Abstract
Immotthia is a poorly known genus, and currently, no DNA sequence data are available to ascertain its proper phylogenetic placement and evolutionary relationships with other bitunicate fungi. To date, there are only two species accepted in the genus. During our ongoing research study of bambusicolous fungi in southwest China and Thailand, a fungus associated with stromata of Hypoxylon sp. was found on dead bamboo culms in Loei Province, Thailand. Preliminary morphological identification revealed that the fungal collection belongs to Immotthia. A novel species, Immotthia bambusae, is introduced herein based on a comparison of morphological characteristics with the type specimen of I. hypoxylon (≡ Amphisphaeria hypoxylon Ellis and Everh.), a synonym of I. atrograna (Cooke and Ellis) M. E. Barr. Phylogenetic analyses of a concatenated ITS, LSU, SSU, and TEF1-α DNA sequence matrix showed that Immotthia belongs to Dictyosporiaceae, Pleosporales. Despite I. bambusae strains constituting a supported subclade, they are nested with the genus Pseudocoleophoma. Pseudocoleophoma clematidis is morphologically different from all other Pseudocoleophoma species, while its conidial characteristics are similar to Cyclothyriella. Multigene phylogenetic analyses showed that P. clematidis formed a clade basal to Immotthia, separated from Pseudocoleophoma with strong statistical support. Therefore, we introduce a monotypic genus, Pseudocyclothyriella Phukhams. and Phookamsak, gen. nov. to accommodate the single species, Pseudocyclothyriella clematidis (Phukhams. and K. D. Hyde) Phukhams. and Phookamsak, comb. nov. Detailed descriptions, color micrographs, and phylogenetic trees to show the placement of the new taxa are provided. In addition, an updated taxonomic treatment of the genera Immotthia and Pseudocyclothyriella is also provided based on the study of the type materials and phylogeny generated from DNA sequence data.
Highlights
Immotthia was introduced by Barr (1987a) with I. hypoxylon (Ellis and Everh.) M
An updated taxonomic treatment of bambusicolous fungi has been conducted since the last decade by Japanese mycologists (Tanaka et al, 2009, 2015) and followed by many Asian mycologists
More than 1,300 bambusicolous fungi have been reported consisting of 150 basidiomycetes and 1,150 ascomycetes
Summary
Immotthia was introduced by Barr (1987a) with I. hypoxylon (Ellis and Everh.) M. E. Barr (≡ Amphisphaeria hypoxylon Ellis and Everh.) as the type species. Through examinations of the type material of I. hypoxylon and Australian collections of I. atrograna (Cooke and Ellis) M. E. Barr (≡ Sphaeria atrograna Cooke and Ellis), Jaklitsch et al (2002) concluded that these two taxa are conspecific. Two species are accepted in this genus, viz. I_atrograna and I. atroseptata (Piroz.) M. E. Barr (Species Fungorum, 2020) based on morphology, but no DNA sequence data are available to confirm their phylogenetic placement (Hyde et al, 2017; Doilom et al, 2018)
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