Agaricus subg. Minoriopsis Linda J. Chen, L.A. Parra, Callac, Angelini & Raspé, Persoonia

Parra, Luis A., Angelini, Claudio, Ortiz-Santana, Beatriz, Mata, Gerardo, Billette, Christophe, Rojo, Carlos, Chen, Jie & Callac, Philippe, 2018, The genus Agaricus in the Caribbean. Nine new taxa mostly based on collections from the Dominican Republic, Phytotaxa 345 (3), pp. 219-271 : 240

Agaricus subg. Minoriopsis Linda J. Chen, L.A. Parra, Callac, Angelini & Raspé, Persoonia 38: 180. 2017.

Agaricus sect. Minoriopsis (Linda J. Chen, L.A. Parra, Callac, Angelini & Raspé) L.A. Parra, Angelini, Linda J. Chen & Callac , sect. & stat. nov.

MycoBank: MB823277.

Type: Agaricus martinicensis Pegler, Kew Bulletin, Addit. Ser. 6: 446. 1983.

Basionym: Agaricus subg. Minoriopsis Linda J. Chen, L.A. Parra, Callac, Angelini & Raspé, Persoonia 38: 180. 2017.

Etymology: Referring to the similarities to Agaricus sect. Minores .

Original description, Morphological description: Schäffer’s and KOH reactions not performed on fresh collections. Schäffer’s reaction positive dark reddish purple or reddish brown and KOH reaction yellow when observed on the pileus surface of dried collections. Odor of anise or almonds when rubbed or cut (see note below). Annulus superous, thick at the margin, two layered (double), fibrillose squamose sometimes with the scales radially arranged as a cogwheel near the margin in its lower surface. Cheilocystidia generally simple or with one or two septa at the base, usually clavate, pyriform, more or less globose or fusiform, sometimes rostrate or absent in some collections. Spores lacking a rudimentary apical pore.

Section-specific ITS markers: Within A. subg. Minoriopsis, all samples of A. sect. Minoriopsis differ from all samples of A. sect. Kerrigania in ten nucleotide positions in the alignment (37, 70, 118, 147, 204, 236, 278, 509, 524 and 549). Because Agaricu s sect. Minoriopsis currently includes only two species, the number of section-specific markers might easily decrease when more species of this new section will be sequenced. Therefore, we do not describe in details these markers with the exception of the G nucleotide at position 37 in the alignment. Indeed, we verified that this G, which is located at position 36 in the individual ITS sequences of A. martinicensis and A. argenteopurpureus [ggctcGtcaga@36], distinguishes all samples of A. sect. Minoriopsis from all other sequenced samples of the subgenera A. subg. Minoriopsis and A. subg. Minores , which represent about a hundred named or putative species ( Chen et al. 2017; He et al. 2017).

Stem age and phylogenetic support: in the MCC tree of Chen et al. (2017) the well-supported (PP ≥ 0.99) clade, corresponding to A. sect. Minoriopsis, is sister to A. sect. Kerrigania (also proposed in this paper as new section), and consequently has the same stem age of 22.83 Ma. In our ITS tree ( Fig. 1 ), it is also well supported (ML bootstrap support 99%; PP = 1) and includes two species.

Figures

FIGURE 1. Maximum likelihood phylogram of Agaricus subg. Minores, A. subg. Minoriopsis, and A. subg. Flavoagaricus resulting from analysis of ITS sequence data. The best scoring RAxML ITS tree is rooted with A. campestris. The bootstrap support values greater than 50% are indicated, and branches with Bayesian posterior probabilities greater than 0.8 are in bold. Species sampled from the Dominican Republic are in red; new taxa are in bold. T = Type specimen.