Mycetinis prasiosmus (Fr.: Fr.) R.H. Petersen, comb. nov.

Petersen, Ronald H. & Hughes, Karen W., 2017, An investigation on Mycetinis (Euagarics, Basidiomycota), MycoKeys 24, pp. 1-138 : 41-47

9. Mycetinis prasiosmus (Fr.: Fr.) R.H. Petersen, comb. nov.

Agaricus prasiosmus Basionym. Fr.: Fr. (1821). Systema Mycol. 1: 148. ≡ Agaricus prasiosmus Fr. 1818. Observationes Mycologicae 2: 153.] ≡ Marasmius prasiosmus Fr.: Fr. 1838. Epicrisis p. 378.

Type specimen

(Neotype, hic design.). Sweden, Västergötland, Mölndal Parish [N57°30'00", E12°01'00"], Gummebo, 5.X.1940, coll. T. Nathorst-Windahl (no. 2313), Fungi Exsiccati Suecici no. 1155 (S, BPI and presumed other distributions).

Diagnosis.

1) Basidiomata of moderate size, gracile (pileus 15-28 mm broad; stipe 60-100 × 1.5-4 mm); 2) lamellae close to crowded; 3) stipe vestured over all; 4) pileipellis a hymeniform layer of inflated, ventricose-rostrate cells; 5) cheilocystidia not differentiated; 6) long, individual caulocystidia arising from a turf of cespitose, shorter individuals; 7) fruiting on rotting deciduous leaves; 8) distribution from Scandinavia to Italy.

See Appendix 2 for rationale of inclusion.

Description.

Basidiomata (Fig. 59) of moderate size, gracile. Pileus (5-)15-28(-40) mm broad, convex, then applanate, with slightly involute then straight margin, hygrophanous, pale brown to reddish brown, drying to near “chamois” 4B4, smooth to suede-like, or sometimes slightly rugulose or grooved at margin when old; margin translucently striate 1-2 mm, when moist. Context relatively thin, white or brown. Lamellae adnate, slightly anastomosing when old, thin, ventricose, -2.5 mm broad, characteristically crisped when dried, seceding on drying and then appearing weakly pseudocollariate, now taffy colored with somewhat paler edge, total lamellae 70-80, through lamellae 18-28; lamellulae usually in one rank (rarely two). Stipe (20-)60-100 × 1.5-4 mm, terete to compressed, gradually tapering upward, slightly broadened above, straight or often curved at base, fistulose to lightly stuffed, upward avellaneous-tan to brown, downward becoming duller brown, paler at apex, darker at base, entirely white pruinose to pubescent, sublannose villosity ranging from overall to sparse upward, extirpated by handling in midsection and resuming downward with dirty white to brown basal mycelium; stipe apex revealed by seceding lamellae white (not dark brown as in typical Marasmius ); stipe base strigose, non-insititious, disappearing into surface of substrate. Rhizomorphs (see Antonín and Noordeloos 2010, fig. 119) rarely reported, apparently very slender, pallid, curly, probably not branched. Odor strong, of garlic; taste with distinct garlic component.

Habitat and phenology.

Fruiting chiefly on decaying Quercus leaves but occasionally on other deciduous leaves(i.e. Fagus , Betula , Carpinus , etc.); widely distributed through Scandinavia and continental Europe; Autumn to late Autumn.

Pileipellis (Fig. 60) including pileus margin a more or less hymeniform layer of inflated hyphal termini; inflated elements (14-)20-40 × (7-)10-22 µm, staked (stalk 6-16 × 5-8 µm), ranging from obpyriform, vesciculose, ventricose-rostrate to broadly clavate, mitten-shaped or lobate, conspicuously clamped, firm walled, hyaline or occasionally weakly pigmented. Pleurocystidia (Fig. 61 A–D) 32-46 × 4-7 µm (at widest point), narrowly to broadly fusiform, stalked, conspicuously clamped. Subhymenial hyphae branched, thin-walled, 2.5-4.0 µm diam. Pileus and hymenophoral trama subregular to irregular; hyphae cylindrical or slightly inflated, hyaline, thin-walled, 2.0-14(20) µm diam. Basidioles 19-38 × (3.0)4.5-10 µm, cylindrical to subampulliform; basidia (Figs 61 E–H, 62) (26-)30-38 × (5.0-)6.0-10 µm, cylindrical or clavate, hardly subcapitulate, (2-)4-sterigmate, conspicuously clamped; contents heterogeneous, appearing oily. Basidiospores (Fig. 63B) (7-)9-10.5(-12.5) × (3.5-)4-5.5(-6) µm (Q = 1.63-2.25; Qm = 1.97; Lm = 9.2 µm), ellipsoid to elongate pip-shaped, tapered slightly proximal ly, thin-walled, inamyloid; contents more or less homogeneous. Lamellar edge fertile; cheilocystidia undifferentiated, but clavate to subampulliform structures present. Stipe medullary hyphae strictly parallel, free (not involved in slime matrix), of two types: 1) 6-15 µm diam, firm- to thick-walled (wall -2 µm thick, hyaline), obscurely clamped; and 2) 2-4 µm diam, thick-walled (wall -1 µm thick, weakly pigmented), seldom but conspicuously clamped. Stipe cortical hyphae 3-5 µm diam, thick-walled (wall -1.5 µm thick, weakly pigmented), seldom and obscurely clamped, producing caulocystidia as side branches. Caulocystidia (Fig. 63A) of two types: 1) 20-45 × 7-9.5 µm, gnarled, thick-walled (wall -1.0 µm thick, hyaline), occasionally branched, in a turf; and 2) 49-120 ×7– 10 µm, sinuous, occasionally branched, rarely internally clamped, thick-walled (wall -1.0 µm thick, hyaline to weakly pigmented); caulocystidia on lower stipe retaining the basic turf but with densely gregarious (not synemmata-like) longer caulocystidia.

Commentary.

This treatment includes Mycetinis querceus ss Antonín and Noordeloos (2010). The case for typification and acceptance of Mycetinis prasiosmus is included as Supplementary Data 1.

It might be expected that Noordeloos (2012) followed the nomenclature set out by Antonín and Noordeloos (2010), including Mycetinis querceus as part of the Scandinavia mycota but citing as synonymous " M. prasiosmus (Fr.: Fr.) Fr. ss. auct." Included was "occasional in temp.-hemib., very rare in southern bore."

Redhead (1982) reported that stipe cortical tissue (as "pigmented hyphal walls") of Marasmius copelandii (later re-identified as M. salalis ) produced a greenish gray to blue-green pigment in KOH solution. These reactions were also reported for Marasmius olidus and M. prasiosmus . We have been unable to confirm this report in the present study, but if Redhead’s concept of M. prasiosmus followed that of Kauffman (see supplementary data): it is not the European M. prasiosmus . Moreover, later research has proposed M. olidus to accommodate M. prasiosmus ss Kauffman.

Specimens examined.

Czech Republic, Moravian Karst, Brno-Líšeň, Hádecká planinka,1 Nov. 2001, coll. V. Antonín (as Mycetinis querceus ), VA 01.340 (BRNM 666586); Moravia, Lipůvka, Dubová hora, 28 Oct. and 12 Nov. 1960, coll. F. Šmarda s.n. (as Mycetinis querceus ) (BRNM 314016). Sweden, Uppland, Uppsala parish, Bondkyrka parish, Eriksberg, forest between Granitvägen and Hågaån, 21.X.1974, coll. S. Ryman (as Marasmius prasiosmus ), SR 3241 (UPS-F-740438); Uppland: Uppsala parish, Bondkyrka parish, Kvarnbo lund, 12.XI.1974, coll. Svengunnar Ryman (as Marasmius prasiosmus ). SR 3281, (UPS-F-740439); Uppland, Gamla Uppsala Parish, Fullerö backar (3 km N of the church), 13.X.2001, coll. N. Lundqvist (as Marasmius prasiosmus ), NL 21502 (UPS-F-740442); Västergötland: Mölndal Parish, Gummebo [N57°30'00", E12°01'00"], 5.X.1940, coll. T. Nathorst-Windahl, No. 2313, Fungi Exsiccati Suecici, Praesertim Upsaliensis [FES as Marasmius prasiosmus ), no. 1155 (S, BPI and other presumed distributions; neotype); Västergötland, Vänersborg parish, Botered, X.1860, coll. G. Linnarsson (as Marasmius prasiosmus ), s.n. (UPS-F-574708); Västmanland, Västerås-Barkarö parish, Ridön, Munkkällan, 12.X.1986, coll. Herbert Kaufmann (as Marasmius prasiosmus ), s.n. (UPS-F-02106).