An Updated Classification of the Recent Crustacea

Brusca and Brusca, 1990; Mayrat and Saint Laurent,
1996; Camp, 1998 (in Camp et al., 1998);
Young, 1998). But as with nearly all other crustacean
assemblages, this grouping has its opponents
as well. Most of the disagreement concerns whether
the mysidaceans (i.e., either mysids, lophogastrids,
or both) should be placed here (see earlier discussions
on mysids and lophogastrids) and what the
relationships are among the three currently recognized
orders Euphausiacea, Amphionidacea, and
Decapoda (see Jarman et al., 2000; Richter and
Scholtz, in press). Eucarid relationships have been
analyzed by Schram (1984) and by Christoffersen
(1988). Our classification is consistent with both of
these analyses at higher levels but differs in the constituent
suborders.
ORDER EUPHAUSIACEA
The Euphausiacea still contains only the two families
Bentheuphausiidae (monotypic) and Euphausiidae
(all other species). The treatment by Baker et
al. (1990) follows this arrangement as well. A recent
analysis of 28S rDNA sequence data by Jarman
et al. (2000) suggests that euphausiaceans may
be more closely related to the Mysida than to the
Decapoda.
ORDER AMPHIONIDACEA
This order remains monofamilial and monogeneric
(Amphionides).
ORDER DECAPODA
The decapods have been the subject of more published
papers than have all other crustacean groups
combined. This popularity stems in part from the
economic importance of many groups (especially
penaeoid shrimps, palinurid and nephropid lobsters,
and portunid and xanthoid crabs) but also in
part because of their marvelous diversity. The convenient
size of most decapods predisposed them to
become subjects of some of the earliest papers using
biochemical and molecular data to resolve crustacean
relationships. Yet we are as far from reaching
a consensus on the relationships among the decapods
as we are for the more obscure groups, and
opinions and datasets remain sharply divided. In
the treatment that follows, we have tried to address
the many changes and arrangements that have been
suggested since 1982 under the taxonomic heading
for each major group of decapods. However, we are
certain to have missed several important papers,
and we hasten to remind the reader that the literature
on this topic is vast. In general, we have settled
on a fairly conservative classification of the
decapods, knowing that, as with all other crustacean
taxa, this group is destined for revision. Some
of the many reviews of decapod classification that
have appeared since the Bowman and Abele (1982)
classification are Felgenhauer and Abele (1983),
Abele and Felgenhauer (1986), Kim and Abele
(1990), Abele (1991), Holthuis (1993a), and
Scholtz and Richter (1995).
The creation of two major branches of decapods,
Dendrobranchiata and Pleocyemata, by Martin
Burkenroad (1963, 1981) was a rather bold departure
from previous schemes of decapod classification.
According to Fenner Chace (pers. comm.), T.
Bowman more or less accepted Burkenroad’s arguments
without much questioning, and thus the
use of the Dendrobranchiata and Pleocyemata in
the Bowman and Abele (1982) classification. Chace
(pers. comm.) feels that there is ample evidence for
elevating many of the major groups of the Decapoda
as Burkenroad did with the penaeoids and
that singling out the penaeoid shrimp was to assign
that group an artificial distinction. He is not alone.
Holthuis (1993a; see especially pages 11–13 for a
concise historical overview of the many attempts to
classify the decapods) felt that treating the penaeoids
as a separate group (the Dendrobranchiata)
equal in rank to the combined Natantia Macrura
Reptantia Anomura Brachyura (the Pleocyemata
of Burkenroad) was unsatisfactory. Holthuis
(1993a) proposed to revert to the older classifications
and treated the Natantia and the Macrura
Reptantia as ‘‘full suborders of equal rank with the
Anomura and Brachyura.’’ In his own words (Holthuis,
1993a:6):
I know that this classification will generally be considered
old-fashioned: in several modern handbooks the
suborder Natantia has been abandoned altogether; a
small part of it, namely the Penaeoidea, is elevated to
the rank of a separate suborder Dendrobranchiata
while the rest of the Natantia plus the Macrura Reptantia,
plus the Anomura, plus the Brachyura are
placed in a single suborder Pleocyemata. This to me
seems a very artificial and unsatisfactory arrangement,
and I therefore still keep to the old classification.
This ‘‘old’’ classification to which he refers, probably
because of its simplicity and relative lack of
controversy, is often encountered in popular and
lay versions of crustacean classification. As an example,
the publishers of the BIOSIS and Zoological
Record databases (see URL http://www.york.
biosis.org/zrdocs for the BIOSIS/Zoological Record
Taxonomic Hierarchy, Section 10, Crustacea) have
‘‘thrown up their hands in despair’’ (Chace, pers.
comm.) and have reverted to this older and simpler
classification. There, Natantia is treated as a taxon
containing all of the known shrimp groups (Penaeidea,
Caridea, and Stenopodidea) and the Reptantia
is treated as containing the anomurans, astacurans,
brachyurans, and palinurans.
Yet the distinct nature of the penaeoids (the Dendrobranchiata)
has been supported by additional
morphological (e.g., Schram, 1984, 1986), embryological,
spermatological (e.g., see Jamieson,
1991a), and molecular data. Kim and Abele (1990)
reviewed previous schemes of decapod classification
and concluded, based on somewhat limited
data from 18S rRNA, that the penaeids were distinct
from other decapods. This view was support-
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