Isodictya kerguelenensis ( Ridley & Dendy, 1886 )

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 : 411-412

Isodictya kerguelenensis ( Ridley & Dendy, 1886)

( Figure 5g –i )

Restricted synonymy: Homoeodictya kerguelenensis Ridley & Dendy, 1886 , Isodictya antarctica ( Kirkpatrick, 1908) , Isodictya cactoides ( Kirkpatrick, 1908) .

Material examined: 3 specimens collected in stations 10 ( SOI; 60°59'S, 46°43'W; 307 m; 5/3/2014; MACN-In 44379; IEO-CSIC Col.) and 18 ( SOI; 60°47,561'S, 45°36,854'W; 96 m; 10/3/2012; MACN-In 44380) .

Description: Polymorphic species, with a massive or erect and digitiform morphology. Specimens are not flexible. Grey-light, beige in colour ( Figure 5g ). The largest specimen here studied had rizhoids at its base. The choanosomal skeleton is made of multispicular tracts of oxeas. The ectosomal skeleton is very fragile, not always present, depending on the preservation state of the specimen. Spicules are thick straight or slightly curved oxeas 530–750 µm × 20–30 µm, although some thinner oxeas (probably in-formation spicules) were also present (about 10–15 µm). Small palmate isochelae of 15–25 µm are present but not very common in our specimens ( Figure 5h–i ).

Remarks: This species has been recorded from Antarctic waters (many times with its synonyms) by Topsent (1908), Burton (1938), Boury-Esnault & Van Beveren (1982), Ríos et al. (2004), and Göcke & Janussen (2013), among others. Our specimens agree with the descriptions in Ríos et al. (2004) and Göcke & Janussen (2013). This is a new record for the SOI.

Figures

FIGURE 5. a–f. Crella (Pytheas) crassa. a, general morphology, scale: 1 cm; b, Strongyle, scale: 110 µm; c, Acanthostyle, scale: 60 µm; d, Isochela, Scale:12.5 µm; e–f, Skeleton, scale: 200 µm; g–i. Isodictya kerguelenensis. g, General morphology, scale: 4 cm; h, isochelae, scale: 8 µm; i, Oxea, scale: 170 µm; j–l. Isodictya verrucosa. j, General morphology, scale: 3 cm; k, Isochela, scale: 12 µm; l, Oxea, scale: 200 µm; m–p. Isodictya lankesteri. m, General morphology, scale: 8.5 cm; n, Canonochela, scale: 30 µm; o, Oxea, scale: 130 µm; p, skeleton, scale: 100 µm.