Niwaella nigrolinea Chen & Chen, 2017

Chen, Yongxia, He, Dekui, Chen, Hao & Chen, Yifeng, 2017, Taxonomic study of the genus Niwaella (Cypriniformes: Cobitidae) from East China, with description of four new species, Zoological Systematics 42 (4), pp. 490-507 : 494-496

Niwaella nigrolinea Chen & Chen , sp. nov. ( Figs 2–7 )

Holotype. HU 2013112, 58.7 mm SL, the Shuaishui River (a tributary of the Xin'anjiang River), Xiuning County (29°78′N, 118°16′E), Anhui, China, October 2013, collected from the Xiuning farm product market by Yongxia Chen.

Paratypes. HU 2013113–5, 2013117–8, 5 ex., 52.0– 62.2 mm SL, same data as holotype; HU 1505136–7, 2 ex., 56.4– 59.5 mm SL, the Shuaishui River , Xiuning County, Anhui, China, April 2015, collected from the Xiuning farm product market by Yongxia Chen ; HU 1608211, 1608209, 1608206, 3 ex., 54.9–63.3 mm SL, the Hengjiang River (a tributary of the Xin'anjiang River ), Xiuning County , Anhui, China, April 2016, collected from the Xiuning farm product market by Yongxia Chen .

Diagnosis. The new species can be distinguished from its congeners by possessing the following combination of characteristics: a conspicuous black stripe from the occiput to the caudal fin on the dorsum, with 19–22 inconspicuous surface blotches ( Fig. 7 ); short and dense vertical bars on the dorsolateral surface, and a row of 8–11 long, sparse, broad vertical stripes below the lateral midline posterior to the dorsal fin ( Figs 2 , 6 ); lower lip and mandible separated, with undeveloped mental lobes ( Fig. 3 ); suborbital spine thick and curved, with long processus latero-caudalis, less than onethird of processus medio-caudalis ( Fig. 4 ); caudal peduncle long, length of caudal peduncle 5.8–6.8 (mean 6.2) in SL.

Description ( Figs 2–7 , Table 2). D. III–7; A. III–5; V. I–6; P. I–6–7; C. IV–14–16–IV. Body slender, compressed, depth 9.4–10.6 (mean 9.8) in SL. Head small. Snout rounded. Preorbital part of head shorter than postorbital part of head. Mouth small, inferior, with three pairs of long barbels. Length of maxillo-mandibular barbels longer than diameter of eye. Lower lip and mandible separated, with undeveloped mental lobes ( Fig. 3 ). Suborbital spine thick and curved, with a long processus latero-caudalis, less than one-third of processus medio-caudalis ( Fig. 4 ). Subdorsal scales round, with a large focal area, 15– 21 radial grooves, and 3–8 supplementary ones ( Fig. 5 ).

Dorsal fin long, inserted the midway between the posterior margin of eye and the base of the caudal fin. Pectoral fins short. Length of the pectoral fin ray 9.0–11.9 (mean 10.5) in SL. Ventral fins short, approximately at the same level as the second branched dorsal-fin ray. Anal fin short, located in far behind dorsal extremity and not reach the caudal fin. Anal orifice close to the anal fin. Caudal fin emarginated tip.

Pigmentation pattern. Head sprinkled with many black spots, a black stripe extended from the insertion of the rostral barbels through the eye to the occiput. On the dorsum, a conspicuous longitudinal black stripe from the occiput through the dorsal fin to the caudal fin, with a surface pigment containing 19–22 small inconspicuous blotches. Short and dense vertical bars on the dorsolateral surface, and a row of 8–11 long, sparse, broad vertical stripes below the lateral midline posterior to the dorsal fin. One conspicuous large oval spot present on the upper half of the caudal fin base; the upper spot as large as the diameter of the eye. Three or four rows of brownish dots present on the dorsal and caudal fins.

Sexual dimorphism. Not obvious in external morphology.

Distribution. This new species occurs in the Xin'anjiang River (the upper reaches of the trunk stream of the Qiantangjiang River) in Anhui Province in east China ( Fig. 1 ).

Etymology. The specific name derives from the Latin niger, meaning black, and Latin linea meaning line, in reference to the dorsum coloration of the species.

Figures

Figure 1. Currently known localities of the eight Niwaella species in China.

Figures 2–5. Niwaella nigrolinea Chen & Chen, sp. nov., the Shuaishui River, Xiuning, Anhui, China. 2. Holotype, HU 2013112, lateral view. 3. Mouth characters, front view. 4. Suborbital spine, left dorsal view, right interior view. 5. Subdorsal scales, dorsal view. Scale bars: 2=1cm; 3–4 =1mm; 5=100μm.

Figures 6–7. Niwaella nigrolinea Chen & Chen, sp. nov., color in life. 6. Lateral view. 7. Dorsal view. Scale bars=1cm.