A phylogenetic and morphological overview of sections Bohusia, Sanguinolenti, and allied sections within Agaricus subg. Pseudochitonia with three new species from France, Iran, and Portugal.

ABSTRACT

The genus Agaricus was recently rearranged to accommodate numerous tropical taxa. Accordingly, the genus was split into six subgenera and 22 sections of which 12 are included in A. subg. Pseudochitonia. Preliminary data indicated that three putative new species belong to this subgenus. Our objectives were to describe these species, to determine to which sections they belong, and to experience the interest of some traditional traits in this new context. We morphologically described Agaricus coniferarum from France and Portugal, Agaricus iranicus from Iran, and Agaricus lusitanicus from Portugal. Multi-gene phylogenetic analyses based on ITS, LSU, and tef1 sequence data of representatives of the 12 sections clearly indicated that A. coniferarum and A. lusitanicus are placed in Agaricus sect. Bohusia, while A. iranicus is in A. sect. Sanguinolenti. Incidentally, we replaced the illegitimate name Agaricus magnivelaris by Agaricus fiardianus. In a phylogenetic tree, based on all available ITS sequence data and focussing on six related sections, we examined the phylogenetic distribution of various characters. The intensity of red discolouration when the sporocarp is rubbed or cut appeared as a phylogenetically weak informative trait. We propose a determination key leading to a group of three hardly distinguishable sections (Bohusia, Nigrobrunnescentes, and Sanguinolenti).