Clathrina pulcherrima

Clathrina aff. pulcherrima (Dendy, 1891)

Figures 27a–e

? Leucosolenia pulcherrima Dendy, 1891: 52, pl. I fig. 7, pl. IV fig. 3, pl. X fig.3.

? Clathrina blanca; Jenkin 1908: 438, figs 85–87 (not: Miklucho-Maclay 1868)

? Clathrina blanca f. pulcherrima; Borojević 1967: 191 (? not: Dendy 1891)

Material examined. ZMA Por. 22408c, Mozambique Channel, between Mozambique and Madagascar, E of Juan de Nova Island, 17.2817°S 43.1567°E, depth 60 m, trawl, coll. RV‘Pelagia’ Around Africa II expedition, field nr. 20- ASC 10, 1 April 2001.

Description. Stalked Guancha -like sponge with flattened cormus (Fig. 27a) consisting of a tightly anastomosed mass of thin tubuli. The upper rim of the cormus has a row of tiny oscules (Fig. 27a 1). Size entire specimen 3.3 cm high, stalk 1.8 cm long and 0.17 cm thick, cormus 1.3 cm wide, 0.4 cm thick. Tubuli about 0.05–0.1 mm in thickness, with thicker tubuli running the entire length of the cormus. Color in alcohol dirty white to light beige.

Aquiferous system. Asconoid.

Skeleton. (Fig. 27b) Stalk and outer tubule walls consist of strongly sagittal triactines and to a lesser extent regular triactines; inner tubuli predominantly have regular triactines in their walls.

Spicules. (Figs 27c–e) Triactines only.

Triactines, in two distinct types, (1) equiradiate equiactinal triactines (Fig. 27c) with thin cylindrical actines 59– 101 –126 x 5 – 6.3 –8 µm, occasionally slightly sagittal with thicker conical actines (Fig. 27d), and (2) strongly sagittal (parasagittal) triactines (Figs 27e), with conical actines, with unpaired actines usually thicker halfway, paired actines usually tapering gradually, but occasionally also thicker halfway, unpaired actines strongly variable in length, 151– 226 –267 x 7.5– 11.5 –13 µm, paired actines 61– 114 –140 x 7 – 10.1 –12 µm.

Distribution and ecology. Mozambique Channel, possibly SE coast of South Africa, possibly Southeast Australia, shallow water to 60 m depth.

Remarks. The shape of this specimen closely resembles the description and drawing of the Southeast Australian species Clathrina pulcherrima Dendy, 1891 (see Dendy, 1891, p. 52, pl. I fig. 7, as Leucosolenia). This is likewise a stalked sponge with upper body of laterally compressed oval shape, with the upper rim provided with a row of oscules. The spicules are also divisible in regular equiradiate and equiangular triactines and parasagittal triactines. However, there is a significant difference in the lengths of the actines: the equiradiate actines measure 84 x 4.2 µm, the parasagittal unpaired actines are 100 x 8 µm long and the paired actines are 56 x 8 µm. Although Dendy did not give ranges of the actines, it is clear from these data that the spicules are distinctly shorter and thinner than the present ones. It is currently judged to be uncertain whether this difference merits specific distinction.

Jenkin (1908) reported a flattened specimen of Clathrina blanca (Miklucho-Maclay, 1868) from Zanzibar, which reminds of our specimen, but is more irregular and the stalk is not a separately developed structure. It likewise has two types of triactines, regular triactines with actines of 60–100 x 4–9 µm and sagittal triactines with long unpaired actines of 100–160 x 7–11 µm. These measurements are somewhat inbetween those of Dendy and ours. Clathrina blanca is not flattened and is confined to the North Atlantic.

Borojević (1967) described specimens from South Africa (East London and Durban) as Clathrina blanca forma pulcherrima, but since he did not give spicule measurements, nor illustrations, it is not certain his specimens belonged to the same species as the present. He also signaled the presence of tripods, shaped similar to the regular triactines but with raised centre, which were not clearly present in the above-described specimen.

Haeckel (1872) reported (p. 16) and illustrated (his pl. 2 figs 5 and 6) stalked Clathrina primordialis specimens from the Red Sea, which he obtained from Miklucho-Maclay with the manuscript name ‘ Nardoa arabica ’. The specimens had only a single oscule and the spicules were all regular triactines. Row (1909) also reported C. primordialis but gave no description or illustration. Recently, Klautau et al. 2016 redescribed C. primordialis from the Adriatic and restricted that species to the Mediterranean. The identity of the Red Sea population referred to by Haeckel and Row remains uncertain. Voigt et al. 2017 stated that it possibly was conspecific with their Clathrina rowi.

Although there is no morphological similarity, molecular sequence analysis of partial 28SrRNA put this species closest to Clathrina rotundata Voigt et al., 2017. Still, a trimmed alignment with length of 395 sites showed 45 site differences between the present species and C. rotundata. This result merely expresses the isolated positions of these two species.

Guancha Miklucho-Maclay, 1868, for a long time used for stalked Clathrina - type sponges, has been synonymized with Clathrina s.s. because its type species C. blanca conforms to the new definition of Clathrina. However, it is quite possible that a species group of that genus with the combination of stalked habitus and differentiated regular and long-unpaired actine sagittal triactines deserves to be recognized at the genus level. This is not further elaborated here.