PHYLOGENY OF AMBLYOSPORA (MICROSPORIDA, AMBLYOSPORIDAE) AND RELATED GENERA BASED ON SMALL-SUBUNIT RIBOSOMAL DNA DATA - A POSSIBLE EXAMPLE OF HOST-PARASITE COSPECIATION

Small subunit ribosomal RNA (SSU rRNA) gene sequences were analyzed fo r six species and four genera of microsporidia from mosquito hosts; Am blyospora stimuli (Aedes stimulans), Amblyospora californica (Culex ta rsalis),Amblyospora sp. (Culex salinarius), Edhazardia aedis (Aedes ae gypti), Culicosporella lunata (Culex pilosus), and Parathelohania anop helis (Anopheles quadrimaculatus), Comparison of these sequences to th ose of other microsporidia show that these sequences are longer with t he SSU rRNA gene of E. aedis being the longest microsporidia sequenced to date (1447 base pairs), Parsimony, maximum likelihood, and distanc e methods produced identical trees, suggesting that the above microspo ridian taxa, contrary to current classification schemes, form a monoph yletic group. Relationships within this group are further supported by high bootstrap and decay analysis values. Based on the molecular anal ysis, P. anophelis is the most divergent species in this group of mosq uito parasites. Amblyospora is paraphyletic with A. californica and Am blyospora sp,, forming a sister taxon to a clade composed of E. aedis and A. stimuli. Culicosproa/Edhazardia lunata comprises a sister taxon to the Amblyospora/Edhazardia clade. The pattern of host relationship s on the tree provides preliminary evidence that the branching pattern seen here may indicate that host-parasite cospeciation is an importan t mechanism of evolution in this group. (C) 1998 Academic Press.