Skeletocutis cummata A. Korhonen & Miettinen

Korhonen, Aku, Seelan, Jaya Seelan Sathiya & Miettinen, Otto, 2018, Cryptic species diversity in polypores: the Skeletocutisnivea species complex, MycoKeys 36, pp. 45-82 : 45

Skeletocutis cummata A. Korhonen & Miettinen sp. nov. Figures 6G, 7

Holotype.

China. Jilin: Antu, Changbai Mountains, alt. 1300 m, Picea jezoënsis, 18 Sep 1998 Niemelä 6408 & Dai (H 7008666).

Description.

Basidiocarps annual; half-resupinate to pileate; up to 3 cm wide and (pilei) up to 1 cm thick; hard when dry but easy to break apart; pilei nodulous or thick but steeply sloping, protruding up to 1 cm; margin of pileus curved downwards, blunt, with narrow, woolly ridge on the underside; upper surface matted to minutely pubescent, white to cream coloured when young, turning ochraceous with almost orange hues; pore surface with ochraceous or sometimes salmon/peach coloured tints, sometimes a greenish-grey tint is visible in the tubes; context and subiculum finally coriaceous but looser and fibrous near cap edge and surface; context faintly zonate in longitudinal section with thin dark lines separating layers of growth; tube layer up to 1 mm thick; pores (5 –)7–8(– 13) per mm.

Hyphal structure: the outer layer of context typically with a loose, fibrous texture composed of radially orientated encrusted hyphae (tomentum). Skeletal hyphae in context / subiculum (1.0 –)2.0–3.5(– 5.0) µm wide, in trama 2.0 –4.0(– 5.0) µm wide, generative hyphae in trama 1.0 –2.0(– 2.6) µm wide.

Basidiospores (2.8 –)2.9–3.4(–3.9)×0.5–0.8(– 0.9) µm, L=3.1 µm, W=0.66 µm, Q’=(3.3–)3.8–6.0(– 6.6), Q=4.68, n=270/9.

Distribution and ecology.

Boreal, Eurasian taiga; known from Fennoscandia, Czech Republic and Far East. The species seems to be rather rare in Europe but possibly more common in the Far East where Spirin (H) has collected it abundantly. The species has been found growing on fallen spruce logs ( Picea abies , P. jezoënsis) but also on Abies nephrolepis and Larix sp.

Etymology.

Cummatus (Lat.), resinous, refers to the brown upper surface of basidiomes.

Specimens examined.

CHINA. Jilin: (holotype, see above). FINLAND. Etelä-Häme: Hämeenlinna, P. abies (fallen, fairly thin, still corticated tree), 17 Sep 2013 Niemelä 9088 & Spirin (H). RUSSIA. Khabarovsk Reg.: Khabarovsk Dist., Levyi Ulun, P. jezoënsis, 21 Aug 2012 Spirin 5472 (H); 5484 (H); Malyi Kukachan, Larix sp., 19 Aug 2012 Spirin 5430 (H); Malyi Niran, P. jezoënsis, 6 Aug 2012 Spirin 4897 (H); Ulun, P. jezoënsis, 26 Aug 2012 Spirin 5676 (H); Solnechny Dist., Igdomi, Abies nephrolepis , VIII.2011 Spirin 3857; Suluk-Makit, P. jezoënsis, 17 Aug 2011 Spirin 4170 (H).

Discussion.

S. cummata is most notably distinguished from other Eurasian species in the S. nivea complex by its occurrence on conifer wood. Spores of S. cummata are also larger than those of angiosperm-dwelling species apart from S. futilis . The pubescence on pileus surface in pileate specimens provides an additional identification cue. Very wide but thin-walled tramal skeletal hyphae seem to be particularly pronounced in this species. All distinctive features of S. cummata are shared with the North American conifer-dwelling species S. ochroalba .