On unknown host, Auckland, Titirangi, Bishop's Reserve, 26.XII.l966, R. F. R. and R. J. McNabb, (HOLOTYPE, PDD25610); 6.I.l967, R. F. R. McN., 25611

Fructifications waxy-mucilaginous, resupinate, thin, effused, indeterminate, forming irregular areas to 6 cm longest dimension, pruinose, hyaline when fresh, drying to an almost invisible, white or pallid greyish white film; margins concolorous, adnate. In section to 50 µm thick excluding cystidia, consisting of basal layer and hymenium. Basal layer poorly defined, thin, composed of indistinct, interwoven, hyaline hyphae lying parallel with substratum, clamp; connections present. Hymenium composed of cystidia, paraphysoids and basidia, dikaryophyses, absent; cystidia straight or flexuous, grouped in fascicles, 75-150 x 4-5µm, projecting 50-100 µm beyond basidia, thick-walled with narrow lumina basally, thinner walled apically, smooth, tinted yellowish-brown; paraphysoids abundant, rarely projecting beyond basidia, cylindrical to subclavate, often flexuous, hyaline, thin-walled, contents hyaline, 19.5-29 x 4-5.4 µm; probasidia at first subclavate to clavate later globose to broadly obovate, 7.2-10.5 x 6.5-7.8 µm becoming longitudinally cruciate-septate; sterigmata subulate, to 10 µm long. Basidiospores oblong-cylindrical, sometimes ovate and flattened on one side, hyaline, inconspicuously apiculate, smooth, 5.8-7.5 x 3.2-4.1 µm. Germination by repetition.

Dead angiosperm wood.

Fructificationes ceraceo-mucilaginosae, resupinatae, tenues, pruinosae, hyalinae; ordo basalis tennis, factus ex hyphis indistinctis, nodosis. Dikaryophyses absunt: cystidia fasciculata, crassiparietia, 75-150 x 4-5 µm; paraphysoidea cylindrica ad subclavata, 19.5-29 x 4-5.4 µm, probasidia globosa ad late obovata, 7.2-10.5 x 6.5-7.8 µm, per longitudinem cruciata-septata; sterigmata sublata, ad 10 µm it longa. Basidiosporae oblongo-cylindricae, 5.8-7.5 x 3.2-4.1µm. Germinantes pet repetitionem. Habitat in mortua angiospermatum silva.

The thick-walled, erumpent cystidia indicate that this species belongs in Sect. Heterochaetella. Luck-Alien (1960) accorded Heterochaetella full generic rank and recognised three species in the genus. Of these, Sebacina pruinosa appears to be most closely related to S. dubia (Bourd. & Galz.) Bourd. and Heterochaetella bispora Luck-Allen. It may be distinguished from Sebacina dubia by the presence of paraphysoids and absence of stellate, spinose, or irregularly shaped crystals. From Heterochaetella bispora it differs in the presence of 4-celled basidia and constantly fasciculate cystidia, and the absence of branched dikaryophyses. As explained in an earlier publication (McNabb, 1966), the conservative approach to the taxonomy of Sebacina (sensu lato) adopted in this series of papers is occasioned by the present of agreement on the limits of some generic segregates of this large and artificial genus. This approach has been adopted mainly for convenience and does not imply rejection of the studies of Luck-Alien (1960, 1963) and Wells (1959; 1961). On the contrary, they make it clear that further genera will be recognised with in Sebacina in the near future, but taxonomic readjustments in a group as complex as this are outside the scope of a series of publications dealing exclusively with a regional flora. However, efforts have been made to indicate the position of new species in the generic segregates currently accepted by Luck-Allen and Wells.

Typus Auckland Province, Titirangi, Bishop's Reserve, 26.XII.l966, R. F. R. and R. J. McNabb, PDD25610.