Mycale (Aegogropila) magellanica ( Ridley, 1881 )

Goodwin, Claire E., Berman, Jade & Hendry, Katharine R., 2019, Demosponges from the sublittoral and shallow-circalittoral (<24 m depth) Antarctic Peninsula with a description of four new species and notes on in situ identification characteristics, Zootaxa 4658 (3), pp. 461-508 : 491-492

Mycale (Aegogropila) magellanica ( Ridley, 1881)

( Figure 17 )

Synonomy: Esperella magellanica ( Ridley, 1881) ; Esperia cunninghami Carter, 1882 ; Esperia magellanica Ridley, 1881 ; Mycale (Mycale) magellanica ( Ridley, 1881) ; Mycale antarctica Hentschel, 1914 ; Mycale lilliei Dendy, 1924 ; Mycale magellanica ( Ridley, 1881) ; Mycale pellita Topsent, 1913 ; Mycale rossi Hentschel, 1914 ).

Specimens. BELUM. Mc 2015.717 Port Charcot, Booth Island (65°03.853’S, 64° 01.868’W), depth 6–16 m; collected by C. Goodwin and E. Priestley, 23/02/2015 ; BELUM. Mc 2015.685 Rocks NW of Laktionov Island (65°45.536’S, 65° 47.319’W), depth 6–23 m; collected by C. Goodwin and E. Priestley, 22/02/2015 ; BELUM. Mc 2015.762 Paradise Bay Wall (64°53.841’S, 62° 52.391’W), depth 14–21 m; collected by C. Goodwin and E. Priestley, 24/02/2015 .

External morphology. In situ appearance ( Figure 17A ): Thick pale yellow crust with large oscules and ecto- somal mesh clearly visible through surface.

Preserved appearance. White ectosomal crust supported by large skeletal columns of spicules.

Skeleton: Chonosomal skeleton formed of branching fibres of 10–20 styles ( Figure 17B ). These are fused to- gether in the interior of the sponge to form larger columns then branch towards the surface. Ectosomal mesh ( Figure 17C ) formed of columns of 5–10 spicules.

Spicules: Mycalostyles ( Figure 17D ): BELUM.Mc2015.685 399(488)560 by9(14) 18µm, BELUM.Mc2015.717 433(530)576 by 9(10) 14 µm.

Microxeas ( Figure 17E ): BELUM.Mc2015.685 27(57)130 by 3(4) 5 µm, BELUM.Mc2015.717 60(108)148 by 3(4) 5 µm.

Anisochelae ( Figure 17F ): BELUM.Mc2015.685 26(40) 51 µm; BELUM.Mc2015.717 34(39) 44 µm.

Remarks. The type specimen of Mycale (Aegogropila) magellanica ( Ridley, 1881) has styles 462–544 by 12.6 µm, chelae 44–54 µm, and rare microxea 44–63 µm. Koltun (1964) reports that the spicule complement of this species is very variable with frequently microscleres represented only by chelae and raphides, or chelae and sigmas, so it is possible that it represents a species complex and molecular work is required to determine if South American and Antarctic specimens are the same species. The external appearance of our specimens is very similar to that recorded by Hajdu et al. (2016) from the South Shetland Islands.

Distribution. The type locality for the species is Patagonia Bay, southern Chile. It is one of the most widely distributed species in the southwest Atlantic ( López Gappa & Landoni 2005) with records from Argentina, Chile and the Falkland Islands ( Ridley & Dendy 1887; Topsent 1913; Burton 1932, Burton 1934; Burton 1940; Sarà 1978; and Schejter et al. 2012). It has been recorded from the Antarctic (Hentshel 1914), South Shetlands ( Burton 1932; Hajdu et al. 2016) and South Georgia ( Burton 1932) George V Land ( Burton 1938), East Antarctic Wilkes Land ( Koltun 1964) Enderby Land, Princess Elizabeth Land and Kerguelen ( Koltun, 1964), the Ross Sea ( Kirkpatrick 1908), Weddell Sea ( Barthel et al. 1990) Lazarev Sea ( Gutt & Koltun 1995) and recently from Marguerite Bay in 355m ( Rios 2006).

Figures

FIGURE 17. Mycale (Aegogropila) magellanica (Ridley, 1881). BELUM.Mc2015.717. A. In situ appearance. B. Choano- somal skeleton, scale bar 1000 µm. C. Ectosomal skeleton, scale bar 1000 µm. D. Mycalostyle. E. Microxea. F. Chelae. Spicule scale bars all 10 µm.