26
Systematic Account
the P5 Re2 as figured by Brodskii (1950, fig.
258) but this spine has short hairs along its
length. This spine reaches the base of the 3rd
inner marginal seta of the Re3, while in A. I.
it reaches the 2nd marginal seta as reported
by Tanaka (1964b). Apparently, only the
males of A. glacialis and A. longicaudatus
can easily be separated by characters of the
P5: only inA. I. males does the left exopodite
end with a very long apical spine.
Distribution
This species is primarily reported for the
North Atlantic-Arctic region (Sars 1925;
Brodskii 1950; Johnson 1963), penetrating
far to the south in the Atlantic Ocean,
apparently absent in the North Pacific and
scarcely represented in the Antarctic
(Vervoort 1951). In the Arctic and Atlantic
Oceans, the species occurs in sub-surface
waters and at intermediate depths, but in the
temperate and tropical Atlantic the occurrence of A. glacialis is exclusively confined to
cold, deep waters (Vervoort 1965b). Tanaka
and Omori (1971) recorded this species in the
Izu Region, central Japan, at depths of 01200 m. In the present study, A. glacialis was
present only at Pacific stations in the Straits
of Magellan with maximum abundances from
400-500m.