Hydroids of the genus Sertularella (Cnidaria: Hydrozoa: Sertulariidae) from the Pacific coast of Canada in the collection of the Royal Ontario Museum, with descriptions of four new species
Author
Choong, Henry H. C.
text
Zootaxa
2015
3925
3
387
408
journal article
41950
10.11646/zootaxa.3925.3.4
9cef1bf3-1491-424d-bd24-02bbe81411e5
1175-5326
236318
8CA0F940-B481-4D02-AC6E-B254AE4EF986
Sertularella pacifica
sp. nov.
(
Figure 6
)
Sertularella fusiformis
—
Torrey, 1902
: 61
, pl. 6, fig. 53–54.—
Fraser, 1937
: 153
, pl. 34, fig. 181 [not
Sertularella fusiformis
(
Hincks, 1861
)
]
Material
.
Holotype
:
CANADA
: British
Columbia
. Vancouver Island, Juan de Fuca Strait, Race Rocks, 48˚18’00”N, 123˚32’00”W, 0
5. iv.1986
, 6–10 meters, two short hydrocauli, with gonothecae, coll. A. Brinckmann- Voss,
ROMIZ
B670.
Paratype
:
CANADA
: British
Columbia
. Queen Charlotte Land District. Masset Harbor,
14. ix.1935
, without gonothecae,
ROMIZ
B4065.
Other material:
CANADA
: British
Columbia
. Queen Charlotte Land District. Masset Harbor, 54˚03’00”N, 132˚13’00”W,
14. ix.1935
, colony arising from stolon at the base of
Abietinaria pulchra
(
Nutting, 1904
)
colony, without gonothecae,
ROMIZ
B4066.
CANADA
: British
Columbia
. Queen Charlotte Land District. Masset Harbor,
14. ix.1935
, two short hydrocauli, without gonothecae,
ROMIZ
B4067.
CANADA
: British
Columbia
. Queen Charlotte Land District. Masset Harbor,
14. ix.1935
, colony arising from stolon at the base of
Sertularia
sp.colony, without gonothecae,
ROMIZ
B4068.
CANADA
: British
Columbia
. Queen Charlotte Land District. Masset Harbor, 54˚03’00”N, 132˚13’00”W,
14. ix.1935
, hydrocauli, without gonothecae,
ROMIZ
B4069.
Reported distribution
. California: San Francisco, as
Sertularella fusiformis
(
Hincks, 1861
) (
Torrey, 1902
)
. Oregon: Three locations off Heceta Head, 0–113 meters (
Fraser, 1937
).
Description.
Colonies erect, hydrorhiza stolonal, occasionally anastomosing. Hydrocaulus geniculate, unbranched. Perisarc thickened throughout, up to
60 mm
thick. Hydrocaulus monosiphonic, unfascicled, divided into internodes. Internodes
1003–1530
mm
long, with one to three (usually two) complete annulations basally; proximal-most annulation often spirally twisted (
Fig. 3
A,B). Internode has tendency to spiral relative to main axis. Single hydrotheca distal to internode. Hydrothecae alternate, often not on same plane (
Fig. 3
A). Hydrotheca tubular, walls asymmetrical; abcauline and adcauline wall slightly swollen basally, swelling on abcauline wall more proximal. Perisarc of hydrothecae thickened, up to
60 mm
thick. Distal half of hydrotheca narrowed towards aperture, greater narrowing on abcauline side. Adcauline hydrothecal wall adnate for approximately 1/4–1/2 of length. Hydrothecal margin dentate with four equally-developed cusps; one adcauline, one abcauline, and two laterals. Opercular flaps triangular, four present; when closed forms roof extending slightly beyond opercular margin. Intrathecal cusps present, three in number, occasionally missing; two small intrathecal cusps proximal to and flanking adcauline marginal cusp, one long and narrow intrathecal cusp on abcauline side (
Fig 3
A).
Gonothecae (♂) few, attached to internode or directly below base of hydrotheca; large, up to three-times longer than hydrothecae, spindle-shaped, widest medially, longer than wide, flexed or bent mid-axis. Gonothecal body strongly annulated throughout; 10–12 complete, well-developed annulations. Neck short or barely discernible, four low rounded cusps around gonothecal aperture. Occasionally, one of the four cusps may be more developed than other three.
Differential diagnosis
. The records from the west coast of North
America
(
Torrey 1902
;
Fraser 1937
) seem to be morphologically distinct from descriptions of
S. fusiformis
elsewhere as shown by the absence of four intrathecal cusps and the presence of two annulations at the base of the internodes. These descriptions correspond to the specimens examined by the author in this study. Given the variability of the species included in the
S. fusiformis
/
S.ellisii
complex, this species was most likely misidentified as
S. fusiformis
. Measurements of the internodes, hydrothecae, and gonothecae (
Table 4
) show that these specimens are much larger than
S. fusiformis
. The intrathecal cusps are never as well-developed as in
S. fusiformis
.
Moreover, the hydrothecae of
Sertularella pacifica
sp. nov.
lack the considerably swollen basal portion and strongly tapered upper portion characteristic of the fusiform hydrothecal shape, and the gonothecae are distinct from those belonging to
S. fusiformis
in being spindle-shaped and bent around their mid-axis.
TABLE 4.
Measurements of
Sertularella pacifica
sp. nov.
and
Sertularella fusiformis
.
Measurements (in µm) |
Sertularella fusiformis
(From Ramil
et al.
1992)
|
Sertularella pacifica
sp. nov.
|
Axial segment (internode) length |
605–720 |
1003–1530 |
Axial segment (internode) diameter |
130–173 |
390–460 |
Hydrotheca, adnate part adcauline wall |
288–331 |
550–660 |
Hydrotheca, free part adcauline wall |
360–432 |
880–980 |
Hydrotheca, abcauline wall |
560–576 |
1350–1410 |
Hydrotheca, diameter at rim |
216–245 |
470–590 |
Gonotheca, maximal length |
1000–1300 |
3730–3780 |
Gonotheca, maximal width |
520–740 |
1450–1670 |
Remarks
. This material agrees with the hydroids attributed to
Sertularella fusiformis
(
Hincks, 1861
)
from the west coast of North
America
by
Torrey (1902)
, and subsequently included in reports by
Fraser (1911
,
1937
).
Sertularella fusiformis
is well distributed in temperate and subtropical parts of the Atlantic as well as in the Mediterranean, but records of occurrences elsewhere are few and dispersed (
Ramil
et al
. 1992
). The latter are from the Indian Ocean coast of
South Africa
(
Millard 1975
) and from the Pacific coast of North
America
: Californian Pacific coast (
Fraser 1911
); off Heceta Head, Oregon (
Fraser 1937
). I consider the reports of
Sertularella fusiformis
from the Pacific coast of North
America
to be erroneous. Its biogeographic distribution, and the distinct morphological characteristics of
Sertularella pacifica
set this species apart from its congeners. Even within the Atlantic, it is probable that the nominal species
Sertularella fusiformis
is part of a species complex.
Sertularella fusiformis
, along with
S. mediterranea
,
S. ellisii
,
S. ornata
, and
S. polyzonias
are morphologically similar and so have been variously kept separate or synonymised with other taxa (
Cornelius 1979
;
Ramil
et al.
1992
;
Medel & Vervoort 1998
).
Millard (1958)
considered
S. fusiformis
to be a variable species, but accepted the diagnostic value of the presence of 4 intrathecal cusps that alternate with the marginal cusps in this species, a view shared by
Corrales
et al.
(1980)
. Others, such as
Picard (1956)
considered
S. fusiformis
to be an extreme, Atlantic form of
S. ellisii
. 16S genetic data has provided evidence that nominal species of
Sertularella fusiformis
from Madeira and the Azores in the North Atlantic fall into distinct clades likely corresponding to different species (
Moura
et al.
2011
).
Etymology
. The species name refers to the Pacific Ocean and emphasizes its distinctiveness from its congeners elsewhere.