Paracanthocobitis nigrolineata, Page, 2017

Page, Lawrence M., 2017, A revision of the Paracanthocobitis zonalternans (Cypriniformes: Nemacheilidae) species complex with descriptions of three new species, Zootaxa 4324 (1), pp. 85-107 : 98-101

Paracanthocobitis nigrolineata , new species

Blacklined Zipper Loach

Figs. 8 & 9

Holotype. NIFI 5080 , 33.1 mm SL, Thailand, Kanchanaburi Province, Thong Pha Phum, Mae Khlong drainage, unnamed tributary of Khwae Noi just S of rte. 323, 14.540N, 98.780E, 27 January 2015.

Paratypes. Thailand, Kanchanaburi Province: ANSP 179829, 2, 35.6–36 mm SL, Ulong River, tributary of Khwae Noi, at rte. 323 bridge, 5–10 km from Thong Pha Phum , 14.782N, 98.669E, 4 March 2001 ; NIFI 3087, 4, 27–29.4 mm SL, Thong Pha Phum, Huay Ulong, 14.760N, 98.638E, no date; UF 188053, 9, 24.9–35.8 mm SL, same locality as holotype, 27 January 2015 ; UMMZ 209461, 7, 29.9–35.5 mm SL, Khwae Yai , 14.227N, 99.234E, 28 February 1975 ; Ratchaburi Province: ZRC 42002, 2, 29.7–42.4 mm SL, Suan Pheng District, Suan Pheng Waterfall , 13.524N, 99.239E, no date.

Diagnosis. Paracanthocobitis nigrolineata is distinguished from all other species of Paracanthocobitis by combination of incomplete lateral line ending near dorsal-fin insertion; 9½–10½ branched dorsal-fin rays; axillary pelvic lobe present; black stripe along side of body, ending near caudal-fin, usually overlying black lateral blotches extending ventrally from lateral stripe; circular black spot on upper margin of caudal-fin base; black pigment extending from lateral stripe onto pectoral-fin base; no marmorated pattern anterior to dorsal-fin origin; black dorsal saddles short, not connecting to lateral blotches; 8 branched upper caudal-fin rays.

Description. Meristic and morphometric data are in Tables 4 and 5. Body deepest just anterior to dorsal-fin origin; slightly compressed before dorsal fin, strongly compressed postdorsally. Head depressed, snout gently rounded to slightly pointed when viewed dorsally or laterally. Dorsal-fin origin far in front of pelvic-fin origin; distal margin convex. Pectoral fin 0.18–0.23 SL, not reaching pelvic fin; pelvic fin 0.16–0.19 SL, not reaching anal fin; caudal fin emarginate. Lateral line incomplete, reaching just beyond dorsal-fin insertion; 21–56 pores. Axillary pelvic lobe present. Mouth arched with heavily papillated lips; upper lip with 3–5 rows of papillae, continuous with large pads on lower lip. Three pairs of barbels; inner rostral barbel extends to or slightly past base of maxillary barbel, maxillary barbel and outer rostral barbel extend to or slightly past eye. Body covered with scales; 9½ (13 specimens)–10½ (66 specimens) branched dorsal-fin rays; 9–13, usually 10, pectoral-fin rays; 6 pelvic-fin rays; 5½ branched anal-fin rays; 8 branched upper caudal-fin rays; 8 branched lower caudal-fin rays. Suborbital flap in male. Maximum SL 42.4 mm female.

Body yellow-brown with 10–13 dark brown to black blotches along lateral line overlain with black stripe usually obscuring lateral blotches and ending at caudal-fin origin; 13–24 small dark brown dorsal saddles. Dark spots and blotches on head; uninterrupted black bar from eye to tip of snout. Ocellus with black center near upper margin of caudal peduncle; 3–6 concentric rows of dark spots in dorsal fin, 2–3 rows of dark spots in anal fin, 4–6 dark bands on caudal fin. Black lateral stripe extending onto pectoral-fin origin.

Comparisons. Paracanthocobitis nigrolineata differs from all other species of Paracanthocobitis except P. zonalternans , P. phuketensis , P. triangula , and P. marmorata in having an incomplete lateral line ending near the dorsal-fin insertion (vs. lateral line to the end of the caudal peduncle) and 9½–10½ (vs.>10½) branched dorsal-fin rays. Paracanthocobitis nigrolineata is most similar morphologically to P. zonalternans but differs in having a black stripe along the side of the body, usually overlying black lateral blotches, ending near the caudal fin (vs. stripe absent or dusky and ending near the dorsal-fin insertion), and in always having 8 (vs. sometimes 7) upper branched caudal-fin rays. Paracanthocobitis nigrolineata differs from P. phuketensis in having a black stripe along the side of the body, usually obscuring black lateral blotches (vs. a series of black blotches, sometimes overlain with a faint dusky stripe not obscuring the black blotches); black pigment extending from the lateral stripe onto the pectoral-fin base; axillary pelvic lobe present (vs. absent, occasionally rudimentary), and 8 (vs. sometimes 7) branched upper caudal-fin rays. Paracanthocobitis nigrolineata differs from P. triangula in having a circular (vs. triangular ) black spot on the upper margin of the caudal-fin base and in having black pigment extending from the lateral stripe onto the pectoral-fin base. Paracanthocobitis nigrolineata differs from P. marmorata in having a circular (vs. teardrop-shaped) black spot on the upper margin of the caudal-fin base, black pigment extending from the lateral stripe onto the pectoral-fin base, an axillary pelvic lobe, and in not having a marmorated pattern between the dorsal saddles and lateral blotches.

Distribution. Paracanthocobitis nigrolineata is known from Irrawaddy and Sittang drainages of Myanmar and the Mae Khlong drainage of Thailand with a large geographic gap in-between ( Fig. 5 ). This gap is likely due to the paucity of sampling in Myanmar.

Etymology. The epithet nigrolineata refers to the black stripe along the side of the body.

Material Examined (excluding types). Myanmar: Irrawaddy drainage: CAS 32368, 13 , 19.0– 26.6 mm, near Indaw, Chaung and Karnaing, 24.226N, 96.143E ; CAS 34752, 2, 23.5–31.3 mm, Ngamoeyeik Creek , 9 mi NW Hlegu, 17.219N, 96.201E ; UF 30191, 2, 36.3– 35.7 mm, Gyobu Reservoir , 9 km N of Taik-Kyi Taik-Kyi township, Rangoon, 16.831N, 96.250E ; ZRC 43453, 10 , 17.3 –38.0 mm, Shan State, Ma Gawe River, along Kalaw-Thazi Hwy between Mandalay and Nampantet, 21.397N, 96.245E . Sittang drainage: USNM 378439, 10, 31.5–39.7 mm, Kayin Stream near the Sittang River, east of Taungoo , 18.958N, 96.478E . Thailand: Kanchanaburi Province: Mae Khlong drainage: NIFI 0 1435, 13, 24.6–32.0 mm, Khao Noi , 13.967N, 99.590E ; NIFI 0 2057, 7, 19.9–33.9 mm, same locality as NIFI 01435 ; UF 172979, 1, 31.3 mm, Lichia River , at 323 bridge, 15.071N, 98.581E ; UF 176389, 2, 29.1–34.8 mm, Huay Ka Yeng County, Kring Ta Ko , 14.753N, 98.501E ; UF 176411, 1, 22.8 mm, Huay Ka Yeng , at 3272 bridge, 14.660N, 98.534E ; UF 176449, 35 (10 ex.), 22–30.1 mm, Mae Nam Khwae, Huay Ban Rai, 14.7193N, 98.506E; UF 176546, 2, 24.9–25.5 mm, Huay Ka Yeng, trib. of Mae Nam Khwae at Huay Pok Kok , 14.680N, 98.527E ; UF 176554, 23 (10 ex.), 25.4– 24.4 mm, same locality as UF 176449 ; UF 181138, 2, 34.5–36.4 mm, Mae Nam Khwae Noi at Ban Huay Pakkok , 14.380N, 98.480N ; UF 181149, 7, 29–36.4 mm, Pakkok River— Mae Nam Khwae Noi at Ban Huay Paousa , 14.633N, 98.800E ; UF 182821, 13, 27.7–37.4 mm, Thong Pha Phum , near rte. 3272, 14.690N, 98.521E ; UF 188054, 3, 33.8–38.8 mm, Thong Pha Phum, Mae Klong River , 14.650N, 98.530E ; UF 188055, 4, 25.7–31.6 mm, Sangkhla Buri Co., Song Karia River at rte. 323, 15.220N, 98.440E ; UF 188056, 1, 25.4 mm, Sangkhla Buri Co., unnamed trib of Lake Vajiralongkorn , 15.060N, 98.560E .

Figures

FIGURE 5. Localities of examined specimens of Paracanthocobitis.

FIGURE 8. (A) Dorsal and lateral views of holotype of Paracanthocobitis nigrolineata, NIFI 5080, Kanchanaburi Province, Thailand, 33.1 mm SL; (B) live photo of holotype. Live photo by Z. S. Randall.

FIGURE 9. Geographic variation in color pattern in Paracanthocobitis nigrolineata. (A) UF 188053, Kanchanaburi Province, Thailand, 33.4 mm SL; (B) USNM 378439, Taungoo, Myanmar, 37.6 mm SL; (C) ZRC 43453, Shan State, Myanmar, 38.0 mm SL.