On a collection of shallow-water hydroids (Cnidaria: Hydrozoa) from Guadeloupe and Les Saintes, French Lesser Antilles
Author
Galea, Horia R.
text
Zootaxa
2008
1878
1
54
journal article
10.5281/zenodo.184149
086e0d63-8af0-4ad1-8884-03fa56b5ea98
1175-5326
184149
Sertularella peculiaris
(
Leloup, 1935
)
(fig. 6A–E, table 12)
Thyroscyphus intermedius
f.
peculiaris
Leloup, 1935
: 33
, figs 15–17.
not
Thyroscyphus intermedius
Congdon, 1907
: 482
, figs 33–36 [=
Symmetroscyphus intermedius
(
Congdon, 1907
)
].
Sertularella peculiaris
Leloup, 1974
: 34
, footnote 1.
Sertularella parvula
—
Vervoort, 1968
: 46
, fig. 22.—?
Vervoort, 1972
: 131
, fig. 41B–C. not
Calamphora parvula
Allman, 1888
: 29
, pl. 10 figs 3, 3A.
Sertularella conica
—
Calder, 1983
: 11
, fig. 4.—
Calder, 1991d
: 99
, fig. 52.—
Migotto, 1996
: 67
, fig. 12J–K. not
Sertularella conica
Allman, 1877
: 21
, pl. 15 figs 6–7.
Material examined
.
Stn. 2
:
22.01.2008
—several small, fertile colonies, on algae;
26.01.2008
—several sterile colonies, on algae.
Stn. 3
:
01.04.2008
—several small, sterile colonies with both stolonal and erect growth forms, on concretions and algae.
Stn. 7
:
25.03.2008
—several small, sterile colonies, on
Dictyota
sp. and other algae;
27.03.2008
—several colonies, with both stolonal and erect growth forms, some with gonothecae, on
Halimeda
sp. and other algae (
MHNG
INVE
60981).
Type
locality
.
Bonaire
Island
,
Netherlands Antilles
, Caribbean Sea [Leloup’s (1935) station 27].
Description
. Colonies mostly stolonal, occasionally bearing a few erect, sparingly branched stems. Stolonal form with both hydrothecae and gonothecae arising at more or less regular intervals from linear hydrorhiza creeping on algae. Hydrothecae borne on short, slightly undulated pedicels, both separated by a relatively thick diaphragm (the hydrothecal base). Erect form slender, geniculate, with stems of up to 13 hydrothecae. Side branches arising below stem hydrothecae, the latter becoming axillar. Internodes of variable length, delimited by nearly imperceptible oblique nodes; perisarc slightly undulated to smooth. Hydrothecae alternate; bilaterally symmetrical in both stolonal and erect forms; flask-shaped, adnate for one third or less their length; widest basally, narrowing towards aperture, margin flaring; walls provided with 6–8 transverse ridges completely encircling the theca. Margin rhomboidal with rounded corners; with 4 triangular, pointed cusps separated by 4 shallow, rounded embayments. Operculum composed of 4 triangular flaps forming a shallow roof. Five large, conspicuous, intrathecal cusps present just below the aperture: one abcauline, 2 latero-abcauline, and 2 latero-adcauline; easily seen through the hydrothecal wall, exact position best visible in apical view of aperture; cusps protruding at about one third inside lumen of hydrotheca. Gonotheca (male=female?) arising from stolon via short pedicel; elongated-ovoid, with 7–8 transverse ridges; a short neck below aperture, the latter surrounded by 3–4 small, rounded, apical projections.
Remarks
. The present material is identical in every respect with that described and figured by
Leloup (1935)
as
Thyroscyphus intermedius
f.
peculiaris
from
Bonaire
Island
, southern Caribbean. Later on,
Leloup (1974)
recognized important differences with Congdon’s (1907) species (presently known as
Symmetroscyphus intermedius
), and gave his specimens the new name
Sertularella peculiaris
.
Sertularella peculiaris
shares some features with
S. robusta
Coughtrey, 1876
, as follows: 1) colonies with both stolonal and erect growth forms; 2) stems always monosiphonic; 3) hydrothecae flask-shaped, with slightly swollen basal part, narrowing distally, rim slightly everted; walls provided with a number of external ribs; several internal projections of perisarc below aperture; 4) gonothecae elongated-ovoid; walls with a number of external folds; aperture encircled by projections of perisarc.
Two important differences allow the separation of both species, as follows: 1) the hydrothecae of
S. peculiaris
possess 5 conspicuous, internal projections of perisarc below the aperture, whilst only 3 (one abcauline and two lateral) are normally found in
S. robusta
; 2) the gonothecal opening of the former possesses 3 or 4 small, rounded perisarcal projections, whilst the latter has 4 prominent spines. The number of external ribs on both hydrotheca and gonotheca of
S. robusta
is a variable character (see
Galea, 2007
) and has no taxonomic value.
A hydroid strikingly resembling
S. peculiaris
was described by
Vervoort (1968)
under
Sertularella parvula
(
Allman, 1888
)
. His material originated from St. Thomas (
British Virgin Islands
, northeastern Caribbean) and was rather scarce, but fortunately contained three hydrothecae and a gonotheca, all arising directly from the stolon.
Vervoort (1968)
found his material in perfect agreement with that of
Leloup (1935)
but, however, synonymized it with Allman’s species, most probably due to its stolonal condition.
Later on,
Vervoort (1972)
described a similar hydroid with stolonal habit from the Strait of Magellan. Though considering his material as being conspecific with Leloup’s (1935) hydroid, he assigned it again to Allman’s species. Because the South-American material was sterile and had hydrothecae with variably developed internal projections of perisarc (
Vervoort 1972
), it is here thought to be different from the Caribbean specimens. Vervoort’s hydroid might be a variant of
S. robusta
, a hydroid abundantly found along the coast of southern
Chile
(
Galea 2007
); it was present on the same substrate,
Symplectoscyphus subdichotomus
(
Kirchenpauer, 1884
)
as the material described by
Galea (2007)
. However, in possessing 5 internal hydrothecal cusps, instead of 3, it does not match the current concept of
S. robusta
.
Although
Calamphora parvula
Allman (1888)
may superficially resemble the material studied by
Vervoort (1968
,
1972
), there are some arguments supporting their separation: 1) both the hydrothecae and gonothecae of
C. parvula
have a greater number (10–12) of closely-set, “annular ridges” (see
Allman 1888
, p. 29 and pl. 10 fig. 3A) than Vervoort’s specimens; 2) no internal perisarcal projections have been described in the hydrothecae of
C. parvula
, although this feature may not have been considered as of any taxonomical importance by Allman; 3) the gonotheca of
C. parvula
has 4 large, prominent marginal projections of perisarc around its aperture; 4) Allman’s species originated from the Bass Strait,
Australia
, a quite remote locality compared with that from which Vervoort’s material was found. Therefore, I consider at least Vervoort’s (1968) material as being conspecific with
S. peculiaris
.
Additionally, the present specimens of
S. peculiaris
from
Guadeloupe
very much resemble the hydroids from
Bermuda
and
Brazil
described by
Calder (1991d)
and
Migotto (1996)
, respectively, under
Sertularella conica
Allman, 1877
. The hydrothecae of both specimens exhibit the characteristic 5 large, intrathecal cusps below the rim of hydrotheca. Moreover, the general shapes and dimensions of both hydrotheca and gonotheca fit those observed in
S. peculiaris
(see table 12).
FIGURE 6
. A to E:
Sertularella peculiaris
(Leloup, 1935)
—two erect colonies (A); fragment of colony with stolonal hydrotheca, a small erect stem and a gonotheca (B); stolonal hydrotheca in posterior (C) and lateral (D) views; frontal view of the hydrothecal aperture (E). F and G:
Sertularia loculosa
Busk, 1852
—fragment of stem (F); gonotheca (G). H and I:
Sertularia marginata
Kirchenpauer, 1864
—fragment of stem (H); gonotheca (I). J and K:
Sertularia notabilis
Fraser, 1947
—fragment of stem (J); frontal view of the hydrothecal aperture (K). L and M:
Sertularia rugosissima
Thornely, 1904
—fragment of stem (L); latero-dorsal view of hydrotheca, showing the internal, abcauline projection of perisarc and the opercular flaps (M). Scale bars: 50 µm (E, K); 100 µm (M); 200 µm (C, D, F, J, L); 300 µm (B); 400 µm (A, G); 500 µm (H, I).
TABLE 12.
Measurements of
Sertularella peculiaris
(
Leloup, 1935
)
, in µm. (1)The dimensions given by
Leloup (1935)
are obviously erroneous and should be read as given below. (2)Dimensions calculated from fig. 12J. (3)The length of the abcauline wall is here considered as an approximation of the height of hydrotheca.
|
Present study,
Sertularella peculiaris
(Leloup, 1935)
|
Leloup (1935), as
T. interme- dius
Congdon, 1907 f.
pecu- liaris
|
Vervoort (1967), as
Sertularella parvula
(All- man, 1888)
|
Calder (1983), as
Sertularella conica
All- man, 1877
|
Calder (1991d), as
Sertularella conica
All- man, 1877
|
Migotto (1996), as
Sertularella conica
All- man, 1877
|
| Hydrotheca (stolonal form) |
| – height |
560–700 |
500–800 |
525 |
– |
– |
– |
| – maximum width |
305–355 |
350–450 |
250 |
– |
– |
– |
| – diameter at rim |
205–245 |
200–250 |
– |
– |
– |
– |
| – number of ridges |
6–8 |
4–5 |
8–9 |
– |
– |
– |
| – internal projections of perisarc |
5 |
5 |
5 |
– |
– |
– |
| – pedicel length |
210–315 |
300–450 |
150 |
– |
– |
– |
| – pedicel diameter |
110–150 |
100–150 |
– |
– |
– |
– |
| Hydrotheca (erect form) |
| – abcauline wall |
445–525 |
– |
– |
398–562 |
404–638 |
400–448 |
| – free adcauline wall |
335–380 |
– |
– |
293–445 |
319–553 |
272–352 |
| – adnate adcauline wall |
150–170 |
– |
– |
211–257 |
181–340 |
135–152 |
| – maximum width |
205–240 |
350–450 |
– |
– |
– |
240–256 |
| – base diameter |
125–150 |
– |
– |
– |
138–213 |
– |
| – diameter at aperture |
170–190 |
200–250 |
– |
187–211 |
181–213 |
184–228 |
| – number of ridges |
5–6 |
5–6 |
– |
4–8 |
4–5 |
4–5 |
| – internal cusps |
5 |
5 |
– |
5 |
5 |
5 |
| Internodes (erect colony) |
| – length |
205–820 |
– |
– |
– |
362–851 |
ca.
270–280(2)
|
| – diameter at node |
105–120 |
– |
– |
135–181 |
138–255 |
ca.
100–110(2)
|
| Gonotheca |
| – height |
1270–1385 |
ca.
1200(1)
|
– |
– |
ca.
1250
|
720 |
| – maximum width |
760–860 |
ca.
900(1)
|
– |
– |
ca.
660
|
600 |
| – diameter at aperture |
270–300 |
– |
– |
– |
245 |
240 |
| – number of ridges |
7–8 |
6 |
– |
– |
8–12 |
7–8 |
| – number of apical projections |
3–4 |
3 |
4 |
– |
4 |
– |
The description of
S. conica
given by
Allman (1877)
is very succinct and was based on sterile material. The main typical features of his species are: the long stem internodes; the flask-shaped hydrothecae, narrowing from base to margin; the rather straight free adcauline wall, with several slightly-marked folds on its surface. There is no mention of the presence of internal cusps below the hydrothecal aperture. Therefore, the features listed above are very insufficient to allow a positive identification of the species.
Sertularella conica
shares, for example, more morphological similarities with the trophosome of
S. unituba
(
Calder, 1991d
)
than with the specimens described by
Calder (1991d)
and
Migotto (1996)
under Allman’s species.
Sertularella conica
should be regarded as an unrecognizable species, pending the discovery of additional, fertile material from the
type
locality. In my opinion, both Calder’s and Migotto’s specimens undoubtely belong to
S. pecu-