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 Aleurodiscus sparsus
SynonymsAcanthophysium sparsum
Stereum sparsum
BiostatusPresent in region - Indigenous. Non endemic
Article: Cunningham, G.H. (1963). The Thelephoraceae of Australia and New Zealand. New Zealand Department of Scientific and Industrial Research, Bulletin 145: 359 p. Wellington:.
Description: Hymenophore annual, cretaceous,
adherent, at first composed of numerous orbicular or linear small colonies 2-10
mm across, coalescing to form effused areas 11-14 x 1-2 cm; hymenial surface
chalk white, even, at length deeply and areolately creviced; margin thinning
out, at first fibrillose, later definite and cliff-like, adherent. Context
white, to 250 µm thick, basal layer of compact hyphae densely intertwined and
almost pseudoparenchymatous, intermediate layer scanty, of erect hyphae;
generative hyphae 3-5 µm diameter, walls 0.25 µm thick, naked, without clamp
connections. Acanthophyses arising from the surface of the basal layer and
forming a dense palisade, coralloid, with lateral branches, spinose throughout.
Gloeocystidia commonly fusiform, oval, or obpyriform, 32-72 x 18-50 µm, contents
orange when fresh. Hymenial layer occupying the greater part of the context, a
close palisade of basidia, paraphyses, and acanthophyses. Basidia cylindrical or
slightly clavate, 65-110 x 20-25 µm, bearing 4 spores; sterigmata arcuate,
subulate, to 32 µm long. Paraphyses ovate, fusiform, or subclavate, varying in
length and shape, deeply embedded, 35-80 x 8-16 µm. Spores elliptical,
apiculate, 25-36 x 16-20 µm, walls covered with irregular aculeae to 3 µm long,
hyaline; 1 µm thick, amyloid.
Habitat: HABITAT: Effused on bark or decorticated wood of dead
branches.
Distribution: DISTRIBUTION: Australia, New Zealand.
Notes: The
type collection in Kew herbarium, ex "Wangaretta, Victoria" consists of eight
small, irregularly orbicular colonies 1-5 mm wide. It is immature since spores
were not found. Sections agree with the collections from Australia listed above,
save that paraphyses are more clavate. The description given differs in several
particulars from that of Hoehnel & Litschauer (1907, p. 809) which was drawn
from specimens collected near the Murray River, Victoria. For they had described
a different type of acanthophysis, and stated that spores were smooth. Basidia
and paraphyses arise from the surface of the basal layer and are completely
embedded in masses of acanthophyses which form the greater part of the context.
At maturity basidia become elongated and. project above the hymenium, shed their
spores, then collapse. Paraphyses remain deeply embedded. Gloeocystidia are
scanty or abundant, apparently absent from some collections, assume many shapes,
vary appreciably in size, and when fresh contain orange contents. In a previous
paper (1956b, p. 259) I stated they were not present; but in a recent collection
they were readily seen, and on re-examination of the other collections were
found in some but not all, by aid of a differential stain. Fig. 101 was prepared
from a section without gloeocystidia. Acanthophyses are coralloid and arise
mainly from the surface of the basal layer. They are freely branched and usually
clothed throughout with spines which in turn may branch. Spores are the largest
recorded for the genus. In lactic acid aniline blue mounts they appear to be
almost smooth; but in Melzer's reagent are seen to be covered with irregular
aculeae which may reach a length of 3 µm. Early stages are cupulate or
pezizaeform, and fructifications may remain so, or colonies fuse to form effused
fructifications typical of most species of Acanthophysium. Pezizaeform
plants could be placed under Aleurodiscus, but as their structure is
corticioid, acanthophyses coralloid, and the species close to A.
coralloides, it has been treated as an Acanthophysium.
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