Aspergillus bombycis, a new aflatoxigenic species and genetic variation inits sibling species, A-nomius

A new aflatoxigenic species of Aspergillus, A. bombyris, was discovered dur ing isolation of fungi from insect frass collected in silkworm rearing hous es in Japan. The new species resembles A. flavus, but produces B and G afla toxins. 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 th e beta-tubulin, calmodulin, norsolorinic acid reductase, ITS, and 1su-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 rel ated to A. nomius and which belongs in Aspergillus section Flavi. Analysis by partition homogeneity did not reveal evidence of genetic recombination i n A. bombycis, but in A. nomius the patterns of polymorphisms in different genes strongly suggest cryptic genetic recombination.