Global delimitation of Cyanoboletus, Cacaoporus and Cupreoboletus (Basidiomycota: Boletaceae)

Abstract

This investigation aimed at compiling all phylogenetic lineages within and around genus Cyanoboletus. The evolutionary inference obtained from the nuclear rDNA internal transcribed spacer region (ITS) suggests excluding part of the species currently classified in Cyanoboletus, leaving only the species that develop a strong staining reaction to touch and to air exposure of the context. The excluded lineages are the monotypic Cupreoboletus genus and a few species that do not develop such reaction, the latter forming a clade together with genera Cacaoporus and Acyanoboletus, thus broadening the concept of Cacaoporus to encompass all of them. The emerging '3C' perspective of Cupreoboletus, Cacaoporus and Cyanoboletus offers a remarkably consistent morphological diagnosis, overcoming the problems of a too broad concept for Cyanoboletus. Boletus neotropicus, B. novae-zelandiae and B. sensibilis belong respectively in Cyanoboletus, Cacaoporus and Lanmaoa, and lineages are indicated that probably represent undescribed species, at least four in Cacaoporus and at least five in Cyanoboletus. Diagnostic tables and dichotomic keys are presented by geographic region. The present work also includes a study of the phylogenetic position of Neoboletus flavosanguineus, a species once classified in Cyanoboletus. The complexity of assigning species epithets in some lineages is addressed, namely for the boundaries between Cacaoporus instabilis and Ca. fagaceophilus as well as the diversity under the names Cyanoboletus sinopulverulentus and Cy. pulverulentus. The overall picture of evolutionary lineages sets a framework for the choice of reference data that can provide a balanced and efficient coverage in future phylogenetic studies that involve the 3C.