>Don't most superfamilies end in -acea?

Actually, they should all end in -oidea, at least for animals.  The acea ending has widespread traditional use and is hard to confuse with the family ending -idae or the traditional ordinal ending -oida but -oidea was recently made official by the International Commission on Zoological Nomenclature.  Groups higher than the superfamily are outside the jurisdiction of the ICZN, so you are free to pick your preferred stem (no requirement for priority or basing it on an included genus) or ending.  The debate over the proper ending of higher categories has had some interesting side effects.  Nuculoidea is a genus and a superfamily.  I believe the author of the genus was strongly opposed to the oidea ending for higher taxa and named the genus in order to cause trouble for its use at other levels.

    Dr. David Campbell
    "Old Seashells"
    Biology Department
    Saint Mary's College of Maryland
    18952 E. Fisher Road
    St. Mary's City, MD  20686-3001 USA
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"Mollusks murmured 'Morning!'.  And salmon chanted 'Evening!'."-Frank Muir, Oh My Word!