Hydroids (Cnidaria, Hydrozoa) of the Danish expedition to

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176 branched, unsegmented or only few nodes present, bearing a double row of alternate, overlapping hydrothecae on the frontal face, the two rows contiguous with one another. Hydrotheca tubular, basal half parallel to hydrocladium, distal half curving away, length of abcauline side 0.6 mm, no internal teeth, rim with two indistinct lateral teeth, operculum composed of an adcauline flap, the base of which is not distinctly demarcated from hydrotheca, margin of hydrotheca often renovated and elongated like duck-bill. Gonothecae on stem, urn-shaped, 1.6 mm long, diameter 0.8 mm, with 8–10 longitudinal ridges, these partly serrated, distal aperture on conical collar. Remarks The alternate hydrothecae on the anterior surface of the hydrocladia, as well as the characteristic hydrothecae, make this species easy to identify. However, it is arguable why this species should be placed in a separate genus Idiellana and not in the genus Diphasia. The only difference between the two genera is the alternate arrangement of the hydrothecae in Idiellana. Hydrothecae on one side of the hydrocladium are also frequently found in Diphasia species. Distribution Widely distributed in tropical and subtropical regions of the world. Type locality: Australasia (as New Holland in Lamouroux, 1816). Salacia hexodon (Busk, 1852) Fig. 33. Pasythea hexodon Busk, 1852: 395. – Bale 1884: 113, pl. 9: fig. 13. – Bale 1888: 771, pl. 14: figs 8–9. – von Campenhausen 1896b: 311. – Watson 2000: 21, fig. 16A–B. Salacia hexodon. – Billard 1925b: 207, fig. 49C–D. Material examined: Kei Islands Expedition stations: 15. – 18. – 20. – 60. – 61. – 67. – 68. – 71, with gonothecae. – 72, with gonothecae. – 90. – 107. Description Colonies erect, simple or irregularly branched, 0.5–2 cm high, monosiphonic, with regular P. SCHUCHERT Fig. 33. Salacia hexodon (Busk, 1852); station 71. Part of shoot showing typically clustered hydrothecae, a sidebranch, and a gonotheca. – Scale: 0.5 mm. transverse nodes above groups of hydrothecae. Hydrothecae on lateral sides, clustered in groups of 5–7 (range 2–10, reportedly also more), within these clusters consecutive individuals of one row in contact, the two rows not contiguous, long, tubular regions between the groups of hydrothecae. Branching points of side-branches below a hydrotheca. Hydrotheca tubular, abcauline side 0.4 mm, curved, adnate for half of its adcauline length, opening circular, angle variable, opening-plane parallel to stem or inclined towards below, with single operculum attached to abcauline side. Hydranth without abcauline caecum, one abcauline tentacle longer than others, thick club-shaped with larger nematocysts than in other tentacles. Gonothecae arising below lowest hydrotheca
HYDROIDS OF THE DANISH EXPEDITION TO THE KEI ISLANDS of a cluster, urn-shaped, 1.4 mm long, diameter 1 mm, with 8–10 transverse ridges or ribs. Distribution Australia, Indonesia. Type locality: Whitsunday Islands, Queensland, Australia (as Cumberland Islands in Busk, 1852). Salacia sibogae Billard, 1924 Fig. 34. Salacia sibogae Billard, 1924: 64, fig. 1B–C. – Billard 177 1925b: 206, fig. 49, pl. 8: fig. 30. – Hirohito 1995: 185, fig. 60f. Material examined: Kei Islands Expedition stations: 3. – 12, with gonothecae. – 14, with gonothecae. – 58. Description Colonies erect, pinnate. Stem 5–12 cm, monosiphonic, unbranched, zigzag, thicker than hydrocladia, regularly segmented by transverse to slightly oblique nodes, nodes flanked by bulges of the segment ends. Each stem segment with Fig. 34. Salacia sibogae Billard, 1924; A, station 12; B–E, station 14. A. Colony silhouette. B. Stem segment with base of hydrocladium. C. Segment from hydrocladium, note faint lateral crease lines originating from hydrothecal margin. D. Oblique view of hydrotheca, note possible upper opercular valve (dotted). E. Gonothecae in oblique view. F. Distal part of gonotheca in side view, shown transparent, same scale as E. – Scales: A = 1 cm; B, E = 0.5 mm; C, D = 0.2 mm.
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