Kgaria (Boletaceae, Boletoideae) gen. nov. in Australia: Neither a Tylopilus nor a Porphyrellus

Abstract

Kgaria is described as a new porphyrellus-like genus of Boletaceae to accommodate Tylopilus cyanogranulifer, a dark brown to dull lilac/violet, or rarely, nearly black bolete with a series of oxidation reactions progressing from blue to red then nearly black and a dark brown spore deposit. Idiosyncratic blue-green pigment encrustations (cyanogranules) and a similarly colored reaction of the hyphae located on pileus and stipe surfaces are also diagnostic. Phylogenetic analyses of nuclear large-subunit rDNA (nrLSU), translation elongation factor 1-alpha (tef-1), and the second largest subunit of RNA polymerase II (rpb2) infer Kgaria as a unique generic lineage with two species, one of which is newly described (K. similis). Tylopilus olivaceoporus, originally described at the same time and as distinct from T. cyanogranulifer, appears to be conspecific with the latter. Some darkly pigmented taxa with similar oxidation reactions that were recently described from Brazil, Guyana, and China are further supported by morphology and molecular data as discrete lineages in separate genera in subfamily Boletoideae.