A revision of Agaricus section Arvenses with nine new species from China.

Agaricus sect. Arvenses includes numerous species that are potential candidates for cultivation, and some have high nutritional and medicinal interests. Between 2012 and 2017, 147 specimens of A. sect. Arvenses were collected in China. For this study, nuc rDNA internal transcribed spacer region ITS1-5.8S-ITS2 (ITS), nuc 28S rDNA (28S), and translation elongation factor 1-alpha (tef1) sequences were used to assess species boundaries of these samples from China. Combined with morphological examination, we recognize 22 species of A. sect. Arvenses from China, of which 12 are known species, one is new record for China, and nine are proposed as new.