Paenibacillus durus (Collins et al. 1994, formerly Clostridium durum Smith and Cato 1974) has priority over Paenibacillus azotofixans (Seldin et al. 1984). Opinion 73

Clostridium durum was described by Smith & Cato (1974) and the name was validly published by inclusion in the Approved Lists of Bacterial Names (Skerman et al., 1980). Seldin et al. (1984) described a nitrogen-fixing spore-forming bacterium and named it Bacillus azotofixans. Ten years later, Ash et al. (1994) proposed that Bacillus azotofixans be transferred to the newly established genus Paenibacillus, and Collins et al. (1994) proposed that Clostridium durum be transferred to the same new genus as Paenibacillus durum [sic]. A thorough comparison of two strains of Paenibacillus durum [sic] and five strains of Paenibacillus azotofixans by Rosado et al. (1997) showed convincingly that all strains belonged to the same species. Rosado et al. (1997) then united the two species under the name Paenibacillus azotofixans, a step that clearly violated Rule 23a of the Bacteriological Code (1990 Revision) (Lapage et al., 1992).

This irregularity was detected by Logan et al. (1998), who – emphasizing that Paenibacillus durum [sic] deserves priority over Paenibacillus azotofixans – submitted a respective Request for an Opinion.

The Judicial Commission adjusted the gender of the specific epithet to durus (masculine) and decided that the name Paenibacillus durus has priority over Paenibacillus azotofixans; furthermore, it was decided that the type strain of Paenibacillus durus is VPI 6563 (=ATCC 27763=DSM 1735), not P3L5 (=ATCC 35681). The name Paenibacillus azotofixans is a later synonym of Paenibacillus durus. The argument that the specific epithet azotofixans would be more informative than the specific epithet durus cannot be taken into consideration when the priority is clear.