Resolving the Phoma enigma

Abstract

The Didymellaceae was established in 2009 to accommodate Ascochyta, Didymella and Phoma, as well as several related phoma-like genera. The family contains numerous plant pathogenic, saprobic and endophytic species associated with a wide range of hosts. Ascochyta and Phoma are morphologically difficult to distinguish, and species from both genera have in the past been linked to Didymella sexual morphs. The aim of the present study was to clarify the generic delimitation in Didymellaceae by combing multi-locus phylogenetic analyses based on ITS, LSU, rpb2 and tub2, and morphological observations. The resulting phylogenetic tree revealed 17 well-supported monophyletic clades in Didymellaceae, leading to the introduction of nine genera, three species, two nomina nova and 84 combinations. Furthermore, 11 epitypes and seven neotypes were designated to help stabilise the taxonomy and use of names. As a result of these data, Ascochyta, Didymella and Phoma were delineated as three distinct genera, and the generic circumscriptions of Ascochyta, Didymella, Epicoccum and Phoma emended. Furthermore, the genus Microsphaeropsis, which is morphologically distinct from the members of Didymellaceae, grouped basal to the Didymellaceae, for which a new family Microsphaeropsidaceae was introduced.

Coelomycetous Fungi in the Clinical Setting: Morphological Convergence and Cryptic Diversity

“…Currently, Phoma sensu stricto is included in the family Didymellaceae, and the other Phoma-like fungi belong to other phylogenetic families, i.e., Cucurbitariaceae, Leptosphaeriaceae, Phaeosphaeriaceae, etc. (39,40,42,43). It is of note that one of the frequently isolated species in our study, Didymella heteroderae (5.2% of isolation frequency), has never been mentioned as an etiologic agent of human infections even though our results reveal its ability to grow and to sporulate at 37°C, which is uncommon in that genus and suggests its potential pathogenicity.…”

“…Both cases are from immunocompromised patients; in one case P. cyclothyrioides caused skin lesions of the lower extremities, and in the second case it produced a systemic coinfection together with Phaeoacremonium parasiticum (37,38). Even though Phoma sporulates easily, it is commonly misidentified as other related genera, such as Ascochyta, because the genera have similar morphologies, physiologies, and nucleotide sequences (39,40). Boerema et al carried out one of the most comprehensive revisions of the taxonomy of the genus Phoma.…”

Towards incorporating asexual fungi in a natural classification: checklist and notes 2012–2016

“…However, Hashimoto et al (2017) introduced Hermatomycetaceae to place this genus. Chen et al (2015) introduced this coelomycetous genus and phylogenetic analyses showed that it belongs in Didymellaceae.…”

“…Chen & L. Cai Chen et al (2015) introduced this genus with a coelomycetous asexual morph and DNA sequence analyses showed that it belongs in Didymellaceae.…”

“…Chen & L. Cai Chen et al (2015) introduced this coelomycetous genus and showed that it belongs to Didymellaceae in their phylogenetic analyses.…”