Piptoporus pseudobetulinus is a white rot and was taxonomically remote from the type of P. betulinus, because the last one is a brown rot.  Polyporus pseudobetulinus has been proposed for the first time by Thorn et al. (1990). Later, De (1998) rename the specie Royoporus pseudobetulinus comb. nov., in the light of detailed studies on the morphological and anatomical characters. A recent phylogenic study (Yu-Cheng Dai et al. 2014) support the new combinaison of Polyporus pseudobetulinus as Favolus pseudobetulinus (Murashk. ex Pilat) Sotome & T. Hatt. (Sotome et al. 2011, 2013)

Very rare specie found in Canadian provinces of Quebec and Ontario and never found in United States.

This specie have been reported in many countries in the word ; R. pseudobetulinus occurs in Austria, Canada (provinces of Quebec and Ontario), Finland, Sweden (Niemela and Kotiranda 1991 ; Ryvarden 1978 ; Thorn et al. 1990), Japan and Russia (Numez and Ryvarden 1995).

R. pseudobetulinus is a rare polypore anywhere (Niemela 1978) and so the current trend is uncertain. None the less, recent unrecorded collections have expanded the known range and provided little more information with particular reference to the province of Quebec (Canada) (Thorn et al. 1990 ; Boulet 2003 ; Patrick Poitras, pers. comm.)(see the regional status comment). R. pseudobetulinus has never been recorded from U.S. herbaria by Murrill (1914), Lowe (1934), Overholts (1953) or Gilbertson and Ryvarden (1987).

Rare specimens of this species are kept at the National Herbarium in Ottawa Mycology (Canada) and some mycologists’s private herbaria.

 

R. pseudobetulinus is a rare polypore anywhere and so, little information is known about its ecological requirements, biology or cultural characters. Decay of sapwood is a mottled white rot. The fruiting period begins in mid-May and extends to late June (Boulet 2003).

The few canadian collections of this specie were only recorded on dead balsam poplar (P. balsamifera L.) (Boulet 2003), and were not found on adjacent dead stems of trembling aspen (P. tremuloides Michx) nor large-toothed aspen (P. grandidentata Michx). Nevertheless, these later tree species are very common with a large distribution in North America (Ministère des Ressources naturelles 2013).

R. pseudobetulinus growth in wet and open stands of pure balsam poplar or in mixed woods with white elms, white birchs, basswood and northern white-cedars. This polypore growth usually on dead standing trees with bark (see photo 3), and occasionally on fallen trunks. The sporocarp growth sometimes in wounds , dead branch-stubs or exposed wood of living trees. Another feature of this fungus is that it often occurs quite low in the stem.

The habitat is different in Finland. Is seems this specie growth on tall, standing dead Populus tremula in dry open woods (Thorn et al. 1990).

Most collections are from the middle and southern zone (Canada) and hemiboreal zone (Russia), with a few from the northern boreal sub zone (Finland, Sweeden) and the temperate zone (Austria).

In Canada, the few collections provided from private lands surrounding cities of Ottawa (Ontario) and Gatineau (Quebec) (Boulet 2003) and more recently on ornamental balsam poplar in Abitibi region (Patrick Poitras, pers. comm).

The only site where this specie is known to occur in Finland is in the Pisavaara Strict Nature Reserve located near from the Arctic circle (Thorn et al. 1990).

Residential development in wood sites surrounding the cities is a real threat to maintain this polypore in his natural habitat.

1 - Stand protection of sites where the specie has been recorded more recently.
2 - Survey the oldest historical natural sites to know the growing conditions of sporocarps and the status of the different populations of R. pseudobetulinus in Quebec and Ontario

More information would be useful to known the actual population size, status and range of this polypore in Canada. Monitoring is important also to evaluate the impact of urban development and others natural perturbations, and to know the effects of successional stages of stands on population dynamic of this polypore. We need more myco-explorers in May and June to search other suitable spots mainly in the Ottawa River and Abitibi Regions (with Google Earth) and to find other populations of R. pseudobetulinus.

Boulet, B. 2001. “Les champignons des arbres : un aperçu de leur importance u sein des écosystèmes forestiers”, [On line], Le Naturaliste canadien, Vol. 125, no 3, p. 187-191. [http://www.provencher.qc.ca/upload/file/125_3 p 187-191.pdf]

Boulet, B. 2003. Les champignons des arbres de l’est de l’Amérique du Nord, sainte-Foy, Québec, Les Publications du Québec, 727 p.

De, A. B. 1998. “Taxonomy of Royoporus pseudobetulinus comb. nov.”, Mycotaxon, Vol. LXIX, p 137-143.

Gilbertson, R. L. and L. Ryvarden. 1987. North American Polypores - vol. 2 : Megasporoporia-Wrightoporia. Oslo, Norway, Fungiflora, p. 434-885.

Lowe, J. L. 1934. The Polyporaceae of New York State (Pileate Species), Bull. NY St. Coll. For., Syracuse Univ., Tech. Publ. no 41, 142 p.

Ministère des Ressources naturelles. 2013. Le guide sylvicole du Québec, Tome 1, Les fondements biologiques de la sylviculture, ouvrage collectif sous la supervision de B. Boulet et M. Huot, Les publications du Québec, 1044 p.

Murrill, W. A. 1914. Northern Polypores. New York, W. A. Murrill Ed., 64 p.

Niemela, T. 1978. “The occurrence of some rare pore fungi in Finland”, Ann. Bot. Fennici, Vol. 15, p. 1-16.

Nunez, M. et L. Ryvarden. 1995. Polyporus (Basidiomycotina) and related genera, Synopsis Fungorum, Vol. 10, p. 1-85.

Overholts, L. P. 1953. The polyporaceae of the United States, Alaska and Canada. Stud. Scient. serv., vol. XIX, Univ. Michigan Press, Ann Arbor,
466 p.

Ryvarden, L. 1978. The Polyporaceae of North Europe. Vol. 2, Inonotus to Tyromyces, Fungiflora, Oslo, Norway, p. 217-507.

Sotome, K., T. Hattari, and Y. Ota. 2011. “Taxonomic study on a threatened polypore, polyporus pseudobetulinus, and a morphologically similar specie, P. subvarius”. Mycoscience, Vol. 52, p. 319-326.

Sotome, K., Y. Akari, S.S. Lee, N. K. Ishikawa, and T. Hattari. 2013. Taxonomic study of Favolus and Neofavolus gen nov. segregated from Polyporus (Basidiomycota, Polyporales), Fungal Diversity, Vol. 58, p. 245-266.

Thorn, G., H. Kotiranta, and T. Niemela. 1990. “Polyporus pseudobetulinus comb. nov.: new records in Europe and North America”, Mycologia, Vol. 82, no 5, p. 582- 594.

Dai, Yu-Cheng, Hui-Jun Xue, Josef Vlasák, Mario Rajchenberg, Bing Wang, Li-Wei Zhou. 2014. “Phylogeny and global diversity of Polyporus group Melanopus (Polyporales, Basidiomycota)”, Fungal Diversity, Vol. 64, p. 133-144. DOI 10.1007/s13225-013-0248-3.