Xerocomellus (Boletaceae) in western North America

Abstract

Understanding diversity in the genus Xerocomellus in western North America has been obscured by morphological variability, widespread use of species epithets typified by specimens from Europe and eastern North America, misunderstood phylogenetic relationships, and species complexes. We collected extensively and used genetic and morphological data to establish the occurrence of ten Xerocomellus species in western North America. We generated ITS sequences from five type collections and from vouchered representative collections to clarify our understanding of existing species concepts. We describe three new species (Xerocomellus atropurpureus, X. diffractus, and X. salicicola) and propose two new combinations (X. amylosporus and X. mendocinensis), transfer Boletus coccyginus to Hortiboletus, and provide a dichotomous key to species of Xerocomellus in western North America.

Delimiting species in Basidiomycota: a review

“…Regarding sequence-based molecular methods, ITS is still the most widely used marker in species delimitation within Boletales (Badotti et al 2017). ITS is a reliable barcode marker for species in several genera, e.g., Astraeus (Phosri et al 2014), Chroogomphus (Scambler et al 2018;Kiran et al 2020), Phylloporus (Neves et al 2012), Rhizopogon (Sulzbacher et al 2016), Suillellus (Vizzini et al 2014c), Suillus (Kretzer et al 1996;Wu et al 2000;Manian et al 2001;Nguyen et al 2016), Xerocomellus (Frank et al 2020), and Xerocomus (Taylor et al 2006a(Taylor et al , b, 2007, but a poor marker in other genera (e.g., Butyriboletus, Pisolithus; Badotti et al 2017). Some genera in Leccinoideae (Leccinum, Octaviania, Rossbeevera and Turmalinea) are characterized by a minisatellite-like insertion within the ITS region (den Bakker et al 2004;Orihara et al 2012).…”

“…The more commonly used loci in combined analyses in Boletales (besides ITS) are SSU, 5.8S, LSU, atp6, cox1, cox3, mtSSU, mtLSU, rpb1, rpb2, tef1, gdp, Gapdh, btub, and hsp, and a combination of actA, gpiA, hydA, rabA, and btub (Kretzer and Bruns 1999;Peintner et al 2003;den Bakker and Noordeloos 2005;den Bakker et al 2007;Beugelsdijk et al 2008;Hedh et al 2008;Dentinger et al 2010Dentinger et al , 2011Li et al 2011;Skrede et al 2011;Neves et al 2012;Wilson et al 2012;Gelardi et al 2013Gelardi et al , 2015Moreau et al 2013;Jargeat et al 2014Jargeat et al , 2016Phosri et al 2014;Wu et al 2014Wu et al , 2016Wu et al , 2018Zhao et al 2014a, b;Balasundaram et al 2015;Sato and Hattori 2015;Trappe et al 2015;Henkel et al 2016;Orihara et al 2016;Raspé et al 2016;Davoodian et al 2018, Farid et al 2018Song et al 2019;Vadthanarat et al 2019a, b;Varga et al 2019;Frank et al 2020;Haelewaters et al 2020a;Han et al 2020;Kuo and Ortiz-Santana 2020;Liu et al 2020;…”

Exploring the Relationships between Four New Species of Boletoid Fungi from Northern China and Their Related Species

“…Most Boletaceae species have value for humans and are essential for mutualistic symbiosis with trees [3][4][5][6]. Although the family Boletaceae was established nearly two centuries ago, the species diversity of the family increased significantly in the last few decades [7][8][9][10][11][12][13][14][15][16][17][18][19]. Because the morphology of Boletaceae has convergent characteristics, the classification did not correspond to the phylogeny of Boletaceae for a long time.…”

Xerocomellus carmeniae (Boletales, Basidiomycota), a new fungus from northeastern Mexico

“…Xerocomellus Šutara is a genus in the family Boletaceae characterized by boletoid, hypogeous to secotioid basidiomata, usually with small fruit body, sometimes cracked pileus, and smooth to ornamented spores; some species have hypogeous forms with ridged to globose-equinulate spores (Šutara, 2008;Smith et al, 2018;Frank et al, 2020). As other boletes, the species of Xerocomellus form ectomycorrhizas with members of Fagaceae and Pinaceae (Rinaldi et al, 2008;Tedersoo et al, 2010;Wu et al, 2016;Frank et al, 2020). The genus was segregated from Xerocomus Quél.…”