17 Sep Laetisaria
Laetisaria Burds., Trans. Br. Mycol. soc. 72(3): 420(1979)
The genus Laetisaria was established by Burdsall (1979) for L. fuciformis (asexual Isaria fuciformis) with effuse, whitish pink fruiting bodies, causing red thread disease in turfgrasses. Each of the other three species assigned to Laetisaria represents a different trophic habit: L. agaves is saprotrophic, L. arvalis is a mycoparasite and L. lichenicola is lichenicolous. Laetisaria arvalis is soil-inhabiting and has been proposed as a biocontrol agent against some fungal pathogens such as Pythium and Rhizoctonia.
Classification – Agaricomycetes, incertae sedis, Corticiales, Corticiaceae
Type species – Laetisaria fuciformis (Berk.) Burds., Trans. Br. Mycol. Soc. 72(3): 420 (1979)
Distribution – Europe, N. America, Australasia.
Disease Symptoms – Red thread
Small water-soaked spots covering a large portion of the grass leaf can be observed. Infected grass blades soon die and fade to a bleach-tan colour (Smiley et al. 2005).
Hosts – Turf grasses
Morphological based identification and diversity
Laetisaria currently contains four species (Index Fungorum 2018). However as stated by the authors, due to the taxonomic confusion, the species have been placed only tentatively in Laetisaria. Laetisaria agaves and L. lichenicola are sexual morph only, while L. arvalis and L. fuciformis produce asexual morphs as well.
Molecular based identification and diversity
The species of Laetisaria do not form a monophyletic clade in phylogenetic studies. The generic type L. fuciformis groups with several Marchandiomyces species and Limonomyces, while L. arvalis shows affinity to Waitea circinata. Laetisaria lichenicola was recently described for a lichen parasite forming resupinate, pink fruiting bodies on lichen talli (Diederich et al. 2011). The ongoing taxonomic reconsideration of genera in Corticiaceae would help resolve the phylogeny of Laetisaria and allies (Ghobad-Nejhad et al., unpublished).
Recommended genetic markers (Genus level) – nLSU
Recommended genetic markers (Species level) – ITS
Accepted number of species: Four species
References: Burdsall 1979 (morphology), Diederich et al. 2011 (morphology, phylogeny).