, Myanmar: Kachin, Irrawaddy drainage, hillstreams at Tonpan village , on road from Myitkyina to Tanai, coll. Hain Zin & Hlaing Hlaing Oo, 20 Feb.2005.

Paratypes – UMMZ 245490 , 3 ex., 25.8–36.0 mm SL, data as for holotype .

Diagnosis. – Amblyceps carinatum can be distinguished from congeners in having the adipose fin in the form of a long, low ridge (vs. blade-like, length of adipose-fin base 37.5– 44.6% SL vs. 13.6–33.5; Fig. 2 ). It further differs from congeners on the Indian subcontinent with a deeply forked caudal fin ( A. mangois , A. tenuispinis , and A. macropterus ) in having poorly developed (vs. well developed) pinnate processes along the median caudal-fin rays ( Fig. 1 in Ng & Kottelat, 2001). Amblyceps carinatum can be further distinguished from A. apangi , A. laticeps and A. murraystuarti in having a deeply forked (vs. truncate or emarginate) caudal fin, and from A. caecutiens in having a deeper body (13.1– 15.0 vs. 9.8–10.7) and larger eyes (9.4–11.8% HL vs. 2.0– 3.4). It further differs from A. foratum in having larger eyes (9.4–11.8% HL vs. 5.5–8.5), from A. platycephalus in having a deeper head (10.6–13.6% SL vs. 8.3), and body (13.1– 15.0% SL vs. 11.5), from A. serratum in having a smooth (vs. serrated) posterior edge of the pectoral spine and more vertebrae (39–40 vs. 34–36), and from A. variegatum in having larger eyes (9.4–11.8% HL vs. 5.3–6.9) and a uniform (vs. mottled) body coloration.

Description. – Biometric data in Table 1. Head depressed, body cylindrical. Anus and urogenital openings located at vertical through middle of adpressed pelvic fin. Skin tuberculate. Lateral line midlateral, apparently extending to base of caudal fin; visible externally anterior to, but not posterior to, middle of dorsal-fin base. Only individual laterosensory pores visible externally posterior to middle of dorsal-fin base. Vertebrae 19+20=39 (1), 20+19=39 (1), or 20+20=40* (2).

Head depressed, with expanded cheek muscles imparting slightly swollen appearance in front of opercular region. Anterior and posterior nares separated only by base of nasal barbel. Gill openings broad, extending from immediately ventral to post-temporal to isthmus. Dorsal surface of head covered with thick, tuberculate skin. Eye ovoid, horizontal axis longest; located entirely in dorsal half of head and subcutaneous.

Barbels in four pairs. Maxillary barbel long and slender, extending to middle of pectoral-fin rays. Nasal barbel slender, extending to opercle. Inner mandibular-barbel origin close to midline, extending to middle of pectoral-fin base. Outer mandibular barbel originatesing posterolateral of inner mandibular barbel, extending to middle of pectoral-fin rays.

Mouth terminal, with lower jaw very slightly longer than upper; anterior edge barely visible dorsally. Lips fleshy and slightly fimbriated, with very well developed rictal fold present below anterior border of eye. Oral teeth small and villiform, in irregular rows on all tooth-bearing surfaces. Premaxillary teeth in single broad semilunate band. Dentary teeth in two narrow crescentic bands separated at midline.

Dorsal fin located above anterior one-third of body, with I,6 (4) rays; fin margin convex; spine very short and straight, encased in thick skin and with fluid-filled cavity imparting somewhat bulbous appearance along entire length. Adipose fin long and low, anterior origin at vertical through pelvicfin origin. Caudal fin strongly forked, with upper lobe longer than lower (but less than 1.5 times length of lower lobe) and i,8,7,i (4) principal rays. Procurrent rays symmetrical and extending considerably anterior to fin base. Anal-fin base ventral to adipose-fin origin at distance about half length of anal-fin base. Anal fin with straight anterior margin and straight or slightly concave posterior margin, spanning posterior half of adipose-fin base and with v,9 (1), v,10* (2) or vi,10 (1) rays. Pelvic-fin origin midway between verticals through posterior end of dorsal-fin base and anal-fin origin. Pelvic fin with convex margin and i,5 (4) rays; tip of adpressed fin not reaching anal-fin origin. Pectoral fin narrow, with I,6* (3) or I,6,i (1) rays; posterior fin margin strongly convex. Pectoral spine short and straight, with smooth anterior and posterior margins. Spine encased in thick skin, with fluidfilled cavity imparting somewhat bulbous appearance along proximal half.

Coloration. - In 70% ethanol: Dorsal and lateral surfaces of head, and body brown, fading to off white on ventral surfaces.

Dorsal and anal fins brown for proximal half, distal half hyaline. Pectoral and pelvic fins hyaline. Adipose fin brown, with hyaline distal margin. Caudal fin with brown fin rays and hyaline interradial membrane. Nasal and maxillary barbels brown at base, off white for almost entire length, mandibular barbels off white.

Distribution. - Known only from the middle part of the Irrawaddy River drainage in Myanmar ( Fig. 3 ).

Etymology. - From the Latin carina (keel), in reference to the long, low adipose fin of this species.

Figures

Fig. 1. Amblyceps carinatum, holotype, UMMZ 245588, 34.7 mm SL, Myanmar: hillstreams at Tonpan village.

Fig. 2. Adipose fins of: a. Amblyceps carinatum, holotype, UMMZ 245588, 34.7 mm SL; b. other Amblyceps species (A. mucronatum, UMMZ 245497, 41.2 mm SL illustrated). Arrows indicate origin of adipose fin and scale bar represents 10 mm.

Fig. 3. Collecting locality for the type series of Amblyceps carinatum.