Raspailia (Raspaxilla) frondosa, Ekins & Debitus & Erpenbeck & Hooper, 2018

Ekins, Merrick, Debitus, Cécile, Erpenbeck, Dirk & Hooper, John N. A., 2018, A new species of the sponge Raspailia (Raspaxilla) (Porifera: Demospongiae: Axinellida: Raspailiidae) from deep seamounts of the Western Pacific, Zootaxa 4410 (2), pp. 379-386 : 380-383

Raspailia (Raspaxilla) frondosa sp. nov.

( Figs 1–4 , Table 1)

Etymology. Latin for leafy, reflecting the gross morphology of the sponge resembling the frond of a fern. Material examined. Holotype: MNHN-IP-2015-1402 (fragment of the holotype QM G335124) Station DW3110, New Caledonia Ridge 23o1.35’ S 168o16.99’ E to 23o1.71’S 168o15.86E, 270–310 m, Coll. Cécile Debitus, 28.x.2008 ( Samadi 2008).

Paratypes: QM G335144 (same data as holotype). QM G318701 NORFOLK 1 Station DW 1724 , Norfolk Ridge Seamount Banc.no.1. 23o17.05’S 168o14.28’E, Dredge 200–291 m, Coll. Bertrand Richer de Forges , 27.vi.2001 (Richer de Forges 2001).

Description. Growth form: A stalked foliaceous, flabellate to reniform sponge growing mainly in one plane but showing some undulations. The blades are between 55 and 65 mm high and 55 to 85 mm wide, with a maximum thickness of 3 mm at the base sloping to less than 1 mm at the apex. It has a circular stalked base with a diameter of 10 mm and small basal holdfast.

Colour: Pale cream to orange on deck and beige to brown in ethanol.

Texture: Firm and barely compressible, but easy to tear.

Surface: Oscules are not visible, however on the surface the absence of parchment-like ectosome over the aquiferous channels resembles leaf veins (this is could also be due to friction or predation). Otherwise the surface is highly hispid and velvety from protruding long styles.

Ectosomal skeleton: Membranous, parchment-like, without a specialised ‘raspailiid’ skeleton of spiculebouquets, but with a thick palisade of subectosomal styles protruding through the ectosome up to 0.5–2 mm.

Choanosomal skeleton: With well-differentiated axial and extra-axial skeletons. The axial skeleton is compressed, lacking spicules, but with heavy interlaced spongin fibres forming a wide core up to 50% of the diameter of the skeleton. Long subectosomal styles and shorter choanosomal rhabdostyles have their bases embedded in the axial spongin skeleton, standing perpendicular to the axis forming a radial extra-axial skeleton, with the subectosomal styles protruding through the ectosome and the choanosomal rhabdostyles supporting the parchment-like ectosome on both dorsal and ventral surfaces of the sponge.

Megascleres ( Table 1). There are only two categories of megascleres. Choanosomal rhabdostyles are very smooth, moderately thick, with a smooth non-tylote base, varying from slight to well-developed rhabds (97–469 x 6.2–31.6 µm). Subectosomal styles are rare (<0.2%), smooth, long, thick and either straight or slightly curved (1010–4640 x 10.2–29.1 µm).

Microscleres: Absent.

Molecular data. DNA barcodes for 28S and CO1 could not be retrieved for the holotype or for the paratypes. All samples underwent two different DNA extractions (see Methods section) and multiple amplification attempts with different deviations from the PCR protocol, but amplification success could not be achieved under the described methods.

Figures

FIGURE 1. Fixed specimens of R. (R.) frondosa sp. nov., clockwise from the top left: paratype QM G335144; holotype MNHN-IP-2015-1402 (fragment QM G335124); paratype QM G318701.

FIGURE 2. Spicules of the holotype R. (R.) frondosa sp. nov., MNHN-IP-2015-1402 (fragment QM G335124). A subectosomal style, B terminationsof subectosomal style, C–G choanosomal rhabdostyles

FIGURE 3. An undigested cross section of the holotype of R. (R.) frondosa sp. nov., MNHN-IP-2015-1402 (fragment QM G335124), showing the choanosomal rhabdostyles supporting the fragile ectosome and the subectosomal styles penetrating the ectosome.

FIGURE 4. Transmitted light micrograph of a crossection of the paratype QM G318701 of R. (R.) frondosa sp. nov., showing the well-differentiated axial and extra axial regions of the skeleton, and the restriction of rhabdostyles and styles to the subectosomal and ectosomal regions.