New records of demosponges (Porifera) from the South Orkney Islands (Antarctica) with a checklist for the region Author Schejter, Laura Author Cristobo, Javier Author Ríos, Pilar text Zootaxa 2024 2024-01-23 5403 4 401 430 http://dx.doi.org/10.11646/zootaxa.5403.4.1 journal article 10.11646/zootaxa.5403.4.1 1175-5326 10562154 C2EAB19C-07CB-4013-9C93-D25259EA2673 Artemisina plumosa Hentschel, 1914 ( Fig. 3f–j ) Material examined: 1 specimen collected at the station 11 ( SOI ; 60°53'S , 42°35'W ; 487m ; 10/3/2014 ; MACN-In 44359) . Description: shrub-like dried specimen about 3 cm high, light beige ( Figure 3f ). Surface very hispid due to the echinating spicules ( Figure 3j ). The main axis of the skeleton is composed of thick styles. The ectosomal skeleton is made of thin styles. Microscleres are found in the main skeleton, and in our specimen chelae were abundant. Spicules dimensions are: thick styles of 1350–750 µm by 20–50 µm; thin styles, sometimes subtylostyles 320–500 µm by 5–15 µm; small isochelae of 10–15 µm and toxas of 70–250 µm, sometimes with spined ends ( Figure 3g –j ). Remarks: According to Hentshel (1914), Desqueyroux (1989), Burton (1929 , 1932 ), and Koltun (1964) , this species exhibits differences in the size and type of spicules. However, we considered that our specimen matched the species' typical traits in general. Caution should be taken because except for the presence of chelae, this species may be confused with Clathria (Axosuberites) nidificata (see characteristics below). Although this species was previously recorded in several locations in the Antarctic domain and also in Malvinas (Falkland) Islands, this finding represents the first record for the SOI.