Hincksina calpensis, Reverter-Gil & Souto & Fernández-Pulpeiro, 2012

Reverter-Gil, Oscar, Souto, Javier & Fernández-Pulpeiro, Eugenio, 2012, New and little known species of Bryozoa from Iberian Atlantic waters, Zoosystema 34 (1), pp. 157-170 : 162-164

Hincksina calpensis n. sp.

( Figs 2 ; 3A, B; Table 3)

Hincksina sceletos – Harmelin & d’Hondt 1992: 32, pl. 1, figs A-C.

HOLOTYPE. — MNHN IB-2009-1520 : BALGIM stn DR42, 35°54.5’N, 6°13.3’W, 135 m. One colony on a shell.

PARATYPES. — MNHN IB- 2009-1521: BALGIM stn DR151, 35°55.2’N, 5°25.4’W, 115 m. One colony on a fragment of a shell. — MNHN IB- 2009-1522: Cassis, Cassidaigne Canyon, 300 m. One colony on a fragment of a shell.

DISTRIBUTION. — Hincksina calpensis n. sp. has been collected in the area of the Strait of Gibraltar at 115 m and 135 m depth and in the Cassidaigne Canyon (southern France) at 300 m depth.

ETYMOLOGY. — From Mons Calpe, the Latin name for Gibraltar.

DESCRIPTION

Colony encrusting, unilaminar. Autozooids oval, arranged in irregular series. Gymnocyst developed, especially in the proximal end. Frontal membrane, except for the operculum, obscured by a convex shield of 15-18 stout, flattened spines, intertwined and fused in the midline of the autozooid. Oral spines often absent in non-ovicellate zooids; when present, similar to spines in ovicellate zooids, short, flattened, subtriangular, sometimes with the beginning of a bifurcation. Avicularia interzooidal, as many or even more than autozooids; often placed distally to an autozooid. Mandible short, rounded, transversally directed; opesia semicircular, slightly wider and shorter than the mandible. Ovicell immersed in the distal avicularium, globular, conspicuous. Periances -

trular zooids with a less developed gymnocyst; oral spines always present, and marginal spines slender.

REMARKS

This species was originally reported in the area of the Strait of Gibraltar by Harmelin & d’Hondt (1992) as Hincksina sceletos , a species only reported from Madeira at that time ( Busk 1858; Hincks 1880; Waters 1898; Norman 1909). The holotype of this species is held at the NHM (1899.7.1.1144), as well as two colonies collected by Norman (NHM 1908.3.23.1).We have examined some photographs of these samples (see Fig. 3C-E) kindly sent by B. Berning, who will redescribe the species in a future paper. Some other material of H. sceletos was conserved in the Waters collection at the Manchester

Museum; unfortunately, it seems that these slides have been mislaid.

The original material from Gibraltar area we have revised shows several important differences with H. sceletos . Some of them had already been mentioned previously by Harmelin & d’Hondt (1992).

Hincksina calpensis n. sp. has 15-18 marginal spines covering the frontal membrane; they are flattened, and they intertwine and tighten over the zooid midline. In H. sceletos the number of marginal spines is smaller (9-15 according to different authors), and they are laterally compressed, curved, rib-like in the words of Busk (1858) or even falciform (see Fig. 3D and Waters 1898: pl. 49, fig. 5). On the other hand, in both species there is some variability in the development of the marginal spines: in H. calpensis n. sp. the periancestrular autozooids present slender, not flattened, marginal spines; in H. sceletos the autozooids in a concave area of a colony also present thinner spines (B. Berning pers. comm. September 2011). Finally, some periancestrular zooids in H. calpensis n. sp. may show a duplicate frontal shield (inner and outer) as a result of regeneration processes (see Fig. 3A).

The oral spines in H. calpensis n. sp. are often missing in non ovicellate zooids, being present in periancestrular zooids and in ovicellate ones; they are small, flattened and may even show a beginning of bifurcation with uncalcified pores in the tips. In H. sceletos the oral spines are present in all the autozooids; they are also flattened, hollow, but with three or up to five tips, and much developed (see Fig. 3C, D). The ovicell has not been formally described in this species, though Hincks (1880) reported it as “rounded, smooth and silvery”.

The avicularia are clearly smaller in H. calpensis n. sp.: 0.175 mm against about 0.23 mm in the holotype of H. sceletos , and even longer in the Norman material of this species (see Fig. 3E). Moreover, they are almost always transversally directed, while in H. sceletos they are often distally directed.

Finally, the gymnocyst is well developed in H. calpensis n. sp., while it is absent in H. sceletos .

Harmelin & d’Hondt (1992) indicated that on a specimen collected in the NW Mediterranean (Porquerolles Island) at 150 m depth, the features of the oral and opesial spines were intermediate between the Gibraltar form and that described at Madeira; we examined several photographs of this specimen, which may correspond to H. calpensis n. sp. We also have examined a similar colony, sent by J.-G. Harmelin, collected in the Cassidaigne Canyon at 300 m depth. In this specimen the zooids and the spines show a development similar to the periancestrular zooids of the holotype of H. calpensis n. sp., i.e. oral spines are always present (though small), marginal spines are slender, and the gymnocyst is less developed. These minor differences would have a geographic and/or ecological origin.

Hincksina calpensis n. sp. must be then a Mediterranean species, while H. sceletos would represent an Atlantic, closely related species.

Family SETOSELLIDAE Levinsen, 1909

Figures

FIG. 2. — Hincksina calpensis n. sp. (holotype MNHN IB-2009-1520): A, B, views of the colony; C, autozooid; D, ovicellate zooid.