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
Coryne
sp.
(fig. 3A–D)
Material examined
.
Stn. 3
:
01.04.2008
—several colonies of various sizes, some with propagulae and/or medusa buds, on algae and concretions.
Stn. 7
:
25.03.2008
—a few sterile colonies, some hydranths with propagulae, on concretions (
MHNG
INVE
60982);
29.03.2008
—a small, sterile colony, propagulae absent, on hydrocoral.
Description
. Colonies stolonal, cauli relatively short (
0.2–2.3 mm
high); perisarc smooth, diameter gradually increasing from base (105–120 µm) towards distal end (170–260 µm). Hydranths cylindrical, 0.5–2.0 mm high, 300–325 µm wide, hypostome short, dome-shaped. Perisarc collar at hydranth base absent. One whorl of 4 tentacles around hypostome held nearly vertically; five additional, more or less distinct rows of lower tentacles scattered over 2/3–3/4 of body; a total of up to 26 tentacles per hydranth; all capitate, filiform tentacles absent. Oral tentacles with diameter of capitula exceeding those of lower tentacles (115–125 µm
vs
. 70–100 µm); stalks short and slightly tapering distally, length decreasing from distal to proximal row. Some stems with lateral, branch-like structures covered with perisarc, these irregularly ramified several times; propagulae budded off from open tips; 190–215 µm long, 115–125 µm wide. Gonophores developing among the lowest whorl of tentacles, the latter occasionally less numerous than in sterile specimens; liberated as free medusae; up to 8 buds per polyp. Medusa buds globular to pear-shaped; borne on short pedicels; 4 tentacle bulbs visible as brown patches, each with one red ocellus. No other structures could be examined. Some polyps simultaneously producing frustules and medusae. Color: white-milk to pale pink, hypostome of polyp and manubrium of medusa buds brownish. Cnidome of polyp and propagula (undischarged capsules): two size classes of stenoteles, large (17.8–20.8) × (13.6–14.7) µm and small (8.6–10.4) × (6.6–7.4) µm. Cnidome of medusa buds (undischarged capsules): desmonemes (6.4–7.1) × (3.7–4.1) µm; three distinct size classes of stenoteles,
i.e.
large (11.4–12.7) × (8.7–10.4) µm, medium-sized (9.3–10.7) × (6.6–8.4) µm, and small (7.1– 7.4) × (5.6–6.1) µm.
FIGURE 3
. A to D:
Coryne
sp.—Hydroid with propagulae budding off from tips of branch-like structures (A); fragment of fertile colony with medusa buds (B); propagula (C); nematocysts of the hydroid (left) and medusa bud (right) (D). E:
Pennaria disticha
Goldfuss, 1820
—hydranth with gonophore. F:
Sphaerocoryne bedoti
Pictet, 1893
—hydroid. G to I:
Zyzzyzus warreni
Calder, 1988
b—hydroid with gonophores (G); female gonophore in frontal (above) and lateral (bottom) views, showing blastostyle and two developing actinulae (H); nematocysts of hydranth (I). J to L:
Zanclea migottoi
sp. nov.
—pedicels, showing the structure of perisarc (J); fertile (left) and sterile (right) hydranths (K); nematocysts (L). M and N:
Aequorea
sp.—fragment of colony (M); nematocysts of hydranth (N). O and P:
Clytia gracilis
(M. Sars, 1850)
—hydrotheca with pedicel (O); gonotheca (P). R and S:
Clytia hummelincki
(Leloup, 1935)
—hydrotheca with pedicel (R); gonotheca (S). Scale bars: 10 µm (D, I, L, N); 100 µm (C); 200 µm (M, P); 300 µm (F, H, J, K, R); 400 µm (S); 500 µm (E, O); 1 mm (A, B, G).
Remarks
. This species, from areas with high water movement, exhibits two simultaneous modes of reproduction and dispersal: asexual, by massive production and release of frustules, and sexual, liberating free swimming medusae.
The formation of frustules in the genus
Coryne
has been rarely described, as for instance the South-African record by Millard (1975) of a dwarf, sterile form, provisionally assigned to
C. pusilla
Gaertner, 1774
.
Due to its peculiar mode of reproduction, the present material may belong to a new species, but I refrain in naming it until the adult medusa is known.
Distribution
. Presently known from
Guadeloupe
and Les Saintes.