On a collection of hydroids (Cnidaria, Hydrozoa, Hydroidolina) from the west coast of Sweden, with a checklist of species from the region 3171
Author
Calder, Dale R.
text
Zootaxa
2012
2012-01-24
3171
1
1
77
https://biotaxa.org/Zootaxa/article/view/zootaxa.3171.1.1
journal article
10.11646/zootaxa.3171.1.1
11755334
5247704
Halecium halecinum
(
Linnaeus, 1758
)
Fig. 30
Sertularia halecina
Linnaeus, 1758: 809
[the specific name
halecina
Linnaeus, 1758
conserved and placed on Official List of Specific Names in Zoology, Opinion 1220 (ICZN 1982)].
Halecium halecinum
.—
Segerstedt, 1889: 15
, 26.—
Jäderholm, 1909: 57
, pl. 4, figs. 13, 14.—
Rees & Rowe, 1969: 12
.—
Jägerskiöld, 1971: 62
.
Halecium
cf.
halecinum
.—
Gislén, 1930: 329
.
Type
locality.
England
:
Kent
,
Whitstable
(
Cornelius 1975b: 394
)
.
Museum material.
Kosterhavet
,
58°52.567’N
,
11°06.313’E
,
6–30 m
,
07.ix.2010
,
SCUBA
,
three colonies with fragments, up to
7 cm
high, two colonies with female gonophores and one with male gonophores, coll.
B.E. Picton
,
ROMIZ
B3897
.
Remarks.
Halecium halecinum
(
Linnaeus, 1758
)
is one of the most distinctive species of the genus in the typical shape of its trophosome. With a regularly pinnate colony form and moderately short, relatively straight branches, it resembles a herring skeleton. As noted by
Cornelius (1995a)
, this hydroid was aptly called the “herring-bone coralline” by
Ellis (1755)
.
Schuchert (2005)
noted that there are variations from this well-known form of the species. Identifications are best made from examination of female gonothecae, if present, which are oblong and have an aperture at the end of a terminal, asymmetrically placed collar. In the sympatric
H. beanii
(
Johnston, 1838
)
and
H. sessile
Norman, 1867
, and in the circumpolar
H. scutum
(
Clark, 1877
)
, such gonothecae are mitten-shaped, with the aperture occurring laterally. Several other characters distinguishing
H. halecinum
from
H. beanii
were noted by
Medel & Vervoort (2000)
: (1) hydrocladia usually arise from the front or back of hydrothecae instead of laterally, (2) the first internode of a hydrocladium is usually thecate rather than athecate, (3) secondary hydrophores are longer.
Characters of hydranths of
H. halecinum
have been studied by
Cornelius (1998)
, and by
Gravier-Bonnet (2007)
, who described a new
type
of hydranth in the species termed an “extensible polyp.” Such polyps were capa- ble of great extension and contraction, and were thought to have defensive, excretory, and possibly sensory functions. They were scattered irregularly over the colony.
Contemporary taxonomic accounts of
H. halecinum
include those of
Cornelius (1975a
,
1995b
), Medel
et al
. (1998),
Medel & Vervoort (2000)
, and
Schuchert (2005)
. An extensive synonymy was listed by
Medel & Vervoort (2000)
, together with detailed distribution records of the species worldwide.
According to
Rees & Rowe (1969)
, this is the most abundant species of the genus
Halecium
Oken, 1815
on the west coast of
Sweden
. Records by
Jägerskiöld (1971)
support that conclusion (see Checklist). It is also the most common species of
Halecium
in waters around
Denmark
(
Kramp 1935b
), and it occurs up the Oslofjord of
Norway
as far as Steilene (
Christiansen 1972
).
Reported distribution.
West coast of
Sweden
.—From Säcken to southern Kattegat,
9–200 m
(
Jägerskiöld 1971
).
Elsewhere.—Atlantic Ocean from Spitzbergen and northern seas of the
Russian Federation
to
South Africa
in the east (
Cornelius 1995a
), and from the Strait of Belle Isle to Chesapeake Bay (
Calder 2004
) in the west, with questionable records from the Caribbean Sea and Gulf of Mexico (
Flórez González 1983
;
Bandel & Wedler 1987
;
Reyes & Campos 1992
;
Calder & Cairns 2009
). It has also been reported from the western and eastern Pacific, and from the Indian Ocean (
Medel & Vervoort 2000
).