> The names of animal orders regularly end in -oida, superfamilies in -acea, families in -idae, subfamilies in -inae, and all are based on the names of genera such as Etheria. The names of classes and higher taxa are not regulated by the International Code of Zoological Nomenclature; they are in Latin or Latinized Greek, but are descriptive rather than being based on particular genera, and that is why different people can refer correctly to the same group as Bivalvia ('two-valves'), Pelecypoda ('hatchet-foot'), and Lamellibranchiata ('platelet-gilled' if I interpret correctly). But what are these 'Muteloidea' and 'Etherioidea'?<

Although -acea is traditional and popular for molluscan superfamilies, it was recently replaced with -oidea by the ICZN.  Thus, Muteloidea and Etherioidea are superfamilies.

The -oida ending is widely used for orders (one reason why -oidea seems an odd choice for superfamilies), but the ICZN does not regulate them; thus, orders are also subject to individual inclination and do not have to be based on genera.  However, use of traditional names obviously helps communication.  In practice, widely used molluscan orders are generally based on genera, e.g. Veneroida, Cerithioida.  There are proposals out there to standardize nomenclature at higher levels.  These tend to conflict with widely-used, traditional names.  For example, for birds, orders end in -iformes, so requiring -oida would ruffle the feathers of ornithologists.  However, if you have occasion to make a new infraclass, for example, you might want to use one of these systems as a source of ideas on suitable endings that might not already be in use.

    Dr. David Campbell
    Old Seashells
    University of Alabama
    Biodiversity & Systematics
    Dept. Biological Sciences
    Box 870345
    Tuscaloosa, AL  35487-0345 USA
    [log in to unmask]

That is Uncle Joe, taken in the masonic regalia of a Grand Exalted Periwinkle of the Mystic Order of Whelks-P.G. Wodehouse, Romance at Droitgate Spa