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Botryopera (?) chlamida Petrushevskaya, 1975

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The walls are thick. The pores variable and numerous. The spongy
layer envelops the main shell. This is the distinguishing character of
the species. The shell is bigger but the shell outline is similar to B.
triloba group: the cephalis of nearly the same width as the thorax.
However, thorax (ellipsoidal or cylindrical) is somewhat broader than
the cephalis. The arrangement of the outer spines A, D, L and Vert
typical for Botryopera. No horn on the top of the cephalis. The species
may belong in the same genus with Antarctissa (?) capitata. B. (?)
chlamida
differs from A. (?) capitata by the longer and broader thorax,
better developed outer spines D, A, L and Vert, and more pronounced
spongy layer. B. (?) chlamida differs from Botryometra spongiosa n. sp.
(Plate 13, Figure 11) in having a cephalis nearly the same size as the
thorax. Also, in B. (?) chlamida the branches a are arranged low (no
higher than at l of the spines A), while in the species mentioned these
branches are highly arranged, nearly going in the upper walls of the
cephalis. The most characteristic feature of Botryometra (?) spongiosa
is the well-developed antecephalic lobe (of nearly the same type as in
Cannobotyods), this lobe in B. (?) chlamida is small and confused (as it
is characteristic for Botryopera and some other Dicyrtids) with the
thorax. In the species mentioned the cephalis is well separated from
the thorax. The author is not sure if this species and B. (?) chlamida are
related. It is possible that their spongy layers represent only a
convergent- or parallel-developed structure. B. (?) chlamida is very
rare. The description is based on 3 specimens from Ob Stations 16 and
153 surface sediment. Holotype No. 63118 in Marine Department.
Petrushevskaya 1975


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