From one to six: unrecognized species diversity in the genus Acantholichen (lichenized Basidiomycota: Hygrophoraceae)

Abstract

We present a taxonomic revision of the lichenized basidiomycete genus Acantholichen, species of which produce a characteristic blue-gray, microsquamulose thallus with spiny apical hyphal cells known as acanthohyphidia. Since its discovery, the genus was thought to be monospecific, only including the generic type, A. pannarioides. However, a detailed morphological and anatomical study of recently collected specimens from the Galápagos, Costa Rica, Brazil and Colombia, combined with a molecular phylogenetic analysis of the internal transcribed spacer (ITS1-5.8S-ITS2) region and 28S of the nuc rDNA and RPB2 sequences, revealed a much more diverse and widespread species assemblage. Based on the results of these analyses, we describe five new species in the genus: A. albomarginatus, A. campestris, A. galapagoensis, A. sorediatus and A. variabilis. We also provide an identification key to all species, anatomical and morphological descriptions, photographs and a table comparing main characters of each species.

• Basidiolichens
• lichenized fungi
• montane forest
• phylogeny
• taxonomy
• tropical diversity

Acknowledgments

The study was supported by NSF grant DEB 0841405, “Phylogenetic diversity of mycobionts and photobionts in the cyanolichen genus Dictyonema, with emphasis on the Neotropics and the Galápagos Islands” (PI J. Lawrey, Co-PIs R. Lücking, P. Gillevet, local Galápagos coordinator F. Bungartz).

We acknowledge help from participants in a course organized by the Organization for Tropical Studies (OTS), during which we were permitted to collect in several areas of Costa Rica. We want to thank L.S. Canêz and E. Gumboski for their help during a collection trip that lead to the discovery of A. campestris. Similarly we thank Bianca Regina da Hora and Agnes Elisete Luchi, for their field help in the Itatiaia National Park. Morgan Gostel is thanked for providing the SEM image of A. galapagoensis. The Charles Darwin Foundation continues to support the Galápagos Lichen Inventory, which permitted access to Acantholichen specimens freshly collected in the archipelago. For this we are especially indebted to Galápagos National Park, particularly Washington Tapia and Galo Quedaza for granting specimen export permits. The lichen inventory is part of the Census of Galápagos Biodiversity by Charles Darwin Foundation (donors cited at http://www.darwinfoundation.org/datazone/checklists/). Taxonomic research on Galápagos species, with the goal of establishing the first IUCN red list of endemic Galápagos lichens, is supported by the Mohamed bin Zayed Species Conservation Fund, project 152510692. This study is contribution number 2122 of the Charles Darwin Foundation for the Galápagos Islands.