Asterotexis cucurbitacearum, a poorly known pathogen of Cucurbitaceae new to Costa Rica, Grenada and Panama

A pathogenic bitunicate ascomycetous fungus, identified as Asterotexis cucurbitacearum, was found repeatedly on living leaves of Cucurbita pepo (gourd) and Sechium edule (chayote) in Panama. A. cucurbitacearum represents a new report for Panama and S. edule is a new host plant for this fungus. Based on an examination of herbarium specimens, this species is also reported for the first time from Costa Rica and Grenada. Cells of the scutellum extending to the base of the fruiting structure and producing an appressorium on the leaf surface are documented for the first time. As shown by LSU sequence data, A. cucurbitacearum represents a divergent, hitherto molecularly unsampled, phylogenetic clade of the Dothideomycetes. The closest relatives, for which sequence data are available, are members of the Pleosporomycetidae and Dothideomycetes incertae sedis with sequence similarity below 90%, as shown by BLAST search. A preliminary neighbour-joining analysis indicates that A. cucurbitacearum probably belongs to the Dothideomycetidae (incertae sedis).