Abstract
The Judicial Commission rules that the name Corynebacterium ilicis Mandel et al. 1961 is represented by the type strain ICMP 2608 =ICPB CI144 and is reported to be a plant-pathogenic species. Arthrobacter ilicis is represented by the type strain DSM 20138 =ATCC 14264 =NCPPB 1228 and is not a homotypic synonym of Corynebacterium ilicis Mandel et al. 1961, and is reported not to be a plant pathogen. The authorship is to be cited as Arthrobacter ilicis Collins et al. 1982 and typification and the description of this species are to be found in Collins et al. (1981) [Collins, M. D., Jones, D. & Kroppenstedt, R. M. (1981). Zentralbl Bakteriol Parasitenkd Infektionskr Hyg Abt I Orig C2, 318–323].
At its meetings in 2005 at the IUMS Bacteriology and Applied Microbiology Congress in San Francisco, the Judicial Commission of the International Committee for Systematics of Prokaryotes ruled that the name Arthrobacter ilicis is represented by the type strain DSM 20138 =ATCC 14264 =NCPPB 1228. The authorship is to be cited as Arthrobacter ilicis Collins et al. 1982 and the effective publication where this name is first published, typified and described is to be found in Collins et al. (1981). The name Arthrobacter ilicis appeared on Validation List no. 9 (Collins et al., 1982). In dealing with typification of Arthrobacter ilicis Collins et al. 1982, the type of Corynebacterium ilicis Mandel et al. 1961 is affected and must also be dealt with by the Judicial Commission. The type of Corynebacterium ilicis Mandel et al. 1961 is represented by the type strain ICMP 2608 =ICPB CI144.
It is evident from a number of publications that the organisms represented by the strains ICMP 2608 =ICPB CI144 and DSM 20138 =ATCC 14264 (cited on the Approved Lists of Bacterial Names; Skerman et al., 1980) =NCPPB 1228 are members of different taxa; although it was initially thought that DSM 20138 =ATCC 14264 =NCPPB 1228 were derived from a strain (CR2) that Mandel et al. (1961) considered to be pathogenic on American holly (Ilex opaca), this has proven not to be the case. Strains CR2 and Y-1 of Mandel studied by Dye & Kemp (1977) under the numbers CJ2 and CJ3 are clearly not members of the same taxon as CJ1 =NCPPB 1228 (=CR2). It is clear that DSM 20138 =ATCC 14264 =NCPPB 1228 does not exhibit one of the original diagnostic features of Corynebacterium ilicis, namely pathogenesis on American holly, and cannot represent this species. The Judicial Commission has therefore ruled that DSM 20138 =ATCC 14264 =NCPPB 1228 cannot serve as the type of the species Corynebacterium ilicis, but may serve as the type of a different taxon, Arthrobacter ilicis. Although this name is considered by Collins et al. (1981) to be a homotypic synonym of Corynebacterium ilicis Mandel et al. 1961, this is obviously not the case, since the strain studied is not an authentic representative of this taxon. The Judicial Commission therefore rules that the name Arthrobacter ilicis Collins et al. 1982 is to be typified by DSM 20138 =ATCC 14264 =NCPPB 1228 and that it is not a homotypic synonym of Corynebacterium ilicis Mandel et al. 1961. Reference to Mandel et al. 1961 in the author citation Arthrobacter ilicis (Mandel et al. 1961) Collins et al. 1982 is to be removed and any reference to Mandel et al. (1961) is not to be included in any future descriptions. The Approved Lists of Bacterial Names (Skerman et al., 1980, 1989) make reference to the publication of Dye & Kemp (1977) as the source of the description of Corynebacterium ilicis Mandel et al. 1961, and care must be taken in interpretation. Clearly, the strain listed as CJ1 (derived from NCPPB 1228) is not a member of the same taxon as CJ2 (=ICMP 2608) and CJ3 (=ICMP 2609). Based on later work, it would appear that data on strain CJ1 (=ICMP 2607) refer to Arthrobacter ilicis Collins et al. 1982, whereas the results from strain CJ2 and CJ3 are atypical. Notes held in the International Collection of Phytopathogenic Bacteria (ICPB), now housed at the USDA-ARS Foreign Disease-Weed Science Research Unit, Fort Detrick, MD, USA, indicate that strain ICPB CI144 (=CJ2 =ICMP 2608) could reinfect holly, and obviously refer to the pathogen Corynebacterium ilicis Mandel et al. 1961. This strain was accessioned to the ICPB (then in Davis, CA, USA) in 1960. It was also noted that ICPB CI145 (=CJ3 =ICMP 2609) did not reinfect holly.
Further work has shown that the species Arthrobacter ilicis Collins et al. 1982, represented by the type strain DSM 20138 =ATCC 14264 =NCPPB 1228, is not pathogenic for American holly and should not be listed as a plant-pathogenic species. In contrast, Corynebacterium ilicis Mandel et al. 1961, represented by the type strain ICMP 2608 =ICPB CI144, is pathogenic for American holly and has also been shown to be a member of the species Curtobacterium flaccumfaciens, where it is recognized as Curtobacterium flaccumfaciens pv. ilicis (Dye & Kemp, 1977; Young et al., 2004). Although not covered by the Bacteriological Code, the strain ICMP 2608 =ICPB CI144 may serve as the pathotype under the International Standards for Naming Pathovars of Phytopathogenic Bacteria (Young et al., 2001).