Iophon unicorne Topsent, 1907

Goodwin, Claire & Brickle, Paul, 2012, Sponge biodiversity of South Georgia island with descriptions of fifteen new species, Zootaxa 3542, pp. 1-48 : 8-10

Iophon unicorne Topsent, 1907

( Figure 5)

Synonymy: Iophon unicornis Topsent, 1907 .

Iophon spatulatum Kirkpatrick, 1907 .

Material: All samples in 95% ethanol, tissue section and spicule preparation on slides. BELUM Mc 7634 and BELUM Mc 7635. Bird Sound Site 1, South Georgia (54°02.058’S, 38° 00.242’W); depth 18m; collected by C. Goodwin, S. Cartwright and P. Brickle, 22 nd November 2010 . BELUM Mc 7636. Bird Sound Site 2, South Georgia (54°01.149’S, 38° 01.026’W); depth 18m; collected by C. Goodwin, S. Cartwright and P. Brickle, 22 nd November 2010 .

Comparative material examined: MNHN DT1665 Iophon unicornis Topsent, 1907 . Île Anvers, collected by ‘Le francais’. Microscope preparations of tissue section and spicules.

External morphology: In situ appearance: Bright yellow thickly encrusting sponge with papillate mammiform processes, often bearing terminal oscules ( Fig. 5a).

Preserved appearance: Chocolate brown crust, firm but compressible. Surface composed of flattened lobes with thin edges.

Skeleton: The choanosomal skeleton consists of pronounced ascending columns of oxea up to 10 spicules in width, overlain by an irregular triangular isotropic reticulation of bundles of 1–3 oxea. The ectosome is comprised of brushes of strongyles, which fan out towards the surface ( Fig. 5b).

Spicules: Measurements from BELUM Mc7636.

Choanosomal oxeote styles: 314(341)394 by 11.7(16.6)21.2µm, stylote oxea with abruptly pointed ends, often bent near to one of the ends ( Fig. 5c).

Ectosomal strongyles: 204(228)246 by 8.4(11.0)13.3µm, fusiform strongyles with flattened ends which bear a variable number of large spines ( Fig. 5d,e).

Bipocoelles: 12.6(14.8)17.9µm, thin curved bipocoelles with numerous claws at each end ( Fig. 5f).

Anisochelae: 16.8(18.0)19.7µm, spurred aniosochelae ( Fig. 5g).

Remarks: The spicule categories of our specimens are similar in size to those of the type but have shorter oxea (spicules measurements from type: oxea 398(439)473 by 10(15)18µm, strongyles 212(234)248 by 8(11)14µm, chelae 17(20)24µm, Table 2). The form of the oxea is similar to those of the type but the strongyles differ slightly in that those in the type tend to have more pronounced swelling at the ends. Whilst the chelae are a similar form and size we could not find bipocoelles in the type to compare. Topsent (1907) does not record biopocoelles as being present in the species description but Rios (2006) made new preparations from the type specimen and found them to be common; they are of a similar size and form to those of our specimens.

Iophon flabellodigitatus Kirkpatrick, 1907 , is currently regarded as a synonym of I. unicorne (van Soest et al. 2012) , Rios (2004) regarded them as separate species but on further examination reconsidered ( Rios, 2006). The ectosomal strongyles of the type of I. flabellodigitatus differ from those of I. unicorne in having one end with a very large spine, but otherwise have similarly formed and sized spicules.

Topsent (1907) recognised that the oxea-like choanosomal spicules in this species were superficially similar to oxea but considered the mucron to be ornamentation, similar to basal spination of styles found in other Iophon species , and consequently regarded them as modified acanthostyles. This has been followed by Rios (2004; 2006) who terms the spicules styles with mucronate ends.

Distribution: The type locality is Île Anvers (Anvers Island) on the Antarctic Peninsula. The species is widely distributed in the Antarctic with records from Bransfield Strait, Bellinghausen Sea, Ross Sea, Kerguelen Island, South Orkney Islands, South Shetland Islands, and Weddell Sea ( Kirkpatrick 1908; Topsent 1913, 1917; Hentschel 1914; Desqueyroux-Faúndez 1989; Pansini et al. 1994; Gutt and Koltun 1995; Rios 2006). Burton (1929) considered the majority of Antarctic species of Iophon to be synonyms so it is not clear if his specimens include this species.

Species Choanosomal Echinating Ectosomal Chelae Bipocoelles External appearance/Notes/Distribution megascleres µm acanthostyles spicules µm

µm (tylotes unless specified)

Iophon pictoni Goodwin, Jones, Acanthostyles n/a 135– 150 17 n /a Type locality Falkland Islands. Bright yellow thick Neely and Brickle, 2011. 132–150 crust.

Iophon proximum (Ridley, Acanthostyles 83–157 109–252 10–35 6–16 (rare) Encrusting(on Zygochlamys patagonica ), irregular and 1881) 106–272 massive forms. Chile, Argentina and Falkland Islands.

Iophon proximum reticulare Acanthostyles n/a 120–160, ends 18–24 none Type from Kerguelen, Antarctica. Hentschel, 1914 104–152 spined

Iophon gaussi Hentschel, 1914 Oxeote , smooth n/a 288–360 16 11 Antarctic.Originally I. spatulatus var. gaussi .

465–560 225–290, ends 9–19 10–13 Measurements in bold Hentschel (1914), normal font from

480–620 spined c-shaped, Rios (2006) measurements from otherAntarctic specimens.

spined shafts.

Iophon terranovae Oxeote , smooth 200–580, n/a 265–275 51–64 9–15 Massive/sub cylindrical. Antarctic, type locality Calcinai and Pansini, 2000 also juvenile thin styles Terra Nova Bay and Faraglione, Ross Sea.

375–540 single spine on head.

Iophon tubiforme Oxeote , smooth n/a 141–243, ends 8–19 6–19 (rare) Chile. Sponge in form of several joined tubes. Desqueyroux–Faúndez and van 150–272 spined Soest, 1996

Iophon aceratum Hentschel, Oxeote , smooth n/a 320–408, ends 20–24 12– 13 Type massive, 2.5cm long. Type locality Gauss 1914 592–640 spined station, Antarctic.

Iophon flabellodigitatum Oxeote , smooth with n/a 344 by 12.5, 35 5.5–11 Large digitate growth in one plane with oscules along Kirkpatrick, 1907 mucron on head 590 by 25 ends spined 17.5 edge. Type locality Winter Quarters,Antarctic.

Iophon flabellodigitatum var. Style 344–376 n/a 208–272 17–20 15–16 Massive 6cm long. Type Kerguelen, Antarctic. gaussi Hentschel doesn’t mention if styles are Hentschel, 1914 oxeote/mucronate and terms them ‘styles’ (he uses

‘Amphioxe’ for oxeote spicules).

Iophon unicorne Topsent, 1907 Oxeote styles with n/a 240 18–20 none Massive yellow attached to algae.Antarctic, Falkland mucronate ends/short 270–390 22.5–25 13–20 abundant Islands ( Burton 1934). Bold Topsent’s original sizes.

pointed oxeas unequal Normal from Rios (2006) schizotype measurements.

435–470 tornotes, style Topsent described no bipocoelles in type but Rios (2006)

370–575 like with spined found them to be present. Rios (2006) considers this a ends. synonym of Iophon flabello–digitatus Kirkpatrick, 1907,

revising ( Rios et al. 2004).

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