Sineuchiloglanis chishuiensis Lv, He, Lei & Liu, 2026, sp. nov.

Sineuchiloglanis chishuiensis sp. nov. Figs 2, 3 Type material. Holotype • IHB 202507021, 113.00 mm SL; Chishui River in the upper Yangtze River drainage in Zhenxiong County, Yunnan Province, China (27°45N, 105°13E; 779 m elevation); August 2024, Liu. F. Paratypes • IHB 202507003, 1, 84.99 mm SL; Erdao River (a tributary of the Chishui River in the upper Yangtze River drainage) in Bijie City, Guizhou Province, China; March 2023, Liu. F. • IHB 202507001, 202507002, 2, 106.46– 121.63 mm SL; Chishui River in the upper Yangtze River drainage in Zhenxiong County, Yunnan Province, China; June 2023, Liu. F. • IHB 202507004–202507011, 202507014, 202507015, 10, 78.98–147.68 mm SL; Tongche River (a tributary of the Chishui River in the upper Yangtze River drainage) in Zhenxiong County, Yunnan Province, China; April 2024, Liu. F. • IHB 202507012, 202507013, 2, 150.15– 164.57 mm SL; Chishui River in the upper Yangtze River drainage in Zhenxiong County, Yunnan Province, China; April 2024, Liu. F. • IHB 202507016 –202507018, 3, 87.77–134.79 mm SL; Tongche River (a tributary of the Chishui River in the upper Yangtze River drainage) in Zhenxiong County, Yunnan Province, China; September 2024, Liu. F. • IHB 202507019, 202507020, 202507022, 3, 81.12–182.92 mm SL; Chishui River in the upper Yangtze River drainage in Zhenxiong County, Yunnan Province, China; August 2024, Liu. F. • IHB 202507045, 1, 120 mm SL; Chishui River in the upper Yangtze River drainage in Zhenxiong County, Yunnan Province, China; March 2025, Liu. F. • IHB 202507046, 1, 52 mm SL; Tongche River (a tributary of the Chishui River in the upper Yangtze River drainage) in Zhenxiong County, Yunnan Province, China; May 2025, Liu. F. Diagnosis. Sineuchiloglanis chishuiensis sp. nov. can be readily distinguished from congeners by the following characters: dorsal-fin rays i, 5 1 / 2; pectoral-fin rays i, 12–13; anal-fin rays i, 4 1 / 2; caudal-fin rays i, 7 + 8, i; gill opening extending to the base of second to third pectoral-fin elements; tip of maxillary barbel not reaching or extending beyond the lower corner of the gill opening; tip of nasal barbel not reaching anterior orbital margin; pelvic-fin tip reaching or extending beyond anus; the ventral abdominal surface slightly convex (Fig. 4). And it can be further distinguished from congener by the following characters: eye enlarged, with diameter 6.8–9.1 % of HL; head length behind the eyes 35.6–40.3 % of HL; interorbital width 24.1–24.8 % of HL; maxillary barbel length 67.1–84.4 % of HL; caudal-peduncle length 21.5–29.2 % of SL; pelvic-fin origin to anal-fin origin length 23.4–28.5 % of SL; dorsal-fin insertion to adipose-fin origin length 14.1–23.2 % of SL; post-adipose length 8.2–12.7 % of SL; caudal-peduncle depth 27.1–40.3 % of caudal-peduncle length; pectoral-fin depth 53.0–70.5 % of pectoral length. The primary diagnostic characters for species of Sineuchiloglanis are summarized in Table 2. Description. Morphometric characters of 22 type specimens are shown in Table 3. Dorsal-fin rays i, 5 1 / 2; pectoral-fin rays i, 12–13; pelvic-fin rays i, 5; anal-fin rays i, 4 1 / 2; branched caudal-fin rays i, 7 + 8, i; vertebra 13 + 25 = 38 (n = 1); 13 + 24 = 37 (n = 1); 12 + 24 = 36 (n = 2) (Table 4). Body compressed, with a slightly raised back. Depth of body 11.7–18.2 % of SL, width of body 12.6–17.5 % of SL. Head depressed, rostral margin rounded when viewed dorsally. Depth of head 8.8–12.3 % of SL, width of head 18.5–24.5 % of SL. Body smooth and scaleless, lateral line complete and midlateral. Oral region and anterior part of abdomen with dense papillae, density gradually decreasing posteriorly. Lateral abdominal regions slightly convex, forming a shallow medially invaginated groove along the ventral midline. Caudal fin truncate, with two unbranched and 7 + 8 branched fin rays (Fig. 3). Dorsal-fin located in anterior third of body, with one unbranched and six branched fin rays without spine, outer margin straight; tip of dorsal-fin rays extending beyond vertical through pelvic-fin base when depressed. Adipose fin located in anterior three-fifths of body, not confluent with caudal fin. Pectoral-fin enlarged, located in anterior one-fifth of body, with one unbranched and 12 branched fin rays; first ray of each broadened; regular striae on ventral surface; tip of pectoral-fin rays not reaching, reaching, or extending beyond pelvic-fin origin. Pelvic-fin enlarged, located in anterior two-fifths of body, with one unbranched and five branched fin rays; first element on each broadened; regular striae on ventral surface; tip of pelvic-fin rays reaching or extending beyond anus. Anal-fin located in anterior two-thirds of body, with one unbranched and five branched fin rays (last branched fin ray branches from the base of the dorsal-fin). Anus located approximately at midpoint of the distance between the pelvic-fin insertion and the anal-fin origin, close to the anal-fin origin. Mouth wide (mouth width of 32.1–40.2 % of HL), inferior, transverse. Premaxillary tooth band with a deep median indentation, sides not extending posteriorly. Dentary tooth band with two short, wide patches. Oral teeth conical, pointed. Barbels four pairs. Maxillary barbel with flap of skin fringing posterior margin, tip pointed, not reaching or extending beyond lower gill opening corner. Lower lip connected to base of maxillary barbel by skin flap, without sulcus between them. Mandibular barbels two pairs, inner mandibular barbel shorter than outer mandibular barbel. Origin of inner mandibular barbel close to midline. Outer mandibular barbel originating posterolateral of inner mandibular barbel. Post-labial groove interrupted, ending at base of inner mandibular barbel. Nasal barbel with small flap of thin skin fringing posterior margin, not reaching anterior margin of orbital. Eye small, almost round, subcutaneous, located on upper lateral surface of head, closer to dorsal-most extremity of gill opening. Gill opening extending to the base of second or third pectoral-fin elements. Coloration. In fresh specimens, body green-yellow on dorsal surface. On venter, from snout to the pelvic-fin insertion milky white, after pelvic-fin green-yellow. Around the anus pale yellow. Pectoral-fin and pelvic-fin with pale yellow distal margins, lateral green-yellow and medial pale yellow. Dorsal-fin, adipose-fin, and anal-fin green-yellow with pale yellow distal margins. Caudal fin green-yellow with a small pale yellow patch and pale yellow distal margin. In alcohol-fixed specimens, body grey, ventral surface, and margins of fins milky white. Ecology and habitat. Sineuchiloglanis chishuiensis sp. nov. inhabits rapids and riffles, with primarily rocky substrates (Fig. 5). The water temperature was 20.0–26.5 ° C during the survey period in August 2024. The species co-occurred with Schizothorax grahami Regan, 1904 and Sinogastromyzon sichangensis Chang, 1944, in this type locality. Distribution. This new species is presently only known from the headwaters of Chishui River in the Yangtze River drainage in Zhenxiong County of Yunnan Province, and Bijie City of Guizhou Province, China. Etymology. The specific epithet is derived from its type locality, Chishui River.