Lanlabeo duanensis, Yao & He & Peng, 2018

Yao, Min, He, You & Peng, Zuo-Gang, 2018, Lanlabeo duanensis, a new genus and species of labeonin fish (Teleostei: Cyprinidae) from southern China, Zootaxa 4471 (3), pp. 556-568 : 560-563

Lanlabeo duanensis , sp. nov.

( Figs. 2–3 )

Holotype. SWU 20170110006 , 90.3 mm SL, collected from a tributary flowing into the Hongshuihe River in the Xijiang River drainage basin in Longwan, Du’an County, Guangxi Province, southern China (23°53′N 108°15′E); collected by J. Lan, August 2016.

Paratypes. SWU 20170110002–4(3), SWU 20170110007–9(3), six specimens, 90.3–142.6 mm SL, same collection data as the holotype.

Diagnosis. See generic diagnosis for characters distinguishing the species from all other genera of Labeonini.

Description. Whole body and oromandibular structures illustrated in Figs. 2 and 3 , respectively. Morphometric data for 7 type specimens presented in Table 2. Body elongate and slightly compressed; breast slightly carinate; highest point of body immediately anterior to the dorsal-fin origin; caudal peduncle slender with smallest depth close to base of caudal fin. Dorsal profile of body gradually ascending from snout tip to dorsal-fin origin; from there to origin of dorsal procurrent caudal-fin rays slightly concave. Ventral profile of body rounded from anterior to anal-fin origin; slightly concave from anal-fin origin to origin of ventral procurrent caudal-fin rays.

Head relatively small, longer and deeper than wide, its length accounting for 20.1%¯22.9% of SL. Eye medium-sized, dorsolaterally situated in middle of head, visible from ventral view; interorbital space wide, slightly convex. Snout rounded and blunt, snout length 44.3%¯51.9% of HL. Nostrils closer to anterior margin of eye than to snout tip. Mouth inferior and arched. Ventral margin of rostral cap fringed, not covering base of upper jaw. Rostral cap connected to lower lip at corner of mouth. Postlabial grooves very deep, dividing lower lip into three parts including median portion and two lateral portions. Median lobe of lower lip large, with papillae densely and regularly arranged in many transverse rows. Two lateral fleshy lobes present and devoid of papillae. Two pairs of long barbels, with rostral barbels almost as long as maxillary barbels; maxillary barbels close to corners of mouth. Three rows of pharyngeal teeth, tooth pattern 5,4,2–2,4,5, with compressed and pointed distal tips ( Fig. 4C ). Gill rakers on outer side of first gill arch 14–16; rakers short and small.

Body scales moderate in size. Lateral line complete, horizontal with 36–38 scales; 5 scale rows between lateral line and origin of dorsal fin; 3 scale rows between lateral line and origin of pelvic fin; circumpeduncular scale rows 14–16. Dorsal fin inserted slightly before pelvic fin. Ventral scales between pectoral fins and pelvic fins halfhidden and subcutaneous. Axillary scale present at pelvic-fin base; two scales between vent and anal-fin origin.

Dorsal fin with 2 soft unbranched and 8 or 9 branched rays; insertion of dorsal fin nearer to tip of the snout than to caudal-fin base; distal margin slightly concave, its length accounting for 22.2%¯27.3% of SL. Pectoral fin with 1 simple and 12 or 13 branched rays, no longer than HL, reaching two-fifths of distance to pelvic-fin insertion. Pelvic-fin origin roughly at midpoint of body and slightly posterior, with one unbranched and 7 or 8 branched rays, inserted vertically posterior to fourth branched dorsal fin ray base, and extending to anal fin origin. Anal fin with one unbranched and 5 branched rays; distal margin concave; origin nearer pelvic-fin insertion than caudal fin base. Caudal fin with 9+9 branched rays, deeply forked; upper and lower lobes equal in length and similarly shaped, with tapering, rounded tips.

Color pattern in formalin. Body dark brown dorsally; dark brown laterally, darker above; yellowish-white ventrally. An indistinct longitudinal black stripe, roughly two scales in depth, originates at upper extremity of gill opening and extends along lateral line on flank ending at middle of caudal-fin base. Fin rays black, membrane hyaline ( Fig. 3 ).

Distribution. Lanlabeo duanensis is only known from the Hongshuihe River of the Xijiang River drainage basins in Du’an County, Guangxi Province, China ( Fig. 1 ).

Etymology. The specific epithet, used as an adjective, is based on the type locality: Du’an County, in southern China.

Figures

FIGURE 1. Map showing the distribution of Lanlabeo duanensis sp. nov. in Guangxi Province, southern China.

FIGURE 2. Oromandibular structures of Lanlabeo duanensis sp. nov., SWU20170110006, 90.3 mm SL.

FIGURE 3. Lanlabeo duanensis sp. nov., SWU20170110002, paratype, 142.6 mm SL. Collected from the Hongshuihe River in Du’an County, Guangxi Province, southern China. (A) Lateral, (B) dorsal, and (C) ventral views.

FIGURE 4. Head skeleton and pharyngeal dentition of Lanlabeo gen. nov. holotype, SWU 20170110002 (A–E), Rectoris posehensis 3# (F–J), and Ptychidio jordani 1# (K–O). Abbreviations: den, dentary; pcl, postcleithrum. A, F, and K in lateral view; B, G, and L in ventral view; C, H, and M in anterior view; D, E, I, J, N, and O in oblique-dorsal view. Scale bars: 3.0 mm in A, B, F, G, K, and L; 1.5 mm in C, D, E, M, N, and O; 0.9 mm in H, I, and J. Pcl=pectoral; den=dentary.