Molecular systematics of the Sordariales: the order and the family Lasiosphaeriaceae redefined

Abstract

The Sordariales is a taxonomically diverse group that has contained from seven to 14 families in recent years. The largest family is the Lasiosphaer-iaceae, which has contained between 33 and 53 genera, depending on the chosen classification. To determine the affinities and taxonomic placement of the Lasiosphaeriaceae and other families in the Sordariales, taxa representing every family in the Sordariales and most of the genera in the Lasiosphaeriaceae were targeted for phylogenetic analysis using partial sequences of the large-subunit (LSU) nrDNA. Based on molecular data, only genera within the families Chaetomiaceae, Lasiosphaeriaceae and Sordariaceae are retained within the redefined Sordariales. The order is a coherent group with morphologies that vary along well-defined lines, including large ascomata with large-celled membraneous or coriaceous walls and ascospores that show variation on a distinctive developmental theme, often with appendages or sheaths. The paraphyletic chaetomiaceous complex and the strongly supported Sordariaceae are nested among taxa traditionally placed in the Lasiosphaeriaceae. Analyses also indicate that 11 genera belong in the paraphyletic lasiosphaeriaceous complex. These taxa share a similar developmental pattern in their ascospore morphology that extends to the Sordariales as a whole. Based on these similarities in morphology, 13 additional genera are retained within the lasiosphaeriaceous complex and more than 35 genera have relationships in the order overall. Based on LSU data, 17 genera that have been assigned to the Lasiosphaeriaceae sensu lato are transferred to other families outside the Sordariales and 22 additional genera with differing morphologies subsequently are transferred out of the order. Two new orders, Coniochaetales and Chaetosphaeriales, are recognized for the families Coniochaetaceae and Chaetosphaeriaceae respectively. The Boliniaceae is accepted in the Boliniales, and the Nitschkiaceae is accepted in the Coronophorales. Annulatascaceae and Cephalothecaceae are placed in Sordariomycetidae inc. sed., and Batistiaceae is placed in the Euascomycetes inc. sed.