Mitochondrial divergence suggests unexpected high species diversity in the opsariichthine fishes (Teleostei: Cyprinidae) and the revalidation of Opsariichthys macrolepis

Abstract

Opsariichthine (sensu Oceanologi Et Limnologia Sinica , 1982, 13, 293–298) is a cyprinid group consisting of five genera and endemic to East Asia. Previous studies suggested that there may be many possible cryptic species in this group, but this has not been confirmed. In this study, using mitochondrial cyt b sequences on 1,388 samples and 739 haplotypes, we showed very high species diversity within this group. The results showed that phylogenetic relationships of the opsariichthine group were as ([ Nipponocypris ‐ Parazacco ‐ Candidia ] + [ Zacco + Opsariichthys ]), and there were multiple deep lineages within several species, flagging putative cryptic species. When a 3% genetic distance was used as a threshold for species delimitation, 35 haplogroups were found, nine haplogroups in Candidia ‐ Parazacco ‐ Nipponocypris group, six haplogroups in the Zacco group, and 20 haplogroups in the Opsariichthys group. We consider all of them to be putative until determination of distinct species based on the tree topology, geographic distributions, or a combination of both. In addition, two kinds of species delimitation tools, ABGD and PTP, were applied to construct molecular operational taxonomic units (MOTUs). The ABGD method revealed nine MOTUs in Candidia ‐ Parazacco ‐ Nipponocypris group, two MOTUs in the Zacco group, and 17 MOTUs in the Opsariichthys group. And the PTP method revealed 10 MOTUs in Candidia ‐ Parazacco ‐ Nipponocypris group, 10 MOTUs in the Zacco group, and 29 MOTUs in the Opsariichthys group. Therefore, there should be more species in the opsariichthine group than presently described. Based on the molecular data and morphological characteristics, we proposed Opsariichthys macrolepis as a valid species and described its morphological diagnostic characters.

Phylogeographic analysis revealed allopatric distribution pattern and biogeographic processes of the widespread pale chub Opsariichthys acutipinnis-evolans complex (Teleostei: Cyprinidae) in southeastern China

“…In the past decade our extensive sampling work throughout southeastern China has yielded plenty of morphologically similar specimens that could be identified as either O. acutipinnis and O. evolans. However, we found out that morphological identification based on diagnostic characteristics proposed by Huynh and Chen (2013) and Wang et al (2019) would be problematic, e.g., specimens with features of O. acutipinnis and O. evolans co-existed in most populations. As a consequence, we tentatively treated these fishes as the Opsariichthys acutipinnisevolans complex in the current study.…”

“…We sequenced 622 samples and retrieved 199 sequences from our previous study (Wang et al, 2019). We also included another 193 sequences from GenBank submitted by previous authors (Perdices et al, 2004;Perdices and Coelho, 2006;Lin, 2008;Zheng et al, 2015;Yin et al, 2016;Wang et al, 2019; Supplementary Table S1).…”

“…Later studies generally treated O. acutipinnis and O. evolans as two closely related but distinct species based on deep divergence in mitochondrial gene (s), allopatric distribution, and morphological differences (Huynh and Chen, 2013;Wang et al, 2019). A recent work conducted by Wang et al (2019) revealed a deeply divergent mitochondrial lineage that related to O. acutipinnis and O. evolans ("O. sp. A"), indicating the existence of previously ignored cryptic diversity.…”

Diversity, Distribution, and Biogeography of Freshwater Fishes in Guangxi, China

“…In recent years, fish biodiversity, community structure, and fish integrity in Guangxi have emerged [20][21][22][23], and new species and non-native species have also been reported [16,24]. Moreover, the taxonomic statuses of some species have been corrected [25,26].…”

Updated species checklist of fishes from Lake Dongting in Hunan Province, South China: Species diversity and conservation

“…Lake Dongting is one of two largest river-linked freshwater lakes in China, lying within the lower Chang-Jiang (= the mid-lower Chang-Jiang) basin which forms a freshwater ecoregion of the world for biodiversity conservation ( Abell et al 2008 ). This lake is an important portion of fluvio-lacustrine complex ecosystems of the mid-lower Chang-Jiang basin ( Wang et al 2019b ), and also one of the priority areas for biodiversity conservation in China ( Li et al 2016a ) and the Ramsar-listed floodplain wetlands ( Dong et al 2021 ), which serves as crucial habitats of migratory birds of East Asia-Australian flyway ( Zou et al 2019 ). Moreover, Lake Dongting, as a flood buffer zone, provides Elaphurus davidianus (Milu or Père David’s deer) with seasonal sanctuaries ( Yang et al 2016 ).…”