Tubularia hodgsoni Hickson & Gravely, 1907

ÁLVARO L. PEÑA CANTERO, 2017, Benthic hydroids (Cnidaria, Hydrozoa) from the Ross Sea (Antarctica) collected by the New Zealand Antarctic expedition BioRoss 2004 with RV Tangaroa, Zootaxa 4293 (1), pp. 1-65 : 17-18

Tubularia hodgsoni Hickson & Gravely, 1907 (*)

( Fig. 5 ; Table 4)

Tubularia hodgsoni Hickson & Gravely, 1907: 13 –14, pl. 2 fig. 13, pl. 4 fig. 34; Dayton et al., 1970: 247. Tubularia ralphii — Hickson & Gravely, 1907: 13, pl. 2 fig. 12.

Material examined. Tubularia hodgsoni Hickson & Gravely, 1907 (type material, Natural History Museum, London, Coel no. NHM 1907.8.20.7): McMurdo Bay , Ross Sea, Winter Quarters, January 1st, 1902, No. 6 hole, 240 m.

Other material examined. Tubularia ralphii Bale, 1884 (sensu Hickson & Gravely 1907) (Natural History Museum, London, Coel no. NHM 1907.8.20.8): McMurdo Bay , Ross Sea, Winter Quarters, February 28th, 1902, 37 m.

Description (Type of Tubularia hodgsoni ). Hydrocaulus 40 mm high ( Fig. 5 A) provided with hydrorhizal stolons (one of them branched). Stem diameter increasing distally, from ca. 0.5 mm basally to ca. 1 mm distally. Tube tortuous ( Fig. 5 A), quite soft, particularly at distal part, yellowish, transversally striated throughout ( Fig. 5 B). Polyp large, with marked constriction between head and neck ( Fig. 5 C–D). Polyp with oral crown of ca. 60 filiform tentacles ( Fig. 5 E), up to 2 mm long, in several rows, and aboral whorl of 24 filiform tentacles ( Fig. 5 C–D), ca. 5 mm long. Polyp with 10 unbranched blastostyles, each with ca. 30 firmly adpressed gonophores ( Fig. 5 D, F); lessdeveloped basally.

Measurements (in µm). Cnidome: stenoteles [range 8.5–10.0 x 7.0–7.5, mean 9.3±0.5 x 7.2±0.2 (n=10); ratio, range 1.2–1.4, mean 1.3±0.1 (n=10)]; rounded haplonemes [range 14.0–15.5 x 10.0–13.0, mean 14.8±0.5 x 11.5±0.9 (n=10); ratio, range 1.2–1.4, mean 1.3±0.1 (n=10)]; tear-shaped haplonemes [range 13.5–15.0 x 4.5–6.0, mean 14.3±0.6 x 5.2±0.5 (n=10); ratio, range 2.5–3.1, mean 2.8±0.2 (n=10)]; desmonemes [range 6–6.5 x 4 –4.5].

Description ( Tubularia ralphii sensu Hickson & Gravely 1907 ). Eight hydrocauli and fragments, up to 50 mm high, some quite tortuous. Tubes arising from branched hydrorhizal stolons. Tubes of approximately same diameter throughout, only slightly widening distally (e.g. 500 µm at base and 750 µm at distal end). Tubes yellowish and slightly transversally striated. Only one hydrocaulus with polyp, provided with oral crown of ca. 60 filiform tentacles and aboral whorl with 20 filiform tentacles. Unbranched blastostyles; gonophores firmly adpressed.

Measurements (in µm). Cnidome: stenoteles [range 10.0 x 7.5–8.0, mean 10.0±0.0 x 7.8±0.2 (n=5); ratio, mean 1.3±0.0 (n=5)]; rounded haplonemes [range 14.5–15.5 x 10.5–11.5, mean 15.0±0.3 x 11.5±0.9 (n=7); ratio, range 1.3–1.5, mean 1.4±0.1 (n=7)]; tear-shaped haplonemes [range 13.0–14.0 x 5.0–5.5, mean 13.7±0.4 x 5.1±0.2 (n=5); ratio, range 2.6–2.8, mean 2.7±0.1 (n=5)]; desmonemes [range 6.0 x 4.5].

Remarks. See under discussion of Tubularia longstaffi Hickson & Gravely, 1907 .

Distribution. Only known from McMurdo Bay ( Hickson & Gravely 1907; Dayton et al. 1970).

Figures

FIGURE 5. Tubularia hodgsoni Hickson & Gravely, 1907 (type material): A, general aspect of hydrocaulus; B, part of hydrocaulus with striation; C, polyp (basal view); D, polyp and gonophores (lateral view); E, hypostome; F, detail of gonophores. Scale bar: A, C – D: 5 mm; B, F: 1 mm; E: 2 mm.