Paul,

The ICZN (International Code of Zoological Nomenclature) applies to
species-group, genus-group, and family-group names, but not to higher taxa
such as orders, classes, phyla, and kingdoms. The rules have mainly to do
with the formation of names, validity of names, allowable changes in names
(spelling, synonyms, homonyms), designation of the correct author and date
of publication, and designation of types. They deal with names rather than
real objects, in that you can understand a great deal about nomenclature
without picking up a specimen. Nomenclature does not depend on knowledge of
genetics, cladistics, or morphometrics, or even on simple observation. This
is the distinction between nomenclature (classification of names) and
taxonomy (classification of taxa).

Species-group names include subspecies, species, and other ranks as needed
such as superspecies. Ranks below the subspecies are excluded. Names
originally proposed as forms or varieties are automatically considered to
be subspecies if possible.

Genus-group names include subgenera, genera, and other ranks as needed,
such as sections and supergenera. Usually the extra ranks are needed only
for genera with large numbers of species, or in some cases for cladistic
analysis.

Family-group names include tribes, subfamilies, families, and
superfamilies, as well as any other ranks that are deemed necessary, such
as subtribe.

When someone names a new taxon, the other ranks in the same group are
automatically generated, so that publication of family "Alabamidae
Rindsberg, 1999" would automatically generate subfamily Alabaminae
Rindsberg, 1994 and superfamily Rindsberg, 1994 if those taxa are needed.
All share the same type genus. Likewise, the new genus "Alabama Rindsberg,
1999" automatically generates subgenus Alabama Rindsberg, 1999 with the
same type species; and the new species Alabama alabamiensis Rindsberg, 1999
generates subspecies Alabama alabamiensis alabamiensis Rindsberg, 1999 with
the same type specimen. (Whew.) These extra names may never be used, but
their virtual existence fends off the proposal of numerous superfluous
names by authors trying to immortalize themselves by filling in the gaps
between ranks.

Besides, it's easier to remember that the Alabaminae belong in the
Alabamidae, for the subfamily that contains the type genus Alabamia. The
ICZN requires that all family names end in -idae, and all subfamily names
in -inae. It also recommends the endings -oidea for superfamilies and -ini
for tribes.

Now, every family must be named for its type genus. The Latinized suffix
-idae is added strictly to the stem of the name of the type genus.
Determining the correct stem can be tricky, since the nominative case
commonly has a slightly abbreviated or modified form of the stem. Let's go
through that some other day. In most cases, you remove the ending -a, -us,
or -um and then add -idae, e.g., Alabama > Alabamidae, but Alabamia > Al
abamiidae. The stem of Pecten is Pectin- (nominative pecten, genitive
pectinis), so the family is Pectinidae, which is the source of much
confusion among editors.

What happens if the family is named for a genus that is later found to be a
junior synonym? Well, after 1960, the rule has been that the family still
has the same type genus, even if that name is no longer the correct one, so
the old family name remains in use. For instance, suppose it turns out that
my new genus Alabama is a synonym of Floridia Dall, 1890. Alabama remains
the type genus of Alabamidae, but we relabel our specimens of Alabama as
Floridia. But if anyone had already named a family Floridiidae, then
Alabamidae would be a junior synonym of that, and both Alabama and
Alabamidae would fall into disuse.

The rule was different up through 1960, and we still use the old rule for
old taxonomic revisions. Someone could replace Alabamidae with a younger
synonym Florididae then, and if the name Florididae gained general
acceptance, the younger name is maintained. Yes, it is confusing to have
different rules for taxonomic revisions done before and after December 31,
1960, but the ICZN deems that this is the best way to maintain stability of
established names while revising the rule to make better sense in the
future.

And everyone who keeps their labels up to date likes stability of
nomenclature.

Andrew K. Rindsberg
Geological Survey of Alabama