The genus Cyathus is historically subsampled in the Amazon Forest, which is a potential source of striking taxonomic richness. In this paper, a checklist of Amazonian Cyathus species with detailed descriptions, illustrations and comments of five uncommon species are given. A new species named C. albinus is proposed with morphological and molecular data, being mainly characterized by a light color hirsute exoperidium contrasting with a dark brown emplacement and basidiospores ovoid to elliptical. Three other species, C. amazonicus, C. earlei and C. triplex, are recorded for the first time from their localities. Also, polyphyly is detected into striatum infra-generic group after the addiction of tropical species, but a subclade containing Amazonian species was highly supported.

We wish to thank Programa Nacional de Apoio ao Desenvolvimento da Botânica (PNADB) and the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) for the partial funding of expenses for this study, and for the granting a scholarship for the first author's Master's Degree and second author's Ph.D Degree. The fifth author thanks JSPS Grant-in-Aid for Young Scientists (A) (no. 24680085) and JSPS Grant-in-Aid for Scientific Research (B) (no. 40414362) for partial financial support. We also wish to thank the National Institute for Science Technology and Innovation for Amazonian Biodiversity (INCT-CENBAM), for supplying logistical resources for field expeditions. And finally, to Conselho Nacional de Desenvolvimento Científico (CNPq), process PVE/407474/2013-7.

Peer reviewed