ISSN 1063-0740, Russian Journal of Marine Biology, 2017, Vol. 43, No. 1, pp. 12–24. © Pleiades Publishing, Ltd., 2017.
Original Russian Text © V.G. Chavtur, 2017, published in Biologiya Morya.
The Composition, Structure, and Distribution of Benthic Ostracod
Fauna (Ostracoda, Myodocopa) in Antarctic Waters
V. G. Chavtur
Zhirmunsky Institute of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, 690041 Russia
Far Eastern Federal University, Vladivostok, 690950 Russia
Received May 24, 2015
Abstract⎯The benthic fauna of ostracods of the order Myodocopida of Antarctic waters is characterized by
high diversity, relative species abundance, and a complicated taxonomic and ecological structure, with a sim-
plified biogeographical structure. This fauna, which is distinguished by a high level of endemicity, although
at a low taxonomic rank, includes a great share of deep-sea and subtidal elements. Ostracod populations of
High and Low-Antarctic subzones differ qualitatively and quantitatively. A distinct impoverishment of fauna
is observed in the region of the Antarctic divergence compared to the more northern areas. The number of
species increases with depth to reach its maximum in the lower subtidal zone and on the upper continental
slope at depths of 200–500 m. The number of species decreases with increasing depth. Myodocopida have
not been yet found in the Antarctic waters deeper than 5000 m.
Keywords: Myodocopida, Cypridinidae, Philomedidae, Cylindroleberididae, Sarsiellidae, Antarctic, latitu-
dinal and vertical distribution
The first information about the benthic ostracods
of the order Myodocopida of the Antarctic was
obtained at the beginning of the last century [10, 17,
30]. A considerable amount of data on myodocopids
of the area has been accumulated, including informa-
tion on their distribution in a wide range of depths:
from the upper subtidal to the abyssal zone, inclusive
[12, 13, 16, 18–29, 32, 33]. Special distinction in the
study of this group belongs to the American zoologist
Kornicker [25–28], who described 90% of the total
composition of the presently known Antarctic fauna of
myodocopids. The level of the current knowledge
presents an opportunity to characterize the structure
and the vertical distribution of the Myodocopida
fauna, as well as to conduct a comprehensive analysis
of this biogeographical group.
This work, which is based on published data and
our own studies, is aimed at an analysis of the struc-
ture of the benthic fauna of myodocopids of Antarc-
tica and at revealing the peculiarities of their latitudi-
nal and vertical distribution.
MATERIALS AND METHODS
This work involved Myodocopida collections of
Russian and German expeditions (Table 1) from the
Mawson, Davis, Commonwealth, and Weddell seas,
the area of the South Shetland Islands, and the oce-
anic waters of the Atlantic sector of Antarctica (Fig. 1).
As well, our study considered all the available litera-
ture data on this group for Antarctica (Table 1). The
general list of Atlantic myodocopids, consisting of
70 species, includes 18 species with an open nomen-
clature (Table 2); three of them are described as “spe-
cies” [12, 13], while other species are new for science
and will be described by us in future.
In this paper, the outer boundary of Antarctica was
defined by the spatial position of the Antarctic Con-
vergence and the boundary between the high- and the
low-Antarctic subzones was determined by the posi-
tion of the Antarctic Divergence (approximately 65° S)
; sea borders were determined by charts [1, 6].
The vertical zonation of the benthic zone corre-
sponds to the scheme developed at the Institute of
Oceanology of the Russian Academy of Sciences .
The degrees of similarity between faunas of differ-
ent areas were compared using Jaccard and Sørensen
indices calculated (respectively) by the formulas: K =
c/(a + b) – c and K = 2c/a + b, where a and b are the
number of species found in the areas under comparison
and c is the number of their species in common .