Abyssocladia jeanvaceleti, 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 : 443-452

Abyssocladia jeanvaceleti sp. nov.

Figures 6–7 , Tables 2–3

urn:lsid:zoobank.org:act:0D481EB3-F3F9-4B0F-9D9B-DC57A25D8E42

Material Examined: Holotype: QM G339390 , Small Detached Plunge Pool , Great Barrier Reef, Queensland, Australia, -12.5341061, 143.8600016, 1082.83 m, Site: S0399, Sample: 141, ROV SuBastian, Coll. Mardie McNeil and Rob Beaman on RV FALKOR, cruise FK200802. 18/X/2020

Paratypes: QM G335997 , QM G339387 , QM G338728 , same collection details as QM G339390 .

Other Material: QM G339391 same collection details as QM G339390, sample 141C.

Etymology: Named in honour of Jean (Janus) Vacelet who as both a gentleman and a scholar has described many of the South Pacific carnivorous sponges, and proved the existence of carnivory in sponges.

Distribution: This species is currently known from the Great Barrier Reef in Queensland, Australia, bathyal depth.

Description:

Growth form: The holotype consists of a pedunculated sponge, with a short stem and a vertically orientated disc shaped body with filaments radiating out in a single plane from the disc margin. ( Figs. 6 A–C ). The circular sponge bodies were 6 to 9 mm in diameter, and 0.4 to 0.6 mm thick. There were up to 50 filaments surrounding the body. The preserved filaments were 4.3 to 9.3 mm long and 0.1 mm in width, and highly contracted and or destroyed during collections, compared to the underwater images which show the filaments as up to one and a half times the width of the body ( Figs. 6 A, B ). The stem lengths were 14 to 22 mm long and 0.4 mm in width. All the specimens had spherical structures within the sponge body, which are most likely to be spermatocytes or oocytes. Some of the specimens such as G338728 were still attached via a holdfast to the underlying rock strata.

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

Ectosomal skeleton: Thin membranous layer of the filaments is encrusted with small sigmancistras ( Fig. 6 F ). The sponge body and stem are encrusted isochelae overlaying the sigmancistras ( Fig. 6 E ). The lower stem and roots appear to be devoid of any specific ectosomal layer.

Endosomal skeleton: The axis of the stem consists of longitudinally arranged styles. The main body and filaments consist of the radiating bundles of styles that form the filaments. The root axis consists of longitudinally arranged strongyles ( Figs. 6 G, H ).

Megascleres: The sponge filaments are composed of two different but overlapping size groups of styles. The measurements of spicules for all the specimens are listed in Table 2 , the spicule measurements for the holotype only are listed in the following text. The large mycalostyles present in the filaments are long and straight, with a blunt tip, they are 880–(1120)– 1480 x 12 –(16)–23 µm in size, with the slightest tylostyle thickening ( Figs. 7 C, D ). The smaller styles in the filaments ( Figs. 7 E, F ) are blunt styles, they are 360–(520)–703 x 5–(8)–12 µm in size. The stem is also composed of two different sizes of oxeote styles, the larger are long and straight, with a slight central thickening, and sharp points ( Figs. 7 I, J ), which are 1060–(1240)– 1470 x 18 –(25)–30 µm in size. The shorter oxeote styles of the stem have an obvious central thickening and a blunt tip ( Figs. 7 G, H ) and are 390–(670)–960 x 19–(27)–35 µm in size. The roots are composed of just one class of strongyle ( Figs. 7 K, L ) and are 320–(480)–680 x 8–(11)–26 µm in size.

Microscleres: The microscleres are composed of a single size class of palmate isochelae ( Fig. 7 A ) 45–(53)–61 µm in size and a single size class of sigmancistras ( Fig. 7 B ) 8–(11)–13 µm in size.

Remarks: This species is morphologically very similar to Abyssocladia falkor sp. nov., with the same pedunculated disc shaped body. However, it differs markedly by the shape of the isochelae and the lack of the protective microspheres and microstrongyles. Most of the specimens contained filamentous curved raphide-like spicules, which were often on the outside of the ectosome (such as in Fig. 6 E ), and sometimes presented as bundles in spicule digests. However, examination of the spicules (~100–200 x 1–2 µm) at extreme magnification (X8000) on the SEM, revealed them to have minute thorn-like scales. It is concluded these are non-native and perhaps were snagged from an hexactinellid glass sponge.

One of the specimens (QM G339391) has a much larger range of sizes of chelae (almost two separate size classes of chelae), with a much more robust spine. This specimen was badly damaged during the collection. It may well be a different species, but until there is the collection of another complete specimen, it is retained here as Abyssocladia cf. jeanvaceleti sp. nov.

Both this species and the uncertain specimen (cf. QM G339391) are very different to the umbrella-shaped sponge Abyssocladia bruuni Lévi, 1964 (p.78, Fig 30), with respect to the sponge size and the styles, and the isochelae are 70–75 µm long with the single tooth 30 µm wide, and are of a crab-like shape. The sigmancistras in Lévi’s species are twice as large, being 29–30 µm in length. Abyssocladia bruuni sensu Koltun, 1970 , illustrated in his Fig. 17 (1– 5) and Plate III, Fig. 5 , displays a similar shape of chelae and a similar range in sizes of chelae, a sigmancistra and as well as a large style and a much smaller subtylostyle. However, it differs from this new species (including the cf. specimen QM G339391) mainly by the differences in shape of the sponge body. Koltun’s specimen came from the Vityaz collections, collected in the South Pacific Ocean (Station 3655, Bougainville Trench). Abyssocladia bruuni Lévi, 1964 and Abyssocladia bruuni sensu Koltun, 1970 are clearly unrelated to each other. This is also supported by the redescription of Abyssocladia bruuni by Vacelet (2020). We propose Koltun’s species Abyssocladia bruuni to be renamed Abyssocladia vladimirii nom. nov. The alternate name Abyssocladia koltuni ( Ereskovsky & Willenz, 2007) is preoccupied. Neocladia flabelliformis Koltun, 1970 is accepted as Koltunicladia flabelliformis ( Koltun, 1970) (type by original designation).

Figures

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.

FIGURE 6. Abyssocladia jeanvaceleti sp. nov.. A. Underwater photo the specimens before collection. Arrows indicating individuals of the same species. The black arrow is the holotype QM G339390. B. A close up of the species in side profile. C. Holotype QM G339390 on the right and paratype QM G335997 on the left. D. Scanning Electron Microscope image of the body face and filaments emerging. E. Close up of the ectosome of the sponge body showing the isochelae on the surface and the sigmancistras covering the styles of the filaments. F. Close up of the filaments showing the ectosomal membrane composed of sigmancistras over the style axis. G. The stem showing the axial bundles of styles. H. The root like appendage.

FIGURE 7. Abyssocladia jeanvaceleti sp. nov.. Holotype: QM G339390. A. Isochelae. B. Sigmancistras. C. Mycalostyle from the filaments with faint subtylostyle swelling. D. Magnified ends of the mycalostyle illustrated in C with faint subtylostyle swelling. E. Smaller mycalostyle from the filaments. F. Magnified ends of the mycalostyle illustrated in E. G. Oxeote style from the stem. H. Magnified ends of the oxeote style illustrated in G. I. Thin sharp oxeote style from the stem. J. Magnified ends of the oxeote style illustrated in I. K. Strongyle from the root like appendages. L. Magnified ends of the strongyle illustrated in K.