Hydroids (Cnidaria, Hydrozoa) of the Danish expedition to

158
deep, opening diameter 0.18 mm, cylindrical,
tapering below into distinct pedicel, pedicel corrugated;
rim of opening slightly flared; no diaphragm
or operculum.
Gonothecae absent (see Millard 1975 or Cornelius
1995a).
Remarks
Lafoea dumosa is here recorded in Indonesian
waters for the first time. This cosmopolitan
and extraordinarily variable species has an extensive
and complicated synonymy (see Cornelius
1975b, Rees & Vervoort 1987, Schuchert 2001).
Contemporary authors mostly do not distinguish
anymore between forms having hydrothecae
on stalks or sessile ones. However, Schuchert
(2001) noted that most colonies with sessile
hydrothecae also have significantly smaller
isorhiza capsules, suggesting nevertheless the
presence of two species. The present material
from Indonesia (Fig. 16) had without exception
hydrothecae with distinct stalks and the larger
nematocyst capsule measured around 25 µm in
length, thus conforming with the common Atlantic
form.
Distribution
Cosmopolitan, mostly below 100 m. Type locality:
Arbroath, Scotland.
Zygophylax bifurcata Billard, 1942
Fig. 17.
Zygophylax bifurcata Billard, 1942a: 34, figs 1–3. – Rees &
Vervoort 1987: 79, fig. 13.
Material examined:
Kei Islands Expedition station 52, 3 shoots on small bivalve.
Description
Colonies erect, up to 1 cm, growing on bivalve,
stem polysiphonic, hydrocladia monosiphonic.
Primary tube of stem bears hydrothecae and
hydrocladia.
Hydrocladia unbranched, alternate, in two
rows, thin and delicate, nodes indistinct, below
distal node apophysis for attachment of hy-
P. SCHUCHERT
Fig. 17. Zygophylax bifurcata Billard, 1942. A. Part of
hydrocladium with hydrotheca. B. Apophysis with nematotheca.
– Scales: A = 0.2 mm; B = 50 µm.
drotheca. Apophysis occasionally with nematotheca.
Hydrothecae alternate, with pedicels longer or
as long as hydrotheca, pedicels about 0.4 mm
from base to diaphragm, at base some irregular
annulation, with distinct node delimiting it from
apophysis. Hydrotheca cylindrical, about 0.3
mm from diaphragm to opening, tapering at base
continuously into pedicel; opening diameter 0.12
mm, often slightly inclined; diaphragm thin.
Nematotheca tubular, often curved, lower end
annulated, margin slightly everted. Gonothecae
not present.
Remarks
The present material is only tentatively assigned
to Z. bifurcata because it lacks one of the diagnostic
characters: the bifurcated hydrocladia.
The colonies appear, however, to be juvenile and
as in other hydroids hydrocladia may branch
during later development. The identification was
based on the long pedicels of the hydrothecae.
Zygophylax bifurcata seems to be the only species
in this genus with non-recurved primary
hydrothecae that have pedicels as long or longer
than the hydrotheca.