Gonothyraea loveni ( Allman, 1859 )

Watson, Jeanette E., 2011, New species, new records and redescriptions of Thecate hydroids (Cnidaria: Hydrozoa: Leptothecata) from Southern Australia, Zootaxa 3122, pp. 1-36 : 30-32

Gonothyraea loveni ( Allman, 1859)

Fig. 14 A–D

Laomedea loveni Allman, 1859: 138 .

Gonothyraea loveni – Linko, 1911: 212, fig. 40.– Ralph, 1957: 824, fig 3g –k.– Millard, 1975: 224, fig. 74A–F.– Cornelius, 1982: 92, fig. 15.– Cornelius & Ryland, 1990: 131, fig. 4.12.– Cairns et al., 1991: 23.– Cornelius, 1995b: 262, fig. 60.– Vervoort & Watson, 2003: 422.

Obelia loveni – Naumov, 1960: 264, figs 16i, 152.

Calycella parkeri Hilgendorf, 1898: 205 pl. 17, figs 3, 3a–d, pl. 18.

Gonothyraea parkeri – Bale, 1924: 231.

Gonothyraea hyalina Hincks, 1868: 184 , pl. 35, fig. 2.– Hodgson, 1950: 5, fig. 10.

Material examined. NMV F171373, microslide, colony Port Phillip Heads, on sponge, depth 16 m, coll: J. Watson, 24/07/1992. Material in author’s collection: Halibut oil drilling platform, Bass Strait, colony on barnacle, 10 m, June 1975.

Description. Single pedicellate hydrothecae and erect stems arising from a hydrorhiza creeping on substrate. Hydrorhizal stolons tubular, smooth, perisarc thin, some enclosing sponge spicules. Longer stems monosiphonic, to 6 mm high, junction of stem and hydrorhiza with 9–10 deep annulations; stems with 4–6 widely spaced alternate pedicels, stem internodes long, annulated at base with up to 10 deep rings.

Hydrotheca terminal on a short pedicel held at an acute angle of c. 35° from stem, a slight thickening at junction of stem with pedicel; pedicels annulated throughout. Hydrotheca conical, somewhat variable in length and width, walls smooth, expanding evenly from base to margin, basal chamber distinct, rectangular to quadrangular in shape, merging smoothly into hydrotheca, distal wall of basal chamber a thickened transverse or slightly concave rim, a ring of desmocytes above. Margin of hydrotheca dentate with 10–12 shallow castellated cusps, each cusp shallowly indented.

Hydrorhiza, diameter 200–220

Stem

internode diameter 120–144 distance between pedicels 800–1060

Pedicel

Length 280–448 Diameter 80–112

Hydrotheca

length, diaphragm to margin 480–704 width at diaphragm 128–344 width at margin 352–400 basal chamber, depth 72–88

Marginal cusp

Depth 28–40 width of embayment 44–48 Remarks. This material was originally identified as Obelia bidentata by Watson (1994) but re–examination of the hydrothecal rim shows the cusps to be castellated, not sharply bimucronate as in that species. Hodgson (1950) gave dimensions of G. l o v e n i from the Derwent River estuary but his measurements are difficult to interpret since there is no way of relating the aspects of the hydrotheca to actual measurements. The present material agrees in general with Hodgson’s description of Australian material and that of Ralph (1957) and Vervoort & Watson (2003) for material from New Zealand.

Distribution. Cosmopolitan in littoral temperate zone. The depth record of 10–16 m is unusual.

Figures

FIGURE 14. Gonothryraea loveni. A, part of branch showing alternate pedicels. B, campanulate hydrotheca with thin diaphragm. C, conical hydrotheca with desmocytes above diaphragm. D, indented castellated hydrothecal margin. Scale bar: A, 0.1 mm, B, C, 0.5 mm, D, 0.2 mm.