Notes on Cladosporium species associated with Asphondylia galls on species of Lamiaceae in Poland and in Italy

Recent joint activities carried out by our research groups concerning Asphondylia gall midges and associated fungi on several species belonging to the Lamiaceae confirmed the constant occurrence of Botryosphaeria dothidea as the fungal symbiont of midges both in Poland and in Italy. However, isolations from galls also yielded Cladosporium spp. in high frequencies, with an uncertain symbiotic role. In the past, these fungi were reported as the main inquilines in Asphondylia galls on plants belonging to different botanical families; these combined remarks stimulate a more accurate consideration of Cladosporium strains in order to assess if they eventually play a role in this complex insect-fungus association. Morphological observations indicated that the majority of our isolates belong in the C. cladosporioides species complex, which is reported to include many closely related taxa and a good number of cryptic species yet to be described. Considering our opportunity to collect strains from quite a peculiar biocenotic context, as an additional contribution to the taxonomic resolution of this species complex we further characterized a sample of 47 strains through a phylogenetic analysis based on DNA sequences from the rDNA-ITS region (ITS1, 5.8 rDNA gene, ITS2), and loci coding for actin (Act) and the translation elongation factor 1-α (TEF). Particularly, Act sequence homology was effective in settling this assortment, leading to the ascription of a number of isolates to infrequent species, such as C. allicinum, C. basiinflatum and C. ramotenellum, and to the identification of four well defined isolate clusters possibly representing novel species.