Two new dothideomycetous endoconidial genera from declining larch

Abstract

Two endoconidial, black meristematic fungi, Celosporium larixicolum gen. et sp. nov. (Dothideales) and Hispidoconidioma alpina gen. et sp. nov. (Capnodiales) are described from black subicula on twigs of declining larch ( Larix lyallii Parl) trees in Alberta, Canada. Conidioma morphology and phylogenetic analysis of LSU and ITS regions indicate that these taxa are both distinct from each other and from previously described endoconidial genera. Conidiomata of C. larixicolum consist of black cellular clumps (aggregated conidiogenous cells) that are either naked or enveloped by scant to dense mycelium that sometimes organizes into a cupulate peridium. Endoconidia are 1–3 celled, hyaline when released but become pigmented as they age, and very variable in size and shape, e.g., globose, pear-shaped, osteoid, or discoid with an irregular flange. In H. alpina, colonies are three-layered, consisting of a central pseudoparenchymatous layer sandwiched between an upper and a basal hyphal layers, and conidiogenesis occurs in sporadic areas of the central layer. Endoconidia are unicellular, hyaline, and subglobose to ellipsoid. The strong phylogenetic affinities between these newly described taxa and slow-growing, melanized fungi isolated from rocks suggest individual black meristematic fungus lineages may have broad habitat ranges.