A new endophytic species of Microthecium (Melanosporales, Sordariomycetes, Pezizomycotina, Ascomycota) from Mallorca (Balearic Islands, Spain)

Background

The genus Microthecium contains 31 species worldwide distributed. Most of them are saprobic on soil and plant debris, but a few have been reported as mycoparasites on hypocrealean fungi. By contrast, this genus has never been reported as phytopathogenic, nor endophytic.

Aims

To isolate and identify endophytic fungi from Mediterranean herbaceous plants and trees in order to contribute to the knowledge of the hosts and their geographical location. The present work has been focused on the study of endophytic fungi of hawthorn (Crataegus monogyna).

Methods

The following steps were taken: i, isolation of the fungal strain from living stems of C. monogyna; ii, cultural and micro-morphological study, and iii, sequence comparison of different genetic markers by BLAST search with sequences deposited in GenBank.

Results

At the present work we describe a new species of the genus, Microthecium pleomorphosporum, isolated from living stems of C. monogyna in Mallorca (Balearic Islands, Spain). This fungus is characterized by the production of non-ostiolate perithecia and two sorts of ascospores (some smooth-walled, others delicately reticulated) bearing a germ pore at each end which are frequently ornamented by a surrounding donut-like structures, and a phialidic asexual morph and bulbils. The morphologically closest related species is Microthecium tenuissimum, which has bigger ascospores and lacks asexual reproduction. Phylogenetically, M pleomorphosporum is close-related to other species of the genus, although no genetic marker that discriminates this new species from other phylogenetically closer ones could be elucidated as a gold standard.

Conclusions

M. pleomorphosporum, order Melanosporales, is reported here as the first endophytic species of C. monogyna.