Systematics of spiny‐backed treefrogs ( H ylidae: O steocephalus): an A mazonian puzzle

Spiny‐backed tree frogs of the genusOsteocephalusare conspicuous components of the tropical wet forests of theAmazon and theGuianaShield. Here, we revise the phylogenetic relationships ofOsteocephalusand its sister groupTepuihyla, using up to 6134 bp ofDNAsequences 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 ofOsteocephaluswith respect toTepuihyla, (ii) the placement of ‘Hyla’ warrenias sister toTepuihyla, (iii) the non‐monophyly of several currently recognized species withinOsteocephalusand (iv) the presence of low (<1%) and overlapping genetic distances among phenotypically well‐characterized nominal species (e.g.O. taurinusandO. oophagus) for the 16Sgene fragment used in amphibianDNAbarcoding. We propose a new taxonomy, securing the monophyly ofOsteocephalusandTepuihylaby rearranging and redefining the content of both genera and also erect a new genus for the sister group ofOsteocephalus. The colouration of newly metamorphosed individuals is proposed as a morphological synapomorphy forOsteocephalus. We recognize and define five monophyletic species groups withinOsteocephalus, synonymize three species ofOsteocephalus(O. germani,O. phasmatus andO. vilmae) and three species ofTepuihyla(T. celsae,T. galani andT. talbergae) and reallocate three species (Hyla helenaetoOsteocephalus,O. exophthalmustoTepuihylaandO. pearsonitoDryadercesgen. 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 withinOsteocephalusis discussed in the light of this new phylogenetic hypothesis, and a novel type of amplexus (gular amplexus) is described.