A molecular phylogenetic reappraisal of theGraphiumcomplex based on 18S rDNA sequences

摘要

Based on nuclear encoded small subunit (18S) rDNA sequences, a taxonomic reappraisal ofGraphium(anamorphic fungi) was undertaken using neighbour-joining (NJ) and fast DNA maximum likelihood (fastDNAml) methods and compared with traditional classifications. In common withGraphium putredinis,Graphium penicillioides(the lectotype species) was found to be related to the Microascales, not the Ophiostomatales as previously believed. Both species might be heterogenous and should be treated as species aggregates. The representative mode of conidiogenesis for these two species was nodular-annellidic, rather than the dense-annellidic mode characteristic of the synnematous ophiostomatalean anamorphs.Graphiumis emended to be restricted toG. penicillioides,G. putredinis, and related synnematous anamorphs ofPetriellaandPseudallescheria, and a nomenclator for the nine species presently accepted inGraphiumis presented.Pesotum, originally characterized mainly by sympodial conidiogenesis, is emended to include synnematous anamorphs ofOphiostomaspecies formerly included in a variety of genera with sympodial to dense-annellidic conidiogenesis. Eight new combinations inPesotumare included in a nomenclator for the 26 species currently known. Three new combinations fromCeratocystistoOphiostomaare proposed for species withPesotumanamorphs. The holomorph ofGraphium calicioideshas affinities to the black yeasts and should be classified in the Chaetothyriales. However, the critical morphological, loculoascomycetous characters of the teleomorph are not completely documented. Interpreted from the molecular context, the morphological similarities between these three groups of anamorphs are homoplasies and examples of convergent evolution.Key words: Chaetothyriales,Graphium, Microascales, Ophiostomatales,Pesotum, 18S (SSU) rDNA sequences.