Microxina benedeni ( Topsent, 1901 )

Schejter, Laura, Cristobo, Javier & Ríos, Pilar, 2024, New records of demosponges (Porifera) from the South Orkney Islands (Antarctica) with a checklist for the region, Zootaxa 5403 (4), pp. 401-430 : 420

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).

Figures

FIGURE 10. a–c. Microxina benedeni, a. general morphology, scale: 2,5 cm, b. oxea, scale: 160 µm, c. sigma, scale: 40 µm; d-f. Microxina charcoti, d. general morphology, scale: 5,5 cm, e. oxea, scale: 260 µm, f. microxea, scale: 25 µm.