Ionosporus: a new genus for Boletus longipes (Boletaceae), with a new species, I. australis, from Australia

Boletus longipes was described in 1909 by George Massee from a specimen collected in Singapore. The species was not mentioned again until E.J.H. Corner’s book in 1972 on Malaysian boletes. Corner had collected it many times during his tenure in Singapore, and he synonymized Boletus tristis with B. longipes described nine years after B. longipes by Patouillard and Baker from the same site. Among the distinguishing characters of B. longipes were deep vinous red spore deposit, red oxidation reaction of the hymenophore when bruised, and spores that displayed a strong violet color reaction in contact with KOH. C.B. Wolfe ultimately moved both species to a new genus Austroboletus. During recent efforts to circumscribe Austroboletus in Australasia using morphological and molecular phylogenetic inferences, it became clear that B. longipes was neither in harmony with Boletus, Porphyrellus, nor Austroboletus. Rather, it is a new genus, which we describe here as Ionosporus, allied to Borofutus, Spongiforma, and Rhodactina of subfamily Leccinoideae. In addition, recent collections from Queensland and New South Wales, Australia, that are morphologically similar to I. longipes, are inferred to be a separate new species, I. australis.