An Updated Classification of the Recent Crustacea

that reduction in body segmentation has occurred
independently as a functional adaptation in many
different and unrelated crustacean taxa and that the
unique features of the Ostracoda argue for their
recognition as a separate class (see especially discussions
in Newman, 1992; Boxshall, 1992; Wilson,
1992). Treatment of ostracodes as a subclass
of the Maxillopoda has additional problems as
well. Wilson (1992) could not find support for placing
the former within the latter based on morphological
grounds (although Schram and Hof, 1998,
point out errors in Wilson’s analysis that, if corrected,
would indeed group ostracodes with one
cluster of Maxillopoda). Abele et al. (1992) rejected
the inclusion of ostracodes in the Maxillopoda on
molecular grounds. Spears and Abele (1997) suggest
the possibility that, based on molecular data,
both Ostracoda and Maxillopoda might be paraphyletic.
There is also some evidence, both morphological
and molecular, that the two major groupings of the
Ostracoda (Myodocopa and Podocopa) may not
constitute a monophyletic assemblage (e.g., see
Vannier and Abe, 1995; Spears and Abele, 1997).
On the other hand, Cohen et al. (1998), based on
the many similarities between these two groups,
‘‘regard it more parsimonious and useful to assume
that they do.’’ This older view—that ostracodes are
monophyletic—has been adopted here and is in fact
held by a majority of current workers in the field.
The assignment of ostracodes to a group ‘‘Entomostraca’’
(which included, in addition to ostracodes,
the Branchiopoda, Cirripedia, Branchiura,
and Phyllocarida) by McKenzie et al. (1983) was
clearly an unsupported departure (see also discussions
on Branchiopoda and Phyllocarida and notes
on Entomostraca under the general heading Crustacea).
A modified version of the classification of the Ostracoda
used by Whatley et al. (1993), which will
be the basis for the classification used in the upcoming
revision of the Treatise on Invertebrate Paleontology
(‘‘more or less,’’ according to Whatley,
pers. comm.; R. Kaesler, pers. comm.), was sent to
us by R. Whatley. This classification, which differs
considerably from what was proposed by Mc-
Kenzie et al. (1983) and also from the classification
used by Hartmann and Guillaume (1996), has been
followed fairly closely. Differences include the spelling
of the endings of superfamilies. We use the
ICZN-recommended ending ‘‘–oidea’’ (which in the
latest (fourth) edition of the International Code of
Zoological Nomenclature is mandatory rather than
a recommendation; ICZN, 1999, article 29.2).
Whatley, in one of the more interesting responses
we received, has indicated that the ‘‘-oidea’’ spelling
is an ‘‘attempted imposition’’ by the ICZN. Kaesler
(pers. comm.) and Whatley (pers. comm.) note that
ostracodologists prefer to think of the higher
groups as superfamilies rather than as suborders
and are also more accustomed to the use of the
ending ‘‘-acea’’ for superfamilies and thus are more
familiar with, and prefer, the concept of a superfamily
Bairdiacea as opposed to a superfamily Bairdioidea
or suborder Bairdiocopina. On the spelling
of superfamily names, however, the ICZN recommendation
(ICZN, 1999, fourth edition, article
29.2) is rather clear: ‘‘The suffix -OIDEA is used
for a superfamily name, -IDAE for a family name,
-INAE for a subfamily name . . .’’ etc. And it appears
to us that it is primarily the paleontologists
(who are, we admit, the majority of the ostracodologists)
rather than neontologists who prefer
(and use) the ‘‘-acea’’ ending for superfamilies (e.g.,
see Martens, 1992, and Martens et al., 1998, for
living freshwater ostracode superfamilies, all of
which are spelled according to ICZN recommendation
29.A [now 29.2]). As Martens et al. (1998:
41) explain in a note to accompany their classification,
‘‘. . . as ostracods are animals, we will follow
the ICZN throughout this book.’’
Thus, we have followed the ICZN recommendation
(as did Bowman and Abele, 1982, and
Schram, 1986) for spellings of superfamilies (e.g.,
Bairdioidea, not Bairdiacea). Whatley (pers.
comm.) also feels that, relative to the Podocopida,
the Myodocopa is probably ‘‘one hierarchical level
too high.’’ Whatley (pers. comm.) considers his
own arrangement (Whatley et al., 1993) ‘‘old fashioned
but acceptable to people who actually work
on the group,’’ a justification that we feel is baseless
but that, at the moment, faces nothing in the way
of a serious alternative classification. Martens
(1992) and Martens et al. (1998) appear to base
their decisions more on shared derived characters
and more often than not employ characters of the
entire animal (as opposed to those of the shell
only). Consequently, we have followed their lead
for the names, spellings, and arrangement of the
superfamilies and families of the freshwater families
as far as was possible (not all families are treated
in those works). Thus, although Whatley would remove
the superfamilies Macrocypridoidea and Pontocypridoidea
(placing their families among the Cypridoidea),
we have maintained these groupings
following Martens (1992) and Martens et al.
(1998). Whatley (pers. comm.) also feels that the
family Saipanettidae ( Sigilliidae; see later) is no
more than a subfamily of the Bairdiidae, whereas
Martens (1992) recognized a separate superfamily,
the Sigillioidea Mandelstam, to accommodate this
unusual group, and here again we have followed
Martens (1992).
Whatley (pers. comm.) and Whatley et al. (1993)
also place the unusual and primitive family Punciidae
in the Platycopida (he considers Manawa to be
a member of the Cytherellidae), indicating that
there are still no living members of the Palaeocopidae.
Martens et al. (1998) also feel that there are
no living palaeocopids, which also supports transfer
of the punciids. We have followed Whatley’s advice
in moving the punciids to the Platycopida (although
they appear to share no unique characters
with platycopids and differ in many respects), but
Contributions in Science, Number 39 Rationale 29