Clathrina tenuipilosa (Dendy, 1905)

Klautau, Michelle & Valentine, Clare, 2003, Revision of the genus Clathrina (Porifera, Calcarea), Zoological Journal of the Linnean Society 139 (1), pp. 1-62 : 40-42

CLATHRINA TENUIPILOSA ( DENDY, 1905)

Original name: Leucosolenia tenuipilosa Dendy, 1905

Type locality: Sri Lanka .

Type: BMNH 1907.2 .1.102 (paratype /alcohol). Ceylon ( Sri Lanka) (Stat. LXIV, 9 m, south-east of Modragam, March 17, 1902). Herdman Collection .

Citations: Row (1909); Dendy & Row (1913); Tanita (1942); Burton (1952, 1963).

Colour: Preserved specimen is light yellow.

Description: Cormus formed of large irregular and loosely anastomosed tubes of equal size ( Fig. 32A ). No large superficial water-collecting tubes are present. Many oscula open independently at the external surface. Special cells were not found.

The wall of the tubes is thick (approximately 48 Mm), composed of an irregular meshwork of spicules, containing triactines, tetractines ( Fig. 32B ) and trichoxeas. Triactines are the most abundant spicules, while tetractines are located surrounding the tubes and projecting their apical actines inside them ( Fig. 32C ). The apical actines do not cross the entire diameter of the tubes and the number of tetractines varies in each tube. Trichoxeas are distributed patchily on the surface of some tubes, where they are projected perpendicularly. They are present in the external as well as in the internal tubes.

Amongst equiangular and equiradiate triactines and tetractines, triactines are the most abundant spicules. Their size is uniform if we compare triactines with tetractines, but triactines alone have variable sizes as a consequence of the presence of very small, young, triactines. Actines are a little undulated in their distal part, where there is sometimes also a slight constriction. They are conical or cylindrical, but conical spicules are more abundant, with a blunt tip. The apical actine of the tetractines has a variable length and its diameter at the base is almost the same as the facial actines. It is smooth and frequently straight, while the longest apical actines are curved in their distal part.

Trichoxeas are not very abundant and their quantity varies in each tube. They are very thin, long, smooth and straight.

Remarks: C. tenuipilosa was described by Dendy in 1905 from Ceylon (now Sri Lanka), and was considered by Thacker (1908) to be a synonym of C. canariensis . Thacker suggested that the presence of trichoxeas was a very variable characteristic, and therefore not a good one for systematics. One year later, Row (1909) rejected this synonym saying that ‘the presence of oxea of such unusual and constant form, being very long and extremely slender, should undoubtedly separate it specifically from forms where oxeas are entirely absent, even though the number and frequency of the oxea may show very considerable variation as they do in Thacker’s specimens’.

Our opinion agrees with Row’s in relation to the validity of this species. However, C. tenuipilosa should not be distinguished from other clathrinas only by the presence of trichoxeas. We analysed specimens with triactines, tetractines and trichoxeas from other localities, and also from the type locality, Ceylon, which showed important differences in the organization of the cormus and in the shape of the spicules. We consider that the presence of trichoxeas is not sufficient to identify this species. C. tenuipilosa should be distinguished from other species by characteristics such as the presence of trichoxeas, the shape of triactines and tetractines, and the organization of the cormus.

C. tenuipilosa has conical and cylindrical actines, with sharp tips. They are slightly undulated in the distal part and have a constriction near the tip. Triactines are present in two different sizes, one of them very small. The apical actine of the tetractines is smooth. The cormus has several oscula, and no watercollecting tubes.

The distribution of this species, as with other clathrinas, seems to be restricted to the Indian Ocean. Furthermore, we have analysed some specimens from Sri Lanka, which although similar to C. tenuipilosa in relation to their kinds of spicules, differ in the organization of their cormus and the shape of their spicules. These specimens are probably a distinct species, new to science.

The specimen deposited at BMNH, considered to be the holotype of this species by Burton (1963) is, in fact, a paratype. In Dendy’s (1905) description, he elected specimen R.N. 158 as the holotype. He also identified two other specimens (R.N. 380 and 381) from Sri Lanka (Cheval Paar) as C. tenuipilosa ; these were deposited together in BMNH under the registration number BMNH 1907.2.1.102, and should be considered to be paratypes. However, they differ from the original description of the holotype with respect to their colour when preserved, which is light yellow and not pale grey as Dendy described. There are also no water-collecting tubes, as suggested by Dendy when he wrote ‘the tubes converge to unite in small, prominent, true vents’.

Figures

Figure 32. Clathrina tenuipilosa. A, photograph of the paratype (¥ 40). B, triactines and a tetractine. C, some apical actines of tetractines projecting into a tube. Scale bar = 100 Mm.