Halisarca korotkovae Ereskovsky, 2007, sp. nov.
Creators: name: Ereskovsky, Alexander V.
Publisher: name: Zenodo
Year: 2007
Subjects: Biodiversity
Taxonomy
Animalia
Porifera
Demospongiae
Chondrosida
Halisarcidae
Halisarca
Halisarca korotkovae

description: Halisarca korotkovae sp. nov.
(Figs. 2–4)
Material examined. Holotype ZIN RAS 10700 - (49°57’,7–50°00’,6 N, 145°51’,3–49’,1 E), SW of Sea of Okhotsk, 600 m, 0 8 Oct.1984, collector A.V. Ereskovsky.
Paratypes: ZIN RAS 10701 - (50°02’,5–05’,3 N, 145°32’,2–30’,6 E), SW of Sea of Okhotsk, 490–500 m, 0 8 Oct.1984; ZIN RAS 10702 - (50°59’,2–51°02’,2 N, 145°21’,2–19’,2 E), SW of Sea of Okhotsk, 620–645 m, 10 Oct.1984; ZIN RAS 10703 - (55°30’,7–30’,7 N, 150°00’,5–08’,4 E), central part of Sea of Okhotsk, 300 m, 20 Oct.1984; ZIN RAS 10704 - (55°13',3–10',8 N, 148°49’,3–55’,4 E), central part of Sea of Okhotsk, 500 m, 20 Oct.1984. Collector is A.V. Ereskovsky.
Description. The sponge is encrusting, 1–3 mm thick, spreading on a skeleton of Aphrocallistes sp. (Hexactinellida) and forming patches from 1 cm up to 5 cm in diameter. Surface is skin-like, smooth, shiny, even or bearing a slight undulation (Fig. 2). Texture is softly collagenous, easily torn. No oscules or pores visible in preserved specimens. Colour in life is dull brownish-yellow, pigmentation is uniform throughout the sponge body.
Soft tissue organisation. A thin ectosomal region 17 to 55 µm deep is bounded by a cuticle from 2.9 to 5 µm deep (Fig. 3 A). The cuticle is mucus-like and acellular–the product of ectosome cell secretion overlapping all of the sponge surface (Figs. 3 A, 4A). Beneath this cuticle is a dense cellular layer in which the cell bodies of T-shaped exopinacocytes occur, as well as conglomerates of big microgranular cells, rare spherulous cells, and vacuolar cells. Below this layer, cell density is greatly reduced in the mesohyl between the abundant inhalant canals and subectosomal cavities (Fig. 3 A).
The choanosome makes up the greatest volume of the sponge body and is composed of choanocyte chambers and mesohyl (Fig. 3 B). The choanocyte chambers are meandering tubular, long, branching, and tight with diameter of 1.5 to 10 µm and length up to 120 µm (Figs. 3 B, 4B).
Cytology. Exopinacocytes (Fig. 4 A) are T-shaped, as typical for order, with thin external cytoplasmic part and internal cell body part. The cell body, about 3.4 µm in diameter, is oval or irregular in form. Both parts are connected by a thin cytoplasmic bridge.
Endopinacocytes (Fig. 4 B) are flat, nonflagellate cells with nucleolate nucleus. The length is about 14 µm and the thickness in the nucleus region is about 1.8 µm.
Choanocytes are small, elongated, monoflagellate cells about 3.3×2.1 µm with anucleolate nucleus.
Big microgranular cells (Figs. 3 A, 4A) are distinctive cells of the new species. These cells are concentrated mainly in the ectosome of the sponge. They are large, oval or egg-shaped (18.7×9.5 to 10.8×7.1 µm) with nucleolate nucleus (nucleolus diameter 1 µm). The cytoplasm is eosinophilic and filled with numerous small (0.5 µm in diameter) homogenous granules. These cells are often concentrated in aggregates up to 40 µm in diameter (Fig. 4 A).
Vacuolar cells (Fig. 4 A, C) are oval or irregular (approximately 7.6 µm in diameter) eosinophyllic cells with anucleolate nucleus. The cytoplasm contains big semi-transparent vacuoles (0.2–0.7 µm in diameter) often with microgranular inclusions. These cells are dispersed in the ectosome (Fig. 4 A) and choanosome (Fig. 4 C).
Spherulous cells (Fig. 4 A, B, D) are oval (6.2 - 7.9 µm in diameter) with anucleolate nucleus. The cytoplasm is filled with spherical granules (diameter from 0.8 to 2.9 µm) homogenous in content. These cells are dispersed in the ectosome (Fig. 4 A) choanosome (Fig. 4 B, D).
Amoebocytes (Fig. 4 A, D) are ameboid cells (from 3.3 to 3.8 µm in diameter) with big nucleolate nucleus (2.1–2.4 µm in diameter), dispersed in all parts of the sponge mesohyl.
Reproduction. In all investigated specimens there were many oocytes (Fig. 4 D) in an early stage of oogenesis before vitellogenesis. Oocytes have oval (from 9.2 to 14.5 µm in diameter) or elongated form (from 14.5×8.3 µm to 22.9×7.9 µm) and are dispersed in the mesohyl of the choanosome. The nucleus (about 5.2 µm in diameter) contains a nucleolus (2.9 µm in diameter).
Habitat and distribution. Specimens of Halisarca korotkovae sp. nov. occur as thin sheets on the skeleton of a hexactinellid sponge Aphrocallistes sp. (Hexactinosida, Aphrocallistidae) in the SW and central parts of Sea of Okhotsk at a depth from 300 to 645 m (Fig. 1). The bottom consists of silt, pebbles and fragments of hexactinellid Aphrocallistes sp. skeleton.
Etymology. The species name refers to the famous Russian spongologist, Prof. Galina P. Korotkova (Saint-Petersburg State University).
description: Published as part of Ereskovsky, Alexander V., 2007, A new species of Halisarca (Demospongiae: Halisarcida) from the Sea of Okhotsk, North Pacific, pp. 57-66 in Zootaxa 1432 on pages 62-65, DOI: 10.5281/zenodo.175835