RIEMERELLA-ANATIPESTIFER GEN-NOV, COMB-NOV, THE CAUSATIVE AGENT OF SEPTICEMIA-ANSERUM EXSUDATIVA, AND ITS PHYLOGENETIC AFFILIATION WITHIN THE FLAVOBACTERIUM-CYTOPHAGA RIBOSOMAL-RNA HOMOLOGY GROUP

The phylogenetic position of the causative agent of septicemia anserum exsudativa, now most often referred to as [Moraxella] anatipestifer ( brackets indicate a generically misnamed taxon) or ''[Pasteurella] ana tipestifer,'' was established by performing rRNA cistron similarity st udies. [Moraxella] anatipestifer belongs to rRNA superfamily V, togeth er with the genera Flavobacterium, Cytophaga, Flexibacter, Weeksella, Capnocytophaga, and Sphingobacterium. The detailed structure of rRNA s uperfamily V, which now contains five major rRNA homology groups, is d escribed. An analysis of various phenotypic parameters, including new data (cellular proteins and fatty acids) and previously published data (respiratory quinones, enzyme activities, and classical phenotypic fe atures), revealed that [Moraxella] anatipestifer differs in many aspec ts from its closest relatives, Flavobacterium indologenes, Flavobacter ium gleum, Flavobacterium indoltheticum, Flavobacterium balustinum, Fl avobacterium meningosepticum, and Weeksella zoohelcum. The combined ge notypic and phenotypic data indicate that this organism should be plac ed in a separate genus; the name Riemerella anatipestifer gen. nov., c omb. nov. is proposed for this bacterium. The specific epithet anatipe stifer is kept in order to avoid nomenclatural confusion. However, it should be emphasized that the illness caused by this organism is a sep ticemic disease which is not restricted to ducks.