Paracanthocobitis zonalternans ( Blyth, 1860 )

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 : 91-94

Paracanthocobitis zonalternans ( Blyth, 1860)

Dwarf Zipper Loach

Fig. 4

Cobitis zonalternans Blyth, 1860:172 . Type locality: Tenasserim provinces, Burma. Two syntypes ( Day, 1869:551; Day, 1872:186), presumed lost ( Hora, 1929:319). Neotype, ZSM 27468, designated by Kottelat, 1990:42, Huai Mae Charno, 4 km south Amphoe Mae Ramat on road 1085 [approximately 16.967N, 98.567E], Tak Province, Salween drainage, Thailand.

Nemacheilus zonalternans .— Day, 1869:551.

Nemachilus zonalternans .— Day, 1889:232.

Noemacheilus zonalternans .— Sen, 1985:119, fig. 63.

Acanthocobitis zonalternans .— Kottelat, 1990:13.

Acanthocobitis (Paracanthocobitis) zonalternans .— Grant, 2007:3.

Paracanthocobitis zonalternans .— Singer & Page, 2015:396.

Diagnosis. Paracanthocobitis zonalternans 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; series of black blotches, usually without black stripe but with faint dusky stripe, along side of body, usually ending near dorsal-fin insertion; 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; dorsal saddles short, rarely connecting to lateral blotches; 8 (occasionally 7) 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 0.17–0.26 SL, not reaching pelvic fin; pelvic fin 0.16–0.22 SL, not reaching anal fin; caudal fin emarginate.

Lateral line incomplete, reaching at most to dorsal-fin insertion; 19–50 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 (12 specimens)–10½ (43 specimens) branched dorsal-fin rays; 9–12, usually 10, pectoral-fin rays; 6 pelvic-fin rays; 5½ branched anal-fin rays; 8 (occasionally 7) branched upper caudal-fin rays; 8 branched lower caudal-fin rays. Suborbital flap in male. Maximum SL 41.8 mm female.

Body yellow-brown with 10–15 dark brown to black blotches along lateral line sometimes overlain with faint dusky stripe usually ending near dorsal-fin insertion; 14–18 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. Dusky lateral stripe extending onto pectoral-fin origin.

pecies P. zonalternans x¯± D P. phuketensis x¯± D P. marmorata x¯± D P. triangula x¯± D P. nigrolineata x¯± D

(n=55) (n=55) (n=4) (n=11) (n=79)

tanđarđ lenǥth 20.5,41.8 17.1,³³.³ 28.2,³³.9 24.6,29.2 21.5,42.4

L Comparisons. Paracanthocobitis zonalternans differs from all other species of Paracanthocobitis except P. phuketensis , P. nigrolineata , 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 zonalternans is most similar morphologically to P. nigrolineata but differs in having a series of black blotches, usually black stripe along the side of the body absent or dusky and ending near the dorsalfin insertion (vs. having a series of black blotches overlain by a black stripe ending near the caudal fin), and sometimes having 7 (vs. always 8) upper branched caudal-fin rays. Paracanthocobitis zonalternans differs from P. phuketensis in having black pigment extending from a black lateral stripe onto the pectoral-fin base, an axillary pelvic lobe (vs. lobe usually absent, occasionally rudimentary) and in having short (not extending ventrally to dorsal stripe) dorsal saddles in the majority of specimens that rarely connect to lateral blotches (vs. dorsal saddles longer than interspaces, frequently connecting to lateral blotches). Paracanthocobitis zonalternans 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 black blotches along the side of the body onto the pectoral-fin base. Paracanthocobitis zonalternans differs from P. marmorata in having an axillary pelvic lobe and a circular (vs. teardrop shaped) black spot on the upper margin of the caudal-fin base and in not having a marmorated pattern between the dorsal saddles and lateral blotches.

Distribution. Paracanthocobitis zonalternans is known from the Salween River drainage in Thailand and Myanmar ( Fig. 5 ).

Material Examined. Thailand: Salween drainage: CAS 35775, 6, 23.5–42.6 mm, Nam Mesarieng, near Mesarieng (Mae Sariang), northern Thailand , 18.151N, 97.934E ; CAS 35776, 2, 41.3–41.8 mm, same locality as CAS 35775 ; CAS 36042, 2, 38.8–40.8 mm, same locality as CAS 35775 ; FMNH 124763, 4, 19.6–27.7 mm, Nam Mae Yuan River, rte. 108, 103 km N of Mae Sariang , 18.807N, 97.931E ; FMNH 124764 , 1 , 29.1 mm, Mae Samat River , rte. 108, 15 km S of Mae Hong Son , 19.189N, 97.984E; NIFI 0 0 874, 14, 28.0– 32.5 mm, Tak Province , Huai Mae Kamui, Amphoe Tha Song Yang, 17.230N, 98.229E; NIFI 6393 , 1 , 35.7 mm, Mae Hong Son Province , Mae Sanga River , 18.238N, 97.961E; ROM 51139, 5, 23–31.9 mm, Tak Province , N of Mae Charao, 16.967N, 98.567E; UF 188197, 7, 20.5–29.5 mm, Mae Hong Son Province , Khun Yuam County, Pai River near Surin River, approx . 1.5 km N of Ban Mae Surin on rte. 108, 18.928N, 97.937E ; UF 188198, 12, 23.3–35.7 mm, Tak Province, Amphoe Tha Song Yang, Moei River at rte. 105, approx. 7 km SE of Nam Tha Song Yang , 17.516N, 97.966E ; USNM 288452 , 26 (10 ex.) 33.5–42.4 mm, Mae Hong Son Province, mountain stream, 5 km W of Mae Sariang , 18.191N, 97.878E ; ZRC 41258, 8, 26.5–36.6 mm, Tak Province, Mae Nam Moi, S of Phop Phra, 16.290N, 98.706E ; ZSM 27468, neotype of Cobitis zonalternans , 33.1 mm, Huay Me Charno, 4 km S of Amphoe Mae Romat on road 1085.

Figures

FIGURE 4. Paracanthocobitis zonalternans from the Salween drainage, Thailand. (A) ZSM 27468, neotype of P. zonalternans, Tak Province, 33.1 mm SL; (B) ZRC 41258, Tak Province, 36.6 mm SL; UF 188197, Mae Hong Son Province, live (C), and preserved (D), 29.5 mm SL. Live photo by Z. S. Randall (UF).

FIGURE 5. Localities of examined specimens of Paracanthocobitis.