FAGACEAE. Nothofagus cliffortioides: Wellington, Pangarara River, Mt. Tongariro, 1,200 m; Oturere River, Mt. Tongariro, 1,100 m; Kaimanawa Ranges, 900-1,100 m; Mt. Holdsworth, 1,000 m; Featherston Reserve, 35 m. Nelson, Maitai Valley, 120 m; Lake Rotoiti, 700 m; Murchison, 170 m. Nothofagus fusca: Auckland, Little Barrier Island; Lake Waikaremoana, 500 m. Hawke's Bay, Upper. Mohaka River, 700 m; Turangakumu Saddle, 850 m. Wellington, Tongariro River, 600 m; Mt. Reeves, Tararua Ranges, 700 m; York Bay, 120 m; Days Bay, 120 m. Nelson, Staircase Creek, Reefton, 700 m; Murchison, 170 m; Orwell Creek, Ahaura; Totara Flat. Otago, Kinloch, 420 m. Nothofagus menziesii: Hawke's Bay, Upper Mohaka River, 700 m. Otago, Lake Manapouri, 120 m. Nothofagus truncata: Auckland, Thumb Track, Little Barrier Island; Waiorongomai Valley, Te Aroha, 170 m; Orere, Hunua Ranges, 300 m.

Hymenophore annual, sometimes reviving a second season, coriaceous, fructifications at first scattered or crowded, discrete, pulvinate, orbicular, attached by a broad base, 0.5-2 mm diameter, becoming confluent in disciform areas 1-1.5 cm across, finally deeply creviced into irregular polygonal or irregular segments; exterior at first even and rounded, naked, becoming crenulate; hymenial surface at first convex, pruinose and even, cream or ochre, at length rugulose or irregular, radiately crenate, finally deeply creviced and discoloured dingy brown. Context white or isabelline, to 1 mm thick, composed of densely intertwined, cemented, partly gelatinised hyphae, almost sclerotioid near the base, embedding massive gloeocystidia and masses of crystals; generative hyphae to 10 µ diameter at the base, 4-5 µ in the subhymenium, walls 1-1.5 µ thick, lumena capillary in context hyphae, with clamp connections. Acanthophyses subclavate, 4-6 µ diameter, covered on the upper third with closely arranged, blunt pointed spines, naked below, confined to the hymenial layer. Gloeocystidia abundant, arising in all parts of the context and hymenium, some penetrating to the surface, 80-160 x 14-18 µ, in the hymenial layer, in the context 30-56 µ diameter with walls 4-8 µ thick, variable in shape, convoluted and distorted, in the subhymenium fusiform, clavate, or flexuous-cylindrical. Hymenial layer to 60 µ, thick, a dense palisade of basidia, paraphyses, acanthophyses, and gloeocystidia. Basidia subclavate, some cylindrical, 20-30 x 5-6 µ, bearing 2-4 spores; sterigmata erect, slender, to 5 µ long. Paraphyses subclavate, 16-22 x 4-5 µ. Spores allantoid with rounded or acuminate ends, apiculate, 9-12 x 4-4.5 µ walls smooth, hyaline, 0.2 µ thick, amyloid.

DISTRIBUTION: New Zealand.

HABITAT: Crowded on bark of attached dead branches and dead standing saplings.

On examination the type of Hypocrea berggreni in Kew herbarium, ex "Maungatua, S. Berggren, No. 241" proved to be an Acanthophysium, identical with that later described as Aleurodiscus peziculoides. The species is endemic to New Zealand and found on four endemic species of Nothofagus, where it develops upon attached dead branches or dead standing saplings. At first, fructifications are small, pulvinate, scattered or crowded, and coloured cream or ochre. Later, between them develop others which become confluent, forming disciform fructifications with roughened surfaces, scalloped margins, and discoloured edges. Finally these larger plants become creviced so deeply that segments separate and persist as individual colonies, in this stage resembling mature fructifications of Stereum frustulatum, for which species they have been mistaken by several overseas workers. The older form is often biennial, reviving a second season. Fructifications then exhibit on the margins discoloured or black often zoned areas indicating stages of growth. In appearance these two stages are so diverse that each would be regarded as a different species if collected alone; but intermediate stages are present in collections listed showing transition from the pulvinate to the disciform condition. Both are identical in microfeatures.
Context hyphae and acanthophyses are similar to those of certain other species of Acanthophysium. Hyphae are thick-walled, and densely compacted so that basal tissues of the context appear sclerotioid, lumena often being capillary. Acanthophyses are abundant, subclavate, and bear upon the upper third crowded blunt spines. Basidia are much smaller than those of typical species of the genus, and bear delicate sterigmata. Gloeocystidia are large, abundant, with unusually thick walls in those present in the context. Spores are abundant, amyloid, and may be seen embedded in the hymenial layer as well as lying upon the surface when sections are treated with Melzer's reagent. When fresh, specimens are scented not unlike sandalwood.
Acanthophysium aberrans, A. apricans, A. australiensis, and A. berggreni form a small section linked by the clavate acanthophyses.

TYPE LOCALITY: Mt. Maungatua, Otago, New Zealand.