Clathrina atlantica Klautau & Valentine, 2003

Klautau, Michelle & Valentine, Clare, 2003, Revision of the genus Clathrina (Porifera, Calcarea), Zoological Journal of the Linnean Society 139 (1), pp. 1-62 : 7-9

CLATHRINA ATLANTICA ( THACKER, 1908) COMB. NOV.

Original name: Leucosolenia atlantica Thacker, 1908

Type locality: Boa Vista Island , Cape Verde Islands .

Type: CUMZ-R.N.5 (holotype /alcohol) and CUMZ- R.N.4 (paratype /alcohol); slides BMNH 1924.7 .2.6 (from the holotype) and BMNH 1924.7 .2.5 (from the paratype). Cape Verde Islands, 37 m depth, North Point, Boa Vista Island .

Citations: Dendy & Row (1913); Tanita (1942, 1943); Burton (1963); Borojevic & Peixinho (1976).

Colour: White when preserved.

Description: Cormus formed of a few isolated white tubes ( Fig. 4A ), the largest measuring 0.6 ¥ 0.2 ¥ 0.1 cm, with a diameter of 0.1 cm. Consequently, there is no true anastomosis, although there is fusion at some points. Oscula are present at the end of the tubes, and there are no water-collecting tubes. The surface of the tubes is a little hispid because of the presence of diactines, which are particularly more abundant near the base.

The skeleton comprises triactines, tetractines of two different sizes ( Fig. 4B ), diactines ( Fig. 4C ) and trichoxeas. The triactines and tetractines are equiradiate and equiangular, and triactines are the most abundant spicules. The actines are straight, cylindrical or conical, with a sharp tip. Both triactines and tetractines are approximately the same size. The apical actine of the tetractines protrudes into the interior of the tubes, and it is smooth, conical, sharp and thinner and shorter than the facial ones.

Large tetractines are only found on the surface of the tubes. Their actines are conical and stout, with a sharp tip. Their apical actine projects inside the tubes. It is conical, smooth, straight and sharp, and always shorter than the facial ones.

Diactines are not evenly distributed. They are found mainly in the basal tubes, where they are located perpendicular to the wall. They are slightly curved at one tip or, sometimes, at both tips. In the latter case, they are curved in opposite directions (sigmoid). Very occasionally they are straight. Both tips are sharp, and the proximal tip is a little thicker, while the distal tip is curved.

Trichoxeas are also present. Thacker had observed these, but considered them to be a character with no taxonomic value. We believe by contrast that they are important in the description of C. atlantica and should be considered as a distinctive taxonomic character to distinguish it from other species.

Remarks: Clathrina atlantica was first described by Thacker (1908) as Leucosolenia atlantica , when he analysed two specimens from the Cape Verde Islands (Crossland Coll.). Many years would pass before another specimen was identified as atlantica . Tanita (1943) described this species from Japan. Borojevic & Peixinho (1976) described it from Brazil, calling it Clathrina for the first time.

Although the specimens collected in these three localities have the same kind of spicules - triactines, tetractines of two different sizes and diactines - they are not identical. There are important differences involving the organization of the cormus and the size and shape of the spicules.

The specimens from Japan and from Brazil have a clathrate cormus while those from the Cape Verde Islands have nonanastomosed tubes, which are sometimes fused, as in C. ascandroides . The shape of the diactines is different. The types have cylindrical diactines, with sharp tips, while in the specimens from Japan and from Brazil, the diactines are more fusiform and, in the Brazilian specimens, one of the tips resembles an arrow. The size of the spicules in the specimens from these three localities is also different (see below) .

Considering these morphological differences, we believe that specimens from these three localities are in fact distinct species and that the distribution of C. atlantica is restricted at the moment to the Cape Verde Islands. The specimens from Japan and Brazil should be considered as distinct species, new to science. However, as they were unavailable to us, they could not be studied, and were not included in this revision.

Figures

Figure 4. Clathrina atlantica. A, photograph of the holotype (¥ 40). B, triactines and tetractines. C, diactines at the surface (arrow). Scale bar = 100 Mm.