The Isopods of Abyssal Depths in the Atlantic Ocean

186 ROBERT J. MENZIES
The three subtribes of the Flabellifera have been
reported from the abyss, where each is represented
by several species. The subtribes are the Anthuroidea,
the Seroloidea, and the Cirolanoidea. It is highly
probable that the records of the latter are due to
pelagic species caught on the way up.
Diagnosis: Flabellifera with the fourth and fifth
pairs of pleopoda large and operculiform, pleopods
1-3 normal, smaller than 4 and 5. Cephalon united
medially with first peraeonal somite. Body strongly
depressed, much wider than high (thick). Uropoda
small, normal, subapical, not arching over pleon.
(From Menzies, in press.)
Composition: The serolids have been revised by
Nordenstam (1933). The majority of the species have
been recovered from shallow water, and although a few
abyssal species have been described, only one—
Serolis neaera Beddard—had been known from the
Atlantic abyss. The genus is well represented in
Antarctic polar regions, but is yet unknown from the
Arctic. In fact, only one species is known from
the Northern hemisphere—namely, Serolis carinata
Lockington (Richardson, 1905). Here five species of
abyssal serolids are described from the abyss of the
South Atlantic.
Genus: SEROLIS Leach
Subgenus: SEROLIS Nordenstam, 1933
Type species: Serolis (Serolis) paradoxa (Fabricius,
1775).
Diagnosis: Uropoda two-branched (biramous, not
spiniform). Tergum of seventh peraeonal somite
vanished. Tergum of sixth peraeonal somite well
demarcated from first abdominal segment in its
entire length. Second article of maxillipedal palp
cordate. (Modified after Nordenstam, 1933.)
Serolis (Serolis) neaera Beddard
Figure 65 A
Synonyms: Serolis neaera Beddard, 1884, pp. 331-332.
Diagnosis: Serolis with coxal plates marked off on
Tribe: FLABELLIFERA
Family: SEROLIDAE
A KEY TO THE FLABELLIFERAN SUBTRIBES
(From Menzies, in press)
1. Individual peraeonal somites longer than
wide Anthuroidei
1. Individual peraeonal somites much wider than
long
2. Peraeon with first somite fused medially with
cephalon. First to third pleopoda smaller than
operculiform fourth and fifth pairs Seroloidtc
2. Peraeon and cephalon not fused. Pleopods all
similar in size Cirolanoida
peraeonal somites 2-4 inclusive. Third article of
maxillipedal palp small. Pleon with apex acute,
dorsum with stout wide tooth at proximal end and a
Figure 65. A: Serolis (Serolis) neaera Beddard,
dorsal view. B: Serolis (Serolis) margaretae,
n. sp., dorsal view female holotype.
smaller one near midpoint having a tooth on either
side and a carina connecting with paired converging
carinae near proximal tooth. Second pleonal epimera
extending beyond posterior margin of pleon.
Uropoda biramous, extending beyond apex of pleon.