Oxychaete Miettinen

Miettinen, Otto, Spirin, Viacheslav, Vlasak, Josef, Rivoire, Bernard, Stenroos, Soili & Hibbett, David S., 2016, Polypores and genus concepts in Phanerochaetaceae (Polyporales, Basidiomycota), MycoKeys 17, pp. 1-46 : 14-15

Oxychaete Miettinen gen. nov.

Type species.

Oxychaete cervinogilva (Jungh.) Miettinen

Etymology.

Constructed from Oxyporus and Phanerochaete , but can be interpreted as "bearing sharp setae".

Description.

Effused-reflexed polypores with yellow-brown colors, light cardboard-like consistency and large, shallow pores. Monomitic, simple-septate, with slightly thick-walled hyphae and abundant subulate, naked, thick-walled cystidia of subhymenial origin. Hymenial branching corymb-like. Spores curved cylindrical, large (6 –8×3– 3.5 µm).

Remarks.

Other hydnoid and poroid genera with simple-septate hyphae and encrusted, thick-walled cystidia include Australohydnum , Phlebiopsis , Flavodon and Irpex . The latter two are phylogenetically distantly related to Oxychaete , and they possess dimitic hyphal structure quite different from the loose monomitic structure of Oxychaete . Phlebiopsis is phylogenetically distinct from Oxychaete (Figure 2), and its hyphal structure is more compact, even agglutinated (basal layer). Hyphae are also winding and covered with abundant brownish encrustation, which is lacking in Oxychaete . Cystidia are tramal in origin (as opposed to hymenial in Oxychaete ). Due to the hyphal structure the basidiocarp is tougher and not board-like when cut as in Oxychaete .

Australohydnum is a more difficult case to decide on since there are no good references on the microscopic characters of the type species, Hydnum griseofuscescens Reichardt from Australia. Descriptions vary so much that it is possible that many species and even genera have been recognized as Australohydnum dregeanum (Berk.) Hjortstam & Ryvarden and its supposed synonyms ( Jülich 1978, Hjortstam and Ryvarden 1989, Gilbertson and Adaskaveg 1993, Melo and Hjortstam 2002, Zmitrovich et al. 2006). Sometimes the structure is monomitic, sometimes dimitic; cystidia may be subulate or obtuse; basidiocarps may be resupinate with smooth hymenophore or hydnoid with caps.

Reid (1955, 1963) refers directly to Australian material and the type, and provides an illustration (under Irpex vellereus ). His Australohydnum griseofuscescens is a pileate, hydnoid species with violaceous brownish basidiocarps, very thick-walled, simple-septate hyphae 4-9 µm in diameter, and abundant long, obtuse, poorly differentiated cystidia with tramal origin and fine apical encrustation. Reid states that the hyphal structure is monomitic, but has also drawn long aseptate hyphae. Spores are ellipsoid, medium-sized. The description and illustrations provided by Melo and Hjortstam (2002) from Portugal are very similar to those of Reid, and agree largely with an Indian specimen we have studied.

Morphology suggests that Australohydnum griseofuscescens is not congeneric with Oxychaete cervinogilva , the latter being a polypore with regular pores, much looser hyphal structure without wide-spread encrustation, more regular and less-thick-walled hyphae, different type of cystidia with hymenial origin, differently shaped spores and lighter color of the basidiocarp.