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

Abstract

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 β-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.

• anamorph
• β-tubulin
• phylogeny
• rDNA
• taxonomy
• teleomorph

This project was supported by a National Science Foundation PEET (Partnerships for Enhancing Expertise in Taxonomy) Grant (DEB-9521926) to the Field Museum of Natural History. Support for Huhndorf’s 1995–1996 fieldwork in Puerto Rico was provided by the National Research Council Resident Research Associate Post-Doctoral Program in cooperation with the USDA Forest Service, Madison, Wisconsin. We thank Dr D. Jean Lodge for generously allowing us the use of her laboratory and for all logistical arrangements in Puerto Rico, Drs. Jill Thompson and Jess Zimmerman for access to the forest grid at the El Verde Research Area and F. Candoussau for the loan of M. vermicularioides.