Clathrina ascandroides, BOROJEVIC, 1971

Klautau, Michelle & Valentine, Clare, 2003, Revision of the genus Clathrina (Porifera, Calcarea), Zoological Journal of the Linnean Society 139 (1), pp. 1-62 : 5-6

CLATHRINA ASCANDROIDES BOROJEVIC, 1971

Type locality: Cabo de São Tomé, Rio de Janeiro, Brazil .

Type: MNRJ 2096 (holotype /alcohol); MNHN-LBIM- C-1971–1 (paratype /alcohol). Cabo de São Tomé, Rio de Janeiro, Brazil; attached to Laminaria brasiliensis . Collected by H. de Souza Lima .

Citations: Borojevic & Peixinho (1976); Borojevic & Boury-Esnault (1987); Klautau & Borojevic (2001).

Colour: The specimen deposited in MNHN was not found; the MNRJ specimen was examined. It is small and fragmented and was collected attached to Laminaria brasiliensis . It is preserved in alcohol. The colour is still white, although other specimens collected in Brazil became brown when preserved in alcohol or when frozen.

Description: The cormus is formed of large tubes, irregular and loosely anastomosed. In the apical region there is no anastomosis. Oscula are distributed through all the tubes. No water-collecting tubes are present. As the type is very fragmented, the organization of the cormus could not be recognized; several other specimens were analysed.

The skeleton comprises tetractines of two different size classes, and triactines of only one size class ( Fig. 2A ). Triactines are the most abundant spicules. Spicules are equiradiate and equiangular.

The triactines and the smaller tetractines are the same size. Their actines are slightly conical and very sharp. Both triactines and tetractines are located outside the tubes, giving them a smooth surface. The apical actine of the smaller tetractines is conical, sharp, smooth, shorter and curved. It is thinner than the facial ones and projected into the tubes.

The large tetractines surround the interior of the tubes, and also project their apical actines into them. Actines are conical and sharp. The apical actine is curved, conical, sharp, smooth, shorter and a little thinner than the facial ones.

Remarks: Clathrina ascandroides was first described by Borojevic (1971), who collected specimens from the Cape of São Tomé in Rio de Janeiro. It is very similar to C. atlantica ( Thacker, 1908) from the Cape Verde Islands, although it differs from the latter by the absence of diactines.

The original description refers to only one kind of triactine and tetractine, measuring, respectively, 60– 110 Mm/8–12 Mm and 300 Mm/40 Mm. Borojevic considered the cormus of this species to be very characteristic, with tubes anastomosing near the base, and not anastomosed in the distal part, as in Ascandra falcata . Another species similar to C. ascandroides , according to Borojevic, is Ascaltis gegenbauri Haeckel, 1872 . Topsent (1936) considered A. gegenbauri to be a synonym of A. falcata , the former being a variety with rare or absent diactines. Borojevic confirmed this after analysing a specimen of A. gegenbauri deposited in MNHN ( Borojevic, 1966). He found some of the rare diactines and the characteristic internal folds of the choanoderm. He suggested that the specimens from the Azores, identified by Topsent (1892) as A. gegenbauri might, in fact, be C. ascandroides . He also suggested that C. ascandroides could be related to A. falcata , but was clearly distinct from it and from A. falcata f. gegenbauri , which has well-developed internal folds.

Borojevic & Peixinho (1976) and Borojevic & Boury- Esnault (1987) identified specimens from, respectively, north-east Brazil (75 m) and the Bay of Biscay (Azores, 340–560 m) as C. ascandroides , which suggested that the distribution of this species was probably amphiatlantic. When describing the specimens from Brazil, they noted the presence of one kind of triactine and two kinds of tetractines.

The size of the spicules of both populations is very similar; the species awaits genetic studies to confirm or refute the hypothesized distribution.

Figures

Figure 2. Clathrina ascandroides. A, triactines and the two populations of tetractines. Scale bar = 100 Mm.