Mycale (Paresperella) moluccensis Thiele, 1903

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 : 166-169

Mycale (Paresperella) moluccensis Thiele, 1903

Figs 108 a–c, 109a –c

Mycale moluccensis Thiele, 1903: 950 , pl. II fig. 17.

Paresperella bidentata Dendy, 1905: 163 , pl. XL fig. 1; Burton 1937: 26, pl. II fig. 7.

Mycale (Paresperella) bidentata ; Van Soest & Hajdu 2002: 684.

Material examined. Holotype ZMB 3151 , Indonesia, Ternate, coll. W. K̹kenthal, 3 December 1902.

ZMA Por. 08958, Indonesia, South East Sulawesi, SW Salayar, reef N of Pulau Bahuluang, 6.45°S 120.43°E, depth 10–15 m , SCUBA, coll. R. W.M. van Soest, Indonesian-Dutch Snellius II Expedition stat. 169, field nr. 169 / IV/29 , 30 September 1984 (live color yellow) ; ZMA Por. 12447, Seychelles, Amirantes, St. François Atoll , west rim, Île Bijoutier , 7.0833°S 52.7333°E, depth 0–10 m , snorkeling, coll. J.C. den Hartog, Netherlands Indian Ocean Expedition stat. 792, field nr. IOP-E 792(bis)/28, 4 January 1993 (beige) .

Description. The holotype ( Fig. 108a) is a spiky mass of 2 x 1.5 x 1.5 cm, dark brown colored in preservation. It appears to have grown upon an unidentified ramose invertebrate, possibly a hydroid or bryozoan. The Seychelles specimen ( Fig. 108a 1) is a spiny, globular mass of beige color in life, lighter colored in preservation. Size 3.5 x 3.5 x 2.5 cm. Surface is flaky, irregular, without larger openings. The sponge grows between the branches of a ramose bryozoan and the composite specimen is compressible. The Indonesian specimen is tiny, encrusting on a piece of coral debris, sharing it with several other species, apparently yellowish colored in life. Very little material was retrieved from the sample.

Skeleton ( Figs 108 b–c). The main skeleton of the Seychelles specimen is carried by the branches of the ramose bryozoan and also some included masses of sand grains. The choanosomal skeleton ( Fig. 108b) consists of anastomosed spongin fibres cored by single or bundles of megascleres, in places the fibres are also filled with sand grains. The surface skeleton ( Fig. 108c) is free from foreign materials and also lacks spongin. It is an irregular layer of intercrossing single megascleres (reminding of subgenus Mycale ) mixed with numerous rosettes of anisochelae I. The Indonesian specimen, contained in a thick section slide along with other sponge material, consists of thin spicule tracts connecting sand grains, with loose spicules and rosettes of anisochelae superimposed. Rosettes are 50–80 µm in diameter.

Spicules ( Figs 109 a–c). Mycalostyles, one category of anisochelae, one of sigmas.

Mycalostyles ( Figs 109a,a 1–a 6), ‘cladotylostyle’-like (see Thiele, 1903, p. 950), with one end with elongated head and constricted neck, the opposite end polyaxone ( Fig. 109a 1), with one ( Fig. 109a 3), two ( Fig. 109a 2), three ( Fig. 108a 4) or multiple ( Fig. 109a 5) bluntly or sharply pointed “teeth’, occasionally without ( Fig. 109a 6) ‘teeth’, but two-teethed forms are the most common, 183– 290.6 –378 x 2– 4.3 – 7 µm.

Anisochelae ( Fig. 109b), shaft curved and free part 35–40% of spicule length, with well-developed upper and lower alae, upper median alae comparatively short and curved outward, 22– 29.6 – 34 µm.

Sigmas ( Figs 109c,c 1), comparatively narrow-shaped, asymmetrical, thickness 1–1.5 µm, with flattened spines on both endings, 51– 65.8 – 87 µm.

Distribution and ecology. Indonesia, Seychelles, Sri Lanka, India, on reefs, down to 15 m.

Remarks. The conspecificity of Thiele’s Mycale moluccensis and Dendy’s Paresperella bidentata is obvious from the comparison of the spicule types, shapes and measurements. Thiele mentions spongin-encased megasclere tracts like they occur in our Seychelles specimen, and he mentions 2–3 spines on the ending of the megascleres. The spiculation of the type specimen, Dendy’s and Burton’s bidentata material and ours is basically similar. This synonymy was already proposed by Halmann (1914) (p. 411) in his discussion of the properties of Esperella penicillium Von Lendenfeld, 1888 . This latter species from the SE coast of Australia is close to the present species, but differs in possessing two size categories of anisochelae (I: 34–39 m, II: 18–22.5 µm). Its megascleres measure 325–410 x 8 µm, clearly in excess of measurements of the present species. Junior synonyms, according to Hallmann are West Australian Mycale moluccensis var. dichela Hentschel, 1911 and South East Australian Paresperella repens Whitelegge, 1907 . We believe Hallmann’s conclusion is correct. We attempted to confirm the identity of P. repens , but a fragment (obtained by Eduardo Hajdu and donated to the ZMA collection) studied by us appeared to consist only of Myxilla (Myxilla) fusca ( Whitelegge, 1906) , the sponge upon which M.(P.) repens was observed to grow (cf. Whitelegge 1907: 487). No Mycale spicules were found in the fragment. It was apparently small and quite localized, and was missed when subsampled.

The present species appears to be a typical consolidating sponge, making use of rubble and dead coral material to reach an above-substratum mass without building too much skeletal support itself. This would explain the rather large divergence in skeletal properties described in the various specimens known so far.

The morphological diversity of endings of the mycalostyles was already observed with hesitation by Dendy in the type specimen of Paresperella bidentata . SEM observations show that the diversity is even greater than indicated by Dendy.

Possibly, there is regional difference in some of the spicule sizes found in the present species. Our Indonesia specimen has megascleres 183–273 x 2–4 µm, the Seychelles specimen 276–378 x 3.5–7 µm, sigmas were respectively 60–84 µm and 56–64 µm. Future comparisons are necessary to confirm this trend.