Raspailia (Hymeraphiopsis) hentscheli van Soest & Hooper, 2020

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 : 418-420

Raspailia (Hymeraphiopsis) hentscheli van Soest & Hooper, 2020

( Fig. 9d–i )

Restricted synonymy: Raspailia (Hymeraphiopsis) irregularis Hentschel, 1914 , Raspailia irregularis Hentschel, 1914 .

Material examined: 1 specimen collected at station 11 ( SOI; 60°53'S, 42°35'W; 487 m; 10/3/2014; IEO-CSIC Col.) .

Description: Specimen fixed directly to a pebble. Erect arborescent shape, tubular with the base narrower than the apex. Dimensions of the specimen: 22 mm height × 5.3 mm at the apex and 2.3 m at the base; slightly compressible; hispid surface, with irregular conules from which spicules protrude, giving its characteristic hispidation. No oscules or ostia were visible. Colour beige in vivo ( Fig 9d ). Skeleton: The choanosomal skeleton is formed by dense spongin fibers, simple or dichotomously branched in which between one and four styles, form a central axis. This axis is surrounded by abundant echinating acanthostyles. In the ectosome the spongin fibers protrude, creating a strongly hispid surface. The end of each fibre is topped by the same type of choanosomal styles; each of them is surrounded by fine auxiliary anisoxas or styles which are sometimes also scattered on the surface. In the base of the sponge, around the peduncle, the spongin forms a lining surface where large styles form a clear hispidation (more than 1 mm in length) ( Fig. 9h–i ). Spicules, megascleres ( Fig. 9e–g ). Very long choanosomal styles, with a very pronounced curvature in their middle or in the third closest to the base. Dimensions: 2500 × 45 μm. Acanthostyles typical of the subgenus; straight, with the base thickened and smooth, while the stem is spined, the spines are most abundant at the tip. Dimensions: 131–217 by 16–23 μm. Very thin ectosomal styles with marked curvatures. Dimensions: 491 × 6 μm.

Remarks: This species was recorded for the first time in Antarctic waters by Hentschel (1914) (Gauss station, Wilhelm II coast, 385 m). Burton (1932) synonymised Eurypon miniaceum with Raspailia (Hymeraphipsis) irregularis based on their similarity of structure and speculation; Koltun (1964, 1976) maintained this synonymy. However, Boury-Esnault & Van Beveren (1982) argued that both species are valid; this was also supported by Hooper (1991, 2002). The genus Hymeraphiopsis is monotypic ( Ríos, 2006). Ríos (2006) recorded this species from the Gerlache Strait, it was also recorded by Göcke and Janussen (2013) and Fernández et al. (2021) as R. (H.) irregularis . It has been reported from sub-antarctic waters by Boury-Esnault & Van Beveren (1982), Uriz (1988) and Hooper (1991). Soest et al. (2020) proposed Raspailia (Hymeraphiopsis) hentscheli nom. nov., named after Ernst Hentschel, because they considered that Raspailia (Hymeraphiopsis) irregularis Hentschel, 1914 is the junior secondary homonym of Raspailia irregularis (Von Lendenfeld, 1888) and in the absence of known synonyms, it required a new name (ICZN Art. 60.3). This represents a new record for the SOI.

Figures

FIGURE 9. a–c. Axinella antarctica, a. general morphology, scale: 2 cm; b. style, scale: 450 µm; c. flexuous oxea, scale: 200 µm; d-i. Raspailia (H.) hentscheli, d. habitus of fresh specimen, morphology, scale: 5 mm. e. ends of choanosomal styles, scale: 100 µm. f, slender styles, scale: 100 µm. g. echinating acanthostyles, scale: 30 µm. h. skeletal arrangement, central axis of styles, scale: 500 µm. i. skeletal arrangement, detail of echinating acanthostyles (Smooth arrows) and thin styles (Dashed line arrows), scale: 100 µm.