Systematics of the genus Chaetosphaeria and its allied genera: morphological and phylogenetic diversity in north temperate and neotropical taxa.

Chaetosphaeria is a common saprobic pyrenomycete genus with simple, homogeneous teleomorphs and complex, diverse anamorphs. As currently circumscribed in the literature, the genus encompasses 30 species distributed in four 'natural groups', and includes morphological entities in 11 anamorphic genera. Species frequently have been defined primarily based on characters of the anamorphs resulting in species with almost indistinguishable teleomorphs. This study aimed to assess the value and significance of morphological characters in resolving phylogenetic relationships in Chaetosphaeria and its allied genera. Phylogenetic relationships of 42 taxa, representing 29 species distributed in Chaetosphaeria and five related genera, were estimated with partial sequences of the nuclear LSU rDNA and beta-tubulin genes. Sequences were analyzed with maximum parsimony, maximum likelihood and Bayesian methods. Phylogenetic analyses of these two genes combined revealed two major lineages. The Chaetosphaeria lineage includes 21 species possessing both typical and new sexual and asexual morphologies. The lineage contains a strongly supported monophyletic clade of 13 species and eight paraphyletic taxa; the latter includes C. innumera, the type species of the genus. The second major lineage includes groupings concordant with the morphological circumscriptions of the genera Melanochaeta, Melanopsammella, Striatosphaeria, Zignoëlla and the new genus Tainosphaeria.

Duke Scholars

Author Francois M. Lutzoni Biology