Microxina benedeni (Topsent, 1901)

(Fig. 10a–c)

Restricted synonymy: Gelliodes benedeni Topsent, 1901, Gellius benedeni (Topsent, 1901) .

Material examined: Several specimens collected at station 11 (SOI; 60°53'S, 42°35'W; 487 m; 10/3/2014; MACN-In 44388; IEO-CSIC Col.) .

Description: Tubular specimens, with a densely hairy and conulated surface (Figure 10a). Beige to light-brown in colour. Two specimens used small rocks as settlement substrates. Spicules are straight oxeas with sharp ends of 320–780 µm by 20–30 µm and exclusively c sigmata of 45–55 µm (Figure 10b, c).

Remarks: There are currently six valid Microxina species which are known from the Antarctic: M. charcoti Topsent, 1916, M. benedeni (Topsent, 1901), M. lanceolata Calcinai & Pansini, 2000, M. phakellioides (Kirkpatrick, 1907), M. sarai Calcinai & Pansini, 2000 and M. simplex (Topsent, 1916) . They differ in the size range of the oxeas and the complementary microscleres (sigmas, microxeas, toxas) (see Goodwin et al. 2012, for the comparison).Also, M. myxa Goodwin, Brewin & Brickle, 2012 has been also described from South Georgias Islands. Our specimen fits well with the descriptions of M. benedeni, from other Antarctic records: Campos et al. (2007), Göcke & Janussen (2013), Koltun (1964). This finding represents a new record for the SOI. This species has been also documented in other subantarctic regions, such as Malvinas (Falkland) and South Georgias Islands by Burton (1932).