Cuphophyllus aureus—a new species from Kerala State, India

A new species of Cuphophyllus is described from Kerala State, India. This species is characterized by very small, omphalinoid basidiocarps, a golden yellow pileus with a glabrous and hygrophanous surface, arcuate-decurrent, transvenose and intervenose lamellae, a compressed, appressed-fibrillose and longitudinally-striate stipe with a pale yellow strigose basal mycelium, ellipsoid-oblong to lacrymoid basidiospores, a lamellar trama with an almost regular central strand flanked on either side by somewhat subregular hyphae, a hymenium devoid of pleuro- and cheilocystidia, a repent cutis-type pileipellis and a cutis-type stipitipellis. Phylogenetic analysis, conducted using a concatenated data matrix comprising the internal transcribed spacer (nrITS), nuclear large subunit (nrLSU), and RNA polymerase II subunit 2 (rpb2) genes, reveals that Cuphophyllus aureus forms a distinct lineage, separate from species in the section Virginei of the genus Cuphophyllus. A detailed taxonomic description, photographs, and line drawings of both the basidiocarps and the microscopic structures, comparisons with morphologically and phylogenetically related species, and a phylogram illustrating the position of the new species are provided.