Martin Fikáček, Shûhei Yamamoto, Keita Matsumoto, Rolf G. Beutel, David R. Maddison
{"title":"Phylogeny and systematics of Sphaeriusidae (Coleoptera: Myxophaga): minute living fossils with underestimated past and present-day diversity","authors":"Martin Fikáček, Shûhei Yamamoto, Keita Matsumoto, Rolf G. Beutel, David R. Maddison","doi":"10.1111/syen.12571","DOIUrl":null,"url":null,"abstract":"<p>Sphaeriusidae (Coleoptera: Myxophaga) is a group of shiny, blackish and hemispherical riparian beetles, known for their miniaturized bodies. They are worldwide in distribution, but very limited information is available about taxonomic and morphological diversity, and natural and evolutionary history. The aim of this study is to help fill in these gaps. We examined the external morphology of modern representatives using scanning electron microscopy (SEM), and reconstructed the phylogeny of the family using five DNA markers (cytochrome oxidase I, 18S rRNA, 28S rRNA, CAD and wingless). Our results suggest a larger morphological diversity than previously expected, corresponding to the deep genetic divergences of principal lineages. We also examined two inclusions in 99-million-year-old Burmese amber. The integration of all evidence allows us to recognize three genera: the extinct genus †<i>Burmasporum</i> Kirejtshuk, the newly defined genus <i>Bezesporum</i> <b>gen.nov.</b> preserved in Burmese amber (<i>B. burmiticum</i> <b>sp.nov.</b>) and present in the modern fauna of Southeast Asia, and the genus <i>Sphaerius</i> Waltl with a world-wide distribution. <i>Sphaerius</i> species are morphologically highly uniform, with the exception of species from Australia and South Africa, which share some characteristics with <i>Bezesporum</i> <b>gen.nov.</b> despite being resolved as deeply nested lineages of <i>Sphaerius</i> by DNA data. The presence of <i>Bezesporum</i> <b>gen.nov.</b> in Burmese amber and in recent fauna indicates that Sphaeriusidae largely maintained their specific morphology and specialized riparian lifestyle for at least 100 million years. Therefore, they can be considered an exceptionally conserved group, with a minimum of evolutionary changes over a long period. Our study also demonstrates that the species numbers and fine-scale morphological diversity of Sphaeriusidae are larger than expected in both the past and present-day faunas. Both were apparently underestimated due to the minute body size and cryptic habits of these beetles.</p>","PeriodicalId":22126,"journal":{"name":"Systematic Entomology","volume":null,"pages":null},"PeriodicalIF":4.7000,"publicationDate":"2022-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"4","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Systematic Entomology","FirstCategoryId":"97","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1111/syen.12571","RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ENTOMOLOGY","Score":null,"Total":0}
引用次数: 4
Abstract
Sphaeriusidae (Coleoptera: Myxophaga) is a group of shiny, blackish and hemispherical riparian beetles, known for their miniaturized bodies. They are worldwide in distribution, but very limited information is available about taxonomic and morphological diversity, and natural and evolutionary history. The aim of this study is to help fill in these gaps. We examined the external morphology of modern representatives using scanning electron microscopy (SEM), and reconstructed the phylogeny of the family using five DNA markers (cytochrome oxidase I, 18S rRNA, 28S rRNA, CAD and wingless). Our results suggest a larger morphological diversity than previously expected, corresponding to the deep genetic divergences of principal lineages. We also examined two inclusions in 99-million-year-old Burmese amber. The integration of all evidence allows us to recognize three genera: the extinct genus †Burmasporum Kirejtshuk, the newly defined genus Bezesporumgen.nov. preserved in Burmese amber (B. burmiticumsp.nov.) and present in the modern fauna of Southeast Asia, and the genus Sphaerius Waltl with a world-wide distribution. Sphaerius species are morphologically highly uniform, with the exception of species from Australia and South Africa, which share some characteristics with Bezesporumgen.nov. despite being resolved as deeply nested lineages of Sphaerius by DNA data. The presence of Bezesporumgen.nov. in Burmese amber and in recent fauna indicates that Sphaeriusidae largely maintained their specific morphology and specialized riparian lifestyle for at least 100 million years. Therefore, they can be considered an exceptionally conserved group, with a minimum of evolutionary changes over a long period. Our study also demonstrates that the species numbers and fine-scale morphological diversity of Sphaeriusidae are larger than expected in both the past and present-day faunas. Both were apparently underestimated due to the minute body size and cryptic habits of these beetles.
期刊介绍:
Systematic Entomology publishes original papers on insect systematics, phylogenetics and integrative taxonomy, with a preference for general interest papers of broad biological, evolutionary or zoogeographical relevance.