Hydroids (Cnidaria, Hydrozoa) of the Danish expedition to

142
Fig. 3. Conopora major Hickson & England, 1905. A.
Colony, height 2.5 cm. B. Schematic organization of the
cyclosystem, split longitudinally, with ampulla on its side.
Note that lower dactylopores are not always as distinct as
shown here. – Scale: B = 0.2 mm.
by polychaete irregularly arranged, in distal
branches sympodial in arrangements, shifted
only slightly to one side of branch, distal ones
slightly standing out, proximal ones flush to
slightly recessed into branch coenosteum. Cyclosystems
circular to slightly irregular in shape,
1 mm in diameter, 9–16 dactylopores per nondiastemate
cyclosystem (mean 12.2, S.D. 1.6, n =
P. SCHUCHERT
47, 10 colonies, most frequent value (mode) 12),
one pseudoseptum occasionally thicker than others,
adaxial dactylopores of older cyclosystems
often filled by coenosteum (diastema). Gastropores,
about 0.4 mm in diameter. Gastropore
tubes up to 1.2 mm deep, divided into three
sections of approximately same height. Upper
section cylindrical, bordered by pseudoseptae;
below this part a middle section delimited below
by the ring of the lower dactylopores; lowest part
hemispherical, not delimited by constriction
from middle part or constriction very shallow and
indistinct. Ring of lower dactylopores can be
absent. Ampullae internal, ellipsoidal cavities,
only present around cyclosystems; efferent pores
on the pseudoseptae or in the gaps between them.
Remarks
The present samples came from a site near the
Kei Islands that is only about 40 km away from
one of the type localities of Conopora major. All
colonies showed little variation and matched perfectly
the description of Conopora major given
in Hickson & England (1905), notably also the
colony form (Fig. 2A). Broch (1936) assigned
material from Mauritius to C. major. His colonies
were more or less regularly pinnate and had their
cyclosystems on the anterior side only. Furthermore,
the diameter of the cyclosystems in
Broch’s samples measured 1.5–1.8 mm in diameter,
which is considerably more than the 1 mm
observed here, or the 1.2 mm observed by
Hickson & England (1905). Thus, the population
studied by Broch perhaps belongs to another
species, but due to the lack of information on the
geographic variability of this species it seems
impossible to draw reliable conclusions.
Cairns (1991) re-described the closely similar
Conopora verrucosa (Studer, 1878) and regarded
Conopora major as a potential junior
synonym. Cairns’ (1991) material from New
Zealand differs from the present one by having a
uniplanar growth versus a bushy and irregular
growth; by the abundant nematopores that make
the surface warty while in the present material
these nematopores are quite rare; by the longer
branches with more than 3 cyclosystems; by
gastropores that are twice as deep, and by the
regular presence of a constriction in the gas-