Lawrynomyces , a new genus of corticioid fungi in the Hymenochaetales

The new genus Lawrynomyces is proposed to accommodate Hyphoderma capitatum, a predominantly European species growing on decayed coniferous wood. The genus belongs to the Rickenella-clade in the order Hymenochaetales, and it includes species characterized by resupinate basidiomes, monomitic hyphal system with simple septate hyphae, presence of cystidia and hyphidia, suburniform to subcylindrical, pedunculate basidia, and subglobose to broadly ellipsoid basidiospores with slightly thickened walls not staining in Melzer’s reagent or Cotton Blue. Published molecular data support the recognition of a distinct genus for Hyphoderma capitatum.

In all published phylogenies, Hyphoderma capitatum was recognized as a member of the Rickenella-clade in the Hymenochaetales and clustered in a clade separate from species of Peniophorella.Morphologically, H. capitatum differs from Peniophorella species in having hyphae without clamps, suburniform-pedunculate basidia, basidiospores with slightly thickened walls, and lacking echinocysts and stephanocysts.Morphologic and molecular phylogenetic data suggest that Hyphoderma capitatum should be accommodated in a new genus that is described and illustrated here.

MATERIALS AND METHODS
Examined specimens were collected from the Kaszubski Landscape Park, northern Poland, in 2007-2008.Laboratory methods and abbreviations follow Karasiński (2010).Specimens are deposited in author's reference fungarium (Herb.D.K.) and duplicates are in KRAM.
Lawrynomyces capitatus is associated with much decayed wood of conifers.In one case, a basidiome was collected from the bark of Picea abies stump in an early stage of decomposition.

DISCUSSION
The main morphological features of the genus Lawrynomyces are a monomitic hyphal system with clampless hyphae, suburniform and more or less pedunculate basidia with prominent sterigmata, and smooth, hyaline, inamyloid, acyanophilous, broadly ellipsoid basidiospores with slightly thickened walls.The basidia of Lawrynomyces are similar to those observed in species of Hyphoderma s.str.but are typically pedunculate, i.e. with a stalk.The phylogenetic position of Hyphoderma capitatum supports recognition of separate genus for this species.
The other species that may be a member of the genus Lawrynomyces is Hyphoderma orphanellum (Bourdot & Galzin) Donk.Although H. orphanellum has basidia and cystidia of similar shape to Lawrynomyces, it has clamped hyphae, thin-walled spores, encrusted hyphidia, and a dense, agglutinated subiculum (Eriksson, Ryvarden 1975;Bernicchia, Gorjón 2010).In some molecular phylogenetic studies H. orphanellum is shown to be in the same, well supported monophyletic clade with Lawrynomyces capitatus (Larsson 2007a;Miettinen, Larsson 2011;Nakasone, Burdsall 2012).However, these studies used the same ITS and/ or LSU sequence of H. orphanellum derived from NH 12208 from Russia.Another sequence of H. orphanellum was included in the phylogenetic tree presented by Tellería et al. (2012).In this study, H. orphanellum was placed in the Peniophorella clade.Because of these conflicting results, I accept a narrow concept of the genus which so far is monotypic.