Opercularella belgicae ( Hartlaub, 1904 )

Galea, Horia R., 2007, Hydroids and hydromedusae (Cnidaria: Hydrozoa) from the fjords region of southern Chile, Zootaxa 1597 (1), pp. 1-116 : 36-37

Opercularella belgicae ( Hartlaub, 1904)

(fig. 8M, N, table 4)

Campanulina belgicae Hartlaub, 1904: 10 , figs 8–9, pl. 1; Billard, 1914: 12.

Opercularella belgicae: Naumov & Stepanjants, 1962: 77 ; Leloup, 1974: 4, fig. 2; Millard, 1977: 5, fig. 1B; Stepanjants, 1979: 41, pl. 7 fig. 6; Blanco et al., 2000a: 270, fig. 3; Peña Cantero et al., 2004: 2276, fig. 1C–H.

? Opercularella sp. : Vervoort, 1972a: 42, fig. 11B–C.

Material examined. Stn. ILA — 13.iii. 2006, 32 m, S130: a small, sterile colony composed of both stolonal and erect growth forms, on polychaete tube ( MHNG INVE 53402 ) .

Type locality. Bellingshausen Sea , West Antarctica .

Description. A minute, delicate colony, composed of two hydrothecate pedicels and a relatively small (7.6 mm high) erect stem, bearing six hydrothecae. Pedicels of stolonal form longer than their corresponding hydrothecae, smooth, except for the presence of 2–3 basal, spiral annulations. Erect form with smooth, straight, monosiphonic, unbranched and gradually tapering distally main stem. Stem sympodially branched, with branches alternate, each bearing one terminal hydrotheca, borne on basally annulated pedicel. Hydrothecae long, inverted conical, with walls slightly divergent distally, tapering below and merging imperceptibly into pedicel; with delicate diaphragm marking junction between the two. Closing apparatus formed by several triangular flaps meeting centrally and forming a pointed roof; flaps without crease line basally. Gonothecae absent.

Remarks. Naumov & Stepanjants (1962) and Stepanjants (1979) described adult colonies of this species having pedicels with undulated perisarc, and younger colonies with pedicels entirely ringed. Similar observations were also made by Blanco et al. (2000a). Peña Cantero et al. (2004) reported long pedicels usually smooth, except for a few basal rings, while short pedicels were completely ringed.

The material from the Strait of Magellan described and figured by Vervoort (1972a) as Opercularella sp. agrees well with the present material from Chile and both may be conspecific.

The gonothecae of O. belgicae were unknown since their recent description by Peña Cantero et al. (2004). Unfortunately, all their gonothecae were empty and we still do not know if the species produces medusae. Therefore, these authors kept this species in the genus Opercularella , and their opinion is followed here.

World distribution. Eastern and western Antarctica, Kerguélen, Mar del Plata, Strait of Magellan ( Peña Cantero et al. 2004).

Records from Chile. This species was previously reported from south of Tocopilla ( Leloup 1974). The present material originates from Isla Lavinia.