Patterns of geographic speciation in the genus Flammulina based on sequences of the ribosomal ITS1-5.8S-ITS2 area

Previous studies based on morphology and on ability to intercross suggested that new biological and morphological species were sheltered within the ge nus Flammulina as well as varieties within R velutipes. The currently descr ibed or proposed Northern Hemisphere Flammulina species are F. "mexicana, " F: populicola, E: rossica, F: ononidis, F: elastica, F: fennae and E veluti pes. Within F. velutipes are E;: velutipes var. velutipes, var. "lupinicola ," and var, lactea. The ribosomal ITS1-5.8S-ITS2 region was sequenced for e ighteen geographically diverse Flammulina collections, including the three F: velutipes varieties. Results of neighbor-joining and parsimony analysis produced five distinct Northern Hemisphere clades, a clade consisting of Ij : velutipes together with it's varieties, a clade consisting of E;: populic ola and F: "mexicana" and clades representing F: fennae, R rossica and F. e lastica together with F. ononidis. Data are consistent with the hypothesis that F. populicola is a relatively old species which has diverged significa ntly on different continents, possibly giving rise to F: "mexicana" in Nort h America. The ITS sequence for Flammulina stratosa, an isolate from New Ze aland, is highly divergent from all other Flammulina isolates and may repre sent an ancient endemic or the product of very rapid evolution. Species div ersity is highest in Europe and suggests that Europe may be a center of div ersity for this group.