(Bowerbank, 1866)
Species Overview
Haliclona fistulosa (Bowerbank, 1866) forms a whitish to pinkish massive base with irregular, partly erect, partly sprawling fistules, the thicker ones of which have oscules. It is firm and friable, with a smooth transparent skin. Skeleton largely unispicular. Occurs in the rocky sublittoral down to 50 m.
Taxonomic Description
Colour: Whitish transparent at the surface and fistules, yellowish-brown or purplish in the choanosome.
Shape, size, surface and consistency: Roundish massive (Haliclona fistulosa BandW), commonly with fistules arising from the upper (Haliclona fistulosa De Weerdt) and side parts of the sponge (Haliclona fistulosa 2). The thinner more irregular ones are blind, the thicker ones often have wide oscules (Haliclona fistulosa close up). Experiments of Jones (1994) have demonstrated that the shape and frequency blind fistules may be ecologically induced. Size usually not exceeding 10 cm, fistules up to 2-4 cm long. Surface smooth, even, rather strongly punctate. (Haliclona fistulosa situ) Consistency rather firm, friable, slightly brittle. No slime.
Spicules: (Haliclona fistulosa draw) Robust oxea, straight or slightly, evenly curved, with a long and sharp point: 140-220 x 5-12 µm (see also table below).
Skeleton: The ectosomal skeleton (Haliclona fistulosa SEM) is a rather dense, but regular, subisotropic reticulation of single spicules. It is easily detachable. Choanosomal skeleton (Haliclona fistulosa skel): a rather dense, subisotropic to anisotropic reticulation of single or double spicules; there is no clear distinction between primary and secondary lines. There are many subdermal and choanosomal spaces. Fistules: the skeletal architecture of the fistules is the same as that of the ectosome; there are no supporting tracts. Spongin: very scarce, confined to the nodes of the spicules.
Reproduction: To date (1995) no data on reproduction or larvae of this species have been published.
Ecology: In the infralittoral, to 50 m, in fairly sheltered places with moderate water movement. On stones, Laminaria-holdfasts , etc. More frequent on vertical than on horizontal substrates, but may tolerate some silt. Rather common.
Distribution: Shetland, British Isles, Channel Islands, France, Atlantic coast of Spain, reaching south to the Azores and the Mediterranean.
Type specimen information: Holotype: BMNH 1910:1:1:270, Guernsey.
Remarks
The holotype of Isodictya fistulosa is a roundish clump of 6 x 3.5 x 2.5 cm with a few, scattered oscules, 3-5 mm, some of which are slightly elevated. The fistules, which are clearly visible in Bowerbank's figure of the holotype (Bowerbank, 1874, pl. LIII fig. 15 Isodictya fistulosa) are for the greater part lost. Nevertheless, the specimen is well recognizable as the figured sponge. The skeleton of both the ectosome and choanosome is a dense, subisotropic reticulation of robust, straight and long-pointed oxeas which measure 156-178 by 6-7.9 µm. There is only very little, hardly discernible spongin at the nodes of the spicules.
The holotype of Halichondria regularis is a rather small, roundish clump, ca. 2 x 1.5 x 1 cm, with one small, circular osculum of 1 mm, and without fistules. The skeletal architecture is similar to that of the preceding specimen.
Haliclona fistulosa is related to the Mediterranean species Reniera (= Haliclona) latens Topsent, 1892b, Reniera (= Haliclona) magna Vacelet, 1969 and Pellina semitubulosa (Lamarck, 1813) (not Lieberkühn, 1859 as suggested by authors, cf. below) sensu Topsent (not sensu Schmidt, 1870).
H . fistulosa has larger spicules with longer points than H . latens , in which they measure 120-130 x 5-6 µm (Topsent, 1892b: XIX, and a slide in the MNHN collection: D.T. 146). Other differences are the colour, which is orange-greenish in R . latens , and the presence of two sorts of connective filaments in this species, which lack in H . fistulosa , according to Topsent. Although the species share the architecture of the skeleton, which is subisotropic in both species, the skeleton of H . fistulosa is denser than that of R . latens . Topsent and Olivier (1943) considered H . latens as a variety of H . fistulosa .
Haliclona magna has oxeas of rather similar length as H . fistulosa , but they are thinner, viz. 170-185 x 5-7.5 µm (Vacelet, 1969: 211; Griessinger, 1971: 148, as Pellina , and a specimen in the ZMA collection: ZMA POR. 5468), and the points are very short. Another difference is the much larger size and coarser habit of H . magna .
Spongia semitubulosa Lamarck, 1813 was used as type-species for a new genus Pellina by Schmidt (1870). He ascribed the original description of this species to Lieberkühn (1859, as Halichondria) , and placed Spongia semitubulosa Lamarck with a question mark in the synonymy. Lieberkühn (l.c.: 524) described the species, however, as Spongia , not as Halichondria , and ascribed the species evidently to Lamarck. Since Schmidt's creation of Pellina several species have been transferred to this genus, among which H . fistulosa . Griessinger (1971) reported Pellina fistulosa from three Mediterranean localities, but his description and figure (pl. II fig. 5) leave no doubt about the identity of his material, viz. Phloeodictyon isodictyiforme Carter (1882). This little known, cryptic species has been transferred to Oceanapia by de Weerdt (1985) on the basis of study of the type-specimen (BMNH 1872.5.4.1) and other material. Griessinger redefined the genus Pellina as having a very dense, irregularly meshed choanosomal skeleton, a regular ectosomal skeleton, many subdermal spaces, fistules only built up by ectosomal spicules, no spongin, sponge very fragile. Van Soest (1980) emphasized in his definition of Pellina the longitudinal supporting spicule tracts of the fistules. Van Soest and Sass (1981) listed fistulosa , as Pellina , in an array of species which they assigned to this genus. De Weerdt (1985) and de Weerdt and van Soest (1986) mentioned the fact that the type-species of Pellina was formerly misinterpreted and that Pellina had to be considered as a synonym of Haliclona . However, it now appears that there is sufficient evidence to demonstrate that Pellina , on basis of its type-species, most probably is a synonym of Halichondria instead of Haliclona . The species described as Pellina semitubulosa by Topsent (1925b: 709), and which has later been recorded by several authors, is a species which is closely related to H . fistulosa , but which is not conspecific with Lamarck's Spongia semitubulosa , nor with Schmidt's Pellina semitubulosa . The latter most probably conforms to Halichondria bowerbanki or a related form. Lamarck's description seems to be based on a figure of Plancus (= S. G. Bianchi), in "Conchis minus", but this work is very rare (cf. also Burton, 1930a: 513). It is, therefore, very difficult to assess the taxonomic status of the original Spongia semitubulosa . Lieberkühn's description of Spongia semitubulosa agrees with Halichondria . Lieberkühn described the species as an amorphous mass from which rise roundish, sometimes slightly compressed, frequently anastomosing branches. The skin resting loosely on the rest of the sponge, enveloping the sponge as a transparant "bag'' ("...und umhüllt den Schwamm wie ein durchsichtiger Sack.''). The colour greenish or whitish. Spicula pointed at both ends, ca. 508 x 8 µm (recalculated from Lieberkühn, unnumbered figure of pl. XI). No spongin. Most common Venetian species. Later references of this species evidently conform to different species (cf. below). Schmidt (1870: 41) erected the genus Pellina for sponges with an easily detachable dermal membrane. The ZMK holds an original slide of Schmidt labelled "Reniera semitubulosa (Pellina N.g.), Kattegat", containing two cross-sections and one tangential preparation of the ectosome Most probably the slide has been erroneously labelled R . semitubulosa by Schmidt, since he never mentioned the occurrence of this species at Kattegat. Probably the label should have been Pellina bibula . Without doubt the sponge of this slide is Halichondria panicea . In the MNHN there is a slide (D.T. 2226), prepared by Topsent from Schmidt's presumed original specimen from Venice, labelled in Topsent's handwriting: "Reniera semitubulosa O.S., Venedig, Mus. Strasb." This slide contains fragments of a sponge which again is without doubt a Halichondria . The surface characteristics of H. panicea agree very well with Schmidt's description of Reniera (later as Pellina ) semitubulosa : a dermal membrane Iying loosely on the rest of the skeleton, many subdermal spaces, which further contribute to making the membrane easily removable, and the conspicuous presence of numerous exhalant canals running to the oscules. When comparing Schmidt's description of Pellina bibula (Schmidt,
1870: 42) with his first description of Reniera semitubulosa (Schmidt, 1862: 75), the affinity of two species with Halichondria becomes also more apparent. The ectosome of P . bibula (and also of R . semitubulosa ) consists of "ein schönes vielreihiges Netz"; tbe only difference between the two species being the somewhat larger spicules of R . semitubulosa than P . bibula , in which they measure 230-240 µm. In Schmidt's slide the ectosome is a very regular network of multispicular fibres; the choanosome is a somewhat confused reticulation of pauci-multispicular fibres; there is no spongin and the oxeas measure ca. 300 by 7.5 µm. In Topsent's slide they measure ca. 340-380 by 7.5 µm. From the two slides and Schmidt' s descriptions of P . bibula (from the Kattegat) and R . semitubulosa it is evident that Pellina most probably is a junior synonym of Halichondria , not of Haliclona as was erroneously suggested by de Weerdt and van Soest (1986). Schmidt (1870: 41) furthermore described Pellina as sponges with "Renieren-nadeln in unregelmässigen Zügen und bunt durch einander". He placed the genus close to Amorphina in the family Renierinae.
It must be remarked here that P . semitubulosa was described by de Weerdt and van Soest (l.c., as Haliclona ) from the Azores. The specimen, however, is Oceanapia isodictyiformis (Carter).
The species was furthermore recorded as a Mediterranean-Atlantic species, reaching up to the English Channel. This remark was based on the study of a slide in the BMNH (1954.8.12.242), off Plymouth, which was interpreted as being conspecific with H . semitubulosa . It seems more likely that this slide was misinterpreted.
Although the apparently confusing taxonomic status of P . semitubulosa can not be sufficiently solved, it seems useful to review the main literature data concerning the species. Keller (1879: 564-579) reported the species, as Reniera , from Triest. His description and figures (l.c., pl. XXXVI figs. 1-4, pl. XXXVII fig. I) remind of Haliclona aquaeductus (Schmidt, 1862). The size of the oxea of Keller's material was 140-150 µm. Ridley and Dendy (1887: 14) redefined the genus Reniera Nardo, and explained in the same chapter why they did not agree with Schmidt to erect the new genus Pellina . They wrote (l.c.:15): "We can not agree with Schmidt in referring those species which have a separable dermal membrane ("Zusammenhangende Oberhaut") to a distinct genus, Pellina , as we do not regard this character as being of generic importance. His original type of Pellina is P . semitubulosa Schmidt. The so-called dermal membrane is also a very distinct feature of Halichondria panicea , yet Schmidt keeps this species out of his genus Pellina , into which it ought certainly to fall according to his definition, If such it can be called". They are evidently right in this critical remark.
Hanitsch (1889: 160) reported the species as Reniera (agreeing with Ridley and Dendy) from Puffin Island (Great Britain); his material consisted of branches arising from the base, with oxeas of 300 µm, arranged in "multispiculous triangular or quadrangular meshes". This record most probably conforms to H . panicea . Dendy (1922: 30) reported the species, as Reniera , from the Indian Ocean (Diego Garcia), but his identification was solely based on Keller (1878). Dendy seriously misinterpreted the taxonomic status of both Lieberkühn's and Schmidt's records. He wrote that the species was characterized by its branching habit, slender spicules and absence of spongin. The skeleton is weakly developed and consists of a sub-isodictyal reticulation of slender oxea, in which many feebly developed, loose, plurispicular, longitudinal fibres can be recognized. There is no special dermal skeleton and little if any spongin. The oxeas are slender, slightly curved, rather abruptly sharp-pointed 164 x 4 µm. This record must be assigned to another chalinid species.
Table of spicule sizes (in µm) of Haliclona fistulosa specimens: Spicule sizes H. fistulosa.
Source: De Weerdt, 1986