Abyssocladia falkor, 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 : 440-443

Abyssocladia falkor sp. nov.

Figures 4–5 . Tables 1 , 3

urn:lsid:zoobank.org:act:B58AB630-A45C-4DCB-AE83-8BB776394CAF

Material Examined: Holotype: QM G339306 , Ribbon Reef 5, Canyon 8, Great Barrier Reef, Queensland, Australia, -15.35981103, 145.862097, 1822.14 m, Site: S0378, Sample: 54, ROV SuBastian, Coll. Merrick Ekins remotely in Brisbane via live satellite feed directing the ROV pilots onboard the RV FALKOR on the Great Barrier Reef and Jeremy Horowitz on RV FALKOR, cruise FK200802 . Paratype: QM G339307 , same collection details as QM G339306 .

Etymology: falkor , a noun in apposition, named in honour of the Schmidt Ocean Institutes research vessel the RV Falkor.

Distribution: This species is currently known from the Coral Sea in Queensland, Australia, bathyal depth.

Description:

Growth form: The holotype consists of a pedunculated sponge, with a short stem and a disc shaped body with filaments radiating out in a single plane from the disc margin. ( Figs. 4 A–C ). The paratype has the entire stem and roots as well, which were lost from the holotype during collection. The holotype has a body diameter of 7.8 mm, and 1.3 mm thick. The filaments are 2.3 mm long and 0.1 mm in width. The paratype has a body with a 6.7 mm diameter and 1.6 mm width, the stem and root are 40 mm in length, the filaments are up to 4.0 mm in length.

Colour: Cream in situ, on deck and in ethanol.

Ectosomal skeleton: Thin membranous layer of the filaments is encrusted with small sigmancistras and abyssochelae. The sponge body and stem are encrusted with the predominately spherical microstrongyles, but also include the abyssochelae. Immediately under the encrusting layer are the sinuous styles. The ectosomal skeleton of the roots is a thin membranous layer with occasional abyssochelae, sigmas and sigmancistras.

Endosomal skeleton: The axis of the stem consists of longitudinally arranged mycalostyles, styles and sinuous styles ( Figs. 5 D, F, J ). The main body consists of the radiating bundles of subtylostyles that form the filaments ( Figs. 5 H, I ). Within the body between the bundles, the styles form a disorganised almost cross hatching skeleton. The roots are composed of the large mycalostyles, styles, sinuous styles, occasional subtylostyles and rarely strongyles ( Fig. 4 G ). The filaments axis is composed of subtylostyles only ( Fig. 4 D ).

Megascleres: Mycalostyles are long and generally straight, sometimes with a slight curve, and have a rounded point ( Figs. 5 D, E ). Styles usually straight, sometimes with a slight curve, thickest in the centre also with a blunt point, sometimes with a very faint tyle swelling ( Figs. 5 F, G ). They are separated from the mycalostyles often by their location in the body but could well be a continuum of a single category of megasclere. The sinuous styles occur around the mycalostyles that make up the stem, under the dermal microstrongyles ( Figs. 5 J, K ). Subtylostyles are long and straight, with a sharp tip and compose the filaments ( Figs. 5 H, I ). There are also very rare strongyles present from the roots ( Figs. 5 L, M ).

Microscleres: Abyssochelae isochelae with curved shaft, and opposing alae touching ( Fig. 5 A ). There are small sigmas and small sigmancistras that usually occur on the exterior surfaces ( Figs. 5 C, N , respectively). There are also long thin sigmas that only occur on the sponge body, these were rare and only occurred on the paratype and so may not be native ( Fig. 5 B ). The predominately spherical to subspherical shaped microstrongyles are microspined ( Figs. 4 E, F ; 5 O ). However, they are also dumbbell-shaped and rarely dildo—shaped ( Fig. 5 P ). The microstrongyles have either a rounded end (tylomicrostrongyle) or a sharp point (tylomicrostyles).

Remarks: This species is most closely related to the Japanese species A. natsushimae Ise & Vacelet, 2010 . However, this new species has a much smaller and circular body size. The new species also lacks the two size classes of abyssochelae, has subtylostyles, and has only one category of sigmancistras and two categories of sigmas. The microstrongyles of this new species are predominately spherical and lacks the long microstrongyles of A. natsushimae . This species is different from the diminutive species A. bruuni Lévi, 1964 , which has the very large abyssochelae. Abyssocladia bruuni was also recorded by Koltun (1970), but with two size classes of abyssochelae. Abyssocladia bruuni also lack microstrongyles. This new species also has similar abyssochelae and a rough morphological similarity to A. annae Ekins et al., 2020a and another closely related species A. fryerae Hestetun et al., 2019 , both of which have this ridged abyssochelae as well as subtylostyles and sigmancistras.

Figures

FIGURE 4. Abyssocladia falkor sp. nov. A. The holotype and paratype underwater in vivo. B. Paratype QM G339307 fixed. C. Holotype QM G339306 on deck. D. Filaments emerging from the edge of the sponge body. E. Surface of the sponge body. F. Stem. G. Root like appendages.

FIGURE 5. Abyssocladia falkor sp. nov. A. Abyssochelae. B. Large thin sigma. C. Intermediate sigma. D. Large mycalostyles. E. Ends of the mycalostyle in D. F. Styles. G. Ends of styles in F. H. Subtylostyles. I. Ends of subtylostyle in H. J. Sinuous styles. K. Ends of styles in J. L. Strongyles. M. Ends of the strongyles in L. N. Small sigmancistras. O. Spherical microstrongyles. P. Dildo-shaped tylomicrostrongyle.