Septomelanconiella Samarak. & K.D. Hyde, Fungal Divers. Notes 95: 1–273 (2019)

Index Fungorum number: IF555301; 1 species with sequence data.

Type species – Septomelanconiella thailandica Samarak. & K.D. Hyde

Etymology: The generic epithet ‘‘Septomelanconiella’’ reflects the septation of the conidia and parallel morphology to Melanconiella.

Saprobic on Syzygium samarangense in terrestrial habitats. Sexual morph: Undetermined. Asexual morph: Coelomycetous. Conidiomata pycnidial, immersed in the host, partially erumpent at maturity, mostly solitary or confluent, subglobose to irregular, to flattened and collabent, light brown. Conidiomata walls comprising 2–3 layers of hyaline cells, of textura angularis at the base, with a light brown, thin outer layer. Conidiophores mostly reduced to conidiogenous cells, few with conidiophore and cylindrical conidiogenous cells. Conidiogenous cells enteroblastic, phialidic, integrated to discrete, cylindrical, determinate, hyaline, and finely roughened. Conidia cylindrical to clavate, one guttulate, becoming two guttules, hyaline, 1-septate when immature; mature conidia cylindrical to clavate, straight or slightly curved, brown, 1-euseptate, more often with 6 unequal lumina, guttulate, dark brown at the base.

Notes: Septomelanconiella thailandica constitutes an independent lineage basal to Melanconiella syzygii Crous & M.J. Wingf. Despite average phylogenetic support, Septomelanconiella is distinguished from other species as it is characterised by 1-euseptate and luminate conidia. Septomelanconiella is similar to Melanconiella in having finely verrucose, brown, mature conidia. Septomelanconiella thailandica can be phylogenetically distinguished from the other genera in Melanconiellaceae as circumscribed by Senanayake et al. (2017). Melanconiella syzygii was isolated from a prominent leaf spot of Syzygium and is characterized by 2–3 layers of peridium, 1–2-septate conidiophores and hyaline to light brown aseptate conidia (Crous et al. 2016a). Multigene phylogenetic analyses also reveal that Septomelanconiella thailandica is separated from Melanconiella syzygii. Wijayawardene et al. (2016) described Gloeocoryneum and Stegonosperiopsis and referred them to Ascomycota, genera incertae sedis. They have similar brown, septate conidia as in Septomelanconiella thailandica. However, Gloeocoryneum differs in having 2–5 conidial septa, while Stegonosperiopsis is characterized by cylindrical conidiophores. Based on morphology and phylogeny in this study, Septomelanconiella thailandica is introduced as a new genus and species.

Fig 1. – Phylogram generated from maximum likelihood (RAxML) based on ITS, LSU and RPB2 partial sequence data analyses of 23 taxa and Pseudoplagiostoma oldii (CBS 124808) as an outgroup taxon. Bootstrap values for maximum parsimony (green) and maximum likelihood (blue) C 50% and Bayesian posterior probabilities (black) C 0.90 are given at the nodes. The newly generated sequence is in blue. The ex-type strains are in bold. The scale bar represents the expected number of nucleotide substitutions per site.