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| Rhodeus nigrodorsalis &
R. cyanorostris
Li, Liao & Ara,. 2020
DOI: 10.25225/jvb.19055
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Abstract
Rhodeus cyanorostris sp. nov. and R. nigrodorsalis sp. nov. are described from two tributaries of the River Yangtze, in Sichuan and Jiangxi Provinces, China, respectively. Both species have a small number of branched dorsal-fin rays (both with a mode of 8) and anal-fin rays (mode of 7-8 and 8, respectively), which makes them easily distinguished from all congeners. Rhodeus cyanorostris sp. nov. differs from R. nigrodorsalis sp. nov. in having more predorsal scales (14-16 vs. 12-13), fewer pectoral-fin rays (10-11 vs. 12), a shorter major axis of the eggs (2.5-2.8 mm vs. mostly 3.3-3.5 mm), absence of two rows of light spots on the dorsal-fin rays (vs. presence), and absence of a black blotch on the dorsal fin in adult males (vs. presence). The breeding season in winter of the two new species is unique among the Acheilognathinae.
KEYWORDS: bitterling, Breeding season, egg size, lateral line, taxonomy
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| Fig. 6. Rhodeus cyanorostris sp. nov. in breeding season, collected from its type locality. A) male; B) female just before spawning (with ovipositor in maximum length). Specimen not preserved. |
Rhodeus cyanorostris sp. nov.
Diagnosis: Differs from all congeners by a combination of characters, including longitudinal scale series 32-35; pored scales absent; transverse scale series 11 (10-12); branched dorsal-fin rays 8 (rarely 7); branched anal-fin rays 7-8; vertebrae 33-34 (rarely 35); light spots on dorsal-fin rays absent; in males with nuptial colouration, snout blue, and iris, belly and all fins yellow.
Distribution and ecology: Known only from the River Bai-Tiao, a tributary of the River Yangtze, in Pidu District, Chengdu City, Sichuan Province, China (Fig. 8). The type locality was a small river with mud and gravel mixed substrate. The water level varied from approximately 0.5 to 1.0 m depth.
Adult R. cyanorostris sp. nov. are small in size. The smallest female found with mature oocytes was 23.6 mm SL. The main spawning season is in winter, from January to March. Females spawn several times during the spawning period and usually releases clutches of 3-8 eggs when squeezed manually. Host mussels are not known.
Etymology: The specific name, cyanorostris, is derived from the Latin terms cyano for blue and rostris for snout, a noun, alluding to the distinctive blue snout in nuptial males.
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| Fig. 14. Rhodeus nigrodorsalis sp. nov. in breeding season, collected from its type locality. A) male; B) female just before spawning (with ovipositor in maximum length). Specimen not preserved. |
Rhodeus nigrodorsalis sp. nov.
Diagnosis: Differs from all congeners by a combination of characters, including longitudinal scale series 33-35; pored scales 2-4 (rarely 0); transverse scale series 10 (rarely 11); branched dorsal-fin rays 8; branched anal-fin rays 8 (rarely 9); vertebrae 34-35 (rarely 33); iris yellowish, belly yellow, dorsal-fin membrane dark black, and a vertical band on the anterior of flank in nuptial males.
Distribution and ecology: Known only from the River Le-An in Wuyuan County, Jiangxi Province (type locality) and the River Lv in Qimen County, Anhui Province both flowing into Lake Poyang in the River Yangtze basin (Fig. 8). The type locality is a large river where R. nigrodorsalis sp. nov. occurs mostly in shallow marginal areas with a substrate of mixed sand and mud.
Female R. nigrodorsalis sp. nov. starts spawning at just 30 mm SL, but with the maximum length of this species seen in a captive male kept in an aquarium for 17 months of 47.1 mm SL. The main spawning season is during winter, from January to March. Females spawn several times during the spawning period and usually release 2-7 eggs in a clutch when squeezed manually. Host mussels are not known.
Etymology: The specific name, nigrodorsalis, is derived from the Latin terms nigro for black and dorsalis for dorsal fin, a noun, alluding to the diagnostic black dorsal-fin membrane in adult males.
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| Fig. 15. Dorsal fin of adult males of five Rhodeus species. A) Rhodeus nigrodorsalis sp. nov. in life, SOU 1903001, 47.1 mm SL; B) R. nigrodorsalis sp. nov. in preservative, SOU 1712002, 37.9 mm SL; C) Rhodeus cyanorostris sp. nov. in preservative, SOU 1801001, holotype, 32.1 mm SL; D) R. amarus in life, 59.8 mm SL (specimen not preserved), collected from Ballica, Turkey; E) R. shitaiensis in life, 56.1 mm SL (specimen not preserved), collected from Shitai County, Anhui Province, China; F) R. rheinardti in life, 49.3 mm SL (specimen not preserved), collected from Hue City, Vietnam. |
Fan Li, Te-Yu Liao and Ryoichi Arai. 2020. Two New Species of Rhodeus (Teleostei: Cyprinidae: Acheilognathinae) from the River Yangtze, China. Journal of Vertebrate Biology. 69(1); 1-17. DOI: 10.25225/jvb.19055
