On dead (1) Nothofagus fusca, Hawke's Bay, Upper Mohaka River, 31.V.1953, J. M. Dingley, 25009-11. (2) N. solandri, Carry River, 13.IV.l958, J. M. D. (HOLOTYPE, PDD 25008), (3) Nothofagus sp., Otago, Lake Whakatipu, Paradise, 21.VI.l964, S. Davison, 26086.

Fructifications gelatinous to waxy-gelatinous, gregarious, crowded, erumpent through bark, pustulate to pulvinate, to I mm diam., originating as discrete pustules, anastomosing or coalescing to form extensive areas to 15 cm in longest dimension but retaining evidence of pustular origin, dull yellowish-brown when fresh, drying yellowish-brown with reddish-brown borders, often appearing reticulate or meruloid; margins inconspicuous when fresh, often conspicuous, white, fibrillose or arachnoid when dry, extending between adjacent fructifications. In section to 500 µm thick, consisting of ascending layer and hymenium. Ascending layer composed of distinct, hyaline hyphae, 2-3 µm diam., clamp connections present; fibrillose margins composed of similar hyphae. Hymenium composed of dikaryophyses, paraphysoids, and basidia; dikaryophyses simple or irregularly branched apically, with clamp connections throughout their length, projecting beyond basidia; paraphysoids broadly cylindrical, subclavate, clavate, or irregularly strangulated, with basal clamp connections, hyaline, thin-walled, devoid of coloured contents, 24-62 x 4.3-10 µm; probasidia obovate to broadly elliptical, proliferating through or near basal clamp connections, 11.8-16.8 x 8.3-11.2 µm becoming longitudinally cruciate-septate; sterigmata cylindrical, to 55 x 2.5µm. Basidiospores curved-cylindrical to allantoid, hyaline, bluntly apiculate, 11.8-15.5-( 17.5) x 4.3-5.6 µm. Germination by repetition.

Dead angiosperm wood.

Fructificationes gelatinosae ad ceraceo-gelatinosas, gregariae, erumpentes, pustulatae ad pulvinatas, ad 1 mm diam., anastomosantes, obtuse luteo-brunneae, Ordo ascendens factus ex hyphis distinctis 2-3 µm diam., nodosis. Dikaryophyses simplices vel irregulariter ramosae ad apicem; paraphysoidea cylindrica ad clavata, 24-62 x 4.3-10 µm; probasidia obovata ad late elliptica, 11.8-16.8 x 8.3-11.2 µm, per longitudinem cruciata-septata; sterigmata cylindrica, ad 55 x 2.5 µm. Basidiosporae curvo-cylindricae ad allantoides, 11.8-15.5-(17.5) x 4.3-5.6 µm. Germinantes per repetitionem. Habitat in mortua Nothofago fusca.

It is difficult to place this distinctive species with its minute, densely gregarious fructifications in any of the described genera of the Tremellaceae. Depending upon their spore shape, such species usually have been classified in Tremella or Exidia, but it is clear that they cannot satisfactorily be included in either genus. Donk (1966) recognised the difficulty of inserting species with small, crowded fructifications into the existing classification and segregated a group of European species under the general term "Microtremella". He was careful to point out that "Microtremella" was a term rather than a name and that it implied only that the species involved possessed a similar growth habit.
Pseudostypella nothofagi is characterised by the minute, erumpent, densely gregarious fructifications, numerous paraphysoids, and curved-cylindrical to allantoid spores. The fibrillose margins of adjacent fructifications are often confluent, giving the impression that the fructifications are seated on a subiculum as in Stypella, whereas they are in fact erumpent and firmly attached to the substratum.

Typus Canterbury Province, Carry River. 13.IV.l958, J. M. Dingley, PDD 25008.