Homatula anteridorsalis, 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 : 337-340

Homatula anteridorsalis sp. nov.

( Fig. 2A , Fig. 6 )

Holotype. SWFC 1610006, 121.6 mm SL; China: Yunnan: Baoshan City: Longyang District: Lujiang Town , Bingmen Village (25°4'11.23"N 98°49'57.77"E); collected by W. Dao & YC. Wang, 8 Oct. 2016.

Paratypes. SWFC 1610001-1610005, 1610007-1610031, 30 ex., 66.4–129.4 mm SL; other data same as the holotype. SWFC 1510001-1510002, 2 ex., 108.0– 140.8 mm SL; China: Yunnan: Baoshan City: Longyang District: Lujiang Town : Kungong Village (25°4'53.68"N 98°50'24.11"E); collected by C. Sun, 19 Oct. 2015 .

Diagnosis. Homatula anteridorsalis differs from other species of the densely-scaled group in Homatula by the following combination of characters: bars on flank across lateral line more than or equal to 25 (vs. less than or equal to 20 in H. acuticephala and H. erhaiensis ); bars on flank vertical along lateral line (vs. no marks on the flank in H. nigra ); no free protrusions between the pelvic fins (vs. pair of free protrusions between 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. acuticephala , H. anguillioides , H. coccinocola , H. erhaiensis , and H. pycnolepis ) ( Fig. 5 ); with pelvic axillary lobe (vs. without pelvic axillary lobe in H. anguillioides and H. acuticephala ); marked notch on lower jaw (vs. lower jaw spoon-shaped and lacking notch in H. erhaiensis and H. wuliangensis ); dorsal-fin base shorter than longest branched dorsal-fin ray (vs. longer than longest branched dorsal-fin ray in H. acuticephala , H. anguillioides , H. cryptoclathrata , H. erhaiensis , and H. wuliangensis ); dorsal and pelvic fins located anteriorly, predorsal length 44.4% (42.8–46.3%) SL, prepelvic length 45% (43.3–46.7 %) SL (vs. predorsal length 47.7% (45.7–49.6 %) SL, prepelvic length 48.7% (47.0–49.9 % SL) in all congeners of densely-scaled group of Homatula ) ( Tables 1 & 2 ).

Description. Based on holotype and 32 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+41 (2 specimens)–42 (1 specimen).

Body elongate, 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 is 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 and lower lip with marked median incision. Jaws covered by lips; upper jaw with well developed processus dentiformis (described by Kottelat 1990) corresponding with marked notch on lower jaw. Three pairs of barbels; two rostral pairs, inner one not reaching corner of mouth and outer one reaching vertical line of anterior nostril; one maxillary pair long, reaching to vertical line between middle and posterior margin of eye ( Fig. 7A ).

Dorsal fin with 3 simple and 8–9 branched rays; distal margin convex; origin nearer to snout tip than to caudalfin base. Pectoral fin with 1 simple and 9–10 branched rays, inserted slightly posterior to vertical 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 of 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 extending through posterior end of anal-fin base. Anus located posterior approximately 1/3 the distance between pelvic-fin insertion and anal-fin origin, nearer to caudal-fin base.

Coloration: Flank of fresh specimen dark yellow, abdomen pale yellow. After fixation in 95% alcohol, flank is brown, abdomen grayish yellow. Flank with 27 to 34 brown vertical bars; width of each bar approximately equal to space between bars. Bars in front of dorsal-fin base narrow and dense, gradually become 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 a stream connected to the trunk of the Nu-jiang (the upper Salween River) ( Fig. 8 ).

Habitat and Ecology: Homatula anteridorsalis 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 bottom, shuttling back and forth among rocks and gravel.

Etymology: The specific epithet, anteridorsalis , an adjective, is a combination of the Latin anteri – (in front) and – dorsal (in reference to the dorsal fin), alluding to the more anterior origin of dorsal- and pelvic-fins than in other species of Homatula .

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 6. Homatula anteriordorsalis, SWFC 1610006, holotype, 121.6 mm SL; China: Yunnan: Baoshan City: Longyang District: Lujiang Town: Bingmen Village.

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.