Clytia gigantea (, 1866)

Cantero, Álvaro Luis Peña, 2023, On some benthic hydroids from New Zealand deep waters, with the description of a new species, Zootaxa 5389 (2), pp. 241-252 : 245

Clytia gigantea (, 1866)

Hincks

( Fig. 4a–b )

Campanularia gigantea Hincks, 1866: 297 ; 1868: 174, pl. 35 fig. 1.

Clytia gigantea – Vervoort & Watson, 2003: 418, 419, fig. 102J; Calder, 2012: 46–47 , figs. 46–47; Peña Cantero & Horton, 2017: 13 , fig. 5A–B.

Material examined. S0254/58, a few hydrothecae, on Tubularia sp. , no gonothecae ( NIWA 127156).

Description. Stolonal colony. Hydrotheca at distal end of a long pedicel provided with 10–12 basal and three to four distal rings. Hydrotheca elongate, gently tapering basally; maximum diameter at aperture. Aperture circular; rim with 11–12 cusps, slightly directed inwards, with their distal part smoothly curved, and separated by deep rounded embayments.

Measurements (in µm). Pedicel: length 3400. Hydrotheca: height 1300–1400, diameter at aperture 550–590, diameter at diaphragm 130–160, height of basal chamber 70–80.

Remarks. Even when the material is scarce and only two hydrothecae are in good condition, it is possible to assign it to C. gigantea , a species easily distinguishable by the large size of the hydrotheca and the shape of the hydrothecal cusps ( Calder 2012; Peña Cantero & Horton 2017).

Cornelius (1982) considered C. gigantea to be conspecific with Clytia hemisphaerica ( Linnaeus, 1767) , which was followed by other authors ( Calder 1991; Cairns et al. 2002). Calder (2012), however, after examining new material, considered it a valid, different species, based on its robust colony form, sparingly branched pedicels, linguiform cusps and exceptionally large hydrothecae. Calder’s (2012) position was followed by Peña Cantero & Horton (2017) and is upheld here as well on the same grounds, given that in C. hemisphaerica colonies are usually unbranched, its hydrothecae are much smaller, and the hydrothecal cups are distally blunt.

Ecology and distribution. Present material was collected west off Bounty Islands at a depth of 335−337 m. In the region, it has been reported from the Chatham Islands area, at a depth of 512 m ( Vervoort & Watson 2003).

Figures

FIGURE 4. (a–b) Clytia gigantea (Hincks, 1866): a, hydrotheca; b, cusps of hydrothecal aperture. (c–d) Sertularella valdiviae Stechow, 1923: c, part of stem showing hydrotheca and incipient branch; d, hydrotheca. (e–h) Cryptolaria prima Busk, 1857: e, part of stem showing hydrothecal arrangement; f–g, hydrothecae; h, nematotheca. Scale bar: 100 µm (b, h), 200 µm (a, c−g).