Sinocrossocheilus

Yuan, Le-Yang, Zhang, E & Huang, Yan-Fei, 2008, Revision of the Labeonine Genus Sinocrossocheilus (Teleostei: Cyprinidae) from South China, Zootaxa 1809, pp. 36-48 : 44-45

Redefinition of Sinocrossocheilus and comparisons with allied genera

The definition of Sinocrossocheilus by Wu in Wu et al. (1977) consists of the following main characters: (1) a uniquely modified median part (= median lobe) of the lower lip ( Fig. 2 A, which is here divided into two portions: a densely papillated, greatly protruded, crescentic fold and a papillated, somewhat protruded, triangular fleshy pad); (2) a papillated, crenulated, rostral fold disconnected from the lower lip at the corners of the mouth; (3) two rows of pharyngeal teeth; and (4) seven branched dorsal-fin rays [note: this number was given by Wu in Wu et al. (1977) as eight in their generic diagnosis, but seven in their species description. Our examination confirmed that the type material has seven branched rays of the dorsal fin]. In the text by Wu in Wu et al. (1977), the description of the first character should read ‘median part modified into a fan-like, papillose fleshy pad with its anterior and anterolateral margins protruded to be horse-shoe shaped and free, and its posterior margin continuous with the mental region.’ This description is clearly inadequate for the median lobe of the lower lip because Wu in Wu et al. (1977) stopped short of dividing it into two portions as here done: a papillose, crescentic fold and a paplillose, slightly protruded, triangular fleshy pad. Even so, the morphology of the median lobe of the lower lip in Sinocrossocheilus is unique among labeonine genera and truly typical for this genus. The last three characters are not unique to Sinocrossocheilus , but limited only to some labeonine genera. They are thus useful diagnostic characters of the genus.

A rostral fold disconnected from the lower lip at the corners of the mouth is also found in other Asian labeonine genera of the Garrinae sensu Rainboth (1996) : Akrokolioplax Zhang and Kottelat, 2006 , Crossocheilus Kuhl and van Hasselt in van Hasselt, 1823, Epalzeorhynchos Bleeker, 1855 and Paracrossochilus Popta, 1904 . The following characters, though, are absent in Sinocrossocheilus : a pair of rostral flaps on the snout tip situated far from the rostral barbel and sublachrymal groove that is diagnostic for Akrokolioplax , a well-developed upper lip that is separated from the upper jaw for Crossocheilus sensu Roberts (1989) , a pair of rostral lobes on the snout tip positioned between the root of the rostral barbel and sublachrymal groove for Epalzeorhynchos sensu Kottelat, 2001 , and a well-developed, papillated upper lip restricted to and apart from the upper jaw, with the median portion absent or vestigial for Paracrossochilus sensu Roberts (1989) . Moreover, Sinocrossocheilus is distinguished from the above five genera in having 2 (vs. 3) rows of pharyngeal teeth.

Two rows of pharyngeal teeth also occur in three disc-bearing labeonine cyprinid genera, viz. Discocheilus Zhang, 1997 , Discogobio Lin, 1931 and Placocheilus Wu in Wu, Lin, Chen, Chen & He, 1977. These genera are distinguished from Sinocrossocheilus by having a lower lip modified into a mental disc with its posterior margin discontinuous from the mental region (vs. a lower lip with its median lobe modified to form a crescentic fold and a fleshy pad that is continuous with the mental region), a rostral fold connected (vs. disconnected) from the lower lip at the corners of the mouth, maxillary barbels minute or absent (vs. well-developed), and seven (vs. eight) branched dorsal-fin rays.

Besides Hongshuia , two other genera share with Sinocrossocheilus seven branched dorsal-fin rays: Parasinilabeo (excluding P. longibarbus with eight branched dorsal fin rays) and Qianlabeo . Parasinilabeo sensu Zhang, 2000 differs from Sinocrossocheilus in having a non-crenulated (vs. crenulated) rostral fold connected (vs. disconnected) with the lower lip around the corners of the mouth and three (vs. two) rows of pharyngeal teeth. Qianlabeo sensu Zhang and Chen (2004) is separated from Sinocrossocheilus by having an upper lip present only in and fully adnate to the side of the upper jaw (vs. absent); three (vs. two) rows of pharyngeal teeth, a slightly (vs. coarsely) crenulated, slightly (vs. densely) papillated rostral fold disconnected (vs. connected) from the lower lip around the corners of the mouth, and post-labial grooves prolonged anteromedially, but not meeting with its counterpart at the midline (vs. absent)

Figures

FIGURE 2. Ventral view of lower lip morphology in: (A) Sinocrossocheilus guizhouensis, IHB 6650508, lectotype, 59.0 mm SL; (B) Sinocrossocheilus labiatus; KIZ 995338, holotype, 56.1 mm SL; (C) Hongshuia paoli, IHB 200210911, holotype, 54.3 mm SL; (D) Hongshuia microstomatus, IHB 87 IV 506, paratype, 81.7 mm SL; (E) Pseudocrossocheilus bamaensis, IHB 85 VII 056, 152.9 mm SL; (F) Pseudocrossocheilus tridentis, KIZ 774079, holotype, 118.0 mm SL. cf = crescentic fold of median lobe of lower lip; fp = fleshy pad of median lobe of lower lip; mb = median lobe of lower lip; rlf = ring-like fold of median lobe of lower lip.