Crossocheilogobio, Sun & Tang & Zhao, 2025

Sun, Zhi-Xian, Tang, Wen-Qiao & Zhao, Ya-Hui, 2025, Generic revision on the Biwia – Microphysogobio complex (Cypriniformes, Gobionidae) with descriptions of three new genera, Zoosystematics and Evolution 101 (4), pp. 2013-2037 : 2013-2037

Crossocheilogobio gen. nov.

Fig. 12

Type species.

Pseudogobio tafangensis Wang, 1935 .

Diagnosis.

The new genus can be distinguished from all other genera within the Pseudogobionini by the combination of the following characters: (1) mouth horseshoe-shaped and inferior, forming a sucking-disc structure; (2) central portion of the anterior papillae two, semi-covered by rostral cap; (3) lateral portion of the anterior papillae on upper lip fringed, in several rows; (4) lower lip in three burred lobes, without anterior fold; (5) lateral lobes on lower lip not in contact with each other posteriorly from medial pad; (6) medial lobe possessing two elongated thin protrusions; (7) upper jaw extremely narrow, the horny margin width approximately quarter of mouth width; (8) jaws covered by the thick lips; (9) barbel in one pair; (10) midventral region of body usually scaleless before pectoral-fin base end; (11) pharyngeal teeth in one row; (12) anterior chamber of the air bladder enclosed in fibrous capsule; (13) posterior chamber relatively small, length smaller than half eye diameter, thin.

Description.

Body elongated, abdomen rounded; caudal peduncle short, compressed laterally. Mouth horseshoe-shaped and inferior, forming a sucking-disc structure; barbel one pair; lips very thick, with well-developed papillae; central portion of the anterior papillae two, semi-covered by rostral cap, lateral portion of the anterior papillae on upper lip fringed, in several rows; lower lip in three burred lobes, without anterior fold; two lateral lobes on lower lip not in contact with each other posteriorly from medial pad, laterally connected with upper lip anterior papillae around mouth corners; medial lobe possessing two elongated thin protrusions. Jaws with horny sheathed edge; upper jaw extremely narrow, horny margin width approximately quarter of mouth width; jaws covered by the thick lips (Fig. 3 G ). Body covered with moderately large cycloid scales. Thoracic region scaleless, mid-ventral region covered with scales. Anus positioned in anterior one-third of pelvic-fin insertion and anal-fin base. Lateral line complete, almost straight. Lateral-line scales usually 35–38; scales above lateral line 3.5–4; scales below lateral line usually 2–3; predorsal scales 8–10; circumpeduncular scales 12. Distal margin of expanded dorsal fin convex, especially significant in adult male, with three unbranched and seven branched rays, pectoral fin with one unbranched and 10–13 branched rays, pelvic fin usually with one unbranched and seven branched rays, anal fin with three unbranched and five branched rays; caudal fin forked, with one simple ray and nine branched rays on upper lobe and eight branched rays and one simple ray on lower lobe, lobes blunt. Pharyngeal teeth “ 5–5 ” in one row. Air bladder relatively small, possessing two chambers; anterior chamber rounded, enclosed in a thick fibrous capsule; posterior chamber small, length shorter than anterior chamber length, less than half eye diameter, thin. Intestine very long.

Distribution.

This genus has a relatively narrow distribution. It is currently known to be distributed in the Qiantangjiang River and Cao’ejiang River basins. This genus is endemic to China (Fig. 5 F ).

Etymology.

The prefix “ crosso- ” was derived from the Greek word “ krossoi ”, meaning tassel; “ cheilo- ” from the Greek word “ cheilos ”, meaning lip. The generic name refers to the fringed papillae on the upper lips of the species in this genus. The suggested Chinese name for this genus is “ 穗唇鮈 ” 属, and the Chinese Pinyin name is “ Suì Chún Jū ” Shǔ.

Species included.

Crossocheilogobio tafangensis (Wang, 1935) , comb. nov. (type species).

Remarks.

The new genus Crossocheilogobio can be distinguished from the genus Biwia by having barbels (vs. no barbels), reduced air bladder (vs. enlarged) and well-developed lip papillae (vs. thin and simple). It can be distinguished from the genera Microphysogobio and Huigobio by having an extremely narrow upper jaw horny margin, usually quarter mouth width (vs. wide, larger than half mouth width). This new genus is more similar to Platysmacheilus in general because their lobes on lower lips are not well separated or even fused. However, the genus Crossocheilogobio can be distinguished from Platysmacheilus by having central portion of anterior papillae on upper lip in one row (vs. several rows) and a double-lobed medial pad (vs. no obvious medial pad).

Figures

Figure 3. Lip papillae patterns of the type species of seven genera within the Biwia – Microphysogobio complex, with a diagrammatic illustration showing the structures. A. Biwia zezera, KUN-P 040282; B. Microphysogobio hsinglungshanensis, ASIZB 240788; C. Huigobio chenhsienensis, SHOU 20231209015; D. Oriengobio fukiensis, ASIZB 220659; E. Mesophysogobio kachekensis, ASIZB 69768; F. Platysmacheilus exiguus, ASIZB 220879; G. Crossocheilogobio tafangensis, ASIZB 60212; H. diagrammatic illustration based on Microphysogobio chinssuensis. CPAP = central portion of anterior papillae; LPAP = lateral portion of anterior papillae; MP = medial pad; LL = lateral lobe; BB = barbel; UJ = upper jaw; LJ = lower jaw. The photo of Biwia zezera is provided by Seigo Kawase; the other photos and illustration were made by Zhi-Xian Sun.

Figure 5. The distributions of the Biwia – Microphysogobio complex and seven genera. A. The complex; B. Biwia; C. Microphysogobio; D. Huigobio; E. Platysmacheilus; F. Crossocheilogobio gen. nov.; G. Oriengobio gen. nov.; H. Mesophysogobio gen. nov.

Figure 12. The general view of Crossocheilogobio tafangensis, the type species of the genus Crossocheilogobio gen. nov., ASIZB 60212, male, 91.2 mm SL, collected from the Xin’anjiang River in the Qiantangjiang River Basin, Tunxi District, Anhui Province, China. A. Lateral view; B. Dorsal view; C. Ventral view. Scale bar: 10 mm. Photographed by Zhi-Xian Sun.