Sinocyclocheilus longicornus (Cypriniformes, Cyprinidae), a new species of microphthalmic hypogean fish from Guizhou, Southwest China

Abstract

Sinocyclocheilus longicornussp. nov. is described from the Pearl River basin in Hongguo Town, Panzhou City, Guizhou Province, Southwest China. Based on the presence of the long horn-like structure on the back of the head, Sinocyclocheilus longicornussp. nov. is assigned to the Sinocyclocheilus angularis species group. Sinocyclocheilus longicornussp. nov. is distinguished from its congeners by a combination of morphological characters: (1) presence of a single, relatively long horn-like structure on the back of the head; (2) pigmentation absent; (3) reduced eyes; (4) dorsal-fin rays, ii, 7; (5) pectoral-fin rays, i, 13; (6) anal-fin rays, iii, 5; (7) pelvic-fin rays, i, 7; (8) lateral line pores 38–49; (9) gill rakers well developed, nine on first gill arch; and (10) tip of adpressed pelvic fin not reaching anus.

A new cavefish of Sinocyclocheilus (Teleostei: Cypriniformes: Cyprinidae) from the Nanpanjiang River in Guizhou, China

“…clades based on phylogenetic analyses of RAD-seq data, elevating the blind cavefish S. tianlinensis and the micro-eyed S. microphthalmus as two new clades, with the two groups separated from the S. angularis group. Based on the work ofZhao and Zhang (2009), as well as some new species reported byXu et al (2023),Yang et al (2017b) and the results of phylogenetic analysis of this study, 21 species are currently classified as comprising the S. angularis group; they are S. angularis, anshuiensis. These species are characterized by the presence of headhorn or humpback and the following morphological characteristics: eyes small or even lacking, well-developed pectoral fins and long pectoral fins with a rear protraction that reaches up to or extends beyond the insertion of the pelvic fins and a few lateral-line scales(Liu et al, 2018;Wu et al, 2018;Yang et al, 2017b;Zhao & Zhang, 2009;T A B L E 2and Sinocyclocheilus robusius, are also distributed throughout Xingyi, Guizhou, and can be assigned to the S. tingi group, according toZhao and Zhang (2009).Molecular phylogenetic analyses of this study suggest that S. xingyiensis belongs to the S. angularis group.…”

“…Based on the work of Zhao and Zhang (2009), as well as some new species reported by Xu et al . (2023), Yang et al . (2017b) and the results of phylogenetic analysis of this study, 21 species are currently classified as comprising the S. angularis group; they are S. angularis , Sinocyclocheilus altishoulderus , Sinocyclocheilus hyalinus , Sinocyclocheilus rhinocerous , Sinocyclocheilus furcodorsalis , Sinocyclocheilus bicornutus , Sinocyclocheilus tileihornes , Sinocyclocheilus jiuxuensis , Sinocyclocheilus broadhornes , Sinocyclocheilus brevibarbatus , Sinocyclocheilus mashanensis , S. flexuosdorsalis , Sinocyclocheilus convexiforeheadus , Sinocyclocheilus simengensis , Sinocyclocheilus zhenfengensis , Sinocyclocheilus longicornus , Sinocyclocheilus aquihorne , S. tianlinensis , Sinocyclocheilus anatirostris , S. microphthalmus and Sinocyclocheilus anshuiensis .…”

“…During the following decade, many new species of cavefish were discovered (Chen et al ., 2016; Cheng et al ., 2015; Gan et al ., 2013; Jiang et al ., 2019; Lan et al ., 2013; Lan et al ., 2017; Li et al ., 2014; Li et al ., 2018; Li et al ., 2019; Li & An, 2013; Li & Li, 2014; Liu et al ., 2018; Luo et al ., 2016; Pan et al ., 2013; Wang et al ., 2014; Wu et al ., 2010; Wu et al ., 2018; Xu et al ., 2023; Yang, Li, Chen, & Li, 2017a; Yang, Li, & Li, 2017; Zhou et al ., 2009; Zhou et al ., 2011; Zhu et al ., 2011; Zhu & Zhu, 2012). At present, 77 valid species of Sinocyclocheilus are recognized (Jiang et al ., 2019; Mao et al ., 2022; Xu et al ., 2023), of which 14 species occurred in Guizhou Province and 2 species in Xingyi City. Sinocyclocheilus is now the largest cavefish genus in the world, where its diversity is possibly greatly underestimated due to its cryptic nature (Ma et al ., 2019; Mao et al ., 2022).…”

Mitochondrial genome of a typical cavefish of Sinocyclocheilus anatirostris

“… 2022 ; Xu et al. 2023 ), but S. cyphotergous group needs to be studied further using more species. Since the Miocene, the occurrence of orogeny and monsoonal climates in southwestern China have created favorable conditions for the speciation of the genus by geographic isolation (Yuan et al.…”

“… 2022 ; Xu et al. 2023 ), namely Sinocyclocheilus angularis , Sinocyclocheilus cyphotergous , Sinocyclocheilus microphthalmus , Sinocyclocheilus jii , and Sinocyclocheilus tingi groups. Among these five species groups, S. angularis and S. microphthalmus groups have evolved complex morphological characters adapted to the dark environment, such as horn-like structure on the back of the head (long, short, and forked), degeneration or absence of eyes and scales, and strengthening of locomotor and sensory organs (Ma et al.…”