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| Rhinogobius sudoccidentalis & Rhinogobius lithopolychroma L. Li, C. Li, Shao, Fu & Zhou, 2024. |
Abstract
Two previously unknown species of Rhinogobius have been discovered in the streams of the Upper Youshui River, within the Yuan River Basin, Xiushan County, Chongqing, China. These new species are named as Rhinogobius sudoccidentalis and Rhinogobius lithopolychroma. Phylogenetic analysis based on mitochondrial genomes revealed that R. sudoccidentalis is genetically closest to R. reticulatus, while R. lithopolychroma shares the greatest genetic similarity with R. leavelli. Morphological distinctions allow for the clear differentiation of these species. Rhinogobius sudoccidentalis sp. nov. is characterized by having VI–VII rays in the first dorsal fin and I, 8–9 rays in the second dorsal fin. The longitudinal scale series typically consists of 22–24 scales, while the transverse scale series comprises 7–8 scales. Notably, the predorsal scale series is absent and the total vertebrae count is 12+17=29. Rhinogobius lithopolychroma sp. nov. can be distinguished from other species by the presence of 13–15 rays on the pectoral fin. Its longitudinal scale series ranges from 30 to 33 scales, with no scales in the predorsal area. The total vertebral count is 30, with 12 precaudal and 18 caudal vertebrae. The head and body of this species are light gray with irregular orange markings on the cheeks and opercle. Through morphological and molecular analyses, it has been confirmed that R. lithopolychroma and R. sudoccidentalis represent novel species within the Rhinogobius genus.
Key words: China, fish taxonomy, Gobiidae, Gobionellinae, mitochondrial genome, Yuanjiang River Basin
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| Pictures of Rhinogobius reticulatus and Rhinogobius sudoccidentalis sp. nov. with the latter having black lines under the eyes A R. reticulatus B R. sudoccidentalis. |
Rhinogobius sudoccidentalis sp. nov.
Diagnosis: Rhinogobius sudoccidentalis can be distinguished from other species in the genus by the following characteristics: it possesses VI–VII rays in the first dorsal fin and I, 8–9 rays in the second dorsal fin. The longitudinal scale series typically consists of 22–24 scales (most commonly 23), while the transverse scale series typically comprises 7–8 scales (most commonly 8). The predorsal scale series is absent. The total number of vertebrae counts is 12+17=29. Additionally, it features a black line stripe beneath the eye that extends to the mandible. Morphometrics Reference Table 2.
Etymology: This species, discovered in Chongqing and Guizhou Province in the southwestern region of China, has been named R. sudoccidentalis. The Latin roots “sud” meaning “south” and “occidentalis” meaning “western” combine to signify “southwestern”. The suggested Chinese name for this species is 西南吻虾虎鱼.
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| Photographs of Rhinogobius lithopolychroma captured underwater in a tank A male and B female. Photographed by Mr Zhi. |
Rhinogobius lithopolychroma sp. nov.
Diagnosis: Rhinogobius lithopolychroma can be distinguished from other species in the Rhinogobius by the following characteristics: It typically possesses 13–15 rays on the pectoral fin. The longitudinal scale series count ranges from 30 to 33, with the predorsal area lacking scales. The total vertebrae count is 30, comprising 12 precaudal and 18 caudal vertebrae. The head and body of this species are light gray, adorned with irregular orange markings on the cheeks and opercle. Morphometrics Reference Table 3.
Etymology: Rhinogobius lithopolychroma was discovered in a small stream with a colorful cobble substrate. Accordingly, we named this species after its habitat. In Ancient Greek, “litho” means “stone,” and “polychroma” means rich in color. We combined these two words to christen this species. We suggest the Chinese name of this species as “彩石吻虾虎鱼”.
Lingzhen Li, Chaoyang Li, Weihan Shao, Suxing Fu and Chaowei Zhou. 2024. Two New Species of Freshwater Goby (Teleostei, Gobiidae) from the Upper Youshui River, Chongqing, China. ZooKeys. 1210: 173-195. DOI: doi.org/10.3897/zookeys.1210.128121
