(Schmidt, 1862)
Species Overview
Haliclona fibulata (Schmidt, 1862) (also known as Gellius fibulatus ) is a rose-coloured cushion-shaped massively encrusting sponge with a characteristically reticulated, smooth surface. Few oscules. This is one of three Haliclona species in the area with sigma-microscleres. It is a Mediterranean-Atlantic species, occurring along the coasts of France and the British Isles on stones and shells down to 60 m.
Taxonomic Description
Colour: Old rose alive; in alcohol cream, yellowish-white.
Shape, size, surface and consistency: Cushion-shaped (Haliclona fibulata BandW), which may become laterally spreading masses, occasionally with fistular proliferations. The sponge may reach a size of 10 cm or more. Oscules few, 1-2 mm, flush with the surface. Surface smooth, strongly reticulated. Consistency rather firm, but compressible.
Spicules: (Haliclona fibulata skeldraw2) Megascleres : Oxeas straight or slightly curved, with a rather long and sharp point, sometimes with a few strongylote and centrotylote modifications intermixed: 160-270 x 5-11 µm.
Microscleres : Sigmas: irregularly and weakly curved: 9.6-37 x 1.0-2.4 µm.
Skeleton: (Haliclona fibulata skeldraw1) Ectosomal skeleton irregular and rather confused subisotropical reticulation. Choanosomal skeleton consists of a rather irregular and dense reticulation with paucispicular primary and unispicular secondary lines, with many spicules in confusion. Spongin scarce, nodal.
Ecology: In the infralittoral, to ca. 60 m. On stones, conglomerates of shells, calcareous algae, sponges etc. Reported from 450-480 m off the Strait of Gibraltar by Boury-Esnault et al., 1994.
Distribution: British Isles, Atlantic coasts of France, Spain, Mediterranean, ?Spitsbergen, ?Greenland.
Etymology: Fibula (Latin) = buckle or safety pin, presumably referring to the irregular sigmas.
Type specimen information: Holotype: unknown. There is a slide in the BMNH labeled "Reniera fibulata" Schmidt, 1870 from Portugal (see Desqueyroux and Stone, 1992), but this is not conspecific with the present species (see De Weerdt, 1986). This slide registration no. = 1870.5.3.113.
Remarks
Haliclona fibulata is morphologically well characterized by its strongly reticulated surface, and its laterally spreading, thickly encrusting habit. Furthermore the sigmas are characteristically irregularly bent. These differences serve to distinguish it from sigma-bearing species H . angulata and H . rava . Unfortunately the identity of H . fibulata could not be established on the basis of thc original material. However, although Schmidt's description of Reniera fibulata is meagre, he figured the spicules, from which it can be calculated that the oxeas measure ca. 160 x 5.7 µm, and the sigmas ca. 17 µm. The best available, and reliable description of the species is that of Topsent (1925b: 706, pl. Vlll, fig. 6). The photo of the sponge clearly shows the characteristic morphological features of the species.
Schmidt's (1862) first record of R . fibulata is from Lesina (Triest). Later (1870) he reported the species from Portugal. According to Ridley (1884) and Topsent (1925b), who re-examined Schmidt's material from Portugal, this record conforms to Desmacella vagabunda Schmidt, 1870. It is a thick-walled, tubiform sponge with oxeas of 190-220 x 8-9 µm (very similar to H . fibulata ), but with sigmas in three size categories, viz. 30 x 1.5 µm, 65-75 x 7-5 µm, and 80-110 x 4 µm.
Isodictya jugosa and Halichondria couchii are without doubt conspecific with H . fibulata , but the material of both species is scanty (both are only represented in the BMNH by the small and rather amorphous holotypes). The skeletal characteristics agree very well with the other specimens studied. A possible synonymy of H . couchii and H . fibulata has already been suggested by Topsent (1892a). I . jugosa has been recorded from E-Greenland by Burton (1934b, as Haliclona ), but this can not be assigned to H . fibulata . This record was from before Burton did a revision of H . angulata (Burton, 1948), when he placed I . jugosa in the synonymy of H . angulata . In this earlier publication he listed a number of other species and references in the synonymy of H . jugosa , among which Gellius stylifera Lendenfeld, 1897 (which is no haplosclerid, but probably a poecilosclerid: it has long styles, strongyles, oxeas and sigmas), Gellius angulatus sensu Lundbeck (1902), Gellius massa Arnesen, 1903 and Gellius arnesenae Arndt, 1927. The latter three references conform to Gellius arcoferus Vosmaer, 1885, a species which belongs to the genus Hemigellius in the family Niphatidae (cf. de Weerdt and van Soest, 1987).
Gellius pyrrhi Hanitsch, 1895, described from Portugal, is tentatively considered synonymous with H . fibulata . The description of the habit fits with the present species; the size of the oxeas is 150 x 6 µm, the size of the sigmas 12 x 0.4 µm, which is somewhat smaller than those of H . fibulata .
Gellius arcticus Hentschel, 1916 reminds strongly of H . fibulata . Hentschel described the species as massive, with a conspicuously reticulated surface, simple, not elevated, circular oscules of 4-8 mm; the sponge reminding of a polished stone. Colour in spirit whitish. Ectosomal skeleton "renieroid"; choanosomal skeleton confused, with a few paucispicular lines, and with spongin at the nodes of the spicules. Oxeas slightly curved, with rather short points (this is the only difference with H . fibulata , which has long points), size 200-280-336 x 6-10 µm. Sigmas of irregular shape, weakly curved, 27-34 x 1.0 µm. Hentschel reported the species from Spitsbergen, from 57-60 m. If Hentschel's material turns out to be H . fibulata , the species has a remarkably wide geographical range, viz. from the Mediterranean and Azores north into the Arctic. This is an unlikely, but not impossible distribution.
H . fibulata is related to the same species as H . angulata (see remarks under H . angulata ). In addition it is very similar to Sigmadocia (= Haliclona) piscaderaensis van Soest, 1980 (West Indies). The latter species has slightly smaller oxeas (165-216 x 5-5.9 µm), and much smaller sigmas (7.5-12 µm). They are quite certainly closely related.
Source: De Weerdt, 1986