Hydroids (Cnidaria, Hydrozoa) of the Danish expedition to

More documents

Recommendations

Info

238 Differential diagnosis Similar to L. delicatula, differing in: stems only up to 4 cm, hydrocladia wider spaced, stem without hinge-joints, prosegments not visible but with solitary nematothecae on proximal stemregion; hydrotheca deeper (0.26 mm), opening less inclined, lateral margin with three cusps, median inferior nematotheca reaches only to middle of hydrotheca; mature corbula long (2/3 of hydrocladia), with fused broad ribs bearing only one row of nematothecae. Description of gonotheca Corbulae closed, length variable but may reach almost the length of a hydrocladium. First segment hydrothecate and identical to normal hydrocladium, then axis with two alternate rows of costae. Costae leaf-like, at base a hydrotheca on a lobe, distal rim of costa with a row of nematotheca, costae fused to form a tube, distal end mostly open, this even in corbulae with mature gonothecae. Lobe bearing hydrotheca can be elongated like a spur and may bear a terminal nematotheca. Description of trophosome See Stechow (1919) or Ryland & Gibbons (1991). Remarks The Indonesian material assigned here to Lytocarpia phyteuma (Kirchenpauer, 1876) had only one immature corbula. The hydrotheca on the corbula made it clear that it belonged to Lytocarpia. The trophosome matched quite well fertile material from the Andaman Sea as well as the description of Millard & Bouillon (1973), or Ryland & Gibbons (1991). It matched also Stechow’s (1919) re-description of the type specimen, although the median nematothecae of the type material are tubular and not gutter-shaped as observed here. All other authors describing material of L. phyteuma reported gutter-like median nematothecae. Millard & Bouillon (1973) interpreted this as an interspecific variation because such a variation is also known in from other aglaophenids. The material of Vervoort & Vasseur (1977) differs in that the lateral nemato- P. SCHUCHERT thecae extend much towards the rear side of the internode. Watson (2000) had therefore some doubts on the identity of this material. The Australian material of Watson (2000), however, also differs slightly from the Indonesian one in that the median nematotheca reaches much higher up, thus approaching the condition of L. delicatula. The size of the hydrotheca is apparently also smaller. The material of the present investigation is obviously identical to Billard’s (1913) Aglaophenia elongata var. sibogae from various Indonesian localities. Billard had apparently only infertile material at hand and his variant is therefore here regarded as a synonym of L. phyteuma. Aglaophenia elongata Meneghini, 1845 is a Mediterranean species (Svoboda & Cornelius 1991). Lytocarpia leopoldi (Leloup, 1930) from New Guinea is very similar to L. phyteuma. The main distinguishing characters are the gutter-shaped median nematotheca, two nematothecae per cauline segment, and some aspects of the corbula. Vervoort & Vasseur (1977) found that the differences of the corbula are not significant and they synonymized the two names. As mentioned above, tubular or gutter-shaped median nematotheca is likely only representing intra-specific variation. The cauline nematothecae are sometimes not easy to observe, especially in slide preparations, and Leloup might have overlooked one. Lytocarpia leopoldi is therfore very likely a synonym of L. phyteuma, although for a final decision the type material of L. leopoldi should be re-examined. Distribution Polynesia, Great Barrier Reef, northern Australia, Indonesia, Seychelles. Type locality: Tonga Islands. Lytocarpia perarmata (Billard, 1908), n. comb. Fig. 78. Thecocarpus myriophyllum perarmatus Billard, 1908a: 74, fig. 3. Thecocarpus perarmatus. – Billard 1913: 95, figs 81–86. Material examined: Kei Islands Expedition stations: 53, with corbulae. – 54, with corbulae.
HYDROIDS OF THE DANISH EXPEDITION TO THE KEI ISLANDS Fig. 78. Lytocarpia perarmata (Billard, 1908); station 53. A. Colony silhouette. B. Hydrotheca in side view. C. Hydrocladium seen from behind, note asymmetric pair of lateral nematothecae (top), and additional nematotheca on rear side (below), same scale as B. D. Part of corbula. E. Appendage at base of hydrocladium. – Scales: A = 1 cm; B–C = 0.1 mm; D = 0.5 mm; E = 0.2 mm. Description Colonies pinnate, 4–6 cm high, planar, stem not forking, lightly polysiphonic but becoming monosiphonic towards distal, composed of a superficial primary tube and a few auxiliary tubes. Primary tube with nematothecae and apophyses for the hydrocladia. Hydrorhiza a tangled mass of stolons anchoring colony in soft substrate. Hydrocladia, alternate, long (up to 2.5 cm), straight, with oblique nodes, nodes can be indistinct. Hydrotheca cup-shaped, depth 0.3 mm, slightly curved, opening-plane perpendicular to hydrocladial axis, abcauline wall rounded, short intrathecal shelf on adcauline side, hydrothecal rim with one median, rectangular tooth, this tooth slightly gutter-shaped, lateral rim of hydrotheca with two or more shallow teeth. Median inferior nematotheca gutter-shaped, attached up to middle of hydrotheca and more, without foramen leading into hydrotheca. Lateral pair of nematothecae unequal, one nematotheca taller and displaced towards rear side. On rear side at the level of lower third of hydrotheca an 239 additional nematotheca, displaced from median line towards side with smaller lateral nematotheca. Hydrocladial apophysis of primary tube often bearing a flexible appendage consisting of a row of segments with nematothecae, each segment with three nematothecae (Fig. 78E). Gonothecae protected in corbulae. Corbula replacing a hydrocladium, long and thin, tubular, about 1/3 of hydrocladial length, beginning with a few (3) segments having a structure identical to normal hydrocladia (Fig. 78D), then with two rows of costae forming a closed corbula. Costae flattened, fused at distal end with opposite costae, one row of tubular nematothecae along distal rim of each costa, each costa at its base with a lobe bearing a fully formed hydrotheca. Remarks Because Lytocarpia Kirchenpauer, 1872 has priority over its synonym Thecocarpus Nutting, 1900 (Rees & Vervoort 1987), Thecocarpus perarmatus is here used in the new combination Lytocarpia perarmata.
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:
Page 27 and 28:
Page 29 and 30:
Page 31 and 32:
Page 33 and 34:
Page 35 and 36:
Page 37 and 38:
Page 39 and 40:
Page 41 and 42:
Page 43 and 44:
Page 45 and 46:
Page 47 and 48:
Page 49 and 50:
Page 51 and 52: HYDROIDS OF THE DANISH EXPEDITION T
Page 101: HYDROIDS OF THE DANISH EXPEDITION T
show all

Hydroids (Cnidaria, Hydrozoa) of the Danish expedition to

Create successful ePaper yourself

Delete template?

Save as template?