Studies on Agaricus subtilipes, a new cultivatable species from Thailand, incidentally reveal the presence of Agaricus subrufescens in Africa

• A new species, Agaricus subtilipes was described from north Thailand.
• A wild strain of A. subtilipes fructified at 25 °C and 95% humidity.
• Agaricus bambusae var. bambusae was synonymized with A. subrufescens.
• Agaricus bambusae var. australis was renamed as A. horakianus.

The genus Agaricus includes cultivated species of nutritional and medicinal interest, such as A. bisporus and A. subrufescens. The latter and A. flocculosipes were the only species of the A. sect. Arvenses that have been reported from Thailand. In this section, we introduce Agaricus subtilipes, a new species from North Thailand. Bayesian and maximum likelihood phylogenetic analyses of internal transcribed spacer (ITS) ribosomal RNA gene showed that this new species is sister to A. flocculosipes. A comparison of Agaricus subtilipes with tropical species of A. sect. Arvenses led us to revisit the species A. bambusae. Unexpectedly, A. bambusae var. bambusae which was described from Africa was shown to be a synonym of Agaricus subrufescens based on molecular data. In contrast, A. bambusae var. australis which was described from New Zealand was not closely related to A. subrufescens, but was a sister species to A. subantarcticus, also described from this country; this variety is therefore raised to species rank and renamed as A. horakianus. In experimental cultivation, an isolate of A. subtilipes fructified on compost substrate with conditions used for A. subrufescens cultivation. This first fruiting test showed that A. subtilipes can be domesticated, however further investigations are required to optimize conditions for industrial yields.