Smithsonian at the Poles: Contributions to International Polar

(1971) on postnaupliar developmental stages of three species
belonging to the genera Clausocalanus and Ctenocalanus;
Björnberg’s (1973) survey of some copepods from
the southeastern Pacifi c Ocean; Yamanaka’s (1976) work
on the distribution of some Eucalanidae, Aetideidae, and
Euchaetidae; Fontaine’s (1988) on the antarctica species
group of the genus Paraeuchaeta; Markhaseva’s (2001) on
the genus Metridia; and Markhaseva and Ferrari’s (2005)
work on Southern Ocean species of Lucicutia. In addition,
four exhaustive monographs have treated the taxonomy of
a pelagic calanoid family throughout the world’s oceans,
and these also have contributed further to an understanding
of the Southern Ocean fauna: Damkaer’s (1975) work
on the Spinocalanidae, Park’s (1995) on the Euchaetidae,
Markhaseva’s (1996) on the Aetideidae, and Park’s (2000)
on the Heterorhabdidae. These monographs were based
on specimens from an extensive set of samples from the
world’s oceans. As a result, the taxonomy and geographical
range of most of the widespread species of these families
are now well known.
Recently described new species of Southern Ocean
calanoids are either pelagic species that previous authors
failed to recognize as distinct from similar relatives, e.g.,
Pleuromamma antarctica Steuer, 1931 (see Ferrari and
Saltzman, 1998), or species inhabiting extraordinary
habitats seldom explored previously, like the water immediately
above the seafl oor. Bradford and Wells (1983)
described the fi rst benthopelagic calanoid copepods of
the Southern Ocean, Tharybis magna and Xanthocalanus
harpagatus, from a bait bottle. Neoscolecithrix antarctica
was collected in small numbers in the Antarctic Sound adjacent
to the Antarctic Peninsula by Hulsemann (1985b),
who believed the species lived in close proximity to the
seafl oor. More recent additions to the benthopelagic calanoid
fauna include Parabradyidius angelikae Schulz and
Markhaseva, 2000, Paraxantharus brittae Schulz, 2006,
and Sensiava longiseta Markhaseva and Schulz, 2006,
each belonging to a new genus, and Brachycalanus antarcticus
Schulz, 2005, Scolecitrichopsis elenae Schulz,
2005, Byrathis arnei Schulz, 2006, Pseudeuchaeta arcuticornis
Markhaseva and Schulz, 2006, Bradyetes curvicornis
Markhaseva and Schulz, 2006, Brodskius abyssalis
Markhaseva and Schulz, 2007, Rythabis assymmetrica
Markhaseva and Schulz, 2007, and Omorius curvispinus
Markhaseva and Schulz, 2007. These latter species were
collected from the Weddell Sea, an arm of the Southern
Ocean, and from the Scotia Sea.
In this paper, all relevant studies of the taxonomy of
pelagic Southern Ocean calanoid copepods are reviewed.
Lists are compiled of species, genera, and families, and the
PELAGIC CALANOID COPEPODS OF THE SOUTHERN OCEAN 145
geographical range within the Southern Ocean and relative
abundance of each species are noted. Morphological
differences are used to suggest evolutionary relationships
among species. The distribution of all species is reviewed,
and several generalized patterns are hypothesized. Of particular
interest here are the species for which fewer than
50 specimens have been collected during the extensive
history of surveys of the Southern Ocean pelagic fauna.
The distribution of these rare, pelagic calanoids, almost
all deepwater species, contributes favorably to an understanding
of patterns of distribution and of speciation in
the Southern Ocean.
METHODS
Traditionally, the Southern Ocean has been described
physiographically as including the ocean basins adjacent
to the continent of Antarctica plus the following adjoining
seas: Amundsen Sea, Bellingshausen Sea, Ross Sea, Weddell
Sea, and the southern part of the Scotia Sea. In this
review of pelagic calanoid copepods, the southern boundary
of the Southern Ocean is defi ned physiographically
by the Antarctic continent, but the northern boundary is
defi ned hydrographically, by the average position of the
Subtropical Convergence. The Subtropical Convergence
is located around 40ºS (Deacon 1934, 1937), where the
surface temperature of the sea drops sharply from about
18°C to 10°C. In this review, then, the Southern Ocean
includes both the Antarctic region and the subantarctic region.
Antarctic and subantarctic regions are separated by
the Antarctic Convergence, which is located around 55ºS,
where the sea surface temperature drops 3°C to 5°C over
about 30 miles (48.3 km). Although the latitudinal positions
of both the Subtropical Convergence, among the Atlantic,
Pacifi c and Indian oceans, and the Antarctic Convergence,
among the Atlantic, Pacifi c and Indian sectors of
the Southern Ocean, may vary signifi cantly, locally, these
convergences seldom vary more than a degree of latitude
from their mean position.
Studies of the distribution of organisms are one of the
primary purposes of the discipline of taxonomy, and the
scope and effectiveness of taxonomic studies is dictated by
the availability of specimens. Like most pelagic organisms,
calanoid copepods in the Southern Ocean have been collected
mainly with tow nets operated aboard oceangoing
ships, which usually sail to a preselected set of geographic
positions in the ocean. Because of the physical isolation
of the Southern Ocean, studies of its pelagic calanoid
copepods have depended primarily on efforts of national