Hydroids (Cnidaria, Hydrozoa) of the Danish expedition to

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164 highly polysiphonic stem (although also monosiphonic ones occur in the same colony), the shorter hydrothecae, and the broad, rounded cusps. Clytia linearis typically has pointed cusps and the longitudinal inward-fold are very narrow, giving a much more distinct longitudinal striation (see Fig. 20). Recently, Medel & Vervoort (2000) assigned material from Madeira to this species. Their material closely resembles the Pacific material, but has more pointed cusps which are apparently inclined to one side, and the gonotheca has a slight neck formation and lacks an annulated pedicel. Moreover, Medel & Vervoort do not mention longitudinal folds of the hydrothecae in their material. Distribution Indonesia, Vietnam, Seychelles, Gulf of Suez, Gulf of Akaba, Madeira (after Medel & Vervoort 2000). Type locality: Port of Ambon, Moluccas, Indonesia. Clytia gracilis (M. Sars, 1850) Fig. 23. Laomedea gracilis M. Sars, 1850: 138. Clytia gracilis. – Stechow & Müller 1923: 461. – Cornelius Fig. 23. Clytia gracilis (M. Sars, 1850); MHNG INVE 25040. Hydrotheca and gonothecae. – Scale: 0.2 mm. P. SCHUCHERT & Östman 1986: 163. – Calder 1991: 54, fig. 31, synonymy. – Ramil & Vervoort 1992: 235, fig. 67a. – Cornelius 1995b: 246, fig. 56. – Hirohito 1995: 63, fig. 18c–g. – Migotto 1996: 81, fig. 15c. – Medel & Vervoort 2000: 32, bibliography. In part Clytia serrulata. – Pictet 1893: 30, pl. 2: figs 24–25. Material examined : MHNG INVE 25040, as Clytia serrulata, Ambon, material of Pictet (1893), slides and alcohol material. Description Colony stolonal or sparingly branched (1–3 times), height up to 5 mm. Perisarc smooth with annulated stretches. Hydrotheca campanulate, depth 0.6 mm, diameter 0.33 mm, perisarc thin, diaphragm at base thin but distinct, margin with 12 large, pointed teeth, separated by rounded embayments. The teeth are often asymmetric (tilted) with one side almost vertical and the other oblique. The margin in the embayments is slightly everted. Gonothecae arise on stolons and stems, oblong barrel-shaped, at distal end an indistinct neck formation for the aperture. Blastostyle produces medusae with a hemispherical bell and four bulbs. Remarks As discussed under C. linearis, part of the material described by Pictet (1893) as C. serrulata (Bale, 1888) can be assigned to C. gracilis, a fact already suspected by Calder (1991). The material matched rather well material from the North Atlantic (Schuchert 2001), only the hydrothecae are somewhat smaller and apparently not all cusps are asymmetric (tilted). Clytia gracilis has previously been reported for Indonesian waters by Stechow & Müller (1923). Distribution Circumglobal in temperate and tropical waters. Type locality: Lofoten Islands, Norway. Obelia bidentata Clarke, 1875 Fig. 24 Obelia bidentata Clarke, 1875: 58, pl. 9: fig. 2. – Cornelius 1975a: 260, fig. 2. – Cornelius 1982: 113, table 4, synonymy. – Gibbons & Ryland 1989: 405, fig. 23. –
HYDROIDS OF THE DANISH EXPEDITION TO THE KEI ISLANDS Fig. 24. Obelia bidentata Clarke, 1875; hydrothecae and gonotheca. – Scale: 0.2 mm. Calder 1991: 70, fig. 37, synonymy. – Ramil & Vervoort 1992: 241, fig. 68a–b. – Cornelius 1995b: 292, fig. 68. – Migotto 1996: 87, fig. 16c. – Medel & Vervoort 2000: 46, fig. 12, bibliography. Obelia bicuspidata Clarke, 1875: 58, pl. 9: fig. 1. – Fraser 1944: 153, fig. 125. – Millard & Bouillon 1973: 56. – Millard 1975: 226, fig. 75C–D. – Hirohito 1995: 71, fig. 21a–b, pl. 5: fig. A. In part Obelia bidentata var. – Pictet 1893: 25, pl. 1: figs 20– 21. Gonothyraea longicyatha Thornely, 1900: 454, pl. 44: fig. 4–4a. Material examined : Kei Islands Expedition station 81, with gonothecae. Description Colonies erect, up to 4 cm high, arising from a tangled mass of stolons anchoring the colony in the sediment. Main trunk forked several times, polysiphonic, thinning to monosiphonic, branching irregular, primarily in one plane. Short stretches of annulations alternating with long smooth regions of perisarc. Hydrothecae on short, annulated pedicels; hy- 165 drothecae set relatively dense. Hydrotheca deep, conical, often slightly asymmetric in lower region through slightly bulging wall, depth 0.7– 0.75 mm, diameter at opening 0.30–0.33 mm, diaphragm thin, may be oblique, calyx margin with about 12 bimucoronate cusps, embayments all U-shaped, embayments not or only slightly everted. Each cusp with two very pointed teeth, separated by a deep embayment, depth of this embayment about 2/3 of the intercusp embayments. There are no longitudinal lines along the hydrotheca. Gonothecae borne singly along stem, comparatively small, length around 0.8 mm, with annulated pedicel, main body flattened, clubshaped in broad view, end truncated, without neck formation. Blastostyle with medusa buds, most advanced with numerous short tentacles. Remarks The gonothecae seen in the present specimen of O. bidentata were all flattened. Similarly compressed gonothecae were noted for this species by Hirohito (1995) and Thornely (1900, as Gonothyraea longicyatha), although the latter attributed this to the fixation. Although this is a reasonable explanation, living Pacific material should be examined to confirm this. In the present specimen, the regularity of the compression, even in immature gonothecae, led me to suspect that this compression is a natural feature. Perhaps it is confined to some Pacific populations. The gonothecae of O. bidentata are mostly described as having no neck at their end, but Gibbons & Ryland (1989) and Cornelius (1995b) depict and describe specimens having a distinct neck with a much smaller diameter than the main body of the gonothecae, resembling gonothecae found in many other Obelia species. As discussed under C. linearis, material described by Pictet (1893) as O. bidentata is mostly referable to C. linearis, although the figures given by Pictet (1893) are clearly of O. bidentata. Distribution Circumglobal in temperate to tropical waters (Medel & Vervoort 2000). Type locality: Wharf piles of Greenport, Long Island, New York, USA.
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