Axoniderma wanda, Ekins & Hooper, 2023

Ekins, Merrick & Hooper, John N. A., 2023, New carnivorous sponges from the Great Barrier Reef, Queensland, Australia collected by ROV from the RV FALKOR, Zootaxa 5293 (3), pp. 435-471 : 459-468

Axoniderma wanda sp. nov.

Figures 11–12 , Tables 5–6

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Material examined: Holotype: QM G339384 , Wreck Plunge Pool , Great Barrier Reef, Queensland, Australia, -12.131851, 143.979498, 1980.05 m, hanging upside down in a small cave, Site: SO402, Sample: 178, ROV SuBastian, Coll. Merrick Ekins remotely in Brisbane via video live satellite feed directing the ROV pilots onboard the RV FALKOR on the Great Barrier Reef and Martie McNeil onboard the RV FALKOR, cruise FK200930, 27/10/2020 . Paratypes: QM G339392 , QM G339746 , QM G339747 , QM G339748 , QM G339749 —all paratypes have the same collection details as the holotype QM G339384 .

Etymology. This species is named for its resemblance to the alien wanderer/wanda that parasitizes the host Melanie Stryder, played by actress Saoirse Ronan from the movie and novel by the same name i.e. “the Host”, authored by Stephenie Meyer.

Distribution. This species is presently known only from the bathyal zone of the Great Barrier Reef, East Coast of Australia.

Description:

Growth form: The holotype consists of a pedunculated sponge, with a long thin stem that radiates at attachment in the centre of the posterior face of the sponge body. The body is an almost vertically orientated disc, concave on the anterior face, with up to 42 long thin filaments radiating out in a single plane from the disc margin in a complete circle ( Figs. 11 A–G ). From the top of the disc arises a thin stalk, longer and slightly thicker than all other filaments, terminating in a ‘lure’ in the shape of a minute circular fan ( Fig. 11 J ). The sponge body diameter is 8 mm, and 0.4 mm thick. The filaments are 23 mm long and 0.1 mm in width. The lure filament is 24 mm in length and 0.3 mm in diameter, whilst the circular lure is 1 mm in diameter. Interestingly, several specimens such as paratype G339747 has a raised bump on the stem which is most likely an oocyte-embryo swelling.

Colour: The sponge body, filaments and stem are all off white, with a tan coloured lure.

Ectosomal skeleton: The ectosomal skeleton, on the body, the stem and basal attachment and the filaments are covered on the external surface with tridentate ‘unguiferate’ anisochelae ( Figs. 11 H–L ). The lure and the filament supporting the lure are, however, covered with tridentate ‘unguiferate’ anisochelae as well as sigmancistras ( Fig. 11 J ).

Endosomal skeleton: The endosomal skeleton of the body, the filaments, the stem and the basal attachment consist mainly of the larger mycalostyles in concentrated longitudinal bundles ( Figs. 11 G–J, L ), but also include the less common medium sized mycalostyles. The large mycalostyles originate in the centre of the body and radiate out to become the horizontal filaments. The stem and basal attachment and rarely the filaments also contain strongyles. The lure is composed of the medium sized mycalostyles as well as the thin ‘Lure Styles’ ( Fig. 11 K ). The filament for the lure is composed of the large and medium sized mycalostyles.

Megascleres: The megascleres mainly consist of two different sized but overlapping mycalostyles with blunt terminations, with the largest diameter off-centre of the spicule ( Figs. 12 C–F ). The lure styles are long very thin and sinuous with no central thickening ( Figs. 12 G, H ). The strongyles are tapering with an offset thickening and blunt tips ( Figs. 12 I, J ). Dimensions are given in Table 5 .

Microscleres: The microscleres consist of abundant small anchorate ‘unguiferate’anisochelae with three large alae and five smaller alae on each end. The two outer small lower alae are paired, whilst the central lower small alae is solitary ( Figs. 12 A, B ). Sigmancistras are slightly contort, consist of a single size class and are restricted to the lure ( Fig. 12 C , Table 5 ).

Remarks. This species has the ‘unguiferate’ anchorate anisochelae and sigmancistras common to many other species of Cladorhiza , Axoniderma , Bathytentacular and Nullarbora . Axoniderma wanda sp. nov. is unique amongst the known species of these genera in having an external lure originating from the convex face of the body. This species is compared to other described species with any form of structure emerging from the body disk in Table 6 . All species previously and currently belonging to Cladorhiza were also compared in Table 6 of Ekins et al. (2020a), and grouped morphologically by a visual icon in ( Table 6 , Ekins et al. 2020b). The new species Axoniderma wanda sp. nov., has a similar sclerite composition and basic morphological shape to Axoniderma corona ( Lehnert, Watling & Stone, 2005) , Axoniderma kensmithi ( Lundsten, Reiswig & Austin, 2017) and Axoniderma mexicana ( Lundsten, Reiswig & Austin, 2017) . It differs from all three by orders of magnitude of size, and also has a very different lure shape and size from those three species. Axoniderma longipinna ( Ridley & Dendy, 1886) is the only other sponge with a disc and some disc-like structures, but it displays the classic ‘crinorhizoid’ parasol morphology and is not related to the new species. Axoniderma corona , from the Northern Pacific Ocean is the closest related species with the presence of anisooxeas similar to the strongyles in Axoniderma wanda sp. nov. and the sub(tylostyles) from the crown similar to the styles in the lure of Axoniderma wanda sp. nov. and the mycalostyles are of an overlapping size range. However, the much larger (by orders of magnitude) in size, the very short stem of the crown, the difference in crown versus lure shape, and the different shape of the lower alae in the larger anisochelae preclude A. corona from being the same as the new species. Axoniderma kensmithi differs from Axoniderma wanda sp. nov. by the much larger (by orders of magnitude) size, the convex downward facing filaments, the appearance of four lures on the shorter stems, the larger anisochelae and sigmancistras, the shape of the styles, and the shape of the lower alae of the anisochelae. Axoniderma mexicana differs from Axoniderma wanda sp. nov. by the much larger (by orders of magnitude) size, convex body shape, the double layer of filaments, the lack of strongyles and small styles, the presence of pseudoamphiasters and the larger sigmancistras, and the different lower alae of the anisochelae.

All of the specimens of Axoniderma wanda sp. nov. were collected from the underside of an overhang ( Fig. 11 A ), and so live in an inverted position (i.e. hanging upside down), such that the concave body disc actually faces downwards, ensuring the disc does not capture the falling debris ‘snow’, as does the habitat of taking shelter under overhangs. Not all spicules on each paratype were measured, as it was considered that enough of these fragile tiny specimens were already destroyed in order to observe part of the structure under an SEM, and so ‘NM’ (i.e. Not Measured) in Table 5 is a reflection of this, rather than an indication that the spicule type was absent from the specimen.

Figures

FIGURE 11. Axoniderma wanda sp. nov. A. Underwater photo of the types in situ. B. QM G339747. C. QM G339746. D. QM G339749. E. Holotype QM G339384. F. QM G339748. G. QM G339746, showing an amphipod caught on a filament and a semidigested crustacean in the sponge body. H. Filaments emerging from the sponge body. I. A filament showing the encrusting chelae. J. The lure of the sponge. K. The stem of the sponge. L. The basal attachment.

FIGURE 12. Axoniderma wanda sp. nov. Holotype QM G339384. A. Tridentate ‘unguiferate’ anisochelae. B. Sigmancistra. C. Large mycalostyles. D. Magnified ends of the mycalostyle illustrated in C. E. Medium sized mycalostyle. F. Magnified ends of the mycalostyle illustrated in E. G. Lure style. H. Magnified ends of the lure style illustrated in G. I. Strongyle. J. Magnified ends of the strongyle illustrated in I.