Guyoneaud et al. 1998 propose the transfer of Amoebobacter roseus (the type species of the genus Amoebobacter) to the genus Thiocapsa [ Thiocapsa rosea (Winogradsky 1888) Guyoneaud et al. 1998, comb. nov.] and a new type species for the genus Amoebobacter (Amoebobacter purpureus Eichler and Pfennig 1989). However, according to Rule 37a (1) "the name of a taxon must be changed if the nomenclatural type is excluded" and according to Rule 37a (2) "retention of a name in a sense which excludes the type can only be effected by conservation and only by the Judicial Commission".
In order to solve the confusion caused by the publication of Guyoneaud et al. 1998 , Tindall 1999  proposes that Amoebobacter purpureus Eichler and Pfennig 1989 be transferred to a new genus, Pfennigia as Pfennigia purpurea (Eichler and Pfennig 1989) Tindall 1999, comb. nov.Publication:
Tindall BJ. Taxonomic note: transfer of Amoebobacter purpureus to the genus Pfennigia gen. nov. as Pfennigia purpurea comb. nov., on the basis of the illegitimate proposal to make Amoebobacter purpureus the type species of the genus Amoebobacter. Int. J. Syst. Bacteriol. 1999; 49:1307-1308.
The proposal to create a new type species for the genus Amoebobacter is illegitimate.Publication:
Guyoneaud R, Suling J, Petri R, Matheron R, Caumette P, Pfennig N, Imhoff JF. Taxonomic rearrangements of the genera Thiocapsa and Amoebobacter on the basis of 16S rDNA sequence analyses, and description of Thiolamprovum gen. nov. Int J Syst Bacteriol 1998; 48:957-964.