Bouchet and Rocroi 2005/2017, WoRMS dissolved the infraclass. 2024 new family Bathydeviidae. Genus and family changes are constant. iNaturalist for identification. Underwater photographers affected by renaming.
Nudibranchs are the favorites of many underwater photography enthusiasts, and the taxonomy of this group is in constant revolution. The community reflects the difficulty of keeping identification knowledge up to date. Divers debate whether printed guides become outdated too quickly and how new molecular phylogeny tools are changing the classification of groups that visually seemed well defined.
The term "opisthobranchia" is no longer taxonomically valid: the revision by Bouchet and Rocroi (2005), updated in 2017 and adopted by the World Register of Marine Species (WoRMS), dissolved the former infraclass into new groupings based on molecular phylogeny. In 2024, the completely new family Bathydeviidae was described for a pelagic deep-water nudibranch. The practical consequence for the underwater photographer is that the species they have been identifying by a certain name for years may now appear under a different name in iNaturalist or field guides.