Mycale (Rhaphidotheca) coronata ( Dendy, 1926 )

Van, Rob W. M., Aryasari, Ratih & De, Nicole J., 2021, Mycale species of the tropical Indo-West Pacific (Porifera, Demospongiae, Poecilosclerida), Zootaxa 4912 (1), pp. 1-212 : 176-177

Mycale (Rhaphidotheca) coronata ( Dendy, 1926)

Fig. 114a

Sceptrospongia coronata Dendy, 1926: 6 , pl. I figs 1–8; Burton 1928: 121, text-figs 4–5.

Mycale (Rhaphidotheca) coronata ; Van Soest & Hajdu 2002: 684, fig. 14.

Summary description (after Dendy 1926; Burton 1928; Van Soest & Hajdu 2002). The sponge is subspherical, attached to deep-water corals. The larger of the two specimens (the holotype cf. Burton (1928), which is however not further identified by Dendy, so in fact is a lectotype) measuring 1.5 cm in diameter. Surface hispid. Oscules slit-like. Color (in alcohol) yellowish grey. For the skeleton and the spicules we reproduced the illustrations of Burton (1928), text-figure 4 and 5, cf. our Fig. 114 . The ectosomal skeleton is a confused tangential layer of normal mycalostyles upon which are single erect exotyles arranged perpendicularly, heads embedded in the ectosomal layer, giving the sponge the hispid surface. The choanosomal skeleton has thick megasclere tracts radiating from a confused interior spicule mass towards the surface. In between the radial tracts are numeorous microscleres and loose megascleres. Spicules normal mycalostyles, variable in shape, averaging 360 x 13 µm, exotyles (dubbed ‘stephanotyles’ by Dendy), same size as the mycalostyles, anisochelae I 75 µm, anisochelae II 27 µm, anisochelae III 15 µm, sigmas I 45 µm, sigmas II 18 µm, trichodragmas 15–45 x 9 µm.

Distribution. Arabian Sea, 16.6667°N 71.8883°E, also Andaman Islands, approx. 12.88°N 92.62°E, depth of lectotype 1134 m, paralectotype 81– 486 m.

Comments. The exotyles are peculiar in having a spined polyaxone ending, neatly inbetween the globular exotyles of Mycale (Rhaphidotheca) marshallhalli ( Kent, 1870) and the flattened cup-like exotyles of Mycale (Rhaphidotheca) loricata ( Topsent, 1896) . The polyaxone ending of the exotyles is similar to the endings found in non-exotyle megascleres of Mycale (Paresperella) moluccensis and M. (P.) sceptroides sp.nov. (cf. above, Figs 109a , 111a ).

The type material consisting of two specimens from quite distant localities ( Arabian Sea and Andaman Islands) is very casually treated by both Dendy and Burton. Dendy did not indicate in his publication which of the two specimens was the holotype, and Burton subsequently described the ‘holotype’ (which is thus in fact a lectotype), which presumably is the specimen from the Arabian Sea as this is the first specimen mentioned (Indian Museum P. 308) .

Global diversity and distribution of the subgenus Mycale (Rhaphidotheca)

We queried the World Porifera Database (Van Soest et al. 2020) to arrive at the current tentative estimate of known accepted species, which numbers 5. Their distribution over the world oceans summarized as the numbers of species found in Marine Ecoregions of the World (cf. Spalding et al. 2007) is presented in Fig. 115 . The subgenus is common in northern colder waters, with a few penetrating into the tropics.

Figures

FIGURE 109. Mycale (Paresperella) moluccensis Thiele, 1903, ZMA Por. 12447 from Amirantes, Seychelles, SEM images of the spicules, a, cladostyle like mycalostyle, a1, details of the mycalostyle, a2–a6, variation in polyaxone ending of mycalostyles, a2, two-teethed, a3, one-toothed, a4, three-teethed, a5, multiple-teethed, a6, suppressed teeths, b, anisochela, c, serrated sigma, c1, detail of serrated sigma.

FIGURE 111. Mycale (Paresperella) sceptroides sp.nov., holotype ZMA Por. 01739, from Indonesia, SEM images of the spicules, a, mycalostyle, a1, details of mycalostyle, a2–a3, details of the polyaxone ending, b, anisochela I, c, anisochela II, d, serrated sigma, d1, detail of serrated sigma, e, toxa.

FIGURE 114. Mycale (Raphidotheca) coronata (Dendy, 1926), drawings of spicules and skeletal structure of the holotype IM P.308, copied from Burton’s (1928) text-figures 4 (left) and 5 (right). Text-fig. 4a ‘normal’ mycalostyle from the main skeleton, 4b–f, exotyle and details of the opposite endings with flattened bulbous upper ending showing bi-or polydentate structures and lower variously swollen or pointed endings. Text-fig. 5A cross section of peripheral skeleton with palisade of exotyles (a) erect on the tangential surface skeleton (b) which is carried by strong spicule tracts (c), 5B showing the microsclere complement of three size categories of anisochelae (a,b, and c) and two of sigmas (d and e) (trichodragmas are also present but not figured).

FIGURE 115. Global diversity and distribution of the subgenus Mycale (Rhaphidotheca) based on data derived from the World Porifera Database 2020. The map presents the number of species found in each of the Marine Ecoregions of the World (Spalding et al. 2007).