Coryne

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.

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.

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.