Homatula cryptoclathrata, Li & Che & Zhou, 2019

Li, Xu, Che, Xing-Jin & Zhou, Wei, 2019, Loaches of Homatula (Teleostei: Nemacheilidae) from the upper Salween River in Yunnan, China with description of three new species, Zootaxa 4711 (2), pp. 330-348 : 340-341

Homatula cryptoclathrata sp. nov.

( Fig. 2B , Fig. 9 )

Holotype. SWFC 1002001, 138.1 mm SL; China: Yunnan: Baoshan City: Changning County: Gengga Town : Manging Village (24°19'42.65"N 99°32'15.39"E); collected by XJ. Che , 20 Feb. 2019.

Paratypes. SWFC 1902002-19020011, 10 ex., 53.2-110.1 mm SL; other data same as the holotype .

Diagnosis. Homatula cryptoclathrata differs from other species of densely-scaled group in Homatula by the following combination of characters: bars on flank across lateral line equal to or greater than 25 (vs. equal to or less than 20 in H. acuticephala and H. erhaiensis ); bars on flank vertical along lateral line (vs. no marks on flank in H. nigra ); no free protrusions between the pelvic fins (vs. a pair of free protrusions between the pelvic fins in H. pycnolepis ); gill opening smaller, its upper angle level with lower edge of eye (vs. gill opening larger, its upper angle aligned with middle point of eye in H. anguillioides , H. acuticephala , H. coccinocola , H. erhaiensis , and H. pycnolepis ) ( Fig. 5 ); with pelvic axillary lobe (vs. without pelvic axillary lobe in H. acuticephala and H. anguillioides ); marked notch on lower jaw (vs. lower jaw spoon-shaped and lacking notch in H. erhaiensis and H. wuliangensis ); dorsal-fin base longer than length of longest branched dorsal-fin ray (vs. shorter than longest branched dorsal-fin ray in H. anteridorsalis , H. nigra , and H. pycnolepis ); bars on anterior flank crowded together, faintly visible in fresh specimens (vs. obvious in H. acuticephala , H. anguillioides , H. anteridorsalis , H. change , H. coccinocola , H. erhaiensis , H. pycnolepis , and H. wuliangensis ).

Description. Based on holotype and 10 paratypes, maximum standard length is 140.8 mm. Morphometric data are shown in Table 2 . Dorsal-fin rays iii, 8½; anal-fin rays iii, 5½; pectoral-fin rays i, 9–10; pelvic-fin rays i, 7; caudal-fin branched rays 9+8; vertebrae 4+42 (1 specimen)–43 (2 specimens).

Body elongate and cylindrical, anteriorly slightly depressed, posteriorly compressed laterally. Maximum body depth immediately in front of dorsal fin. Dorsal and ventral profiles almost straight. Except for scaleless head and thorax, body entirely covered by small scales, with scattered scales on abdomen. Caudal peduncle compressed laterally. Lateral line complete, extending directly along midline of body.

Head short and depressed in frontal view, wider than high, roughly triangular in dorsal view. Snout blunt, slightly shorter than postorbital length of head. Eye small, close to dorsal profile of head, invisible from ventral view. Interorbital space wide and flat. Nostrils closely set, nearer to anterior margin of eye than to snout tip; anterior nare pierced in front side of a flap-like tube with pointed tip.

Mouth inferior and arched. Lips thick, slightly furrowed, but not papillated; upper lip with small median incision, lower lip with marked median incision. Jaws covered by lips; upper jaw with well developed processus dentiformis corresponding with marked notch on lower jaw. Three pairs of barbels; two rostral pairs, inner barbel not reaching corner of mouth and outer barbel reaching vertical line of anterior nostril; one maxillary barbel pair long, reaching to vertical line between middle and posterior margin of eye ( Fig. 7B ).

Dorsal fin with 3 simple and 8–9 branched rays; distal margin convex; origin almost midway between snout tip and caudal-fin base. Pectoral fin with 1 simple and 9–10 branched rays, inserted vertically through posteriormost point of operculum, tip of longest fin ray not extending beyond halfway to insertion of pelvic fin. Pelvic fin with 1 simple and 6–7 branched rays, inserted below first or second branched rays of dorsal fin, tip of longest fin ray not extending beyond half distance between pelvic-fin insertion and anal-fin origin. Pelvic axillary lobe with pointed tip. Anal fin with 3 simple and 5 branched rays, with convex distal edge; origin closer to pelvic-fin insertion than to caudal-fin base. Posterior margin of caudal fin oblique or micro-concave. Caudal peduncle uniformly deep; with adipose crests along dorsal and ventral midlines. Adipose crest along dorsal midline of caudal peduncle not extend- ing through posterior end of anal-fin base. Anus located posteriorly, approximately 1/3 the distance between the pelvic-fin insertion and anal-fin origin, closer to the caudal-fin base.

Coloration: Flank of fresh specimens dark yellow, abdomen pale yellow.After fixation in 95% alcohol, flank is brown, abdomen grayish yellow. Flank with 25 to 27 brown vertical bars; width of each bar approximately equal to or narrower than spaces between bars. Bars in front of anal-fin origin narrow and dense, gradually becoming wider towards caudal-fin base. Dark brown vertical bar on caudal-fin base. Dorsal surface of pectoral, pelvic, and anal fins reddish orange, dorsal and caudal fins yellowish.

Distribution: Known only from the Damengtong-he, a branch of the Mengboluo-he, the first tributary of the Nu-jiang drainagec (the upper Salween River) ( Fig. 8 ).

Habitat and Ecology: Homatula cryptoclathrata is omnivorous, mainly feeding on algae attached to rocks, organic residues, and small aquatic insects. It inhabits flowing and clear stream environments and dwells on the stream bottom, shuttling back and forth among rocks and gravel.

Etymology: The specific epithet, cryptoclathrata , an adjective, is the combination of the Latin crypto – (cryptic or hidden) and – clathratus (barred), alluding to the indistinct pattern of bars on the flank in front of the dorsal-fin origin.

Figures

FIGURE 2. Relationship between anterior end of adipose crest and anal-fin base of Homatula. (A) H. anteridorsalis, SWFC 1610019, paratype, 108.1 mm SL; (B) H. cryptoclathrata, SWFC 1002001, holotype, 138.1 mm SL; (C) H. nigra, SWFC 1901005, holotype, 99.8 mm SL; (D) H. pycnolepis, SWFC 0612085, 99.6 mm SL; (E) H. laxiclathra, SWFC 1810010, 97.0 mm SL); (F) H. nanpanjiangensis, SWFC 1903001, 97.1 mm SL.

FIGURE 5. Gill openings of Homatula. (A) Larger gill opening; upper angle aligned with middle point of eye (H. pycnolepis, SWFC 0612085, 99.6 mm SL); (B) smaller gill opening; upper angle level with lower edge of eye (H. cryptoclathrata, SWFC 1610006, holotype, 121.6 mm SL).

FIGURE 7. Mouths of Homatula. (A) H. anteridorsalis, SWFC 1610006, holotype, 121.6 mm SL; (B) H. cryptoclathrata, SWFC 1002001, holotype, 138.1 mm SL; (C) H. nigra, SWFC 1901005, holotype, 99.8 mm SL; (D) H. pycnolepis, SWFC 0612085, 99.6 mm SL.

FIGURE 8. Distribution map of the densely-scaled group of Homatula. A symbol may represent several adjacent localities.

FIGURE 9. Homatula cryptoclathrata, SWFC 1002001, holotype, 138.1 mm SL; China: Yunnan: Baoshan City: Changning Co.: Gengga Town: Mangping Village.