Hydroids (Cnidaria, Hydrozoa) of the Danish expedition to

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192 pl. 5: fig. 8. – Billard 1910: 21, fig. 7. – Billard 1925b: 174. – Vervoort 1941: 217. – Watson 2000: 33, fig. 26A– E . Desmoscyphus obliquus Allman, 1888: 72, pl. 34: fig. 3–3a. Sertularia trigonostoma var. alternata Vervoort, 1959: 284, fig. 42. Material examined: Kei Islands Expedition stations: 68. – 71; both colonies without gonothecae. Description Colonies erect, pinnate, up to 7 cm high. Stems monosiphonic, rather thick near base (0.7 mm), tapering distally, bearing alternate hydrocladia and two lateral rows of alternate hydrothecae, nodes distinct to indistinct, if present, alternately slanted and delimiting internodes. Stem internodes with three hydrothecae and an apophysis for hydrocladium, two hydrothecae on side of apophysis, one on opposite side, apophysis below lower hydrotheca. Hydrocladia straight, parallel, regular, arising at an angle of about 45° to axis, unbranched, longest ones in lower region of shoot, well demarcated from apophysis by transverse node, nodes more or less distinct, nodes inclined towards one side, two subopposite hydrothecae per internode; hydrothecae shifted to anterior side of internode, adnate on anterior side, separate on rear side. Hydrotheca adnate for most of its length, sacshaped, walls thick, abcauline side about 0.2 mm long, straight; opening directed upwards, margin with two blunt lateral teeth and sometimes a small adcauline median tooth. Opening elliptical, margin reinforced by thickened perisarc, operculum composed of two valves, difficult to observe. Connection of hydrotheca to internode very wide, thus hydrotheca without true floor. Gonothecae not present (see Watson 2000 for description). Remarks The hydranths in the present samples were not ideally preserved and it was not possible to decide reliably whether an abcauline caecum is present or not. Watson (2000) states that there is no caecum, although she also had badly preserved hydranths. If the absence of an abcauline P. SCHUCHERT caecum can be corroborated, this species should be referred to the genus Dynamena. Distribution Tropical Indo-Pacific, Red Sea, tropical western Africa. Type locality: Torres Strait, Australia. Sertularia malayensis Billard, 1925 Fig. 46. Sertularia malayensis Billard, 1925a: 649. – Billard 1925b: 173, fig. 32. – Vervoort & Vasseur 1977: 57, fig. 25. – Hirohito 1983: 49, fig. 21. – Gibbons & Ryland 1989: 421, fig. 37. – Hirohito 1995: 215, fig. 72a–c. Material examined: Kei Islands Expedition station 26, several shoots without gonotheca on S. quadridens var. timorensis. Description Colonies forming erect unbranched shoots without hydrocladia, height 2–4 mm. Stolons creeping, ramified. Stem thin (about 0.1 mm), with occasional oblique or transverse nodes. Hydrothecae strictly opposite, each pair contiguous on frontal side, separated at rear. Hydrotheca tubular, upper and underside converging and end thus duck-bill shaped, adcau- Fig. 46. Sertularia malayensis Billard, 1925. Pair of hydrothecae. – Scale: 0.1 mm.
HYDROIDS OF THE DANISH EXPEDITION TO THE KEI ISLANDS line wall adnate for 1/3 of its length, abcauline curved, about 0.18 mm long, adcauline wall quite sharply bent where becoming free, margin with two long, pointed lateral teeth, operculum formed by two valves, upper one much larger, lower valve not distinctly delimited from hydrotheca, distal end of hydrotheca very soft and often distorted; floor of hydrotheca complete, lower end of adcauline wall forming short, pointed process. Hydranth with about 8 tentacles, with small abcauline caecum. Gonothecae not observed (according to Hirohito 1983: pear-shaped, smooth walls, with truncate end and opening on short collar). Remarks The hydrothecal margin of this small and delicate species is rather flimsy and the generic characters are very difficult to see. Leloup (1930b) described a variant of this species from New Guinea as Sertularia malayensis var. sorongensis. Leloup’s material was juvenile and not reliably identifiable. It resembles much more S. borneensis, to which it most probably belongs. Leloup (1930b: 6) also discusses the differences of his variant to S. borneensis, but all tabulated characters are of very limited value in discriminating Sertularia species. Distribution Indonesia, Japan, French Polynesia, Fiji. Type locality: Borneo, 2°25’S, 117°43’E, 40–50 m, on hydroids. Symplectoscyphus macrocarpa (Billard, 1918) Fig. 47. Sertularella macrocarpa Billard, 1918: 23, fig. 3A–B. – Billard 1925b: 162, fig. 25, pl. 7: figs 16–17. Material examined: Kei Islands Expedition station 1, with gonothecae. Description Colonies erect, up to 2 cm high, pinnate. Stem and hydrocladia zigzag, both with identical structure, stem with about 2–3 hydrothecae between successive hydrocladia of one side. 193 Fig. 47. Symplectoscyphus macrocarpa (Billard, 1918). A. Two hydrothecae. B. Gonothecae. – Scales: A = 0.2 mm; B = 0.5 mm. Hydrocladia long, may reach the same length as stem, inserting below hydrothecae of stem, nodes oblique, often indistinct or absent. Hydrotheca cylindrical, adnate for 2/5 of its adcauline length, free part held at about 60° to internode, abcauline wall almost straight to slightly concave, 0.35–0.4 mm, abcauline side sharply curved where becoming free; opening diameter 0.14–0.16 mm, margin with three cusps, one median adcauline and two lateroabcauline; operculum composed of three flaps, hydrothecal floor not complete, reaching mostly only to middle. Gonothecae numerous, on hydrocladia.
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Hydroids (Cnidaria, Hydrozoa) of the Danish expedition to

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