Delineation of fungal species within the genus Pseudocercosporella in the sooty blotch and flyspeck complex

The sooty blotch and flyspeck (SBFS) fungal complex causes major losses to apple growers in humid regions of the world. From a collection of 137 isolates in the genus Pseudocercosporella from the eastern and midwestern U.S., parsimony analysis of the Internal Transcriber Spacer region of rDNA delineated 8 putative species. Growth and morphology of representative isolates of each putative species were compared. Optimum temperature for mycelial growth on malt extract agar varied from 20 to 25C, and growth rate differed among putative species. On potato dextrose agar, one or more features of colony morphology (conidial shape, size and color; presence of soluble pigments in agar; and colony shape, texture, color, and height) were distinct among the following groups: putative species RH1.4; RH2.1 and RH2.3; RH2.3 and RH 2.4; RH1.4; and RH5.1. The distinctions noted in this study will complement sequence information in clarifying the taxonomic status of these fungi and enabling assignment of Latin binomials to the putative species.