The nuclear small subunit ribosomal genes of Sphaeronaemella helvellae, Sphaeronaemella fimicola, Gabarnaudia betae, and Cornuvesica falcata: phylogenetic implications

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Abstract
Sequences were obtained from the nuclear small subunit ribosomal RNA genes for representatives of four ophiostomatoid genera (Ceratocystis, Gondwanamyces, Cornuvesica, and Sphaeronaemella) to resolve their phylogenetic position within the Ascomycota. Phylogenetic analysis suggests that these genera are monophyletic and share common ancestry with members of the Microascales. Based on sequence data, strains representing the mitotic species Gabarnaudia betae (Delacr.) Samson & W. Gams were shown clearly to be derived from Sphaeronaemella species. Sequences were also obtained from strains representing the syntype of Sphaeronaemella fragariae, the exholotype of Sphaeronaemella humicola, and the extype of Gabarnaudia tholispora. The results suggest that putative extype cultures for S. humicola and G. tholispora no longer represent the original material deposited. Our data also support the exclusion of S. fragariae from Sphaeronaemella. Key words: Cornuvesica, Gabarnaudia, Gondwanamyces, Sphaeronaemalla fragariae, ophiostomatoid fungi, ribosomal DNA.