Acantopsis thiemmedhi Sontirat, 1999

Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas & Page, Lawrence M., 2017, Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia, Zootaxa 4341 (2), pp. 151-192 : 171-173

Acantopsis thiemmedhi Sontirat, 1999

Blackspotted Horseface Loach ( Fig. 12 )

Acantopsis thiemmedhi Sontirat, 1999: 66 , fig. 1 (type locality: Thailand: Uthai Thani ProVince: Amphoe Lan Sak: Huai Kha Khaeng Wildlife Sanctuary, Nam Khun Creek ; holotype: KUMF 3131 )

Diagnosis. Acantopsis thiemmedhi differs from all other species of Acantopsis ( Table 4) by combination of large black blotch on tip of anterior rays of dorsal fin, large black blotch on tip of each lobe of caudal fin; usually 1 pair of labial barbels, 10½ branched dorsal rays, and 10 pectoral rays; 7–9 dark saddles along dorsal midline, 6–10 black spots along side of body, 1 row of large dark spots on side of head, 39–41 total vertebrae, body depth 9.8– 16.6% SL, body width 5.8–10.3% SL, caudal-peduncle length 12.5–14.7% SL.

Comparisons. Acantopsis thiemmedhi differs from all other species of Acantopsis by having large black blotch on tip of anterior rays of dorsal fin and large black blotch on each lobe of caudal fin. Acantopsis spectabilis has much smaller black blotch (often absent) on tip of anterior rays of dorsal fin, 2–3 irregular bands or blotches on caudal fin, darkest at extremity of lower lobe. Other species of Acantopsis have dusky to dark bands on dorsal fin but no conspicuous black blotch at tip of anterior rays, and dusky bands on caudal fin. Acantopsis thiemmedhi further differs from A. spectabilis in having 1 (vs. 2–3) pair of labial barbels, and usually 10½ (vs. 9½) branched dorsal rays. Acantopsis thiemmedhi further differs from A. dialuzona by lacking well developed ocellus on the upper margin of the caudal-fin base, and having 1 (vs. 3) pair of labial barbels, 7–9 (vs. 11–17) dark saddles along dorsal midline, and 6–10 (vs. 7–13) black spots along side of body. It further differs from A. octoactinotos by having usually 10½ (vs. 8½) branched dorsal rays, large dark spots on side of head, 1 (vs. 2) pair of labial barbels, usually 10 (vs. 9) pectoral rays, 7–9 (vs. 11–17) dark saddles along dorsal midline, shorter caudal-peduncle 12.5– 14.7 vs. 16.1–17.2% SL. It further differs from A. dinema by having 1 (vs. 2) pair of labial barbels, large dark spots on side of head, and no row of black specks beneath midlateral row of black spots. It further differs from A. rungthipae and A. ioa by having 1 (vs. 0) pair of labial barbels and usually 10½ (vs. 9½) branched dorsal rays, from A. rungthipae in lacking distinct small black spot on upper margin of caudal-fin base and in having 6–10 (vs. 9–17) black spots along side of body, and from A. ioa in having 7–9 (vs. 15–23) dark saddles along dorsal midline, 6–10 (vs. 13–21) black spots along side of body, large dark spots on side of head, 39–41 (vs. 46–48) total vertebrae.

Description. As in description of genus; Tables 1, 2, 4. Head long (22.6–26.8% SL); snout long (57.5–68.3% HL); 1, rarely 2, pairs of labial barbels; 10½, rarely 9½ or 11½, branched dorsal rays; 10, less often 9 or 11, pectoral rays; 28–30 abdominal + 10–11 caudal = 39–41 total vertebrae ( Table 1; Sontirat 1999). Maximum SL = 153.3 mm, TL = 191.5 mm (NIFI 2974).

Color. Dark spots in 1 row on top of head, in 1–2 often poorly defined rows on side of head. Black line from eye to tip of snout. Seven–9 dark saddles along dorsal midline; 6–10 large dark spots or blotches along lateral line from head to caudal fin; dark spots and blotches on upper side of body, none on lower side. Large black blotch near tip of anterior rays of dorsal fin, separated from black band near margin of fin; large individuals with second band in middle of fin with black spot anteriorly. Large black blotch on each lobe of caudal fin, sometimes with dark band connecting blotches; often smaller black spots or bands in middle of caudal fin. Faint bands on other fins. No small bold black spot or ocellus near upper margin of caudal-fin origin.

Live individuals yellowish brown dorsally, white below, with large black blotches dorsally and laterally on body; dorsal and caudal fins with black and white bands and spots, iridescent yellow on side of head and lower fins.

Distribution. Acantopsis thiemmedhi is widespread, but seemingly uncommon, in the Chao Phraya River basin, Thailand ( Fig. 13 ). Most of the specimens examined are from the Wang River drainage.

Remarks. The holotype of Acantopsis thiemmedhi , KUMF 3131, was examined and found to differ in fin ray counts from those recorded by Sontirat (1999). It has 9 branched dorsal rays, 11 pectoral rays, and 7 pelvic rays. Pectoral-fin rays for all 21 paratypes range from 9 to 11.

Figures

FIGURE 12. Acantopsis thiemmedhi, UF 188118. (A) Dorsal, lateral, and liVe VieWs, 107.5 mm SL. (B) Lateral VieW, 54.5 mm SL.

FIGURE 13. Localities of specimens examined of Acantopsis thiemmedhi.