Cobitis gracilis, Chen & Chen, 2016

Chen, Yongxia & Chen, Yifeng, 2016, A new species of the genus Cobitis (Cypriniformes: Cobitidae) from the Northeast China, Zoological Systematics 41 (4), pp. 379-391 : 381-385

Cobitis gracilis sp. nov. ( Figs 3–12 )

Holotype. ♂, HU 1600062, 74.4 mm TL, 64.2 mm SL, the Yalu River , Linjiang (41°81′N, 126°92′E), Jilin, China, October 2015, collected from the Linjiang farm product market by Yongxia Chen.

Paratypes. HU 1505136, 1600037, 1600056, 3♀, 75.2–88.4 mm TL, 65.0– 78.4 mm SL, same data as holotype; HU 1506359, 1506347, 1506354, 3♀, 81.5–86.4 mm TL, 71.0– 74.3 mm SL, the Ussuri River , Raohe (46°80′N, 134°02′E), Heilongjiang, China, October 2015, collected from the Raohe farm product market by Yongxia Chen .

Diagnosis. The new species is most similar to C. granoei and C. melanoleuca , but distinguished from C. granoei and C. melanoleuca in the upper jet black spot at the base of caudal fin inconspicuous or absent ( Figs 3–4 , 9–10 ) (vs. jet black spot conspicuous in C. melanoleuca ( Figs 19–20 ) and C. granoei ( Figs 13–14 )); suborbital spine is slender and straight, with long processus latero-caudalis, less than one-second of the processus medio-caudalis ( Fig. 7 ) (vs. suborbital spine thick and straight with short processus latero-caudalis in C. melanoleuca ( Fig. 23 ); suborbital spine slender and curved with long processus latero-caudalis in C. granoei ( Fig. 17 )); males with a small meniscus lamina circularis at the base of the first branched pectoral fin ray ( Fig. 5 ) (vs. an knife lamina circularis in C. melanoleuca ( Fig. 21 ); a larger semilunar lamina circularis in C. granoei ( Fig. 15 )); 15–20 blotches on L 5 (vs. 10–16 blotches on L 5 in C. melanoleuca ; 11–16 large blotches on L 5 in C. granoei ).

Description. General appearance and morphometic data of holotype and paratypes are given in Figs 3–12 and Table 2 , respectively. D. III–7; A. III–5; V. I–6; P. I–7–8; C. IV–14–16–IV. Body slender, depth 8.7 in SL in males and 8.9–11.1 (mean 9.8) in females. Head small, with a length of 5.3 in SL in males and 5.2–5.6 (mean 5.5) in females. Snout rounded. Preorbital part of head shorter than postorbital part of head. Mouth small, with three pairs of short barbels. Length of maxillo-mandibular barbels shorter than diameter of eye. Maxillary barbels not reach under anterior border of eye. Mental lobes undeveloped, two superficial longitudinal lobes short, and lower tip bluntly rounded ( Fig. 6 ). Suborbital spine slender and straight, with long processus latero-caudalis, less than one-second of processus medio-caudalis ( Fig. 7 ). Subdorsal scales small and oval, with a large focal area, 19–22 radial grooves, and 3–5 supplementary ones ( Fig. 8 ).

Dorsal fin inserted midway between posterior nasal and base of caudal fin. Length of predorsal 1.9 in SL in males and 1.8–1.9 (mean 1.8) in females. In males, pectoral fins longer than those in females; first branched pectoral fin ray longest. Length of first branched pectoral fin ray 7.1 in SL. In females, second branched pectoral fin ray longest with length of second branched pectoral fin ray 8.6–11.0 (mean 9.8) in SL. Ventral fins approximately at same level as dorsal fin. Anal fin located in far behind dorsal extremity and not reach caudal fin. Anal orifice close to anal fin. Caudal fin emarginated tip.

Pigmentation pattern. Body color whitish with a variable dark brown pigmentation pattern organized in L 1 –L 5 ( Figs 3–4 , 9–12 ). Color patterns characteristic of sexual dimorphism not obvious. L 1 consisted of a row of 7–9 rectangular blotches before dorsal fin that became less regular behind head; 2 on dorsal fin and 7–10 behind dorsal fin. Gap of rectangular blotches narrower than width of blotches. L 2 comprised a line of irregularly small dots that not intermingle with gap of L 1, and diminished towards end of caudal fin. L 3 comprised a row of horizontally elongated or rounded spots and that decreased beyond anal fin. L 4 spotted with one line of dots and that diminished towards end of caudal fin. L 5 comprised 15–20 oval blotches that together formed an irregular small blotch near head and caudal fin. At base of caudal fin, one inconspicuous jet-black spot found in upper region. In a few individuals, spot absent. Five or six striations on dorsal and caudal fins. Head sprinkled with many black spots on dorsal side, and a black stripe extended from occiput through eye to insertion of rostral barbels.

Sexual dimorphism. Males smaller than females with proportionally longer pectoral, ventral, and anal fins. In males, first branched pectoral-fin ray thickened and elongated, with a small meniscus lamina circularis at base ( Fig. 5 ). In females, second branched pectoral fin ray elongated.

Distribution. This new species occurs in the Yalu and Heilongjiang rivers in Jilin and Heilongjiang Provinces in northeast of China ( Figs 1–2 ).

Etymology. The specific name derives from the Latin gracilis , meaning slender, in reference to the slender body.

Figures

Figure 1. The collection sites (i.e. currently known localities) of 5 species of the genus Cobitis from north to Yellow River in China.

Figure 2. Ecological environment of Cobitis gracilis sp. nov.

Figures 3–8. Cobitis gracilis sp. nov., Yalu River, Linjiang, Jilin, China. 3. Holotype, HU 1505143, lateral view. 4. HU 1505134, lateral view. 5. Lamina circularis in the pectoral fin of male, dorsal view. 6. Mouth characters, front view. 7. Suborbital spine, left dorsal view, right interior view. 8. Subdorsal scales, dorsal view. Scale bars: 3–4=1cm; 5–7=1mm; 8=100μm.

Figures 9–12. Cobitis gracilis sp. nov., color in life. 9, 11. Lateral view. 10, 12. Dorsal view. Scale bars=1 cm.

Figures 19–24. Cobitis melanoleuca, Juma River, Yixian, Hebei, China. 19–20. Color in life, lateral view. 21. Lamina circularis in the pectoral fin of male, dorsal view. 22. Mouth characters, front view. 23. Suborbital spine, left dorsal view, right interior view. 24. Subdorsal scales, dorsal view. Scale bars: 19–20=1 cm; 21–23=1mm; 24=100μm.

Figures 13–18. Cobitis granoei, Huma River, Tahe, Heilongjiang, China. 13–14. Color in life, lateral view. 15. Lamina circularis in the pectoral fin of male, dorsal view. 16. Mouth characters, front view. 17. Suborbital spine, left dorsal view, right interior view. 18. Subdorsal scales, dorsal view. Scale bars: 13–14=1 cm; 15–17 =1mm; 18=100μm.