Aspergillus bombycis, a new aflatoxigenic species and genetic variation in its sibling species,A. nomius

A new aflatoxigenic species of Aspergillus, A. bombycis, was discovered during isolation of fungi from insect frass collected in silkworm rearing houses in Japan. The new species resembles A. flavus, but produces B and G aflatoxins. It is distinguished from A. flavus and A. nomius by differences in growth rates at 37 and 42 C, from A. nomius by roughness of the stipe, and from both of these species by differences in the nucleotide sequences in the beta-tubulin, calmodulin, norsolorinic acid reductase, ITS, and lsu-rDNA genes. Aspergillus bombycis is known from nine isolates, eight collected in silkworm-rearing houses in Japan and one collected in a silk-worm rearing house in Indonesia. Phylogenetic analysis of the DNA sequences shows that A. bombycis is a phylogenetically distinct species which is most closely related to A. nomius and which belongs in Aspergillus section Flavi. Analysis by partition homogeneity did not reveal evidence of genetic recombination in A. bombycis, but in A. nomius the patterns of polymorphisms in different genes strongly suggest cryptic genetic recombination.