Systematics of the enigmatic South American Streblopus Van Lansberge, 1874 dung beetles and their transatlantic origin: a case study on the role of dispersal events in the biogeographical history of the Scarabaeinae (Coleoptera: Scarabaeidae)
Systematics of the enigmatic South American Streblopus Van Lansberge, 1874 dung beetles and their transatlantic origin: a case study on the role of dispersal events in the biogeographical history of the Scarabaeinae (Coleoptera: Scarabaeidae)
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DOI：
10.5852/ejt.2020.603
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发表时间：
2020-02-11
影响因子：
1.2
通讯作者：
Vaz-De-Mello, Fernando Z.
中科院分区：
文献类型：
--
作者：
Cupello, Mario;Ribeiro-Costa, Cibele S.;Vaz-De-Mello, Fernando Z.
Streblopus Van Lansberge， 1874年，一直是新热带动物群中最神秘的屎壳郎类群之一，具有相当奇特的形态，收集的已知标本很少，而且很难在圣甲虫谱系中定位。在这项工作中，基于对最近收集的一系列标本的检查和对文献中一些分散但非常有价值的信息的综合，我们重新解决了过去作者提出的许多问题。研究表明，Streblopus是一个由两种分布广泛的现存物种组成的孑生属，即S. opatroides Van Lansbcrge， 1874年，来自巴西巴伊亚州和圣埃斯皮里图州的大西洋森林斑块，以及S. punctatus （Balthasar， 1938年），来自秘鲁和厄瓜多尔亚马逊森林的SubAndean潮湿森林的一些地方。我们重新描述，并提出详细的证据指向他们的有效性作为两个独立的物种；并讨论了它们显著的两性二态性。本文讨论了南美洲Streblopus的生物地理学，并得出结论认为，该属目前的不间断分布是在新近纪的几个时期，特别是在中新世中期，曾经通过南美洲干对角线连接大西洋森林和亚马逊盆地的热带森林走廊退缩的结果。最后，基于其与一组旧大陆分类群（特别是Circellium Latreille， 1825和Scarabaeini）的密切系统发育关系，我们提出该属起源于非洲。在上白垩纪晚期与这些类群分道扬镳后，我们认为Streblopus的祖先是乘木筏穿越大西洋到达南美洲的。我们提出了来自各种生物群体的综合数据来支持我们的观点，并认为圣甲虫专家应该更认真地对待远距离传播假说。
Streblopus Van Lansberge, 1874 has been one of the most mysterious dung beetle groups of the Neotropical fauna, having a rather peculiar morphology, very few known specimens in collections and a difficult placement among the scarabaeine lineages. In this work, based on the examination of a recently collected series of specimens and a synthesis of some scattered, but deeply valuable, information available in the literature, we readdress many of the questions posed by past authors. It is shown that Streblopus is a relict genus composed of two currently living species of widely disjunct distribution, namely S. opatroides Van Lansbcrge, 1874, from patches of Atlantic Forest in the Brazilian states of Bahia and Espirito Santo, and S. punctatus (Balthasar, 1938), known from a few localities across SubAndean humid forests in the Peruvian and Ecuadorian Amazon Forest. We redescribe both and present in detail the evidence pointing to their validity as two independent species; a discussion of their remarkable sexual dimorphism is also given. The biogeography of Streblopus in South America is addressed, and we conclude that the present disjunct distribution of the genus is a consequence of the retreat of the tropical forest corridors that once connected the Atlantic Forest to the Amazon Basin through the South American Dry Diagonal during several periods of the Neogene, particularly until the Middle Miocene. Finally, we propose an African origin for the genus based on its close phylogenetic relationship with a group of Old World taxa - particularly Circellium Latreille, 1825 and Scarabaeini. Having diverged from those groups in the late Upper Cretaceous, we argue that the ancestor of Streblopus arrived in South America crossing the Atlantic Ocean by rafting. We present a synthesis of data from a wide variety of biological groups to support our ideas and contend that long-distance dispersal hypotheses should be taken more seriously by scarab beetle specialists.