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Page number:29 
Remarks (internal):Ceratobasidium is distinguished by its laterally branching, open-textured hymenium producing a single layer of globose to ellipsoid basidia. These basidia are normally at least twice the width of their supporting hyphae at the sub-basidial septa and are often pleural, bearing a short hyphal projection. Basidia vary in size from species to species, C. globisporum and C. setariae having basidia twice the width of those formed by C. noxium and C. stridii. However, in all species the basidial length/breadth ratio (Q) falls between 1.0 and 1.4 (Table 3). All Ceratobasidium species have unclamped hyphae typically 6 µm diam. and always less than 10 µm diam. (Table 3). Hyphal compartments are typically binucleate (uninucleate in C. bicorne) and the septal pores have discontinuous parenthesomes. Most, possibly all, species are capable of producing monilioid hyphae in culture. Some also produce sclerotia. Basidiospores vary in shape from elongated vermiform to globose, but are always capable of self-replication.
Morphologically, Ceratobasidium is close to Thanatephorus. It differs principally in its laterally branching hymenium, the basidium shape being an associated secondary characteristic, as is the tendency for the basidia to be pleural. Ceratobasidium also has nar10wer, paler hyphae than Thanatephorus, but this is an observation based on known species rather than a defining generic character.
The genus Koleroga was proposed by Donk (1958) to accommodate K noxia, a species morphologically similar to Ceratobasidium but not known to produce self-replicating basidiospores. Talbot (1965) demonstrated that such spores were present in some collections and suggested that Koleroga be synonymized with Ceratobasidium. This synonymy is confirmed here, with the transfer of the type species of Koleroga to Ceratobasidium.
Anamorphs of Ceratobasidium were not differentiated from other rhizoctonias until Moore (1987) proposed the genus Ceratorhiza specifically to accommodate them. Ceratorhiza was additionally characterized by possessing septal pores with discontinuous parenthesomes and binucleate hyphae. Hyphal nucleation, however, is a variable character and not useful in defining genera. Botryobasidium, for example, contains a mixture of binucleate and multinucleate species (Langer, 1994), as does Thanatephorus. Ceratorhiza goodyerae-repentis, the generic type, is a name of uncertain application (as noted by Andersen & Stalpers, 1994) but was intended by Moore (1987) to represent the anamorph of Ceratobasidium cornigerum.
Ceratorhiza pernacatena Zelmer & Currah, isolated from Canadian orchids, was described without reference to a teleomorph. It was said to represent an anamorphic Ceratobasidium (Zelmer & Currah, 1995).
Description type:Non-original description 
Description:Ceratobasidium D.P. Rogers, Univ. Iowa Stud. Nat. Hist. 17: 4 (1935).
Koleroga Donk, Fungus 28: 35 (1958).
Anamorph: Ceratorhiza R.T. Moore, Mycotaxon 29: 94 (1987).
Teleomorph. Basidiome: effused, thin, ceraceous to hypochnoid, pale grey to white. Hymenium: thin, fairly open textured, composed of a single layer of basidia on laterally branching hyphae arising from an open network of subicular hyphae. Hyphae: uni- or binucleate, (1.5-)3-9 µm wide, lacking clamp connexions; hyaline and thin-walled in the subhymenium, composed of short, sometimes swollen, hyphal compartments; hyaline to slightly yellowish with thin or thickened walls in the subiculum, composed of long, straight, hyphal compartments. Septal pores: dolipores with discontinuous parenthesomes (Langer, 1994; Wells, 1994; Andersen, 1996). Basidia: globose to broadly clavate or ellipsoid (Q = 1.0-1.4), (6.5-)9-16(-22) x 6.5-18 µm, normally with short, often wide, often lateral stalk; basidia frequently have a short hyphal outgrowth and then appear cuboid to papillate. Sterigmata: (1-)2-4(-6), up to 20 µm long, occasionally producing secondary sterigmata and then appearing furcate. Basidiospores: variable, globose to ellipsoid, oblong, or vermiform, producing secondary spores by replication.
Anamorph. Ceratorhiza anamorphs produce monilioid hyphae comprising chains of variously swollen, ellipsoid to globose compartments. Sclerotia are produced in some, but not all, species.
Distribution & ecology. Cosmopolitan. Variously saprotrophic, plant pathogenic, or orchid endomycorrhizal.
Type species. Ceratobasidium calosporum (Anamorph) Ceratorhiza goodyerae-repentis
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