Hydroids (Cnidaria, Hydrozoa) of the Danish expedition to

More documents

Recommendations

Info

212 fourth order branching, roughly in one plane, stem and branches polysiphonic, thinning to monosiphonic in distal regions. Stem and branches in polysiphonic parts composed of an embedded main tube and auxiliary tubes. Main tube originally with alternate hydrocladia, but these often broken off in older parts. Branches originating from auxiliary tubes, auxiliary tubes bearing nematothecae. Stem and branches without nodes in large colonies, homomerously segmented in juveniles, with alternate apophyses for hydrocladia, without hydrothecae. In segmented stems two hydrocladia per internode. Two nematothecae associated with each apophysis, additional nematothecae present on stem and branches. Hydrocladia with up to 15 hydrothecae, nodes either mostly absent or homomerously segmented by transverse nodes, each hydrotheca and associated with three nematothecae: one below and two lateral to hydrotheca. Hydrocladium often with numerous, evenly spaced, thick internal ribs formed by annular thickenings, some regions with no or only weakly developed ribs. Hydrotheca tubular, abcauline wall 0.25–0.3 mm, straight and parallel to hydrocladial axis, adcauline side completely adnate, shorter than abcauline side, margin therefore much lowered on adcauline side, lateral rim with two broad and shallow lobes, on inside of abcauline wall frequently a transverse semicircular perisarc thickening, rim on adcauline side with thickened perisarc. All nematothecae two-chambered and movable, conical, walls straight, rim not incurved, adcauline wall of upper chamber emarginated, lower chamber longer than upper one. Median inferior nematotheca far below hydrotheca, not reaching hydrotheca, on distinct prominence of internode. Lateral nematothecae inserted near rim of hydrotheca, about 70 µm high. Female gonotheca inserted in upper axil of apophyses, 0.3 high mm, top-shaped (turbinate), end flat, wall straight, no pedicel. Male gonothecae not seen Remarks The Indonesian population of Plumularia habereri is very variable and Billard (1913) proposed P. SCHUCHERT a number of nominal variants. Because they are sympatric, these variants are not subspecies, but represent phenotypic or genotypic variability. Most of them are quite unlike the form from the original location in Japan (Stechow 1909, Hirohito 1995), from the Caribbean (van Gemerden- Hogeveen 1965), or from Fiji (Ryland & Gibbons 1991). The material examined here clearly matched Plumularia habereri var. mediolineata Billard, 1913 as most hydrothecae had an internal perisarc thickening (Fig. 60D). Some hydrothecae of the same stem or even hydrocladium, however, lacked this thickening and more approached the variant elongata. The more juvenile colony also corresponded to the form elongata (Fig. 60E). Only few specimens of all these variants are known and more material is needed to further evaluate the validity of all of them. Some, especially the form described above, could prove to be separate species. Distribution Japan, Indonesia, Caribbean Sea. Type locality: Between Ito and Hatsushima Islands, Sagami Bay, Japan. Plumularia scabra Lamarck, 1816 Fig. 61. Plumularia scabra Lamarck, 1816; 127. – Billard 1907: 322. – Billard 1913: 47. – Watson 2000: 52, fig. 40A–E. Plumularia effusa Busk, 1852: 400. – Kirchenpauer 1876: 46, pl. 1: fig. 4, pl. 5: fig. 4. – Bale 1884: 129, pl. 18: fig. 5. Acanthella effusa. – Allman 1883: 27, pl. 6: figs 1–4. – von Campenhausen 1896b: 315. – Stechow & Müller 1923: 474. Material examined: Kei Islands Expedition stations: 67, with gonothecae. – 72, large cluster of 25 cm high stems. – 106, with gonothecae. – 107. Description Colonies 5–25 cm high, comprising many stems, multi-pinnate, up to third-order branching, sidebranches in verticels and not in one plane, stem and branches monosiphonic, quite rigid, all bearing alternate hydrocladia, hydrocladia in older parts usually lost, branches of lower part of stem usually broken off. Stem and branches without nodes, with long apophyses for hydrocladia (0.12
HYDROIDS OF THE DANISH EXPEDITION TO THE KEI ISLANDS Fig. 61. Plumularia scabra (Lamarck, 1816); A, station 72; B–D, station 106. A. Colony silhouette, height 13 cm. B. Part of hydrocaulus (branch) with apophysis, scale bar 0.1 mm. C. Segment of hydrocladium. D. Gonothecae. – Scales: B = 0.1 mm; C = 50 µm; D = 0.2 mm. 213 mm), only in most distal portions with oblique nodes, each segment with two apophyses, without hydrothecae. Two to three nematothecae associated with each apophysis: one or two on apophysis, one close to base. Hydrocladia with up to 15 hydrothecae, homomerously segmented by oblique nodes, segments about 0.25 mm long, all segments with hydrotheca and three nematothecae: one below and two lateral to hydrotheca. Internode with internal ribs, variably developed: one at each end, one at rear wall of hydrotheca, one curved between hydrotheca and median inferior nematotheca. Several terminal hydrocladia of some branches often replaced by thorn-like growth of the apophysis bearing a nematotheca. Hydrotheca cup-shaped, depth 0.13 mm, centrally placed on internode, adcauline side adnate, abcauline wall strongly S-shaped, adcauline wall convex, hydrothecal margin with two broad, rounded lateral lobes. All nematothecae two-chambered and movable, conical, walls straight, rim not incurved, adcauline wall of upper chamber emarginated, lower chamber longer than upper one. Median inferior nematotheca immediately below hydrotheca, reaching beyond middle of hydrotheca, not on distinct prominence of internode. Lateral nematothecae inserted near rim of hydrotheca, about 70 µm high. Gonotheca inserted in upper axil of apophyses, 0.5 mm, ovoid, flattened, distal end truncated and oblique, orifice slit-like. Remarks See under Polyplumaria cornuta. Distribution Northern Australia, Singapore, Philippines, Indonesia. Type locality: “South Seas” (Lamarck, 1816). Polyplumaria cornuta (Bale, 1884) Fig. 62. Plumularia cornuta Bale, 1884: 132, pl. 11: figs 1–2. Polyplumaria cornuta. – Billard 1913: 53, figs 65–66, pl. 3: fig. 33, pl. 4: 35–36. – Watson 2000: 56, fig. 44A–F. Polyplumaria cornuta var. longispina Billard, 1913: 56, fig. 67.
Page 1 and 2:
HYDROIDS OF THE DANISH EXPEDITION T
Page 3 and 4:
Page 5 and 6:
Page 7 and 8:
Page 9 and 10:
Page 11 and 12:
Page 13 and 14:
Family Solanderiidae HYDROIDS OF TH
Page 15 and 16:
Page 17 and 18:
Page 19 and 20:
Page 21 and 22:
Page 23 and 24:
Page 25 and 26: HYDROIDS OF THE DANISH EXPEDITION T
Page 75: HYDROIDS OF THE DANISH EXPEDITION T
show all

Hydroids (Cnidaria, Hydrozoa) of the Danish expedition to

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?