Clathrina reticulum, (SCHMIDT, 1862)

Klautau, Michelle & Valentine, Clare, 2003, Revision of the genus Clathrina (Porifera, Calcarea), Zoological Journal of the Linnean Society 139 (1), pp. 1-62 : 36-38

CLATHRINA RETICULUM ( SCHMIDT, 1862)

Original name: Nardoa reticulum Schmidt 1862

Type locality: Zara and Sebenico (Adriatic Sea) .

Type: BMNH 1896.9 .15.13 (proposed neotype / alcohol). Banyuls-sur-Mer, Pyrenees, France. E.A. Minchin Collection .

Citations: Haeckel (1870, 1872); Vosmaer (1881); von Lendenfeld (1891); Minchin (1896); Breitfuss (1898, 1930, 1932, 1935); Dendy & Row (1913); Brondsted (1914); Topsent (1934, 1936); Hôzawa (1940); Arndt (1940, 1941); Tanita (1942, 1943); Burton (1963); Borojevic & Boury-Esnault (1987).

Colour: This preserved specimen is light yellow.

Description: Cormus spherical and formed of regular and tightly anastomosed tubes. Oscula can be seen on the surface and a delicate membrane ( Fig. 29A ) always surrounds them. Below each osculum there is a large tube resembling an atrium (pseudoatrium). The anastomosed tubes are more abundant near the surface of the sponge. Near the pseudoatrium the cormus is less ramified and there are fewer, wider tubes.

The skeleton comprises triactines, tetractines ( Fig. 29B ) and diactines ( Fig. 29C ). Triactines are the most abundant spicule type.

Triactines and tetractines have cylindrical actines with sharp tips. The apical actine of the tetractines ( Fig. 29D ) is much thinner than the others (resembling that of C. contorta ); it is cylindrical, straight and smooth, and frequently shorter. Tetractines can be seen primarily near the pseudoatrium.

The diactines are present only on the surface and, unlike those of C. contorta , perpendicular to it ( Fig. 29E ). These spicules are not uniformly distributed ( Fig. 29F ), but appear patchily distributed like tufts, principally in the intersection points of the anastomosed tubes. They vary in size and both tips are different. One of them is similar to an arrowhead and always located inside the cormus. Sometimes, there are also more fusiform diactines.

There is also another kind of spicule in this specimen that was not described by Schmidt, the trichoxea ( Fig. 29G ). These spicules are very thin, similar to filaments and they are present among the tubes.

Remarks: Schmidt first described this species in 1862 as Nardoa reticulum after analysing a specimen collected in the Adriatic Sea (near Zara and Sebenico at a depth of 27–36 m). It was spherical, with a prominent osculum and three kinds of spicules: triactines, tetractines and diactines ‘fusiformia, paulum curvata e superficie prominentia’ (fusiform, a little curved, prominent from the surface). His description is not quite complete, and the only drawing he made was of the cormus. No holotype was elected.

Haeckel (1872) re-described it as Ascandra reticulum while analysing other specimens from the Adriatic Sea collected by him and by Schmidt. The morphological description was more complete than that given by Schmidt. He also described triactines and tetractines with cylindrical actines and sharp tips, and the apical actine of the tetractines as much thinner than the others and as either shorter or longer ( C. ret (H) in mini-table below). The diactines were described as more or less curved and fusiform. The micrometry is also similar to that which we found in the proposed neotype (triactines and tetractines: 90–120 Mm/7–8 Mm; width of the apical actine: 3 Mm; diactines: 160– 300 Mm/12–16 Mm).

Topsent (1936) re-described the species as Leucosolenia reticulum , and said that the specimens from the Adriatic (described by Haeckel, 1872 and von Lendenfeld, 1891) and from Portugal (described by Breitfuss, 1898), were different from the specimens he and Minchin had both found in the Mediterranean. According to Topsent, the diactines described by the previous authors were fusiform, spiral (sigmoid) or curved, and that both tips were similar (as described by Haeckel). After analysing specimens from the Mediterranean, first Minchin (1896) and later Topsent assumed that the diactines of C. reticulum were curved and possessed different tips, one of them being arrow-shaped (as we also found).

Kirk (1896), Hôzawa (1929) and Topsent (1936) all used the difference in the shape of the diactines to differentiate species from reticulum . Kirk (1896) described another new species, L. laxa , from the Pacific, in which one of the tips has a different thickness; Hôzawa described L. sagamiana . According to Topsent, the only difference between these species and L. reticulum is the size of the diactines, which are shorter in L. reticulum ; Breitfuss (1935) had already placed them in synonymy. C. reticulum is also similar to C. contorta in the composition of the skeleton. The organization of the skeleton, however, is very different. First, in C. reticulum the triactines are more abundant than the tetractines. The diactines in C. reticulum are perpendicular to the external tubes, while in C. contorta they are parallel to these tubes. Moreover, the diactines in C. reticulum are arrowshaped and patchily distributed, whereas in C. contorta they are randomly distributed and fusiform.

Among the specimens we analysed from the Mediterranean, we found great variety in the shape and size of the diactines. In a single specimen, the size can vary from 102 Mm to 306 Mm, and the shape can either be fusiform or have one arrowshaped tip. This could mean that all the authors working on Mediterranean specimens were indeed observing the same species, but had described the various diactine shapes differently. The problem is that Schmidt gave a poor description and did not elect the holotype. Therefore, we need to accept the description given by Haeckel and by subsequent authors such as Minchin (1896) and Topsent (1936).

There was a problem in the alteration of the number of the syntype of C. reticulum of the Bowerbank collection, sent to him by Schmidt. The entry in the Register for specimen registration number BMNH 1955.11.2.27 reads: ‘ Leucosolenia reticulum O.S. dry, from O. Schmidt. Bowerbank Coll. BK.345 (part), Now 67.3.11.87a’.

However, when we checked the specimen and the slide number BMNH 1967.3.11.87a, we found that they were different. Perhaps the slide is from a syntype. The specimen, however, is completely different from the slide. A mistake was probably made when the number of the specimen was changed.

In the BMNH collections there is a specimen from Minchin’s collection that corresponds to the currently accepted description for C. reticulum . This has the registration number BMNH 1896.9 .15.13 and it is from the Mediterranean ( Banyuls-sur-Mer , Pyrenees, France). We propose electing it as the neotype .

Abbreviations. C. ret , C. reticulum ; H, Haeckel’s description; C. cont , C. contorta ; fus, fusiform, arr, arrow-shaped; perp, perpendicular.

Figures

Figure 29. Clathrina reticulum. A, photograph of the neotype (¥ 10). B, triactine and tetractine. C, diactine and triactine. D, apical actines of the tetractines projecting into a tube. E, diactines perpendicular to the surface. F, distribution of the diactines at the surface. G, trichoxea (arrow). Scale bar = 100 Mm.