Radiella pumix, 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 : 63-65

Radiella pumix sp. nov. Ekins, Erpenbeck & Hooper

urn:lsid:zoobank.org:act:E596A9A5-C755-4561-BC2C-A16A6EA21316

Figures 1 , 2 & 4 , Tables 2 & 3

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

Type material: Holotype QM G337516 , Off Byron Bay , New South Wales, Australia, -28.6765, 154.20327 to - 28.709, 154.1897, 2587– 2562 m, Beam Trawl, Coll. Merrick Ekins on RV Investigator, Cruise IN2017_ V03 , Sample 90-202, 7/VI/2017.

Paratypes: QM G337515 same collection details as QM G337516 , Sample 90-180 ; QM G337616 same collection details as QM G337516 , Sample 90-169 ; QM G339368 same collection details as QM G337516 , Sample 90-169.3 .

Etymology: named for its substratum, pumix L., pumice.

Diagnosis: Radiella species attached to pumice, lacking an obvious fringe, but expands by having new discrete hemispherical bouquets outside the ectosome.

Morphology: A convex cream coloured sponge attached to drowned pumice stone ( Fig. 4 A, B ). The holotype QM G337516 , is 8.3 mm in diameter, and 1.2 mm in height. The paratype QM G337616 , is 6 mm in diameter and only 0.83 mm in height, whilst paratype, QM G337515 is 5.8 mm in diameter and 1.4 mm in height. The upper surface is hispid, and the sponge lacks an obvious fringe ( Fig. 4 C-E). The holotype has a single central papilla, the papillae could not be obviously seen on most of the paratypes ( Fig. 4 E ).

Skeleton: The choanosomal skeleton is composed of confusedly arranged small tylostyles ( Fig. 4 E ). The ectosome consists of bouquets of the large principal tylostyles, many of which originate from the choanosome. These bouquets of the principal tylostyles also line the central oscular canal. The ectosome and the periphery of the specimen are characterised by the appearance of discrete bouquets ( Fig. 4 C, D ). In some cases, the bouquets on the surface appear as spheres giving the surface a papillate appearance.

Spicules: The principal tylostyles vary greatly in length and may be possibly divided into two size categories with large overlapping sizes (640–2270 × 7–19 μm) ( Tab. 2 ). There are smaller tylostyles arranged in disorder in the choanosome (100–300 × 3–15 μm) and intermediate tylostyles (339–660 × 5–13 μm) composing the bouquets of the main ectosomal skeleton.

Distribution: Northern New South Wales, Australia, abyssal depth.

Ecology: Found exclusively on submerged pumice stones.

Molecular data: 28S-C region barcode of holotype QM G337516 (ENA Accession number OY741336), paratype QM G337616 (ENA Accession number OY741340), forming a distinct and supported clade ( Figure 2 ) .

Remarks: The new species resembles Spinularia australis Lévi, 1993 from bathyal depths off New Caledonia by the body shape and size and the substrate it grows on, the pumice stones. The individuals of S. australis are slightly larger in diameter, 7 to 12 mm, but similar in height, 1.4 to 3.7 mm. However, our new cream-coloured species differs from S. australis by lacking the lower fringe and associated large tylostyles, with the largest difference being the ectosomal skeleton with many independent small plumose bouquets which is the most distinctive character of this new species. The new species also lacks the radial skeleton seen in S. australis , and it also differs importantly from S. australis by having a new category of much smaller tylostyles and it also lacks raphides. These specimens were previously listed as Radiella irregularis in O’Hara et al. (2020).

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 4. Radiella pumix sp. nov. A. The holotype QM G337516 attached to pumice. B. Paratypes QM G339364, still attached to the pumice. C. Upper surface of paratype QM G337616 showing the central papilla. D. Closeup of the fringe of the paratype QM G337616, showing the bouquets of tylostyles. E. Composite SEM image of a cross section through the holotype QM G337516 showing the central papilla and the radial tylostyle skeleton. F. Large tylostyles involved in the brush formation and the fringe. G. Intermediate tylostyles from the choanosome. H. Small tylostyles from the choanosome.