Data from: Systematics of spiny-backed treefrogs (Hylidae: Osteocephalus): an Amazonian puzzle

Spiny-backed tree frogs of the genus Osteocephalus are conspicuous components of the tropical wet forests of the Amazon and the Guiana Shield. Here, we revise the phylogenetic relationships of Osteocephalus and its sister group Tepuihyla, using up to 6134 bp of DNA sequences of nine mitochondrial and one nuclear gene for 338 specimens from eight countries and 218 localities, representing 89% of the 28 currently recognized nominal species. Our phylogenetic analyses reveal (i) the paraphyly of Osteocephalus with respect to Tepuihyla, (ii) the placement of ‘Hyla’ warreni as sister to Tepuihyla, (iii) the non-monophyly of several currently recognized species within Osteocephalus and (iv) the presence of low (<1%) and overlapping genetic distances among phenotypically well-characterized nominal species (e.g. O. taurinus and O. oophagus) for the 16S gene fragment used in amphibian DNA barcoding. We propose a new taxonomy, securing the monophyly of Osteocephalus and Tepuihyla by rearranging and redefining the content of both genera and also erect a new genus for the sister group of Osteocephalus. The colouration of newly metamorphosed individuals is proposed as a morphological synapomorphy for Osteocephalus. We recognize and define five monophyletic species groups within Osteocephalus, synonymize three species of Osteocephalus (O. germani, O. phasmatus and O. vilmae) and three species of Tepuihyla (T. celsae, T. galani and T. talbergae) and reallocate three species (Hyla helenae to Osteocephalus, O. exophthalmus to Tepuihyla and O. pearsoni to Dryaderces gen. n.). Furthermore, we flag nine putative new species (an increase to 138% of the current diversity). We conclude that species numbers are largely underestimated, with most hidden diversity centred on widespread and polymorphic nominal species. The evolutionary origin of breeding strategies within Osteocephalus is discussed in the light of this new phylogenetic hypothesis, and a novel type of amplexus (gular amplexus) is described.

棘背蛙属（Osteocephalus）的棘背树蛙是亚马逊与圭亚那地盾热带湿润森林中极具代表性的类群。本研究针对来自8个国家218个采样点的338份标本，利用9个线粒体基因与1个核基因总计至多6134个碱基对（bp）的DNA序列，修订了棘背蛙属及其姊妹群特普伊蛙属（Tepuihyla）的系统发育关系，样本涵盖当前已确认的28个定名物种中的89%。系统发育分析结果显示：1. 棘背蛙属相对于特普伊蛙属为并系群；2. ‘Hyla’ warreni被置于特普伊蛙属的姊妹群位置；3. 棘背蛙属内多个当前已定名的物种并非单系群；4. 基于两栖动物DNA条形码常用的16S基因片段，多个表型特征明确的定名物种（如O. taurinus与O. oophagus）之间的遗传距离极低（<1%）且存在重叠。本研究提出全新分类系统：通过重新调整并界定两属的类群组成，确保棘背蛙属与特普伊蛙属均为单系群，并为棘背蛙属的姊妹群建立一新属；将新变态个体的体色作为棘背蛙属的形态共源性状。本研究确认并界定了棘背蛙属内5个单系物种群；将棘背蛙属的3个物种（O. germani、O. phasmatus与O. vilmae）以及特普伊蛙属的3个物种（T. celsae、T. galani与T. talbergae）处理为同物异名；同时重新归类3个物种：将海伦雨蛙（Hyla helenae）划入棘背蛙属，将O. exophthalmus划入特普伊蛙属，将O. pearsoni划入新属Dryaderces。此外，本研究标记了9个疑似新物种，物种多样性将提升至当前的138%。研究认为当前物种数量被严重低估，多数隐存多样性集中于广布且多态的定名物种中。基于这一新的系统发育假说，本研究探讨了棘背蛙属繁殖策略的演化起源，并描述了一种全新的抱对类型——喉抱对（gular amplexus）。