(Bowerbank, 1874)

Species Overview

Hamacantha (Vomerula) falcula (Bowerbank, 1874) is an irregularly lobate, cushion-shaped sponge with a detachable skin. The oscules are slightly raised on low conules. Live colour has not been recorded. It is a deep-water sponge. The genus Hamacantha has characteristic microscleres (diancistras); the present species may be distinguished from the two other Hamacantha species from the area by its possession of toxas.

Taxonomic Description

Colour: Live colour unknown; yellow to white in alcohol.
Shape, size, surface and consistency: Massive, irregularly lobate, roundish. Size up to 9.5 cm in lateral expansion. Surface smooth, with detachable "skin". Oscules on low conules of several mm high. Consistency rather firm.
Spicules: (Hamacantha falcula spics) Megascleres: Styles 340-470 x 5-8 µm. Microscleres: Diancistras in three categories: 100-178 µm, 30-57 µm and 18-28 µm; toxas 60-157 µm.
Skeleton: Ectosomal skeleton a tangential reticulation of spicule tracts. Choanosomal skeleton plumose, with spicule bundles running to the surface where they fan out.
Ecology: Deep water: 85-2280 m
Distribution: Roscoff, W Ireland, Scotland, Sweden, Norway, Faroes, Iceland; also Madeira and Azores.
Etymology: falcula (Latin) = small sickle, referring to the shape of the microscleres.
Type specimen information: The type is in the Natural History Museum, London: Type: BMNH 1910.1.1.191 (dry). Norman Collection.

Remarks

Hamacantha with its characteristic diancistras is represented by three species in the area. H. (H.) johnsoni has oxeas for megascleres and true sigmas; H. (H.) papillata (=H. implicans) has trichodragmas and only a single category of diancistras. Both species lack the toxas of H. (V.) falcula.
Source: Arndt, 1935.

Kingdom Animalia
Phylum Porifera
Class Demospongiae
Order Poecilosclerida
Suborder Mycalina
Family Hamacanthidae
Genus Hamacantha
Subgenus Vomerula
Species Hamacantha falcula

Status in World Register of Marine Species

Synonym of Hamacantha (Vomerula) falcula (Bowerbank, 1874)

Scientific synonyms and common names

Halichondria falcula n.sp. Bowerbank, 1874: 208, pl. LXXIV figs 1-3
Hamacantha bowerbanki n.sp. Lundbeck, 1902: 99, pl. VII figs. 2-3, pl. XVIII fig. 1, pl. XXIV figs. 1-3.
Hamacantha falcula: Stephens, 1916: 242; 1920: 16; Burton, 1930a: 492; Arndt, 1935: 56, fig. 100; Cabioch, 1973: 6

Arndt, W., 1935. Porifera. Tierwelt Nord.-Ostsee, IIIa: 1-140, figs. 1-239.

Bowerbank, J.S., 1874. A monograph of the British Spongiadae, III. Ray Society, London: i-xvii, 1-367, pls. I-XCII.

Burton, M., 1930a. Norwegian sponges from the Norman collection. Proc. zool. Soc. London, 2: 487-546.

Cabioch, L., 1973. Additions à l'inventaire de la faune marine de Roscoff. Spongiaires. Trav. Stat. Biol. Roscoff (n.s.), 20 (31): 5-6.

Lundbeck, W., 1902. Porifera. Part I. Homorrhaphidae and Heterorrhaphidae. Danish Ingolf Exped., 6: 1-108.

Stephens, J., 1916. Preliminary notice of some Irish sponges. Monaxonellidae (suborder Sigmatomonaxonellida) obtained by the Fisheries Branch of the Department of Agriculture and Technical Instruction, Ireland. Ann. Mag. nat. Hist., (8) 17: 232-242.

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