UNKNOWN HOSTS. Queensland, Bunya Mountains. New South Wales, Nowra (herb. Kew).

Hymenophore resupinate, perennial, stratose, adherent, ligneus, effused forming linear areas to 10 x 4 cm; hymenial surface tan or cinnamon, even, at length either sparsely, transversely, deeply creviced, or broken into irregular tubercules each becoming free and developing as a separate colony; margin abrupt and cliff-like, or receding with each successive growth layer, polished, umber or chocolate, adherent. Context wood colour, to 3 mm thick, of many coloured zones (15-30) of erect hyphae with seams of loosely intertwined hyphae embedding crystals; skeletal hyphae 4-6 µm diameter, walls 1-2 µm thick, brown; generative hyphae 3.5-4 µm diameter, walls 0.2 µm thick, hyaline, without clamp connections. Acanthophyses cylindrical, or clavate, 5-6 µm diameter, projecting, walls coloured save in the apical region, upper third bearing numerous digitate processes 1-2.5 µm long. Hymenial layer to 40 µm deep, a dense palisade of basidia, paraphyses, and acanthophyses. Basidia subclavate, 16-22 x 5-6.5 µm, bearing 4 spores; sterigmata erect, slender, to 4 µm long. Paraphyses subclavate or cylindrical, 12-16 x 4-4.5 µm. Spores obovate or pip-shaped, apiculate, 4-4.5 x 3-3.5 µm, walls smooth, hyaline, 0.1 µm thick.

DISTRIBUTION: Europe, Great Britain, North America, Australia.

HABITAT: Effused on decorticated dead wood associated with a pocket rot.

Lloyd (1920c, p. 1008) referred the collection from Queensland to S. annosum Berk. & Br. (syn. S. durum Burt, S. burtiasmus Lloyd, S. rhabarbarinum (Berk. & Br.) Wakef.). With this tropical species it agrees in the presence of acanthophyses and stratose context. It differs in the type of acanthophyses and in being resupinate. Specimens of S. annosum from Ceylon and Uganda examined in Kew herbarium are, pileate with effused-reflexed pilei, and acanthophyses are of different size and shape, and bear digitate processes throughout their length. Australian collections differ from typical specimens of S. frustulatum in that the resupinate fructifications are only tardily laterally creviced (Queensland specimen) or areolately creviced (New South Wales specimen), whereas European collections usually break into polygonal frustules which continue to grow after separation, so that each frustule ultimately becomes pulvinate like those of Corticium kauri. Acanthophyses are the same in both Australian and European collections, as are basidia and spores. Acanthophyses are similar to those present in S. illudens and S. subpileatum Berk. & Curt. (syn. S. insigne Bres., S. sepium Burt). They become cemented into a palisade in the hymenial layer, and persist to form the coloured zones so conspicuous in sections when examined under a lens. When fertile, the hymenial layer consists mainly of basidia and paraphyses, when sterile this layer is composed almost entirely of acanthophyses. Colenso (1886, p. 304) recorded the species from New Zealand, the record being based on two collections so named in Kew herbarium, ex "N.Z. Colenso, b. 252, b. 297". Labelled on the sheet by Lars Romell as S. rufum, they are collections of Acanthophysium berggreni and bear such a striking superficial resemblance to some collections of S. frustulatum that Lloyd (1925, p. 1336) also recorded the species from the Dominion, as his photograph (f. 3087) shows. The specimen from Nowra, New South Wales, was by E. M. Wakefield (1915, p. 370) recorded under the name of Stereum rhabarbarinum. Examination showed it to possess microfeatures of S. frustulatum, differing in that, although deeply creviced, the plant is continuous and not broken into frustules as in most European collections. Because of the arrangement of context hyphae the species is an anomalous Stereum and but for its dimitic hyphal system would be better placed under Acanthophysium.

TYPE LOCALITY: Sweden.