An Updated Classification of the Recent Crustacea

Superfamily Majoidea
Hendrickx (1995, and pers. comm.) brought our
attention to the elevation of several majid subfamilies
to familial rank, such as the elevation of some
inachoid groups by Drach and Guinot (1983), who
recognized as families the Inachidae and Inachoididae.
We have followed Hendrickx’s recognition of
former majid subfamilies as families. To some degree,
our treatment (and Hendrickx’s) of the majoid
families follows the seven subfamilies proposed by
Griffin and Tranter (1986) in their major revision
of the Majidae of the Indo-West Pacific. Additional
subfamilies have been proposed by other workers,
including Števčić (1994), who disagreed with some
of the subdivisions proposed by Griffin and Tranter
(1986). Diversity of the former family Majidae is
incredibly high, and recognition or treatment of the
majoids as a superfamily has been noted or suggested
by many earlier workers (e.g., Guinot, 1978;
Drach and Guinot, 1983; Števčić, 1994; Clark and
Webber, 1991, among others). M. Wicksten (pers.
comm.) suggests that, if we elevate some of the former
majid subfamilies to the family level, then we
should recognize also the family Oregoniidae
Garth, 1958, and possibly also the Macrocheiridae
Balss, 1929, ‘‘for consistency.’’ Indeed, Clark and
Webber (1991) proposed recognition of both of
these families based on a reevaluation of the larval
features of Macrocheira and suggested that extant
majoids be partitioned among four families: Oregoniidae,
Macrocheiridae, Majidae, and Inachidae.
Larval morphology indicates the distinct nature,
and presumed monophyly, of these groups as well
(Pohle and Marques, 2000). We have not taken that
step here, feeling that knowledge of larval majoids
is still rather incomplete, and we recognize here
only the families Epialtidae, Inachidae, Inachoididae,
Majidae, Mithracidae, Pisidae, and Tychidae.
Concerning phylogeny among the higher (heterotrematous)
crabs, Rice (1983:326) depicts the Majidae
(our Majoidea) as basal to the primitive xanthid
stock, which in turn gives rise to all other crab
families and superfamilies. A recent study based on
larval characters (Pohle and Marques, 2000) suggests
that, within the Majoidea, the Oregoniinae
clade is most basal among those majoid families (or
subfamilies) for which larval morphology is
known.
Superfamily Hymenosomatoidea
According to Guinot and Richer de Forges (1997),
members of the family Hymenosomatidae (sole
member of this superfamily) are thought to be
‘‘highly advanced Heterotremata and not Thoracotremata’’
(Guinot and Richer de Forges, 1997:
454, English abstract). In addition, Guinot and
Richer de Forges (1997) revive the idea that the
closest relatives of the hymenosomatids may lie
among the majoid family Inachoididae. The unusual
sperm morphology of one species of the family,
as reported by Richer de Forges et al. (1997),
would seem to exclude the Hymenosomatidae from
the Thoracotremata, and even casts doubts as to
the family’s inclusion in the Heterotremata.
Superfamily Parthenopoidea
The superfamily Mimilambroidea and its sole family
Mimilambridae, both originally erected by Williams
(1979) to contain Mimilambrus, have been
removed following the suggestion of Ng and Rodriguez
(1986) that Mimilambrus can be accommodated
within the Parthenopidae. Hendrickx (1995)
again alerted us to the fact that several former subfamilies
of crabs (in this case, former parthenopid
subfamilies) had been suggested to be deserving of,
or had actually been elevated to, family rank as
long ago as 1978 (Guinot, 1978). Although several
authors (e.g., Hendrickx, 1999) have attributed the
family name Daldorfiidae to M. J. Rathbun, we
have found no indication that the taxon was recognized
by her. Ng and Rodriguez (1986) recognized
the suggested parthenopoid groupings of
Guinot as valid families and first used the names
Daldorfiidae [as Daldorfidae] and Dairidae, and we
have attributed these families to them. We have followed
Guinot (1978) and Ng and Rodriguez (1986)
and recognize the families Aethridae, Dairidae,
Daldorfiidae, and Parthenopidae within a superfamily
Parthenopoidea, although Hendrickx (1995)
stopped short of treating all of these as valid families.
Superfamily Retroplumoidea
The family Retroplumidae was given its own superfamily
by Saint Laurent (1989), and its placement
among the Heterotremata is based on Saint
Laurent (1989) and Guinot (pers. comm.)
Superfamily Cancroidea
The family Cheiragonidae Ortmann, 1893, containing
the genera Telmessus and Erimacrus (formerly
treated by most workers as atelecyclids), was
resurrected and redescribed by Števčić (1988), and
this has been followed by Peter Ng (1998, and pers.
comm., 1997; see also Schweitzer and Salva, 2000),
and so we have included it here as well.
Superfamily Portunoidea
The freshwater family Trichodactylidae has now
been placed in this superfamily, where it joins the
portunids and geryonids, based primarily on a recent
morphological analysis (Sternberg et al., 1999;
see also below under Potamoidea). Fundamental
differences between trichodactylids and other freshwater
crabs were recognized by several earlier
workers. Rodriguez (1982, 1986, 1992), Magalhães
and Türkay (1996a–c), Sternberg (1997),
Sternberg et al. (1999), Christoph Schubart (pers.
comm.), and Spears et al. (2000) all acknowledge
the unique position of the Trichodactylidae and all
consider the family monophyletic. The hypothesis
52 Contributions in Science, Number 39 Rationale