(Fig. 10 A)
Staurotheca compressa — Peña Cantero & Vervoort, 2003: 2673 –2676, fig. 4 (synonymy); Peña Cantero, 2006: 940, fig. 4A; 2008: 459; 2009: 1749; 2013: 131; Peña Cantero & Vervoort, 2009: 87; Soto Àngel & Peña Cantero, 2015: 997, fig. 8b –c.
Material examined. Stn 25, mass of stems, ca. 20 mm in diameter (NIWA 117518); Stn 178, mass of stems, ca. 80 mm high and 70 mm wide, with gonothecae, basibiont of Halecium tangaroasp. nov. and Hebella plana (NIWA 117519); Stn 197, mass of stems, ca. 100 mm in diameter, with female gonothecae (MNCN 2.03/551).
Remarks. This is a species easily distinguishable by the hydrothecal aperture, which is laterally depressed, forming both an adcauline and an abcauline cusp (Fig. 10 A).
Ecology and distribution. Reviewed by Peña Cantero & Vervoort (2003) and Peña Cantero (2006). Eurybathic species (Peña Cantero & Vervoort 2003), collected at depths between 45 (Briggs 1938) and 1042 m (Peña Cantero & Vervoort 2003); present material at depths from 110 to 348 m, basibiont for colonies of Hebella plana and Halecium tangaroasp. nov. and with gonothecae in February.
Circum-Antarctic species (Stepanjants 1979), recently reported from off Livingston Island (Peña Cantero 2006, 2008), Deception and Trinity islands (Peña Cantero 2008), Bransfield Island and Bransfield Strait (Peña Cantero & Vervoort 2009), Low Island (Peña Cantero & Vervoort 2009; Peña Cantero 2013) and Elephant Island (Soto Àngel & Peña Cantero 2015), in West Antarctica, and from the Balleny Islands (Peña Cantero 2009), in East Antarctica. See Peña Cantero & Vervoort (2003) for previous records. In the Ross Sea, already known off Scott Coast (Peña Cantero & Vervoort 2003). Present material off Adare Peninsula and Possession Islands.