Cobitis brachysoma Chen YX & Chen YF, 2018

Chen, Yongxia, Chen, Hao, He, Dekui & Chen, Yifeng, 2018, Two new species of the genus Cobitis (Cypriniformes: Cobitidae) from South China, Zoological Systematics 43 (2), pp. 156-168 : 162-165

Cobitis brachysoma Chen YX & Chen YF , sp. nov. ( Figs 8–17 )

Cobitis sinensis Ye, 1991 (nec. Sauvage & Dabry, 1874): 253 (Guangdong); Jia et al., 2013: 1492 (Zengjiang River, Guangdong).

Holotype. ♂, HU 1506334, 55.2 mm TL, 47.1 mm SL, China: Guangdong, Guangning County (23°64′N, 112°44′E; elev. 65 m), the Suijiang River (a tributary of the Pearl River ), April 2015, leg. Yongxia Chen. Paratypes. HU 1505204, 1505207, 1506320, 1506326, 1506330, 5♂, 50.5–71.4mm TL, 43.1–58.6mm SL, HU 1505209, 1505289, 1505292, 1505296, 1506290, 1506302, 1506307, 1506315, 1506322, 1506325, 1506328, 1506331–3, 1506336, 15♀, 53.1–74.2 mm TL, 44.7– 61.5 mm SL, same data as holotype . Other material examined. HU 1506360, 1506369, 1600080, 1600083, 1600086, 5♂, 47.4–74.4 mm TL, 39.5–63.6 mm SL, HU 1506341–2, 1506349, 1600081, 1600084–5, 6♀, 51.2–61.6 mm TL, 42.3– 52.9 mm SL, China: Guangdong, Yangjiang County (21°86′N, 111°98′E; elev. 65 m), the Nalongjiang River (a tributary of the Moyangjiang River ), April 2015, leg. Yongxia Chen. HU 1608048–9, 1608052–4, 5♂, 50.4–60.8mm TL, 42.9–52.4 mm SL, HU 1608040–1, 1608043–7, 1608050–1, 9♀, 59.4–92.3 mm TL, 51.3–78.7 mm SL, China: Guangdong, Longmen County (23°73′N, 114°25′E; elev. 65 m), the Zengjiang River (a tributary of the Pearl River ), September 2016. leg. Yongxia Chen.

Diagnosis. The new species can be distinguished from its congeners by possessing the following combination of characteristics: small body size, SL mean 50 mm in males and 60 mm in females; a small jet spot far smaller than the eye diameter on the upper part of the caudal peduncle; 7–8 narrow rows of dark spots on the caudal fin ( Figs 8–9 , 14–17 ); males with a slender and finely serrated lamina circularis at the base of the first branched pectoral fin ray ( Fig. 10 ); mental lobes undeveloped, two superficial longitudinal lobes short and bluntly rounded ( Fig. 11 ); suborbital spine straight, with long processus medio-caudalis ( Fig. 12 ). Cobitis brachysoma Chen YX & Chen YF , sp. nov. is similar to C. microcephala in body size and shape of lamina circularis, but differs from it in having long processus medio-caudalis of suborbital spine (vs. short); caudal peduncle short, length of caudal peduncle 7.3–9.2 (mean 8.4) in SL in males and 7.0–9.9 (mean 8.5) in females (vs. caudal peduncle long, length of caudal peduncle 5.9–6.6 (mean 6.3) in SL in males and 5.3–7.2 (mean 6.3) in females); body slender, depth 6.1–6.6 (mean 6.4) in SL in males and 5.5–8.6 (mean 6.8) in females (vs. sturdy, depth 5.8–6.2 (mean 5.9) in SL in males and 5.0–6.5 (mean 5.6) in females).

Description ( Figs 8–17 , Table 2 ). D. III–7; A. III–5; V. I–6; P. I–7–8; C. IV–14–16–IV. Body small, elongated, and compressed. Head small and compressed. Snout rounded. Eyes located on upper part and middle of head. Preorbital part of head shorter than postorbital part of head. Mouth small, inferior, with three pairs of short barbels. Length of maxillomandibular barbels longer than diameter of eye. Mental lobes undeveloped, two superficial longitudinal lobes short and bluntly rounded ( Fig. 11 ). Suborbital spine bifid, relatively slender and straight, with a long processus medio-caudalis. Processus latero-caudalis short, less than one-fifth of processus medio-caudalis ( Fig. 12 ). Subdorsal scales small and oval, with a larger focal area, 17–21 radial grooves, and 4–8 supplementary ones ( Fig. 13 ).

Dorsal fin long, inserted midway of body; dorsal fin slightly shorter than head length. In males, pectoral fins moderately long, second pectoral fin ray longest ( Fig. 15 ). In females, pectoral fins slightly shorter, third pectoral fin ray longest ( Fig. 17 ). Ventral fins short, small, and approximately at same level as third branched dorsal-fin ray. Anal fin moderately long, located on half of space between ventral and caudal fins and not reach caudal fin. Anal orifice close to anal fin. Caudal fin emarginated tip. Caudal peduncle with ventral adipose crest. Lateral line short, not exceeding length of pectoral fins.

Pigmentation pattern. Color pattern characteristic of sexual dimorphism not observed. Head sprinkled with many black dots, and a black stripe extended from the insertion of rostral barbels to eye. L 1 consisted of a row of 5–7 rectangular blotches before dorsal fin that became less regular behind head; 2 on dorsal fin and 6–7 behind dorsal fin. Gap of rectangular blotches larger than width of blotches. L 2 composed of a line of irregularly small spots and that diminished towards end of caudal fin. L 3 composed of a row of horizontally elongated or rounded blotches and diminished towards end of caudal fin. L 4 composed of a line of minute black dots and diminished towards end of caudal fin. L 5 consisted of a row of 11–12 horizontally elongated or rounded blotches. One small jet spot on upper half of caudal fin base and far smaller than eye diameter. 7–8 narrow rows of dark dots on dorsal and caudal fins.

Sexual dimorphism. Males smaller than females with proportionally longer pectoral, ventral and anal fins. In males, second pectoral fin ray thickened and elongated, a slender and finely serrated lamina circularis at base of first branched pectoral fin ray. In females, third pectoral fin ray elongated.

Distribution. This new species occurs in the Suijiang River (a tributary of the Pearl River) in Guangning County, the Zengjiang River (a tributary of the Pearl River) in Longmen County, and the Nalongjiang River (a tributary of the Moyangjiang River) in Yangjiang County, all from Guangdong, China ( Fig. 1 ).

Etymology. The species name is derived from the Greek brachys, meaning short, and soma meaning body, in reference to the short body of the species.

Figures

Figure 1. Map showing the collection sites of the two new species of the genus Cobitis in Guangdong and Hainan Provinces of China.

Figures 8–13. Cobitis brachysoma Chen YX & Chen YF, sp. nov., Suijiang River, Guangning, Guangdong, China. 8. Holotype, HU 1506334, lateral view. 9. HU 1506307, lateral view. 10. Lamina circularis in the pectoral in of male, dorsal view. 11. Mouth characters, front view. 12. Suborbital spine, left dorsal view, right interior view. 13. Subdorsal scales, dorsal view. Scale bars: 8–9= 1cm; 10–12 =1mm; 13=100μm.

Figures 14–17. Cobitis brachysoma Chen YX & Chen YF, sp. nov., color in life. 14, 16. Lateral view. 15, 17. Dorsal view. Scale bars =1cm.