Vosmaer, 1886
Definition: Order Halichondrida sensu Van Soest et al., 1990. Encrusting to massive, mostly amorphous sponges, with skeletons composed of oxeas and/or styles, that might be densely and confusedly arranged in the sponge body and/or forming ill-defined tracts. The megascleres are of intermediate length (200-1500 µm) and generally are present in a wide size range or in size categories. Monaxonic microscleres (rhaphides and microxea) are found in some genera. Large subdermal lacunae might be present and ectosomal skeletal differentiations are common (spicule palisade or detachable tangential skeleton).
Remarks: Ten valid genera are assigned to this family: Axinyssa , Collocalypta , Spongosorites , Topsentia , Epipolasis , Petromica , Amorphinopsis , Ciocalypta , Hymeniacidon and Halichondria . These sponges are found from intertidal habitats down to depths of 2460 m.
Source: Van Soest et al., 1990.
Genera represented in the area:
Axinyssa Lendenfeld, 1897 (type species: A . topsenti Lendenfeld, 1897) (syn. Pseudaxinyssa Burton, 1931; Axinomimus de Laubenfels, 1936): massive-amorphous; ectosome largely organic, tough, with sparsely scattered spicules; choanosomal skeleton disorganised with spicules strewn in confusion and/or composed of vaguely ascending, widely spaced vertical tracts of large oxeas, forming loose bundles, with spicule tracts protruding through surface to produce conules; choanosome with poor or moderate spongin fibres but heavy collagen; spicules oxeas, strongyloxeas or styles usually of only one size class (modified from van Soest et al., 1990).
Ciocalypta Bowerbank, 1862 (type species C . penicillus Bowerbank, 1862) (syn.
Apatospongia Marshall, 1892; Leucophloeus Carter, 1883): with pointed, blind fistules; fistules characteristically semi-transparent parchment-like; with distinct ectosomal tangential reticulation of spicule tracts, occurring as bundles or single spicules; with ectosomal styles together with predominantly stylote choanosomal megascleres (from van Soest et al., 1990).
Halichondria Fleming, 1828 (type species Spongia panicea Pallas, 1766) (syn. Amorphina Schmidt, 1870; Ciocalapata de Laubenfels, 1936; Cioxeamastia de Laubenfels, 1942; Eumastia Schmidt, 1870; Halichondriella Burton, 1931; Menanetia Topsent, 1896; ?Pyloderma Kirkpatrick, 1908; Raspaigella Schmidt, 1868; Trachyopsilla Burton, 1931; Spuma Miklucho Maclay, 1870): Massive-amorphous; ectosomal skeleton with thin, tangential peel, clearly detachable, composed of single or vague bundles of smaller oxeote spicules, supported by choanosomal columns of oxeas traversing subdermal spaces; choanosome has the appearance of a disordered loose reticulation ("halichondroid" structure), and spicule tracts are poorly defined, directionless; oxeote spicules of intermediate to relatively small size, sometimes modified to quasistylote or even true styles; ectosomal structure may be secondarily lost; microscleres absent; larvae are incubated and tufted-ciliate (modified from van Soest et al., 1990, Diaz et al., 1993).
Hymeniacidon Bowerbank, 1862 (type species H . caruncula Bowerbank, 1862) (syn.
Amorphilla Thiele, 1898; Rhaphidostyla Burton, 1935; Nailondra de Laubenfels, 1954; Rhaphoxiella Burton, 1934; Stylohalina Kirk, 1909; Thieleia Burton, 1932; Uritaia Burton, 1932): Encrusting to fistulose; skeletal plan similar to that of Halichondria whereby ectosomal skeleton is thin, membraneous, detachable, containing only tangential ectosomal styles or stylotes; ectosomal spicules are sometimes aligned (e.g. in tracts like in Mycale ), but generally ectosomal skeleton is poorly developed; choanosomal skeleton varies from true "halichondroid" to disorganised with whispy, slightly plumose ascending spicule tracts of styles or stylotes, and most species have a characteristic fleshy consistency; oxeas have been lost completely and megascleres consist only of styles or stylotes (modified from van Soest et al., 1990, Diaz et al., 1993).
Spongosorites Topsent, 1896 (type species S . placenta Topsent, 1896) (Aponastra Topsent, 1927): Massive-amorphous to subspherical; ectosomal skeleton with smooth, thick, flaky crust of paratangentially arranged, relatively thin spicules; choanosomal skeleton with spicules strewn in confusion, occasionally grouped in spongin-enforced tracts, directed mainly parallel or oblique to the surface; choanosome with poor collagen; many species with aerophobic pigments (modified from van Soest et al., 1990, Diaz et al., 1993). Megascleres are oxeas of various sizes, sometimes with their points modified to strongyles or styloids, but typically centrangulate; extra-axial region is cavernous without any obvious skeletal tracts.
Topsentia Berg, 1899 (type species: Anisoxya glabra Topsent, 1898) (syn. Anisoxya
sensu Topsent, 1898 [not Anisoxya Mulsant, 1856]; Alloscleria Topsent, 1927; Coelocalypta Topsent, 1928; Oxeostilon Ferrer-Hernandez, 1923; Laminospongia ; Pulitzer-Finali, 1983;Trachyopsis Dendy, 1905): Massive-amorphous to lobate, brittle and rough texture; bright colours typically absent; ectosomal skeleton composed of crust of compact, smaller ectosomal oxeas lying paratangentially producing a microhispid surface (but optically smooth); choanosomal skeleton with very poor collagen, no spongin fibres, resulting in an utterly confused, directionless arrangement of spicules packed around canals and subdermal spaces; megascleres are oxeas of a wide size range, usually in 2-3 size classes; twisted, bent or doubly-bent spicules sometimes present; no raphide microscleres (modified from van Soest et al., 1990, Diaz et al., 1993).
Species included:
Axinyssa digitata
Ciocalypta penicillus
Halichondria agglomerans
Halichondria bowerbanki
Halichondria panicea
Halichondria sitiens
Hymeniacidon kitchingi
Hymeniacidon perlevis
Spongosorites annandalei
Spongosorites difficilis
Spongosorites genitrix
Species not treated here:
Halichondria diversispiculata Burton (1930), Norway, deep water
Halichondria oblonga Hansen (1885), Iceland, deep water
Halichondria velamentosa Hansen (1885), Iceland, deep water
Topsentia tenuispinosa (Topsent, 1894), deep water
Several other Halichondriidae (Halichondria and Hymeniacidon -) species may occur in deeper water, but their identity is ill-known.