Abstract
In 1993, Ash et al. proposed that members of group 3 within the genus Bacillus should be transferred to the genus Paenibacillus, for which they proposed Paenibacillus (formerly Bacillus) polymyxa as the type species. These proposals were validated by publication of the names in Validation List no. 51 (Paenibacillus polymyxa; Ash et al., 1994) and no. 52 (further species; Ash et al., 1995). Collins et al. (1994), clearly referring to Ash et al. (1993), also proposed that Clostridium durum should be transferred to the genus Paenibacillus as Paenibacillus durum [sic]. This minor orthographic error was corrected by Euzéby (1998), and the statement on priority of Paenibacillus durus over Paenibacillus azotofixans was corrected in Opinion 73 (Judicial Commission of the International Committee on Systematics of Prokaryotes, 2003).
According to the principle of priority based on page numbers in the same issue of the International Journal of Systematic Bacteriology, unintended confusion arose about the type species of the genus Paenibacillus, because Paenibacillus durus (Collins et al., 1994) appeared on page 824, whereas Validation List no. 51, validly publishing the name Paenibacillus polymyxa, appeared on page 852 of the same issue (Int J Syst Bacteriol 44, October 1994). This was certainly not intended by Collins and co-workers, as Collins himself was a co-author of Ash et al. (1993). Furthermore, the problem could have been avoided had the Validation Lists been published at the beginning of the journal, a course of action that has now been adopted.
To clarify the situation, Tindall (2000) published a Request for an Opinion in which he carefully explained the pros and cons of both possibilities. The Judicial Commission considered that the confusion arose unintentionally and decided that Paenibacillus polymyxa is the type species of the genus Paenibacillus.