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Page number:470 
Remarks (internal):As noted by Reid (1970), this clamped species has been widely confused with the equally long-spored but unclamped Sebacina calospora (Bourd. & Galz.) Bourd. & Galz., which was originally described in Exidiopsis. Most if not all references in recent literature to specimens of Exidiopsis calospora Bourd. & Galz. possessing clamp-connexions refer to Ceratosebacina longispora.
Though the unusual spores may appear to be diagnostic for the species, they are in fact identical in shape and size to those of Ceratobasidium calosporum Rogers, a species recently collected in Devon. The Ceratobasidium, however, has nonseptate basidia and unclamped hyphae.
Ingold (1992) received part of the second collection and germinated spores. Some of these produced globose microconidia in culture, quite different from the comma-shaped conidia produced by Exidiopsis effusa. This clearly supports the proposal to place the species in a separate genus. Additionally, a number of spores produced chains of barrel-shaped cells reminiscent of a Rhizoctonia anamorph.
The Devon collections cited above represent the first British records of this species.
 
Description type:Non-original description 
Description:Ceratosebacina longispora (Hauersl.) P. Roberts, comb. nov.
(Fig. 4) Sebacina longispora Hauersl., Friesia 11 (2): 100 (1976). Exidiopsis longispora (Hauersl.) Woj., Mala Flora Grzybów. 2: 107, Warsaw (1981).
Basidiomes effused, resupinate, smooth, ceraceous, dull pale grey. Hyphae clearly visible, not in a gelatinous matrix,
clamped at all septa, rather wide, ca 3.0-4.5 µm diam., extensively branching normally from the outer part of the clamp-connexion at the base of each basidium. Hyphidia absent. Basidia reminiscent of Ceratobasidium or Tulasnella Schröter species but distinctly 2-4 septate, globose, ovoid, ellipsoid, or rather angular and cuboid, often with a short and frequently lateral stalk, often showing hyphal continuation through the basidium as papillose or snout-like outgrowths, rather large, ca 10.0-12.0 µm diam., with a large and often partly open clamp at the base. New basidia or basidia-bearing hyphae proliferate from the outer part of this subbasidial clamp, often creating clusters of basidia. Sterigmata 2-3-4 per basidium, reminiscent of Ceratobasidium species, appearing rigid, short, distinctly wider at the base than at the apex, occasionally with retraction septa, ca 5.0-10.0 (-16.0) µm long. Spores elongated, narrowed at each end, normally obtusely angled at midpoint, 24.0-32.5(-42.0) x 3.5-4.0(-4.5) µm (P. Roberts 319); 18.0-36.5 x 3.0-4.5 µm (P. Roberts 332); (18.0-)24.0-36.0 x (3.0-)3.5-5.0 µm (P. Roberts 493). Frequently replicating, germinating by a tube normally arising from the outer part of the midpoint angle.
Specimens examined: on fallen Quercus branch, Orley Common, Devon (SX 8266), 9 Nov. 1991, P. Roberts 319, K; same locality and substratum, 23 Nov. 1991, P. Roberts 332, K; on fallen deciduous branch, Slapton Wood, Devon (SX 8245), 29 Oct. 1992, P. Roberts 493, K.
 
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