Rossella racovitzae Topsent, 1901

Janussen, Dorte & Reiswig, Henry M., 2009, Hexactinellida (Porifera) from the ANDEEP III Expedition to the Weddell Sea, Antarctica, Zootaxa 2136, pp. 1-20 : 17

Rossella racovitzae Topsent, 1901

( Fig. 10 A)

Material examined: All from ANDEEP III Exped., Weddell Sea, Antarctica , SMF 10610a, and SMF 10610b, R.V. 'Polarstern', stn PS67/074-7, 20 Feb. 2005, 71°18.48'–18.40'S, 13°58.55'–58.14'W, 1055– 1047 m, ethanol; SMF 10705, R.V. 'Polarstern', stn PS67/151-1, 20 Mar. 2005, 61°45.46'S, 47°07.57'W to 61°45.34'S, 47°07.78'W, 1181–1188 m, ethanol.

Description and remarks: Four specimens of this species were collected on the ANDEEP III Expedition. The two from station PS67/074-7 are large barrels, 28.7 cm tall by 15.9 cm flattened diameter and 30.7 cm tall by 17.7 cm flattened diameter, with strong 6 mm-tall conules on outer surface and few prostalia emanating from the conule summits. The two specimens from station PS67/151-1 are a small conic tube, 54 mm tall by 22 mm upper diameter, and a small sac 52 mm tall by 34 mm maximal diameter, both with proportionately large prostalia projecting up to 32 mm from sides and oscular margins. Conules are not present on the small tubular form but very slight conules are evident on the small sac specimen. Although calycocomes are rare in these specimens, they agree in all morphologic features and other spicule details with the descriptions of the common Antarctic species, R. racovitzae by Topsent (1901, 1917), Burton (1929), Koltun (1976) and Barthel and Tendal (1994). Since the anisodiscohexasters have been generally poorly rendered in previous works, a first scanning electron micrograph of this spectacular spicule is provided ( Fig. 10 A) for comparison with those of other rossellid sponges. This species has been reported from ANDEEP II and other recent collections from the Weddell Sea ( Janussen et al. 2004). It is circumantarctic in distribution, occurring at depths of 20–2012 m.

Figures

FIGURE 10. Anisodiscohexaster microscleres of (A) Rossella racovitzae (SMF 10705) and (B) Rossella nuda (SMF 10706) (SEM).