Oceania armata Kölliker, 1853

Schuchert, Peter, 2016, The polyps of Oceania armata identified by DNA barcoding (Cnidaria, Hydrozoa), Zootaxa 4175 (6), pp. 539-555 : 550-552

Oceania armata Kölliker, 1853

( Figs 1‒3 )

Oceania armata Kölliker, in Gegenbaur et al., 1853: 323 .— Metschnikoff 1886: 78, pl. 1 figs 32‒39.— Mayer 1910: 147, figs 80‒81.— Kramp 1959: 99, fig. 63.— Kramp 1961: 65.— Kramp 1968: 27, fig. 67.— Brinckmann-Voss 1970: pl. 4 fig. 2.— Schuchert 1996: 15, fig. 4a‒c.— Schuchert 2004: 333, fig. 5.—Kubota 2007: 67, figs 1‒5.

Oceania flavidula . — Gegenbaur, 1857: 223, pl. 7: fig. 4.

not Oceania flavidula Péron & Lesueur, 1810: 345 [?= Clytia spec.]

Turritopsis armata .— Haeckel, 1879: 65.

Callitiara polyophtalma Haeckel, 1879: 67 , pl. 3 figs 1‒5.

Conis cyclophthalma Haeckel, 1879: 55 , pl. 4 fig. 1.

? Corydendrium chevalense Thornely, 1904: 109 , pl. 1 fig. 4.

Tiarella parthenopia Trinci, 1906: 208 , figs 1‒2.

Turritopsis fascicularis Fraser, 1943: 76 .— Fraser 1944: 37, fig 5.— Calder 2013: 11 , fig. 1f.— Miglietta 2016: 426 , figs 1‒3.

Oceania tydemani Bleeker & van der Spoel 1988: 249 , fig. 7.

Description. Mature medusa 5‒10 mm high, maximal bell diameter about the same as height, umbrella bell-shaped with flat top, jelly uniformly thin. Manubrium on a transparent, shallow peduncle, not encircled by blocks of vacuolated cells but vacuolated cells present along proximal parts of radial canals. Manubrium large, up to 2/3 of subumbrellar height, ovoid, manubrium base constricted, with funnel-shaped mouth region. Stomach and mouth region distinctly cruciform in cross-section. Radial canals where joining manubrium funnel-like dilated and composed of large, vacuolated cells, continued on manubrium as perradial ribs resembling four clasping claws. Mouth rim in folds, with four prominent perradial lips. Margin of mouth with a continuous row of spherical nematocyst clusters, these usually on a short pedicel. Gonads smooth, on interradial surface of stomach. Four quite broad radial canals, margins occasionally jagged, circular canal broad. Marginal tentacles 80‒120, evenly tapering, gastrodermis chordoid. Origins of tentacles somewhat alternately displaced adaxially and abaxially (= in 2 rows). Each tentacle with a slight proximal swelling beginning shortly after origin. Adaxial ocelli near tentacle base. Nematocysts: microbasic euryteles, desmonemes. Colours: manubrium and gonads yellow, orange or orange brown, ocelli brown-red. Egg size about 0.27 mm.

Polyp stage forming erect, branched colonies, 1‒10 cm, strongly polysiphonic, thinning out to monosiphonic. Proximal parts of monosiphonic side-branches and hydranth pedicels adnate to branch of origin. Hydranths at ends of side branches, tubular, 0.6‒1 mm high, with rounded hypostome, up to 18 scattered filiform tentacles. Medusa buds at end of thin side-branches with proximal region adnate, spherical, 0.4‒0.5 mm, in advanced stages with four broad radial canals, manubrium very short, with four interradial pads, four marginal bulbs, about 8 tentacles stubs. Nematocysts of polyps are microbasic euryteles and desmonemes.

Distribution. The medusa occurs in coastal waters of tropical to warm temperate seas. It has been recorded from the Mediterranean, coasts of Senegal and Gambia, Canary Islands, Cape Verde, Azores, Portugal, West Indies, Japan, New Zealand, Tasman Sea, South China Sea, Red Sea; apparently it is absent from the eastern Pacific Ocean ( Kramp 1961; Schmidt & Klinker 1974; Schuchert 1996; Schuchert 2004; Xu & Huang 2006; Kubota 2007). Type locality: Strait of Messina, Mediterranean. The medusa occurs usually in depths of less than 200 m, but not at the surface ( Kramp 1965).

Remarks. While two records of the polyp (as T. fascicularis and T. chevalense , see Table 1 ) were found in depths of 274 to 573 m, they seem not to be restricted to deeper waters as one record ( Portugal sample) was from very shallow waters.

Figures

FIGURE 1. Oceania armata Kölliker, 1853. A. Living medusa (bell height and width about 9 mm) from the Bay of Villefranche – sur – Mer. The specimen was used to obtain the DNA sample DNA 1148. B. Microphoto of mouth margin of sample MHNG-INVE- 87094, note stalked nematocyst clusters.

FIGURE 2. Oceaniidae hydroid from the Andaman Sea initially identified as Turritopsis chevalense, after molecular comparisons attributed to Oceania armata, MHNG-INVE- 78812. A. Preserved colony. B. Terminal branch after removal of soft tissue. Note that the side branch originating near the asterisk (*) remains adnate until it curves away (arrow).

FIGURE 3. Oceaniidae hydroid from the Andaman Sea initially identified as Turritopsis chevalense, after molecular comparisons attributed to Oceania armata, MHNG-INVE- 78812. A. Drawing of hydranth and medusa bud. B. Nematocysts: microbasic eurytele and desmoneme.