Taxonomic revision and systematic notes on some Halecium species (Cnidaria, Hydrozoa)
Author
Schuchert, Peter
text
Journal of Natural History
2005
2005-02-28
39
8
607
639
http://dx.doi.org/10.1080/00222930400001319
journal article
10.1080/00222930400001319
1464-5262
4668977
Halecium halecinum
(
Linnaeus, 1758
)
(
Figures 3
,
4
)
Figure 3.
Halecium halecinum
(
Linnaeus, 1758
)
; colony silhouettes, note variation of shapes. (A) Canary Islands; (B) The Faroes (BIOFAR station 111); (C) The Faroes (BIOFAR station 554). Scale bar: 2 cm.
Figure 4.
Halecium halecinum
(
Linnaeus, 1758
)
. (A–C) Segments of monosiphonic parts, with secondary hydrothecae, note length variation of internodes, BIOFAR station 350, 205 and 351; (D) BIOFAR 351, female gonotheca in side view; (E) as in (D), but seen from anterior side, note bipartite hydrotheca; (F) BIOFAR 597, male gonotheca. Scale bar: 0.2 mm.
Sertularia halecina
Linnaeus 1758
, p 809
.
Halecium geniculatum
Norman 1867
, p 205
.
[Not
H. geniculatum
Nutting
18995
H. tenellum
Hincks 1861
.]
Halecium halecinum
:
Broch 1911
, p 22
, Figure 22;
Broch 1918
, p 36,
Figures 11
,
12
;
Naumov 1969
, p 482, Figures 16K, 335, Plate 17
Figure 3
;
Vervoort 1972
, p 25,
Figure 3a
;
Cornelius 1975
, p 393,
Figure 6
, synonymy;
Millard 1975
, p 150, Figure 49A–H;
Cornelius 1995
, p 279, Figure 63;
Medel and Vervoort 2000
, p 14,
Figure 2
, bibliography;
Schuchert 2001
, p 78, Figure 64A, B.
Not
Halecium halecinum
var.
minor
Pictet 1893
, p 20
, Plate 1
Figures 14
,
15
;
Schuchert 2003
, p 153.
Material examined
MHNG
INVE 34732
,
France
,
Baie de Seine
,
17 September 1987
, dredged at
25 m
depth, female and male colonies.
MHNG
INVE 26671
,
France
,
Brittany
,
Roscoff
,
Roscoff
Bretagne
, coll.
September 1995
.
MHNG
INVE 27667
,
Canary Islands
,
Lanzarote
,
23 September 1999
, coll.
A. Faucci.
MHNG
INVE 33575
(
BIOFAR
station 205),
62.06
°
N
,
5.89
°
W
,
160 m
,
11 May 1988
, with female gonothecae, colony form atypical.
MHNG
INVE 33580
(
BIOFAR
station 402), the
Faroes
,
62.1
°
N
,
8.14
°
W
,
121 m
,
30 May 1989
, with male gonothecae.
MHNG
INVE 33582
(
BIOFAR
station 350), the
Faroes
,
62.26
°
N
,
7.99
°
W
,
107 m
,
22 July 1988
, typical female colonies.
MHNG
INVE 33587
(
BIOFAR
station 554),
61.94
°
N
,
6.49
°
W
,
62 m
,
22 September 1989
, no gonothecae, typical colony form.
BIOFAR
station 111,
62.12
°
N
,
6.50
°
W
,
50 m
,
25 July 1987
, one female gonotheca present.
BIOFAR
station 351,
62.26
°
N
,
7.77
°
W
,
102 m
,
22 July 1988
, with female gonothecae.
BIOFAR
station 597,
The Faroes
,
62.17
°
N
,
6.22
°
W
,
100 m
,
11 April 1990
, male gonothecae present.
Description
Colonies erect, stiff, up to
10 cm
high, colony form often regularly pinnate, sometimes irregular or with several pinnate side-branches. Side-branches alternate, straight, evenly spaced, at constant angle of 40–60
°
to main axis, secondary branching possible. Stem and main branches polysiphonic, thinning out to terminal monosiphonic branches. Segments of similar length within a region of the colony, segment length much variable among colonies, nodes approximately transverse. Hydrotheca sitting on a shallow hydrophore which is oblique to main axis of internode, opening plane inclined. Hydrothecae alternate, walls straight, with desmocytes, hydrotheca diameter at base
0.12–0.14 mm
, depth
30–50 mm
. Secondary hydrothecae frequent, on a long hydrophore, the latter at least twice as long as diameter, secondary hydrophore near base usually with a kink. Male gonotheca clubshaped, length about
0.9 mm
, aperture terminal. Female gonotheca paddle-shaped, tapering below, distally having a terminal aperture on one side and with right-angled ‘‘shoulder’’ on other side, aperture formed by a fused pair of hydrothecae that overtops gonotheca like a chimney, one or two polyps protruding from aperture, one to four eggs. Nematocysts: two
types
,
type
I (8–9.5)X(3.5–4) mm,
type
II (5–6)X(1.5–2) mm.
Distribution
East and
West Atlantic
, Mediterranean,
South Africa
,
Pacific, Arctic Seas.
Type
locality:
Whitstable
,
Kent
,
England
.
Remarks
As discussed under
H. scutum
, this species can be difficult to distinguish from
H. scutum
and
H. beanii
. In waters around the British Isles and continental Europe,
Halecium halecinum
often forms quite regular, pinnate colonies (
Figure 3A, C
).
Cornelius (1995)
considers this an important diagnostic trait of the species. In the material from the Faroes, the colonies were often quite irregular (
Figure 3B
). The pinnate colony form, however, is also found in Faroese waters (
Figure 3C
). Also some of the colonies examined from the English Channel were not so obviously pinnate.
Hincks (1868
, Plate 42, Figure a) depicted a colony originating from the British Isles which also deviates somewhat from the strictly pinnate form shown in the same plate. The colony form of
H. halecinum
is therefore not always regularly pinnate. But if present, the pinnate colony form is certainly a diagnostic trait of
H. halecinum
. Infertile or male colonies with atypical colony form can be impossible to identify if they are not part of a larger series that also includes fertile females.
Broch (1918)
thought that the shape of the secondary hydrothecae in
H. halecinum
differs from those of
H. beanii
in having an asymmetric adcauline wall. Such a difference was not found in the material examined here and neither was it mentioned by
Cornelius (1995)
(compare
Figures 4
A–C and 5D, F).
Millard (1966
,
1975
) also found that only the female gonotheca allows a reliable identification.
Medel and Vervoort (2000)
found that side-branches arise frontally or at the rear in
H. halecinum
, while in
H. beanii
they arise laterally.