Spinularia flagellata, Ekins & Erpenbeck & Wörheide & Hooper, 2023

Ekins, Merrick, Erpenbeck, Dirk, Wörheide, Gert & Hooper, John N. A., 2023, Deep Water Polymastiidae (Porifera, Polymastiida) from the South West Pacific, Zootaxa 5369 (1), pp. 57-88 : 69-72

Spinularia flagellata sp. nov. Ekins, Erpenbeck & Hooper urn:lsid:zoobank.org:act:F7D54F8A-68DF-4602-9C3E-AED029E33337

Figures 1 , 2 & 6 , Tables 3 & 4

Part Radiella irregularis Ridley & Dendy, 1886 , sensu O’Hara et al. 2020: 4

? Part Spinularia sarsii ( Ridley & Dendy, 1886) : 488-489

? Part Spinularia sarsii ( Ridley & Dendy, 1887) : 218-220

? Radiella sarsii : Burton 1959: 208

Type material: Holotype QM G337555 , Coral Sea Commonwealth Marine Reserve , Queensland, Australia, -23.587, 154.194 to -23.617, 154.1947, 1013–1093 m, Beam Trawl, Coll. Merrick Ekins on RV Investigator, Cruise IN2017_ V03 , sample 121-232, 13/VI/2017.

Paratypes QM G337175 , off Byron Bay , New South Wales, Australia, -28.0544, 154.083 to -28.097, 154.081, 999–1013 m, Beam Trawl, Coll. Merrick Ekins on RV Investigator, Cruise IN2017_ V03 , sample 100-114.1, 9/ VI /2017 ; QM G339363, same collection details as G337175, sample 100-115 ; QM G337548, same collection details as QM G337555, sample 121-144 .

Other Material: QM G316338 , North Norfolk Ridge, Pacific Ocean Seamounts , -26.43233333, 167.1811667, 750–774 m, Beam Trawl, Coll. NORFANZ expedition on RV Tangaroa , 43-016, MF140, 18/ V /2003 , 5 specimens; QM G339456 , same collection details as QM G316338 ; QM G339454 , Lord Howe Plateau, Pacific Ocean Seamounts , -32.445, 161.7825, 1130–1147 m, Beam Trawl, Coll. NORFANZ expedition on RV Tangaroa, TAN 308/77-039, MF328, 25/ V /2003 , 13 specimens.

Etymology: named for the whip-like shape of the principal tylostyles, flagellum L. whip.

Diagnosis: Discoid Spinularia with a small fringe, a single layer of bouquet forming tylostyles in the ectosome and long very thin whip like tylostyles.

Morphology: Flattened discoid, with a hispid concave upper surface, a convex smooth lower surface ( Fig. 6 A–D ) and a marginal spicule fringe ( Fig. 6 L ). The holotype is 15 mm in width, including the 2.3 mm basal fringe, whilst the body height is 7.2 mm. The paratypes are identical in shape and similar in size i.e. 14–15.4 mm in width and 4.3–7.2 mm in height with the fringe of 3 mm. The holotype has a single central papilla (1 mm in height). The sponge is white to cream in colour immediately after collection and in ethanol. The sponge is firm, but flexible on the lower surface due to the protective styles, but soft and compressible on the upper surface.

Skeleton: The choanosomal skeleton consists of randomly orientated disorganised smaller tylostyles ( Fig. 6 D, K ). The principal tylostyles originate below the ectosome, from bouquets in the upper choanosome, forming a palisade in the ectosome ( Fig. 6 D, K ). The lower ectosomal skeleton also contains the long fringe styles on the lower surface, which radiate from the centre of the basal surface forming the fringe ( Fig. 6 D ).

Spicules: The large fringe tylostyles forming the fringe range from 1510–3500 μm in length and 14.7–48.8 μm in width ( Fig. 6 E, F ).The principal tylostyles have a very long drawn out thin sinuous tip resembling a whip, these are 696–2430 × 7.4–26.6 μm ( Fig. 6 G, H ). These whip-like tylostyles are very fragile, and can easily be overlooked as the fine ends are usually broken off during collection. The small tylostyles from the choanosome are prominently fusiform ( Fig. 6 I ). The uncommon raphides are also present lying loosely in the choanosome ( Fig. 6 J ). All spicule measurements are summarised in Table 4 .

Distribution: Coral Sea and Tasman Sea seamounts, bathyal depth.

Ecology: Mud substrate.

Molecular data: 28S-C region barcode of holotype QM G337555 (ENA Accession number OY741343). This sample is genetically different from all other samples analysed in this study .

Remarks: This new species is remarkably similar in morphology to Radiella nidula sp. nov., both being very small discs with fringing spicules and often occur together in the same habitats. The new species differs from R. nidula sp. nov., by the shape and size of the principal tylostyles, the wider smaller tylostyles, the whip like styles and the presence of raphides giving generic separation from Radiella . It also differs by having a simpler skeleton, i.e. it only has the single layer of bouquet forming tylostyles in the ectosome and by molecular differences in 28S (see Fig. 3 ).

This new species probably includes one of the specimens of Ridley & Dendy’s (1886), that was collected from Cape York Australia i.e. BMNH 1887.5.2.40. Ridley & Dendy (1887), indicate this Cape York specimen differs from the other specimens by the more convex shape and having shorter choanosomal tylostyles. It is also visibly different by the smaller more compact fringe and the presence of a single papillae from all Northern Hemisphere specimens of S. sarsii as illustrated in Fig. 29 E, F in Plotkin et al. (2018). However, examination of the spicules and skeleton of the paralectotype would be required to complete this determination, as the spicule measurements in Plotkin et al. (2018) have been pooled from 13 specimens and it is unclear if this contains any type material. These specimens were previously listed as Radiella irregularis in O’Hara et al. (2020).

Specimen QM G316338 also contain a small number of subtylostyles. Radiella straticulata has not infrequent subtylostyles as well. One of the five specimens of QM G316338 and QM G339456 also differ from the other specimens listed here by being attached to rock/coral fragments 3–5 mm in size ( Fig. 6 M ) .

Figures

FIGURE 1. Distribution of the specimens of species described herein as they were collected during the expeditions.

FIGURE 2. Maximum likelihood phylogenetic tree of polymastiid species reconstructed from 28S rDNA (C-region). Values> 70 of the bootstrap support for the clades are indicated above the branches. Below branches in italics Bayesian inference posterior probabilities ≥ 0.95. The species sequenced in this studied are highlighted in boldface. Scalebar depicts substitutions /site.

FIGURE 3. Radiella nidula sp. nov. A. The holotype QM G337524 on deck immediately after collection, upper surface up. B. The holotype QM G337524 fixed basal surface. C. Scanning Electron Microscope collage of a cross section through the paratype QM G337532. D. Bouquets of intermediate tylostyles in the basal surface of the paratype QM G337524. E. Exotyles from the basal surface. F. Closeup of ends of the style in E. G. Intermediate tylostyles in the main body of the sponge. H. Ends of the tylostyles in G. I. Small tylostyles from the body of the sponge.

FIGURE 6. Spinularia flagellata sp. nov. A. The holotype QM G337555 upper surface. B. The holotype QM G337555 basal face. C. Paratype QM G337175, upper face. D. Scanning Electron Microscope collage of a cross section through the paratype QM G337175. E. Fringing styles from the basal surface. F. Closeup of ends of the style in E. G. principal tylostyles in the main body of the sponge. H. Ends of the tylostyles in G. I. Small tylostyles from the choanosome of the sponge. J. Raphides. K. Bouquets of principal tylostyles in the ectosome of the paratype QM G337175. L. QM G339456 upper surface. M. QM G339456 basal face.