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| (A) Oreonectes guidongensis Luo, Yu, Liao & Zhou, sp. nov. (B) O. polystigmus Du, Chen & Yang, 2008, (C) O. zhangi Zhong, Yang & Chen, 2024 in Liao, Yu, Luo, Lan, J.-J. Zhou, Xiao et J. Zhou, 2025. 桂东岭鳅 || DOI: doi.org/10.3897/zse.101.160089 |
Abstract
We describe Oreonectes guidongensis sp. nov., a new species collected from Hezhou City, Guangxi Zhuang Autonomous Region, China. Morphologically, it is distinguished from all congeners by the following combination of characters: six branched pelvic-fin rays; seven branched dorsal-fin rays; tip of pelvic fin not reaching the anus; a well-developed posterior chamber of the air bladder; 14–16 branched caudal-fin rays; 10 inner gill rakers on the first gill arch; and a distance between the posterior base of the pectoral fin and the anterior base of the pelvic fin of 18.8–27.9% of standard length. Phylogenetic analysis based on the mitochondrial cytochrome b gene supports the distinctiveness of this species, revealing genetic distances of 5.4–8.5% from its congeners. The discovery of Oreonectes guidongensis sp. nov. underscores the need to re-evaluate O. polystigmus as a potential species complex to better understand the genus’s biodiversity.
Key Words: Cryptic species, morphology, taxonomy, phylogeny
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| Ecological photographs of four species of the Oreonectes polystigmus complex. (A) Oreonectes guidongensis sp. nov. (B) O. polystigmus. (C) O. zhangi. (D) O. damingshanensis. |
Oreonectes guidongensis Luo, Yu, Liao & Zhou, sp. nov.
Etymology. The species name “guidongensis” refers to its distribution in Guangxi (广西), also known as Gui (桂), specifically indicating that the species is found in the eastern region of Guangxi, China. The suggested English name for this species is the Guidong Hilly Loach, and its Chinese name is Guì Dōng Lǐng Qiū (桂东岭鳅).
Diagnosis. Comparative data between new species and all nine known species within the genus Oreonectes are provided in Table 4. Oreonectes guidongensis sp. nov. can be distinguished from O. platycephalus and O. zhangi by the well-developed posterior chamber of air bladder (vs. reduced), from O. damingshanensis, O. guananensis, and O. luochengensis by six branched plevic-fin rays (vs. 7 or 7–8), from O. guilinensis and O. yuedongensis by seven branched dorsal-fin rays (vs. 6), from O. andongensis 10 inner gill rakers on the first gill arch (vs. 11–12), and from O. polystigmus by the tip of pelvic fin not reaching the anus (vs. reaching the anus), distance between the posterior base of the pectoral fin and the anterior base of the pelvic fin is 18.8–27.9% of standard length (18.8–27.9% HL vs. 27.9–34.1%), and five supratemporal pores (vs. 3) (Figs 4, 5).
Mei Liao, Jing Yu, Tao Luo, Chang-Ting Lan, Jia-Jun Zhou, Ning Xiao and Jiang Zhou. 2025. Description of A New Species from eastern Guangxi within the Oreonectes polystigmus complex (Cypriniformes, Nemacheilidae) by integrating morphological and genetic evidence. Zoosystematics and Evolution. 101(4): 1763-1774. DOI: doi.org/10.3897/zse.101.160089
