DOI: 10.3897/zse.102.170882

Authors: Jian-Bing Lyu, Feng Lin, Thaung Naing Oo, Xiao-Yong Chen

Abstract: Mustura arenaria sp. nov., a new species of the genus Mustura, is described from the Chindwin–Irrawaddy basin in central Myanmar. It can be distinguished from other congeners by the following combination of characters: 7–15 vertical lateral blotches alternating with 9–17 saddles, distinctly narrower than the interspaces; lateral blotches more rounded in males; 8+8 branched caudal-fin rays; 8½ branched dorsal-fin rays; and a complete lateral line. Phylogenetic analysis based on combined data of Cyt b and RAG1 revealed that the new species represents an independent lineage and that Mustura is paraphyletic. Additionally, both morphological and molecular data support the transfer of Mustura shanensis to the genus Schistura. Notably, a comprehensive taxonomic revision of this genus and related taxa involving more species is required because the genetic positions of several Mustura species conflict with morphological characters.

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DOI: 10.3897/zse.101.152180

Authors: Da-Song Choi, Hyo-Jin Kim, Myeong-Hun Ko, Ra-Yeon Myung, Yong-Jin Won

Abstract: Pleistocene climatic fluctuations reshaped the East Asian coastline, facilitating the formation of extensive paleo-river networks that influenced freshwater biodiversity. Here, we examine how the formation of ancient river systems has influenced the population genetic structures of two sister species of freshwater loaches, Iksookimia hugowolfeldi and I. longicorpa, found in the southern Korean Peninsula. We conducted a multi-locus genetic analysis of an extensive sample of 208 individuals from 21 populations across their entire distribution range. According to a phylogenetic tree constructed using nuclear DNA, the two sister species diverged approximately 5.5 million years ago. However, there was a discrepancy between the taxonomic identification of I. hugowolfeldi populations and the phylogenetic result. A wrong species boundary between the two sister species previously assumed and a genetic signature of headwater river capture were found to explain the discrepancy. An overall radiative diversification of multiple allopatric genetic clusters in the sister species highlights the significant influence of geographic barriers in today’s isolated river systems. Simulations of ancient river connections, shaped by fluctuating sea levels, compellingly illustrate how localized reconnections through these historic networks during the ice ages have significantly shaped the population genetic structures of these sister species. The present study identifies the important role of paleo-river systems in facilitating the geographic connectivity of Iksookimia, which provides useful insights into the broader phylogeography of other riverine organisms in the Korean Peninsula and East Asia.

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DOI: 10.3897/zse.101.136965

Authors: Mei Liu, Jian-Bing Lyu, Li-Na Du, Xiao-Yong Chen

Abstract: A new species of the genus Yunnanilus, designated Yunnanilus triangulus sp. nov., is described from the Nanpan River in Yunnan Province, southwestern China. Nuptial males of this species are distinguished by the presence of tubercles on the caudal peduncle during the reproductive period, a feature not observed in other members of the genus. The new species is further characterized by the following unique combination of morphological characters: body scaled, smaller eyes than interorbital width, nine inner gill rakers on first gill arch, lateral head length 27.1%–30.9% SL, head width 14.3%–17.2% SL, eye diameter 19.6%–23.8% of lateral head length, and caudal peduncle depth 94.0%–130.6% of its length. Morphological and molecular evidence support the validity of this species, despite its geographic proximity to Y. polylepis. These findings underscore the ecological specialization that exists within the genus Yunnanilus and highlight the urgent need for species-specific conservation strategies, given their restricted distributions and dependence on specific habitats.

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