Skeletocutis nivea (Jungh.) Jean Keller, Persoonia 10(3): 353 (1979).

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 nivea (Jungh.) Jean Keller, Persoonia 10(3): 353 (1979). Figures 4 C–D, 6 D–E, 7

Basionym.

Polyporus niveus Jungh. Praemissa in floram cryptogamicam Javae insulae: 48 (1838).

Holotype.

Indonesia. Central Java: Mount Merapi, Junghuhn 44 (L).

Epitype.

Indonesia. Central Java: Mount Lawu, alt. 2130 m, old-growth montane forest dominated by Castanopsis javanica , indet. angiosperm wood (fallen branch), 22 May 2014 Miettinen 18217 (BO, designated here, duplicate H 7008663). MycoBank No. MBT378098

Description.

Basidiocarps annual; half-resupinate; hard when dry, breaking apart neatly; pilei nodulous to shelf-shaped, sometimes laterally fused and quite fleshy, up to 2 cm wide and 5 mm thick, protruding up to 1.3 cm, often connected to wider resupinate part; upper surface almost smooth to slightly rough, matted, white to cream coloured when young, turning ochraceous and finally blackish with age; pore surface often with a greenish-grey or turquoise tint emerging within the tubes particularly in the pileate part but often in scattered blotches; context and subiculum coriaceous, white; context sometimes faintly zonate in longitudinal section; tube layer up to 1 mm thick; pores (7 –)8–10(– 13) per mm.

Hyphal structure: trama dimitic but sometimes seemingly monomitic with slightly sclerified generative hyphae or sometimes clearly dimitic with solid skeletal hyphae; skeletal hyphae in context / subiculum (1.0 –)2.0–3.0(– 3.9) µm wide, in trama (1.0 –)2.0–3.5(– 4.9) µm wide, but only 2-3 µm wide and solid in specimens from New Zealand, generative hyphae in trama 1.0 –2.3(– 2.8) µm wide.

Basidiospores (2.7 –)2.8–3.2(–3.7)×0.5–0.7(– 0.8) µm, L=2.96 µm, W=0.56 µm, Q’=(3.9–)4.3–6.0(– 6.2), Q=5.27, n=125/5.

Distribution and ecology.

From tropical southeast Asia to subtropical New Zealand in the south and temperate China in the north, on angiosperm wood.

Specimens examined.

CHINA. Jilin: Antu, Changbai Mountains, alt. 1100 m, Alnus sp. (fallen tree crown), 27 Aug 2015 Miettinen 10579.1 (H). INDONESIA. Central Java: (epitype, see above); alt. 2180 m, old-growth montane forest dominated by Castanopsis javanica , indet. angiosperm wood (fallen tree), 22 May 2014 Miettinen 18255 (ANDA, H); (holotype, see above). MALAYSIA. Sabah: Kinabalu Park, alt. 1675 m, lower montane forest, indet. angiosperm wood, 17 Jun 2013 Miettinen 16350 (SNP, H). NEW ZEALAND. Auckland: Hunua Ranges, indet. angiosperm wood, 19 Mar 1996 Ryvarden 38171 (O 916495); 38177 (O 916496).

Discussion.

The holotype of S. nivea is sterile but it possesses the encrusted generocystidia and arbuscule-like 'binding hyphae’ characteristic to the S. nivea complex. Specimens from New Zealand represent a disjunct population and exhibit aberrant hyphal morphology with clearly dimitic trama. However, they do not stand out phylogenetically (in ITS) from the rest of S. nivea .