Sponge biodiversity of South Georgia island with descriptions of fifteen new species Author Goodwin, Claire National Museums Northern Ireland, 153 Bangor Road, Cultra, Holywood, County Down, BT 18 0 EU & Shallow Marine Surveys Group, PO Box 598, Stanley, FIQQ 1 ZZ, Falkland Islands Author Brickle, Paul Shallow Marine Surveys Group, PO Box 598, Stanley, FIQQ 1 ZZ, Falkland Islands & South Atlantic Environmental Research Institute, PO Box 609, Stanley, FIQQ 122, Falkland Islands text Zootaxa 2012 2012-11-07 3542 1 48 journal article 1175-5326 8D917062-2FC8-4EE9-83A0-FDDCB6A08F45 Myxilla (Burtonanchora) ponceti sp. nov. ( Figure 13 ) Type material: Holotype : BELUM Mc 7572. Sample in 95% ethanol, tissue section and spicule preparation on slides; Floating Dock , Grytviken , South Georgia ( 54º 16.937´S , 36º 30.475´W ); depth range: 0–6.6m ; collected by C. Goodwin and S. Cartwright , 18 th November 2010 . Paratypes : Samples in 95% ethanol, tissue section and spicule preparation on slides . BELUM Mc 7573. Floating Dock , Grytviken , South Georgia ( 54º 16.937´S , 36º 30.475´W ); depth range: 0–6.6m ; collected by C. Goodwin and S. Cartwright , 18 th November 2010 . BELUM Mc 7600. Prion Island Site 2, South Georgia ( 54°001.862’S , 37° 15.032’W ); depth 18m ; collected by C. Goodwin , D. Poncet , and P. Brewin , 19 th November 2010 . BELUM Mc 7655. Prince Olav Harbour , South Georgia ( 54°03.579’S , 37° 08.203’W ); depth 18m ; collected by C. Goodwin , D. Poncet , and S. Brown , 23 rd November 2010 . Etymology: Named for Dion Poncet, member of the expedition dive team, who alerted us to this ‘probable sponge’ under Grytviken jetty, and whose knowledge of South Georgia was invaluable to this survey. External morphology: In situ appearance : Specimens are large ( 10–20cm maximum dimension), smooth surfaced, lobed sponges, carrot orange in colour, bearing large terminal oscules on the ends of the lobes. The two largest specimens are fan shaped and bear the oscules in a line along the edge of the fan. They are attached by the base of the specimen to the substrate; the attachment point is quite broad in some specimens but in the fan shaped specimens is smaller and might be considered a stalk ( Fig. 13a ). Preserved appearance: Tissue firm but compressible. Ectosome is a dark brown, choanosome a paler brown. Skeleton: Choanosomal skeleton consists of ascending fibres of 4–10 styles joined by smaller, shorter, fibres of 1–3 styles. There is an ectosomal palisade of tylotes. Chelae scattered throughout skeleton and not forming rosettes ( Fig. 13b ). Spicules: Measurements from Mc7572. Choanosomal subtylostyles: 281(325)369 by 12.2(14.3)18.7µm. Smooth styles, often slightly curved. Some have a faint swelling at the head ( Fig. 13c ). Ectosomal tylotes: 197(276)324 by 6.9(10.3)14.5µm. Anisotylotes in which one or both ends are swollen. In some one end has a mucronate point ( Fig. 13d ). Chelae: In two categories 31(40)49 and 57(66)72µm ( Fig. 13e ). TABLE 7. Myxilla (Burtonanchora) species from the Antarctic and Southern Atlantic.

Species	Choanosomal	Ectosomal spicules	Chelae	Other Microscleres	External appearance/Notes/ Distribution
styles µm	µm	µm	µm
Myxilla	Smooth styles	Tornotes 250 by 8.	2 sizes: 21,42	2 categories of	Small sponge, sub–ramose with flattened branches or
(( Burtonanchora )	470 by 17 bearing	Ends with terminal	sigmata: 25, 42	lobes. South Georgia 106–198m. Currently classified
basimucronata Burton,	basal mucron.	mucron and numerous	in Myxilla (Myxilla) (van Soest et al. 2012) .
1932	microspines.
Myxilla (Burtonanchora)	715–775 by 20	Tylotes 380 by 7–8.	60–70	None	Irregular mass with connulose surface 9x4x7mm.
asigmata (Topsent,	Smooth	(3 teeth)	Type location Antarctic 450m.Distribution Antarctic
1901)	and sub–Antarctic including South Georgia (Burton
1932). See Rios and Cristobo (2007) .
Myxilla (Burtonanchora)	Smooth styles	Tornotes	25–40	70 sigmas	Flattened sheet largest piece 69 by 62 by 6mm.
hastata Ridley and	770 by 40	350 by 10	Wrinkled surface with pores in irregular groups. Rio
Dendy, 1886	del Plata, Argentina, 600 fathoms.
Myxilla ( Burtonanchora )	Smooth styles	Strongyles with spined	11	None	Massive sponge with uneven, shaggy, surface. Chelae
lissostyla Burton, 1938	800 by 35	ends 350 by 10	with thin, rounded shaft and pointed alae. Antarctic.
Myxilla (Burtonanchora)	500–570 by	Tylotes 280–300 by 10	73–80	14–17 normally but	Massive sponge, able to grow very large. Prominent
magna Topsent,1916	27–29 Smooth,	most with terminal	(3 teeth)	up to 19–22;	network of veins on surface. Large oscules often on
strongly curved	spines	23–27	4–7	mounds. Listed as junior synonym of Myxilla (Myxilla) mollis Ridley and Dendy, 1886 in (van
Soest et al. 2012).
Myxilla (Burtonanchora)	Smooth styles	Tylotes with minutely	50	Sigmas 63	Encrusting a worm–tube, 12mm thick. Very bad
mollis Ridley and Dendy ,	700 by 20um	spined oval heads 400	condition specimen—prevents detailed description.
1886	by 10.	Type locality off mouth of Rio de la Plata, 600
fathoms. Is currently listed as Myxilla ( Myxilla ) in
van Soest et al. (2012).
Myxilla (Burtonanchora)	480–500	Curved or flexuose	37–73	Raphides in	Simple column 20 by 3–14mm. Yellow–brown when
pistillaris Topsent, 1916	Smooth, curved	tylotes with spined	trichodragmata 90	living. Type locality Antarctica, collected by the
ends 300 by 10	‘ Porquoi-pas ?’, precise locality not given.
Myxilla (Burtonanchora)	281(325)369 by	Tylotes	31(40)49 57(66)72	None	Large, carrot orange, lobed. South Georgia.
ponceti sp. nov.	12.2(14.3)18.7	197(276)324 by
6.9(10.3)14.5

Remarks: Myxilla (Burtonanchora) is defined by possession of smooth rather than spined choanosomal styles. There are several species of Antarctic Myxilla (Burtonanchora) species ( Table 7 ). However, all of these can be distinguished by having much larger choanosomal styles or the presence of sigmata. Myxilla (Burtonanchora) pistillaris Topsent, 1916 is most similar but has larger styles (480–500µm) and possesses raphides which are not present in this species.