(Fig. 10 C)
Staurotheca dichotoma— Totton, 1930: 178, fig. 27a, c, pl. 2 fig. 9; Peña Cantero & Vervoort, 2003: 2681 –2683, fig. 7 (synonymy); Peña Cantero & Gili, 2006: 768; Peña Cantero, 2010b: 769; 2012: 859; Soto Àngel & Peña Cantero, 2015: 998, fig. 8d –e.
Material examined. Stn 8, fragment 15 mm long (MNCN 2.03/558); Stn 140, mass of stems ca. 60 mm in diameter, basibiont of Hebella plana (NIWA 117530).
Remarks. In the material examined the hydrothecae are arranged in decussate pairs and have a significant free portion (about 200 µm). This is a species characterized by having quite robust hydrothecae (Fig. 10 C) with a relatively large diameter at the hydrothecal aperture (300–320 µm in the present material). The larger microbasic mastigophores are 19–22 x 4–4.5 µm.
Ecology and distribution. Reviewed by Peña Cantero & Vervoort (2003). Found at depths from 82 (Totton 1930) to 799 m (Peña Cantero et al. 1997a); present material from 231 to 541 m, basibiont for colonies of Hebella plana.
Species with an Antarctic –Kerguelen distribution (Peña Cantero & Vervoort, 2003), recently reported from off Bouvet Island (Peña Cantero & Gili 2006), Peter I Island (Peña Cantero 2010b), South Georgia, South Sandwich Islands and Discovery Bank (Soto Àngel & Peña Cantero 2015) and from the Bellingshausen Sea (Peña Cantero 2012). See Peña Cantero & Vervoort (2003) for previous records. In the Ross Sea, already known from McMurdo Sound and off Cape Adare (Totton 1930) and from the central basin and at Pennell Bank (Peña Cantero & Vervoort 2003). Present material off Possession Islands and Moubray Bay