Dendrilla antarctica Topsent, 1905

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 : 502-503

Dendrilla antarctica Topsent, 1905

( Figure 25 )

Specimens. BELUM.Mc2015.553 and BELUM. Mc 2015.544 Gøuvernoren Wreck, Enterprise Island (64°32.407’S, 61° 59.884’W), depth 8–19 m; collected by C. Goodwin and E. Priestley, 12/02/2015 ; BELUM. Mc 2015.813, BE- LUM. Mc 2015.815 , BELUM. Mc 2015.822 Nelson Island, South Shetland Islands (62°59.607’S, 60° 33.601’W), depth 7–18 m; collected by C. Goodwin and E. Priestley, 27/02/2015 ; BELUM. Mc 2015.828 Diomedea Island (62°12.185’S, 58° 56.760’W), depth 10–18 m; collected by C. Goodwin and E. Priestley, 01/03/2015 .

External morphology. In situ appearance ( Figure 25A ): Very bright luminous lemon yellow/neon yellow sponge with pronounced spiky conules. Form varies from simple encrusting specimens to ones with many lobes and branches. Specimens can be very large, some of ours were over 1 m total diameter.

Preserved appearance. Mass with clearly visible fibres within the tissue and protruding from surface conules. Colour is very dark maroon.

Skeleton ( Figure 25B ): Dendritic with fibres arising from a basal plate. These project from the surface, the ends forming the surface conules.

Spicules: None.

Remarks. Some authors have used Dendrilla membranosa (Pallas, 1766) for Antarctic specimens ( Burton 1929, 1932, 1934; Koltun 1964; Baker 1995; Bavestrello et al. 2000; von Salm et al. 2016). This seems to originate with Burton (1929, 1932, 1934) who used D. membranosa for his Antarctic specimens as he considered Dendrilla antarctica Topsent, 1905 a later synonym. Dendrilla membranosa was described as Spongia membranosa from an image of Seba (1734). The type locality of this species is the Indian Ocean and western Indo-Pacific, and it is therefore unlikely to be conspecific with Antarctic specimens. Additionally, since there is no type specimen it has been proposed that S. membranosa should be declared a nomen dubium (Berquist 1995) and, even if conspecifity were probable, it does not make sense to synonymise a well-established valid species with an unknown entity. The species is thought to be slow growing with the majority of individuals studied at McMurdo Sound not growing during a ten-year study period ( Dayton 1989). This sponge is preyed upon by the nudibranch Doris kerguelenensis (Bergh, 1884) ( Barnes & Bullough 1995) .

Distribution. The type locality of Dendrilla antarctica is the Antarctic Peninsula (Booth Island 25–40 m, Wiencke Island 20 m, and Anvers Island, 29 m). It is very common in shallow water along the Antarctic Peninsula ( Hajdu et al. 2016). It is found more widely from Southern South America, the Falkland Islands, the subantarctic and the Antarctic (including McMurdo Sound ( Brueggeman 1998), Wilheim II Coast, Victoria Land, Graham Coast) from depth 10–549 m ( Koltun 1964, 1976).

Figures

FIGURE 25. Dendrilla antarctica Topsent, 1905. BELUM.Mc2015.544. A. In situ appearance. B. Skeleton, scale bar 1000 µm.