PHYLOGENETIC-RELATIONSHIPS AMONG VAIRIMORPHA AND NOSEMA SPECIES (MICROSPORA) BASED ON RIBOSOMAL-RNA SEQUENCE DATA

A portion (approximately 350 nucleotides) of the large subunit ribosom al RNA (rRNA) 5' to the 580 region (Escherichia coli numbering) was se quenced using the reverse transcriptase dideoxy method and compared fo r several species of Nosema and Vairimorpha. Comparison among Nosema s pecies suggests that this genus is composed of several unrelated group s. The group which includes the type species, Nosema bombycis, consist s of closely related species found primarily in Lepidoptera. Other Nos ema species sequenced (Nosema kingi, Nosema algerae, and Nosema locust ae) do not appear to be closely related to each other or to the lepido pteran Nosema group. Comparison among the Vairimorpha species indicate s that two distinct but very closely related groups exist. The Lymantr ia group consists of species isolated from the gypsy moth, Lymantria d ispar, while the Vairimorpha necatrix group consists of species isolat ed from other Lepidoptera. Intergeneric comparison of the sequence dat a suggests that the lepidopteran Nosema species are closely related to the Vairimorpha species. (C) 1994 Academic Press, Inc.