Entoloma

Karstedt, Fernanda, Capelari, Marina, Baroni, Timothy J., Largent, David L. & Bergemann, Sarah E., 2019, Phylogenetic and morphological analyses of species of the Entolomataceae (Agaricales, Basidiomycota) with cuboid basidiospores, Phytotaxa 391 (1), pp. 1-27 : 21-22

Entoloma subgenus Inocephalus Noordel. emend. Karstedt & T.J. Baroni

≡ Entoloma subgenus Inocephalus Noordel., Persoonia 11: 145. 1981.

≡ Inocephalus (Noordel.) P.D. Orton, Mycologist 5: 130. 1991.

= Rhodophyllus subgen. Inopilus Romagn. , Bulletin Mensuel de la Société Linnéenne de Lyon 43: 329. 1974.

Type species:— Entoloma inocephalum (Romagn.) Dennis , Bulletin de la Société Mycologique de France 69 (2): 160 (1953) [≡ Rhodophyllus inocephalus Romagn., Les Rhodophylles de Madagascar: 151 (1941)]

Description:— Basidiomata mycenoid or tricholomatoid; pileus conic, conic-campanulate, may expand becoming broadly conic, often umbonate, mamillate or papillate, with radially fibrillose or appressed squamulose, these often darker than background color; lamellae adnexed; basidiospores with dihedral base and with 4–6(–7) angles in profile; cystidia fusoid or lageniform, leptocystidia or pseudocystidia may be present; pileipellis a trichoderm, a trichoderm in transition to a cutis towards the margin or a cutis, with entangled and prostrate hyphae; hyphae of subpellis not differentiated; intracellular pigment usually present; clamp connection usually present.

Comments:— Inocephalus (as genus or subgenus) was used based on the circumscription proposed by Romagnesi ( Rhodophyllus subgen. Inopilus Romagnesi (1974: 329) . s ensu Romagnesi in Romagnesi & Gilles 1979: 48; Noordeloos 1981). The original concept included species with a broad basidiospore variation (cuboid or pentagonal), but recent phylogenetic studies indicate this concept produces a polyphyletic group ( Fig. 2, 3; Co-David et al. 2009, Baroni & Matheny 2011). As shown in this study, species with cuboid basidiospores are consistently placed into the Entoloma subgenus Cuboeccilia or subgenus Cubospora .

Those species with a hymeniderm pileipellis already considered as belonging to subgenus Inocephalus section Calliderma Romagnesi (1974: 329 ; Noordeloos 1983: 76; Romagnesi & Gilles 1979, Noordeloos 1992) are now known to form a polyphyletic group not related to Inocephalus s.s. ( He et al. 2012b, Noordeloos & Gates 2012, in figs. 2 and 3). While some species with an hymeniderm pileipellis and with basidiospores 5–6(–7) angled in profile view are found in the /Inocephalus-Cyanula clade, other species that have an hymeniderm pileipellis and isodiametric basidiospores with 6–8(–9) angles in profile view consistently fall into the /Prunuloides clade. Species with many angled to nodulose basidiospores in side view, for example, Entoloma plebejum ( Osmundson et al. 2013, available as an ITS sequence in GenBank), also belongs to /Prunuloides.

Here we propose to restrict Inocephalus to species with pileus conic, conic-campanulate then expanding, basidiospores with dihedral base with 4–6(–7) angles in optical microscopy and often with cheilocystidia (as leptocystidia) fusoid, lageniform or cylindrical, also some with pleurocystidia as pseudocystidia with obvious intracellular pigments.

The / Inocephalus clade ( Entoloma subgenus Inocephalus ) forms a sister clade to the / Cyanula clade ( Entoloma subgenus Cyanula ( Romagnesi 1974: 328) Noordeloos (in Noordeloos & Gates 2012: 209)) and both may have the brilliant granules observed inside the tramal hyphae. However, the surface ornamentation of the pileus differs in species that are placed in these two clades (fibrillose or appressed fibrillose in species of Inocephalus versus minutely squamulose at least on the pileus disc when mature in Cyanula ). There are also differences in symmetry of the basidiospores ( Noordeloos & Gates 2012), species of Inocephalus tend to have shorter basidiospores that are more isodiametric and species of Cyanula have basidiospores that are clearly elongate and heterodiametric. We consider the taxon of Inocephalus occupying the same level as Cyanula , as a subgenus of Entoloma .