Hydroids (Cnidaria, Hydrozoa) of the Danish expedition to

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174 hydrotheca. No such patches were found in D. disticha. However, not enough well preserved material could be examined to substantiate this difference. Both D. moluccana and D. disticha have a very thin and delicate hydrothecal perisarc. It is often damaged or distorted in preserved samples. Together with the frequent renovations they can look deceptively like hydrothecae of the genus Salacia. A careful search for undamaged hydrothecae will, however, reveal the difference (cf. Medel & Vervoort 1998: 31 and Cornelius 1979: 309, note 21). The flimsy perisarc is actually an important trait to distinguish D. disticha from D. pumila. A further difference is the separation of the hydrothecae: they are not contiguous on either side. Dynamena pumila also forms branched and unbranched forms (see Cornelius 1995b or Schuchert 2001 for recent descriptions). Dynamena pumila occurs in cooler waters of the North Atlantic, while D. disticha is predominantly known from warmer water. The material identified by Pictet (1893) as Sertularia gracilis Hassal, 1848 (MHNG INVE 25032) is clearly a Dynamena species and resembles somewhat D. moluccana, although it has simple shoots. But the hydrothecae are distinctly smaller (0.2 mm abcauline side) and they are on long internodes. It could thus belong to Dynamena dalmasi (Versluys, 1899) (see Calder 1991 and Medel & Vervoort 1998 for recent descriptions). Distribution Indonesia (Pictet 1893, Billard 1925b), Papua New Guinea (Thornely 1904), Marshall Islands (Cooke 1975), Australia (Bale 1884, as S. divergens), Seychelles (Jarvis 1922 as S. cornicina var. pinnata), southern Africa (Millard 1975), Japan (Hirohito 1995, as D. exigua). Type locality: Bay of Ambon. Geminella ceramensis (Billard, 1925) Fig. 31. Sertularella ceramensis Billard, 1925a: 649. – Billard 1925b: 170, fig. 30, pl. 7: fig. 20. Geminella ceramensis. – Vervoort 1993: 109, fig. 3a–e. Not Geminella ceramensis. – Vannucci Mendes 1946: 570, pl. 4: figs 40–41. P. SCHUCHERT Fig. 31. Geminella ceramensis (Billard, 1925). A. Pair of hydrothecae. B. Hydrothecal opening in oblique view showing the three opercular valves. C. Gonotheca. – Scales: A–B = 0.1 mm; C = 0.2 mm. Material examined: Kei Islands Expedition station 57, with gonothecae. Description Colonies erect, stems irregularly branched, up to 1 cm in height. Stolons tubular, ramified. Stem and branches with identical structure, regularly segmented by more or less distinct transverse nodes. Segments elongate, 0.7–1.1 mm long, each with a pair of opposite to subopposite hydrothecae in its middle. Side-branches originate below a hydrotheca, first segment without hydrotheca, about half as long as other segments. Hydrotheca conical, adcauline side adnate for half or less of length, abcauline side almost
HYDROIDS OF THE DANISH EXPEDITION TO THE KEI ISLANDS straight, 0.20–0.24 mm long; adcauline side bent where becoming free, free adcauline side straight to somewhat convex, opening-plane directed slightly upwards to nearly parallel to segment axis, diameter 0.13–0.15 mm, margin with three distinct cusps: one on adcauline side, two on lateral sides somewhat below middle; operculum pyramidal and composed of three valves; hydrothecal margin often renovated. Hydranths with abcauline caecum and about 12 tentacles. Gonothecae develop immediately below a hydrotheca. Gonotheca vase-shaped, 1.2 mm long, max. diameter 0.5 mm, base rounded and with short pedicel, sides quite straight and converging towards distal end; end truncated, walls with 15– 18 distinct and sharp transverse ridges, some gonothecae with less distinct ridges and rather undulated only. Remarks Most gonothecae observed in this study had rather sharp transverse folds, and were not undulated as described by Vervoort (1993). Geminella ceramensis is the only known species of its genus. Geminella differs from the genus Symplectoscyphus only by its opposite hydrothecae, but Vervoort (1993) noted that initial stages of Geminella ceramensis have alternate hydrothecae. A future revision might thus synonymize Geminella and Symplectoscyphus. Distribution Indonesia, Philippines, New Caledonia. Type locality: Ceram, Banda Islands, 2.475°S, 131.055°E, 118 m, on coarse sand. Idiellana pristis (Lamouroux, 1816) Fig. 32. Idia pristis Lamouroux, 1816: 199, pl. 5: fig. 5. – Allman 1888: 85, pl. 39: figs 1–10. – von Campenhausen 1896b: 311. – Billard 1925b: 219, fig. 58, pl. 7: fig. 33. – Vervoort 1941: 205. Pasythea philippina Marktanner-Turneretscher, 1890: 234, pl. 4: figs 8 & 8a. Idiella pristis. – Stechow & Müller 1923: 469. – Vervoort 1959: 252. Idiellana pristis. – Ralph 1961a: 766, fig. 5c–e. – Mammen 1965: 52, fig. 86. – Millard 1975: 269, fig. 88A–E. – Hirohito 1995: 178, fig. 58a–c. – Vervoort 1993: 188. – Migotto 1996: 64, fig. 12f–g. – Watson 2000: 18, fig. 14A–E. 175 Figure 32. Idiellana pristis (Lamouroux, 1816); A, station 71; B–C, station 66; D, station 53. A. Colony silhouette. B. Hydrocladium seen from anterior side. C. Hydrocladium in side view. D. Gonotheca, scale bar 0.5 mm. – Scales: A = 2 cm; B, C = 0.4 mm; D = 0.5 mm. Material examined: Kei Islands Expedition, Bay of Ambon, 13 m, 28 Feb 1922, sand bottom, fertile. – Kei Islands Expedition, Bay of Ambon, 90 m, 21 Feb 1922, bottom of stones and sand, fertile. – Kei Islands Expedition, Ujungpandang, Samalon Island, 25 m, 29 Jun 1922, sand bottom. – Kei Islands Expedition, Ujungpandang, Samalon Island, 35 m, 28 Jun 1922, sand bottom. – Kei Islands Expedition, Ambon, harbour pier, 13 m, 27 Feb 1922, sand bottom. – Kei Islands Expedition stations: 11. – 14. – 19, fertile. – 20, fertile. – 21. – 36. – 40. – 53, fertile. – 57. – 61. – 64. – 65. – 66. – 67, fertile. – 68. – 69. – 71, fertile. – 72, fertile. – 73. – 74. – 90. – 103. – 104, fertile. – 106, fertile. – 107. – 110. – 117. – 118, fertile. Description Colonies pinnate, up to 7 cm high. Main stem unforked, monosiphonic, with regular nodes, nodes alternate in inclination, each segment with three non-contiguous hydrothecae and an apophysis near lower end. Hydrocladia alternate, widely spaced, un-
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