Clytia cf. gigantea ( Hincks, 1866 )

Galea, Horia R., Häussermann, Verena & Försterra, Günter, 2009, New additions to the hydroids (Cnidaria: Hydrozoa) from the fjords region of southern Chile, Zootaxa 2019, pp. 1-28 : 22-23

Clytia cf. gigantea ( Hincks, 1866)

(fig. 5A–E, table 8)

Campanularia (?) gigantea Hincks, 1866: 297 . – Hincks, 1868: 174, pl. 35, fig. 1. – Fraser, 1944: 119, pl. 21 fig. 90.

Campanularia gigantea – Jäderholm, 1909: 69, pl. 7 fig. 1.

? Campanularia gigantea – Nutting, 1915: 44, pl. 6 fig. 3. – Fraser, 1937: 62, pl. 13 fig. 54.

Clytia gigantea – Leloup, 1974: 13, fig. 12. – Hirohito, 1995 (English text): 61, fig. 18A–B. – Vervoort & Watson, 2003: 418, fig. 102J.

Laomedea gigantea – Leloup, 1952: 161, fig. 93.

Material examined. Stn. 5 – 17.02.2008, 22.8 m, A430: several sparingly-branched stems, up to 3 mm high, gonothecae present, epizoic on polychaete tube. Stn. 6 – 21.02.2008, 12 m, A469 ( MHNG INVE 62825): fertile colonies, up to 4 mm high, epizoic on Synthecium robustum Nutting, 1904 and unidentified substrate. Stn. 8 – 23.02.2008, 26 m, A565 ( MHNG INVE 62823): fertile colonies, up to 4 mm high, epizoic on Symplectoscyphus milneanus (d’Orbigny, 1846) and S. robustum ; A583: a fertile, badly-preserved colony with sparingly-branched stems, up to 2.5 mm high, epizoic on bivalve shell. Stn. 9 – 24.02.2008, 20 m, A494 ( MHNG INVE 62826): small, fertile colonies, epizoic on Amphisbetia operculata ( Linnaeus, 1758) ; A495 ( MHNG INVE 62827): several fertile colonies, 2–3 mm high, epizoic on Symplectoscyphus leloupi El Beshbeeshy, 1991 . Stn. 10 – 24.02.2008, 9 m, A501 ( MHNG INVE 62828): a dense, fertile colony, ca. 7 mm high, on red algae.

Type locality. Lamlash Bay, Arran, Scotland.

Description. Colonies delicate, up to 4 mm high, arising from a creeping hydrorhiza; colony composed of variable number of monosiphonic stems, single or forking several times at acute angles; internodes long. Perisarc quite thick basally, gradually thinning out towards distal parts of colonies, and annulated at base of stems (8–18 annuli) and side branches (5–9 annuli basally). Hydrotheca thin-walled, deep-campanulate, about twice as long as wide; strongly undulated in cross-section, with longitudinal folds passing down and outwards from rounded embayments, separating 8–12 almost squared marginal cusps with rounded distal angles; basal chamber deep, diaphragm thin, transverse; 3–14 annuli on pedicel below hydrotheca. Gonothecae borne either on stolon or axillary on stems/branches (not shown); long (up to 5 times long as wide), tubular, gradually tapering into pedicel of varied length, with 5–12 annuli; apical end truncated, aperture large, circular; perisarc smooth to irregularly wrinkled; several medusa buds per gonotheca.

Remarks. Clytia gigantea is normally easily distinguished by its large hydrotheca with characteristically folded wall and almost castellated cusps. The present material partly fits the concept of this species, but differs in the smaller size of the hydrothecae, compared with the descriptions in the literature (table 8).

Our identification, though provisional, is mainly supported by the previous finding of this species ( Leloup 1974) in the same geographical area as the present material. It is possible that our material belongs to a smaller variant, but additional samples are necessary in order to ascertain the intraspecific variation, as well as the influence of the ecological factors on the size of colonies from various biotopes.

The gonothecae of this species were first described by Leloup (1974). The largest gonothecae in the present material have nearly the same size as those examined by Leloup.

World distribution. North Atlantic ( Hincks 1866, Jäderholm 1909, Fraser 1944, Leloup 1952), Northeast Pacific ( Fraser 1937).

Records from Chile. Gulf of Ancud, Seno Reloncaví, Reloncaví Inlet ( Leloup 1974), South of Chiloé Island, Frödden Channel (present study).

Present study Leloup (1974) Hirohito (1995) Vervoort & Watson (2003)

Hydrotheca

– length 680–775 1450 1120–1290 1650–1885

– diameter at rim 315–360 750 420–670 985

– number of cusps 8–12 8–14 10–11 ca. 14

Gonotheca

– length with pedicel 1045–1550 1600 – –

– maximum width 320–395 – – –

– diameter at aperture 240–295 450 – –