Life Sciences School, Sun Yat-sen University, Guangzhou, Guangdong, 510275, China; and Department of Ecology, Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamýcká 129, CZ-165 00 Prague-Suchdol, Czechia.
State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, China.
Invertebr Syst. 2024 Oct;38. doi: 10.1071/IS24012.
DNA-based studies have revealed that the terrestrial water scavenger beetle genus Cercyon Leach, 1817 (Coleoptera: Hydrophilidae: Sphaeridiinae: Megasternini) is polyphyletic, grouping similarly looking but unrelated species that were not assigned to other genera due to the absence of unusual morphological characters. In this study, we analyse the morphology, DNA data and species diversity of one of the Asian clades of 'Cercyon ' to test whether a natural, phylogeny-based generic classification can be established. We add DNA data (five nuclear and three mitochondrial fragments) for additional species and specimens of the clade to test its monophyly and reveal phylogenetic relationships among species. We perform a detailed morphological study of all species, including SEM micrographs, to reveal synapomorphies of the DNA-based clades. We demonstrate that the lineage, described here as Asiacyon Mai, Jia, Ryndevich & Fikáček, gen. nov., is strongly supported by DNA data, has limited distribution (eastern Asia), and its species share similar biology (inhabiting fresh or decaying plant tissues), though it can be only diagnosed by a combination of plesiomorphic characters. A detailed treatment is provided for the Chinese species, including species diagnoses, illustrations of habitus and male genitalia, (re)descriptions and a key to species. A total of 14 Chinese species are recognised, of which 11 are described as new: Asiacyon pax sp. nov. (Guangdong, Hong Kong, Hunan), A. pseudincretus sp. nov. (Anhui, Jiangxi, Taiwan, Zhejiang), A. vicincretus sp. nov. (Guangdong, Guangxi), A. zhengyucheni sp. nov. (Yunnan), A. huilanae sp. nov. (Yunnan), A. cornipenis sp. nov. (Yunnan), A. belousovi sp. nov. (Yunnan), A. liangchengi sp. nov. (Yunnan), A. paraequalis sp. nov. (Yunnan), A. pengzhongi sp. nov. (Hunan) and A. xiuzhenae sp. nov. (Hainan, Yunnan). Three Chinese species previously classified in Cercyon are transferred to Asiacyon : A. incretus (d'Orchymont, 1941), comb. nov., A. primoricus (Ryndevich & Prokin, 2017), comb. nov. (newly recorded from China) and A. indicus (d'Orchymont, 1926), comb. nov. (newly recorded from China and Laos). Additionally, seven Asian species previously classified in Cercyon are transferred to Asiacyon based on their external morphology, but not studied in detail: A. aequalis (Sharp, 1884), comb. nov., A. conjiciens (Walker, 1858), comb. nov., A. dilutus (Régimbart, 1903), comb. nov., A. placidus (Sharp, 1884), comb. nov., A. pseudodilutus (Satô, 1979), comb. nov., A. retius (Ryndevich & Prokin, 2017), comb. nov., and A. rubicundus (Sharp, 1884), comb. nov. In total, the genus now comprises 21 named species and several undescribed species from India, Myanmar and Indonesia. ZooBank: urn:lsid:zoobank.org:pub:E3C949A0-34E4-46EF-BA6A-2CD048D583B2.
基于 DNA 的研究表明，陆生水甲虫属 Cercyon Leach，1817（鞘翅目：Hydrophilidae：Sphaeridiinae：Megasternini）是多系的，它包含了外观相似但没有关联的物种，这些物种由于缺乏不寻常的形态特征而没有被归入其他属。在这项研究中，我们分析了亚洲“Cercyon '分支的形态、DNA 数据和物种多样性，以测试是否可以建立基于自然进化的通用分类。我们添加了该分支的其他物种和标本的 DNA 数据（五个核和三个线粒体片段），以测试其单系性，并揭示物种之间的系统发育关系。我们对所有物种进行了详细的形态学研究，包括扫描电子显微镜照片，以揭示基于 DNA 的分支的同源特征。我们证明，在这里描述的 Asiacyon Mai，Jia，Ryndevich & Fikáček，gen. nov.，是由 DNA 数据强烈支持的，分布范围有限（东亚），其物种具有相似的生物学特性（栖息在新鲜或腐烂的植物组织中），尽管只能通过组合原始特征来诊断。我们提供了对中国物种的详细处理，包括物种诊断、形态和雄性生殖器的插图、（重新）描述和物种鉴定。共识别出 14 种中国物种，其中 11 种为新种： Asiacyon pax sp. nov.（广东、香港、湖南）、A. pseudincretus sp. nov.（安徽、江西、台湾、浙江）、A. vicincretus sp. nov.（广东、广西）、A. zhengyucheni sp. nov.（云南）、A. huilanae sp. nov.（云南）、A. cornipenis sp. nov.（云南）、A. belousovi sp. nov.（云南）、A. liangchengi sp. nov.（云南）、A. paraequalis sp. nov.（云南）、A. pengzhongi sp. nov.（湖南）和 A. xiuzhenae sp. nov.（海南、云南）。以前归入 Cercyon 的三种中国物种被转移到 Asiacyon：A. incretus（d'Orchymont，1941），组合。nov.，A. primoricus（Ryndevich & Prokin，2017），组合。nov.（新记录于中国）和 A. indicus（d'Orchymont，1926），组合。nov.（新记录于中国和老挝）。此外，以前归入 Cercyon 的七种亚洲物种也基于外部形态被转移到 Asiacyon，但没有详细研究：A. aequalis（Sharp，1884），组合。nov.，A. conjiciens（Walker，1858），组合。nov.，A. dilutus（Régimbart，1903），组合。nov.，A. placidus（Sharp，1884），组合。nov.，A. pseudodilutus（Satô，1979），组合。nov.，A. retius（Ryndevich & Prokin，2017），组合。nov.和 A. rubicundus（Sharp，1884），组合。nov.。总共，该属现在包括 21 个已命名的物种和几个来自印度、缅甸和印度尼西亚的未描述的物种。ZooBank：urn:lsid:zoobank.org:pub:E3C949A0-34E4-46EF-BA6A-2CD048D583B2。
