Abstract
The genus Durotheca is introduced with D. depressa sp. nov., as type. Hypoxylon comedens is transferred to Durotheca, based on its morphology with further evidence from molecular phylogenetic studies; a combined β-tubulin and α-actin gene dataset. Theissenia cinerea is synonymized with D. comedens, and the type of Theissenia, T. pyrenocrata, is shown to occupy a basal, rather distant position in a monotypic clade in relation to sequenced taxa of Durotheca. This clade has an unresolved position in relation to the two informal subfamilies "Xylarioideae" and "Hypoxyloideae" within the Xylariaceae. New distributional data for D. comedens and T. pyrenocrata are presented, with the former found to be widespread in South-East Asia and the latter is reported as new from western Amazonia (Ecuador). One further species described in Theissenia, T. rogersii, is transferred to Durotheca, whilst T. eurima is accepted in Theissenia.
Highlights
The genus Theissenia was introduced by Maublanc (1914) for Ustulina pyrenocrata
Læssøe (1994) accepted this genus within Xylariaceae, and Ju et al (2003) recognized three species in their monographic treatment. Another species was added and a phylogenetic analysis based on DNA sequences from two of the accepted taxa, but not the type species T. pyrenocrata, was provided (Ju et al 2007)
Ju et al (2003) had previously accepted, ad interim, a placement within the Xylariaceae based on a Nodulisporium-morph found in cultures of T. cinerea, but noted that the aleurisporous asexual morph found in T. eurima was not as expected for such a position
Summary
Læssøe (1994) accepted this genus within Xylariaceae, and Ju et al (2003) recognized three species in their monographic treatment. Another species was added and a phylogenetic analysis based on DNA sequences from two of the accepted taxa, but not the type species T. pyrenocrata, was provided (Ju et al 2007). Ju et al (2003) had previously accepted, ad interim, a placement within the Xylariaceae based on a Nodulisporium-morph found in cultures of T. cinerea, but noted that the aleurisporous asexual morph found in T. eurima was not as expected for such a position. Ju et al (2003) noted the extreme variability displayed among the four recognized species, such as the absence/presence of germ slits, surface ornamentation, and variability in ascospore wall thickness and asexual morphs. Ju et al (2003) shed some light on the situation, and we recognized that our fungus was a member of Theissenia in the sense of these authors
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