Castanoporus Ryvarden

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 : 10

Castanoporus Ryvarden

Castanoporus Synopsis Fungorum 5: 121 (1991).

Type species.

Castanoporus castaneus (Lloyd) Ryvarden

Remarks.

This monotypic genus contains one conifer-dwelling resupinate polypore species from East Asia. With its simple-septate hyphae, monomitic and dense structure (in basal layer) with thick-walled hyphae, middle-sized spores and subulate, encrusted cystidia the species brings into mind Phlebiopsis under the microscope. For a more detailed description see Nuñez and Ryvarden (2000).

Phylogenetically the species comes close to Phlebiopsis flavidoalba and Phlebiopsis pilatii . Together those three species form a sister clade to core Phlebiopsis , typified by Phlebiopsis gigantea (Figures 2 and 3). For now the most practical solution is to include Castanoporus in Phlebiopsis (see discussion under Phlebiopsis ). Hjortstam (1987) listed Castanoporus castaneus under Phlebiopsis in his check-list of corticioid fungi, but made no formal combination. If Phlebiopsis would be defined more strictly, then Castanoporus could be put in use.

The genus Cystidiophorus has been described for Castanoporus castaneus , but for nomenclatural reasons described below we think Castanoporus should prevail against Cystidiophorus . Bondartsev and Ljubarsky (1963) described the monotypic genus Cystidiophorus with the species Cystidiophorus merulioideus as the type. Unfortunately, they did not indicate a type specimen for the species, which makes the species name invalid, and also rendered the genus invalid (Melbourne Code Art. 40; the cut-off year for type indication is 1958). Later, Imazeki ( Imazeki and Hongo 1965) made the combination Cystidiophorus castaneus based on Merulius castaneus Lloyd, mentioning Cystidiophorus castaneus and Cystidiophorus merulioideus as synonyms. This combination does not qualify as a validation of Bondartsev and Ljubarsky’s genus name, because Imazeki did not provide reference to the genus description, which is clearly separate from the species description in the original paper (Art. 38.1). In such a case, the genus could be considered valid with the condition that no previously described species is mentioned (Art. 38.5a), but this is not the case as Imazeki mentions Lloyd’s species. Thus, we follow Ryvarden (1991) and regard Castanoporus as the correct name for this genus.

Ginns (1969) lectotypified Cystidiophorus castaneus and gave a description of the type, which agrees well with our concept of the species as well as that of Imazeki’s and Bondartsev’s. Also Maas Geesteranus (1974) studied the lectotype from BPI.

Zmitrovich et al. (2006) combined Cystidiophorus castaneus in Australohydnum . We do not have material of Australohydnum from Australia (the type locality of the type species) or any sequences, but judging from the type of cystidia and hyphal structure we think it is unlikely (but possible) that Australohydnum belongs to Phlebiopsis as delineated here (see Oxychaete for further notes on Australohydnum ). If Phlebiopsis were to be split, Castanoporus and Australohydnum would probably both persist being morphologically quite distinct.