Gobio rivuloides Nichols 1925

Gobio rivuloides Nichols, 1925 Figs 7, 8, Table 2 Gobio rivuloides Nichols, 1925: 5. Gobio (Romanogobio) johntreadwelli: Bănărescu & Nalbant (1973): 145. Gobio (Romanogobio) amplexilabris: Bănărescu & Nalbant (1973): 147. Gobio meridionalis: Chen et al. (1987): 119. Romanogobio johntreadwelli: Naseka (1996): 160. Romanogobio amplexilabris: Naseka (1996): 160. Romanogobio rivuloides: Naseka (1996): 160. Material examined. • AMNH 8420 (Holotype), 1 specimen, 133.5 mm SL; Niang-tze-kwan, Shansi (= Niangziguan Township, Pingding County, Yangquan City, Shanxi Province), collected by C. H. Pope. AMNH 29694, 1 specimen, 93.7 mm SL; Linfen City, Shanxi Province, from the Qingshuihe River, a tributary of the Yellow River drainage. • AMNH 29696, 1 specimen, 80.6 mm SL; Linfen City, Shanxi Province, from the Qingshuihe River, a tributary of the Yellow River drainage. IHB 81–7–1981, 81–7–1983, 81–7–1984, 81–7–1985, 81–7–1987, 81–7–1997, 6 specimens, 60.0– 88.6 mm SL; Lingbao City, Sanmenxia City, Henan Province, from the Hongnongjian River. • ASIZB 241458, 1 specimen, 109.1 mm SL; Hequ County, Xinzhou City, Shanxi Province, from the main stream of the Yellow River (39.3502°N, 111.1931°E, ca 840 m a. s. l.); collected by Yutian Fang, 17 October 2023. • ASIZB 241459, 1 specimen, 96.9 mm SL; Xing County, Lvliang City, Shanxi Province, from the main stream of the Yellow River (38.5145°N, 110.8782°E, ca 760 m a. s. l.); collected by Xin Wang, 2 March 2022. • ASIZB 242016–242018, 3 specimens, 84.5–100.2 mm SL, Wuhai City, Inner Mongolia Autonomous Region, from the main stream of the Yellow River (39.7124°N, 106.7635°E, ca 1060 m a. s. l.); collected by Junyuan Hao, 11 May 2024. • ASIZB 241457, 1 specimen, 82.5 mm SL; Pingshan County, Shijiazhuang City, Hebei Province, from the Hutuohe River (38.3994°N, 113.6947°E, ca 280 m a. s. l.); collected by Zhixian Sun, 6 July 2023. • ASIZB 215395, 1 specimen, 70.3 mm SL; Yangyuan County, Zhangjiakou City, Hebei Province, from the Sangganhe River (40.1735°N, 114.5267°E, ca 820 m a. s. l.); 20 October 2019. • ASIZB 239685–239687, 3 specimens, 73.7–98.9 mm SL; Shangyi County, Zhangjiakou City, Hebei Province, from the Yanghe River (40.8887°N, 114.2029°E, ca 1040 m a. s. l.); collected by Chen Tian, 2 October 2023. • ASIZB 242027–242028, 242042, 3 specimens, 66.9–77.9 mm SL; Luonan County, Shangluo City, Shaanxi Province, from the Luohe River, a tributary of the Yellow River drainage (34.1927°N, 110.0943°E, ca 1010 m a. s. l.); collected by Yutian Fang, 28 May 2024. • ASIZB 242043–242046, 4 specimens, 87.8–93.9 mm SL; Qingtongxia City, Wuzhong County, Ningxia Hui Autonomous Region, from the main stream of the Yellow River (38.0387°N, 106.1837°E, ca 1130 m a. s. l.); collected by Junyuan Hao, 4 August 2024. • ASIZB 242047–242051, 5 specimens, 72.1–92.0 mm SL; Hangjin Banner, Ordos City, Inner Mongolia Autonomous Region, from the main stream of the Yellow River (40.8379°N, 107.8308°E, ca 1030 m a. s. l.); collected by Junyuan Hao, 30 July 2024. • ASIZB 242052–242055, 4 specimens, 75.8–85.1 mm SL; Bohaiwan County, Wuhai City, Inner Mongolia Autonomous Region, from the main stream of the Yellow River (39.8317°N, 106.7551°E, ca 1070 m a. s. l.); collected by Junyuan Hao, 27 July 2024. • ASIZB 242056–242057, 2 specimens, 118.3–119.2 mm SL; Huailai County, Zhangjiakou City, Hebei Province, from the Yanghe River, a tributary of the Haihe River drainage (40.3804°N, 115.3630°E, ca 490 m a. s. l.); collected by Chen Tian, 28 July 2023. Vouchers for molecular study. ASIZB 219283, 1 specimen, Huguan County, Changzhi City, Shanxi Province, from the Xihe River, a tributary of the Haihe River drainage (35.9271°N, 113.6309°E, ca 540 m a. s. l.); collected by Zhixian Sun, 2 September 2020. ASIZB 239687, 1 specimen, Shangyi County, Zhangjiakou City, Hebei Province, from the Yanghe River, a tributary of the Haihe River drainage (40.8887°N, 114.2029°E, ca 1040 m a. s. l.); collected by Chen Tian, 2 October 2023. ASIZB 241457, 1 specimen, Pingshan County, Shijiazhuang City, Hebei Province, from the Hutuohe River, a tributary of the Haihe River drainage (38.3994°N, 113.6947°E, ca 280 m a. s. l.); collected by Zhixian Sun, 6 July 2023. ASIZB 242027–242028, 2 specimens, Luonan County, Shangluo City, Shaanxi Province, form the Luohe River, a tributary of the Yellow River drainage (34.1927°N, 110.0943°E, ca 1010 m a. s. l.); collected by Yutian Fang, 28 May 2024. ASIZB 241459, 1 specimen, Xing County, Lvliang City, Shanxi Province, from the main stream of the Yellow River (38.5145°N, 110.8782°E, ca 760 m a. s. l.); collected by Xin Wang, 2 March 2022. ASIZB 242016, 242018, 2 specimens, Wuhai City, Inner Mongolia Autonomous Region, from the main stream of the Yellow River (39.7124°N, 106.7635°E, ca 1060 m a. s. l.); collected by Junyuan Hao, 11 May 2024. ASIZB 242062, 1 specimen, Daning County, Linfen City, Shanxi Province, from the main stream of the Yellow River (36.4587°N, 110.4876°E, ca 600 m a. s. l.); collected by Zhixian Sun, 8 July 2024. Diagnosis. This species can be distinguished from other Gobio species in the Yellow River drainage by following characteristics: barbel reaching between vertical position of posterior orbit and posterior preopercle margin (vs. reaching beyond posterior preopercle margin in G. huanghensis and G. guentheri); lateral-line scales 40–43 (mode 42, mean 42) (vs. mean 40 in G. coriparoides); circumpeduncular scales 12–16 (mode 12, mean 12) (vs. more than 16 in G. huanghensis, G. coriparoides, and G. guentheri); longitudinal epithelial crests present on pre-dorsal scales (vs. absent in G. coriparoides and G. guentheri); anus centrally located between pelvic-fin base and anal-fin origin or closer to pelvic-fin base (vs. positioned at posterior one-third of distance from pelvic-fin base end to anal fin origin in G. coriparoides and G. guentheri). Redescription. Body elongated, dorsal body profile rising from nostrils to dorsal-fin origin, dropping along dorsal-fin base, then gradually sloping to caudal-fin base. Maximum body depth at dorsal-fin origin. Head relative elongated, length slightly larger than body depth; snout relative elongated. Mouth horseshoe-shaped and inferior, with one pair of maxillary barbels root at extremity of upper lip, barbel relative elongated, reaching from vertical position of posterior orbit to posterior preopercle margin. Lips thin, lower lip fused with throat; lips connected at mouth corner. Eyes positioned on dorsal half of head; interorbital region flattened; width almost equal to eye diameter. Thoracic region flattened, abdomen rounded, caudal peduncle robust, compressed laterally. Anus centrally located between pelvic-fin base and anal-fin origin or closer to pelvic-fin base. Body covered with moderately large cycloid scales. Lateral line complete, almost straight in lateral center. Lateral line scales 40 (4 specimens), 41 (9), 42 (17), 43 (4); scales above lateral line 5.5 (27), 6 (3), 6.5 (3), 7.5 (1); scales below lateral line 2 (1), 3 (30), 4 (3); circumpeduncular scales 12 (23), 14 (9), 16 (2). Longitudinal epithelial crests present on pre-dorsal region scales; the ventral scaleless region extends to middle of pectoral-fin base and to pelvic-fin base. Dorsal fin with three unbranched and seven (34 specimens) branched rays; distal margin concave, origin closer to snout than caudal-fin base. Pectoral fin with one unbranched and 13 (15), 14 (16), and 15 (3) branched rays; tip of adpressed not reaching anterior margin of pelvic-fin insertion. Pelvic fin with one unbranched and seven (34) branched rays; tip of adpressed reaching to posterior anus. Anal fin with three unbranched and six (33), seven (1) branched rays; origin closer to pelvic-fin insertion than to caudal-fin base. Caudal fin deeply forked, with nine branched rays on upper lobes and eight branched rays on lower lobes, lobes pointed, upper lobes slightly more pointed than lower lobes. Total vertebrae 4 + 34–36. Gill rakers rudimentary. Pharyngeal teeth “ 3, 5–5, 3 ”. Coloration in life. Dorsal side of head and body brownish yellow, mid-lateral side shallow brownish yellow, and ventral side grayish white. Dorsal side of body with 5–6 black crossbars (first at posterior of head, second at dorsal-fin base origin, third at posterior of dorsal-fin base, fourth at vertical position above anal-fin base origin, fifth and sixth on caudal peduncle, respectively). Flank with 7–10 black blotches; margin of scales on back and flank black pigmented. One slightly fluorescent yellowish-green stripe extends above lateral line. One distinct black stripe between anterior orbit and snout. Fins translucent, dorsal fin, pectoral fin, pelvic fin, and caudal fin with some black spots (Fig. 8 B). The specimens collected in the main stream of the Yellow River have paler color and less black spots than those specimens that were collected from the tributaries. We assume that because the water from the main stream of the Yellow River is more turbid (caused by sand), the fish present lighter colors. Coloration in preservation. Dorsal side of head and body greyish brown, mid-lateral side greyish yellow, and ventral side greyish white. Dorsal side of body with 5–6 black crossbars in same position as live individual. Flank with 7–10 dark grey blotches, first three or four blotches vague. Margin of scales on back and flank black pigmented. The fluorescent yellowish-green stripe faded. One distinct black stripe between anterior orbit and snout. Fins pale, dorsal fin, pectoral fin, pelvic fin, and caudal fin with some black spots. The color of specimens that were collected in mainstream of the Yellow River could be lighter, dorsal side of head and body shallow greyish yellow, mid-lateral and ventral sides greyish white. Dorsal side of body with 5–6 shallow black crossbars in same position as live individual. The blotches on flank vague, merge into a shallow dark stripe from posterior head to caudal peduncle end. Margin of scal