Oswaldella billardi Briggs, 1938

Peña Cantero, A. L. & Vervoort, W., 2004, Species of Oswaldella Stechow, 1919 (Cnidaria: Hydrozoa: Kirchenpaueriidae) from US Antarctic expeditions, with the description of three new species, Journal of Natural History 38, pp. 805-861 : 818-820

Oswaldella billardi Briggs, 1938

( figure 2)

Oswaldella billardi Briggs, 1938: 40 , figure 3, pl. 15 figure 1; Naumov and Stepan’yants, 1962: 98–99; 1972: 53–54, figure 14c; Stepan’yants, 1972: 74; Peña Cantero and Vervoort, 1997: 269–273, figure 1; 1998: 36; Peña Cantero and García Carrascosa, 1999: 214; Peña Cantero and Marques, 1999: 85.

Oswaldella billardi billardi Stepan’yants, 1979: 113, pl. 21 figure 3a, b.

Not Oswaldella billardi: Blanco, 1984: 45–46 , pl. 41 figure 95, pl. 42 figures 96–97 (= Oswaldella shetlandica Stepan’yants, 1979 p.p.; Oswaldella erratum Peña Cantero and Vervoort, 1997 p.p.); Blanco and De Redolatti, 1977: 1–8, pls 1–4 (= Oswaldella shetlandica Stepan’yants, 1979); Broch, 1948: 13–16, figure 4b; Peña Cantero et al., 1997: 349–353, figures 2, 13b (= Oswaldella erratum Peña Cantero and Vervoort, 1997 ).

Not Oswaldella billardi shetlandica Stepan’yants, 1979 (= Oswaldella shetlandica Stepan’yants, 1979 p.p.; Oswaldella erratum Peña Cantero and Vervoort, 1997 p.p.).

Material examined. 0000X, two stems up to 75 mm high, with immature gonothecae ( USNM 1003304; RMNH-Coel. 30203); 000AM, several fragments up to 35 mm long ( USNM 1003305; RMNH-Coel. 30204); 002/002, two stems up to 90 mm high ( USNM 1003306; RMNH-Coel. 30205).

Description. Colonies consisting of monosiphonic and unbranched stems up to 90 mm high, occasionally with some stolonal tubes. Hydrocaulus provided with apophyses alternately arranged in one plane and in two longitudinal rows. Cauline apophyses directed upwards, forming an angle of ca 45 °, or slightly larger, with long axis of stem, provided with two nematophores, each one emerging through an axillary perisarc hole ( figure 2B). Stems divided into internodes or with occasional internodes. Cauline apophyses supporting hydrocladia; secondary hydrocladia may be present ( figure 2A). Cauline apophyses and hydrocladia separated by distinct node.

Hydrocladia homomerously divided into hydrothecate internodes provided with one hydrotheca and two nematophores ( figure 2 C–H): one mesial superior, emerging through a simple perisarc hole situated behind free adcauline hydrothecal wall, and one mesial inferior nematophore emerging through a hole situated on an elevation of internode and provided with a scale-shaped nematotheca. Top of distal hydrocladial internodes truncated.

Hydrotheca elongate, usually situated slightly above middle of internode ( figure 2 C–H), sometimes slightly below that point; free part of adcauline wall considerable. Hydrothecal aperture circular or kidney-shaped and strongly tilted adcaudally. Abcauline wall of hydrotheca convex.

Immature gonothecae present, originating just below mesial inferior nematophore, cone-shaped; greatest diameter at truncated top ( figure 2I).

Ecology and distribution. Oswaldella billardi is a shelf species (Peña Cantero and Vervoort, 1997). It has been recorded from 7 (Stepan’yants, 1972) to 206 m depth (Naumov and Stepan’yants, 1962) on bottoms of small rocks with red algae ( Briggs, 1938), sand and boulders (Naumov and Stepan’yants, 1972) and rocks, pebbles, sand and mud (Stepan’yants, 1979). Our material was collected from 238 to 412 m depth. It has been found with gonothecae in January ( Briggs, 1938; Stepan’yants, 1979) and in November (Stepan’yants, 1979); our material with immature gonothecae was collected in December.

Oswaldella billardi until now was considered endemic to East Antarctica (Peña Cantero and Vervoort, 1997), where it had been found in the Davis Sea ( Briggs, 1938; Stepan’yants, 1972), off Queen Mary Coast and Enderby Land (Naumov and Stepan’yants, 1962) and off Adélie Coast (Naumov and Stepan’yants, 1972). We also found it in East Antarctica, in the region of Wilkes Land, in particular north of Wilkes Station (Budd Coast). However, part of our material was collected off McDonald Ice Rumples, on the east coast of the Weddell Sea, so its distribution may better be considered circum-Antarctic.