Mycale (Mycale) crassissima

Mycale (Mycale) crassissima (Dendy, 1905)

Figs 70 a–d, 71a–h, 72, 73, Table 4

Esperella crassissima Dendy, 1905: 160, pl. XI fig. 6.

Mycale crassissima; Hentschel 1912: 339 (Indonesia, yellow green); Dendy, 1922: 55, pl. 5 fig. 1; Lévi 1961b: 124 (Vietnam, ochre-rose); Vacelet & Vasseur 1971: 85, fig. 34 (Madagascar, bright orange); Pulitzer-Finali 1993: 289 (Tanzania, light greenish blue or orange); Chervyakova 2007: 241 (Southern Vietnam, listed only).

Mycale (Mycale) crassissima; Pattanayak 2006, figs 42a–f, pl. VII fig. E (Andaman Islands); Azzini et al. 2007: Table 1 (Vietnam, listed only).

Mycale (Aegogropila) crassissima; Lim et al. 2008: 101 (Singapore, light green); Calcinai et al. 2013: 35 (Vietnam, yellow); Minh-Quang Thai 2013: 114 (listed only); Samaai et al. 2019: 43, figs 17A–I.

Material examined. ZMA Por. 01566, Indonesia, Papua, W coast, between Loslos and Broken Island, 1.2092°S 130.5979°E, depth 18 m, dredge, Siboga Expedition, stat. 162, 18 August 1899; ZMA Por. 01567, Indonesia, Kalimantan, Borneo Bank, 2.4166°S 117.7166°E, depth 40–50 m, trawl, coll. Siboga Expedition stat. 080, field nr. SE713, 13 June 1899; ZMA Por. 01568, Indonesia, Sulawesi, Tana Djampea, Kambaragi Bay, 7.1058°S 120.6274°E, depth 0–32 m, trawl, Siboga Expedition, stat. 064, 4 May 1899; ZMA Por. 1569, Indonesia, Sumatera, N tip, Pulau Weh, E coast, 5.828°N 95.378°E, growing on undersea cable, coll. Lt. Van Nouhuys on board of K.S.’ Telegraaf’, 17 August 1906; ZMA Por. 01570, Indonesia, Sumatera, N tip, Pulau Weh, E coast, 5.828°N 95.378°E, growing on undersea cable, coll. Lt. Van Nouhuys on board of K.S.’ Telegraaf’, 17 August 1906; ZMA Por. 01571, Indonesia, Sumatera, N tip, Pulau Weh, E coast, 5.828°N 95.378°E, growing on undersea cable, depth 73 m, coll. Lt. Van Nouhuys on board of K.S.’ Telegraaf’, 17 Augutst 1906; ZMA Por. 01572, Indonesia, Siboga Expedition, station unknown; ZMA Por. 01573, Indonesia, Maluku, Banda anchorage, bottom black sand, coral, 4.5398°S 129.9084°E, depth 9–45 m, trawl and dredge, coll. Siboga Expedition stat. 240, 22 November 1899; ZMA Por. 01574, Indonesia, Kalimantan, Pulu Kaniungan Ketjil, 1.1332°N 118.8897°E, depth 11 m, Siboga Expedition, stat. 089, 21 June 1899; ZMA Por. 01575, Indonesia, Maluku, Banda anchorage, bottom black sand, coral, 4.5398°S 129.9084°E, depth 9–45 m, trawl and dredge, coll. Siboga Expedition stat. 240, 22 November 1899; ZMA Por. 01576, Indonesia, Lesser Sunda Islands, Bay of Bima, near South Fort, 8.05 S 118.695°E, depth 55 m, coll. Siboga Expedition stat. 047, 8 April 1899; ZMA Por. 01577, Indonesia, Papua, Aru Islands, Pearl Banks, anchorage off Pulau Jedan, 5.4134°S 134.6677°E, depth 13 m, dredge, coll. Siboga Expedition stat. 273, field nr. SE139, 23 December 1899; ZMA Por. 01578, Indonesia, Lesser Sunda Islands, Rotti Island, Cyrus Bay, 10.8733°S 123.0183°E, depth 36 m, dredge, coll. Siboga Expedition stat. 299, 27 January 1900; ZMA Por. 01578, Indonesia, Kalimantan, East side, Moearas Reef, Karang Lintang and Pulau Palabangan, 1.7714N 118.9615°E, depth 0–54 m, trawl/dredge, coll. Siboga Expedition stat. 091, 22 June 1899; ZMA Por. 01580, Indonesia, Sulawesi, Salayar anchorage and surroundings, 6.0963°S 120.4481°E, depth 0–36 m, trawl, coll. Siboga Expedition stat. 213, field nr. SE1602, 26 September 1899; ZMA Por. 02907, Indonesia, Maluku, Kai Islands, Duroa Strait, 5.6501°S 132.7103°E, depth 22 m, dredge, Siboga Expedition, stat. 258, 12 December 1899; ZMA Por. 06530, Indonesia, Nusa Tenggara, N of Sumbawa, Bay of Sanggar, 8.3416667°S 118.2616667, depth 0–1 m, snorkeling, coll. J. Brouns, field nr. 120/06A, Indonesian-Dutch Snellius II Expedition, stat. 120, 23 September 1984; ZMA Por. 07997 Indonesia, Nusa Tenggara, E of Komodo, Teluk Slawi, N cape of entrance, 8.6°S 119.52°E, depth 1–4 m, snorkeling, coll. R. W.M. van Soest, field nr. 069 / II/6 A, Indonesian-Dutch Snellius II Expedition, stat. 069, 17 September 1984 (yellow-brown); ZMA Por. 08641 Indonesia, Sulawesi, SW Salayar, NW coast of Pulau Guang, 6.35°S 120.45°E, depth 4–12 m, SCUBA, coll. R. W.M. van Soest, field nr. 152 / III/24, Indonesian-Dutch Snellius II Expedition, stat. 152, 28 September 1984 (dark red, probably caused by red alga); ZMA Por. 08872, Indonesia, Nusa Tenggara, N of Sumbawa, Bay of Sanggar, 8.3383333°S 118.273333, depth 8–11 m, SCUBA, coll. R. W.M. van Soest, field nr. 122 / IV/15, Indonesian-Dutch Snellius II Expedition, stat. 122, 21 September 1984 (yellow); ZMA Por. 10174, Papua New Guinea, coll. M.C. Daz, field nr. 92119; ZMA Por. unregistered slide, Indonesia, Nusa Tenggara, NE coast of Sumba, E of Melolo, 9.9°S 120.708333, depth 6 m, SCUBA, coll R. W.M. van Soest, field nr. 048/ III/4, Indonesian-Dutch Snellius II Expedition, stat. 048, 13 September 1984 (yellow); ZMA Por. 10564, Seychelles, Mahé, N of Bird Island, 3.7°S 55.2167°E, depth 50–52 m, trawl, coll. R. W.M. van Soest, Netherlands Indian Ocean Expedition, stat. 729, field nr. IOP-E 792/05, 22 December 1992 (bright orange); ZMA Por. 11713, Seychelles, Mahé, Bird Island, off E coast, 3.7167°S 55.2167°E, depth 3 m, snorkeling, coll. R. W.M. van Soest, Netherlands Indian Ocean Expedition, stat. 717, field nr. IOP-E 717/04B, 20 December 1992 (pink); ZMA Por. 12037, Seychelles, Amirantes, N of Île Desnoeufs, 6.1333°S 55.0333°E, depth 54 m, trawl, coll. R. W.M. van Soest, Netherlands Indian Ocean Expedition, stat. 782, field nr. IOP-E 782/17, 2 January 1993 (orange); ZMA Por. 12563, Seychelles, Amirantes, Poivre Atoll, N rim, reef flat, 5.7333°S 53.3167°E, depth 7–8 m, SCUBA, coll. R. W.M. van Soest, Netherlands Indian Ocean Expedition stat. 768, field nr. IOP-E 768/06, 30 December 1992 (light grey blue); ZMA Por. 12705, Seychelles, Mahé, W of Aride Island, 4.2167°S 55.5667°E, depth 47 m, rectangular dredge, coll. R. W.M. van Soest, Netherlands Indian Ocean Expedition stat. 702, field nr. IOP-E 702/21, 17 December 1992 (light brown); RMNH Por. 1835, Indonesia, Bali, NE side Pulau Serangan, Loloan Serangan, 8.7275°S 115.2536°E, depth 0–17 m, SCUBA, coll. N.J. de Voogd, field nr. BAL.13/050401/065, Bali-Lombok Strait Expedition 2001, 5 April 2001 (white fluorescent green blue); RMNH Por. 2057, Indonesia, Java, Kepulauan Seribu (Thousand Islands), off Jakarta, 5.698889°S 106.538722°E, depth 12 m, SCUBA, coll. N.J. de Voogd, field nr. SER.25/160905/095, Kepulauan Seribu Expedition 2005, stat. SER.25, 18 September 2005; RMNH Por. 2538, Singapore, Pulau Tekukor (Monkey Island), SE side, 1.23005°N 103.8401667°E, SCUBA, coll. N.J. de Voogd, field nr. SIN.12/300306/100, 30 March 2006 (green); RMNH Por. 2587 Singapore, Terumbu Pempang Tengah, W side, 1.232183333°N 103.73185°E, SCUBA, coll. N.J. de Voogd, field nr. SIN.20/030406/149, 3 April 2006 (fluorescent blue); RMNH Por. 5330, Indonesia, Halmahera, Mataira Mataira W, 0.7299°N 121.3624°E, depth 15 m, SCUBA, coll. N.J. de Voogd, Ternate-Halmahera Expedition 2009 stat. TER:09, field nr. TER:09/291009/081, 29 October 2009; RMNH Por. 5846, Indonesia, Sulawesi, SW Sulawesi, Spermonde Archipelago, Kapoposang, 4.6913°S 118.9456°E, depth 9 m, SCUBA, coll. N.J. de Voogd, field nr. UPG012/210810/046, 21 August 2010 (yellow); RMNH Por. 6541, Indonesia, N Sulawesi, Lembeh Strait, Desa Pandean, 1.42113°N 125.1813°E, depth 12 m, SCUBA, coll. N.J. de Voogd, field nr. LEM28/140212/185, 14 February 2012; RMNH Por. 7234, Indonesia, Java, Semak Daun, 5.73290602°S 108.570303°E, depth 15 m, SCUBA, coll. N.J. de Voogd, field nr. JAK04 PS–NV115, 28 July 2011 (brown); RMNH Por. 11766, Taiwan, Penghu Island, Xiying Rainbow Bridge, 23.5709°N 119.5619°E, exposed during low tide, coll. N.J. de Voogd, field nr. ORC–008, 29 July 2018 (orange).

Description (Figs 70a,a 1, 71a). Massively lobate, cushion-shaped or encrusting sponges with optically smooth surface, but microscopically slightly uneven. Some larger specimens (e.g. RMNH Por. 6541) show surface grooves, making them look similar to M.(M.) dendyi. A subsurface reticulated pattern is often observed in situ. Specimens may occasionally encrust algae and branching octocorals. Lobate specimens have apical small oscules about 1–3 mm in diameter, with size up to 10 x 7 x 4 cm. Color in life mostly yellowish to orange (Fig. 70a 1), but red, pink, brown, light brown, white, fluorescent blueish (Fig. 70a) or greenish specimens have been recorded. Some of these shades may have been influenced by symbiont algae or bacteria. In preserved condition colors vary from pale yellow or white to reddish beige. Consistency is firm, but compressible.

Skeleton (Figs 70 b–d). Choanosomal skeleton plumo-reticulate, built of usually strongly developed spicule tracts, 50–180 µm in diameter (6–14 spicules in cross section), interconnected by thinner tracts. Main tracts end at the surface by fanning out (Fig. 70b) to carry a tangential ectosomal skeleton. The main tracts in peripheral parts are echinated by anisochelae I, which do not form rosettes, but in stead form dense elongated concentrations along the tracts. Ectosomal skeleton (Fig. 70c), tangential, rather lightly developed, with few intercrossing tracts and many individual spicules. Authors, including Dendy, have been characterizing the skeleton as Mycale (Aegogropila) -like, but this is likely based on observation of the subsurface reticulation of choanosomal tracts carrying the true ectosomal skeleton. We maintain this is basically Mycale (Mycale) -like. The ectosomal region of many specimens is characterized by crowded trichodragmas (Fig. 70d).

Spicules (Figs 71 b–h, 72). Mycalostyles, three categories of anisochelae, two of sigmas, and trichodragmas.

Mycalostyles (Figs 71b,b 1), robust, with barely developed elongated heads, pointed opposite end, often curved, size variable, possibly due to regional diversity, 288– 434.7 –663 x 4– 10.5 – 21 µm.

Anisochelae I (Figs 71c, 72), robust, with upper and lower frontal alae slightly flaring outwards, both upper and lower lateral alae well-developed, with free part of the shaft approximately one third of the length of the spicule. In many specimens a considerable part of the anisochelae I have a faint spur-like lower outgrowth (cf. Fig. 72, second row) but smoothly rounded lower parts are also common (Figs 72, first row). Size quite variable between specimens, possibly regionally determined, 37– 56.7 – 86 µm, but there is limited variation within a single specimen.

Anisochelae II (Figs 71d, 72, third row), in overall shape usually similar to anisochelae III, with prominent upper frontal and lateral alae, a short free part of the shaft, but with the lower frontal ala plate-like and the lateral alae developed as usual, not reduced stick-like as in anisochela III. There is usually a lower terminal spur developed but this may be very short or absent in some specimens. The size slightly overlaps with anisochelae III, 19– 25.8 – 33 µm (possibly up to 35 µm, see below).

Anisochelae III (Figs 71e, 72, fourth row) with well developed upper alae, dominating the spicule shape when examined with lower magnification, with the free part of the shaft extending to the lower part of the spicule which lacks developed alae and ends in a prominent spur. Size variable, possibly regionally determined, 12– 15.8 – 20 µm. Sigma I (Fig. 71f), thin, not clearly different in shape from sigma II, but there is no overlap in size despite rather large variation between specimens, 27– 38.6 – 60 µm.

Sigma II (Fig. 71g), thin, not clearly different in shape from sigma I, limited variation in size, 12– 17.4 – 24 µm.

Trichodragmas (Fig. 71h), straight, tightly bound, usually small (20–30 µm long) but in several specimens there was quite a range in size, overall sizes 10– 32.1 –75 x 5– 8.4 – 13 µm. In many specimens the short trichodragmas were observed occurring in larger clusters (Fig. 70d).

Distribution and ecology (Fig. 73). Indonesia, Papua New Guinea, Singapore, Seychelles, Sri Lanka, Andaman Islands, Vietnam, Taiwan, Madagascar, Kenya, South Africa (Sodwana Bay). The species occurs on shallow reefs and in deeper waters on available hard substratums, from the tide mark down to 73 m.

Remarks. This is probably one of the more common widespread Mycale species of the tropical Indo-West Pacific. Due to this wide distribution, most characters are quite variable, but all identified specimens share a massive-encrusting shape, lightly developed ectosomal tangential skeleton, well-developed choanosomal spicule tracts, anisochelae I crowded on the tracts in an echinating position, but not forming rosettes, rare anisochelae II usually spurred, smallest anisochelae spurred, with stick-like lower alae, thin sigmas I and II, and tightly packed trichodragmas.

Anisochelae I in most specimens were of two more or less distinct types, the first (Fig. 72, first row) have a smoothly rounded lower end between the lateral and median alae, the second (Fig. 72, second row) have a small point or spur at their lower end. The frequency of the two types differs in various specimens. Since they were both of approximately the same size, we do not consider them distinct from each other.

Most authors, including Dendy (1905) did not distinguish anisochela II as a separate spicule type. With some effort, in all specimens we examined, anisochelae II were found. The presence of a separate ‘middle-sized’ anisochela was earlier also observed by Vacelet & Vasseur (1971) and Pulitzer-Finali (1993). Nevertheless, anisochelae II were usually quite rare. This meant that they could not always be found in dissociated spicule mounts and in an SEM examination. This is likely the reason that other other authors (Hentschel 1912; Lévi 1961b; Calcinai et al. 2013; Samaai et al. 2019) did not distinguish them from the smaller anisochelae III. They are distinguished from anisochela I by smaller size and a shape lacking offstanding median frontal alae. Anisochela II differs consistently from anisochela III in having proper lower frontal and lateral alae, whereas anisochela III has a narrow stick-like frontal ala only, lacking lateral alae entirely. Anisochela III always has a spur. Both anisochelae I and anisochelae II may or may not have a spur, if present often faintly developed, often blunt.

The lower alae condition in anisochela II with broadly developed frontal alae is also found in Caribbean Mycale (M.) laevis (Carter, 1882) presented in SEM photos in Hajdu & Desqueyroux’s (1994) fig. 41 (from holotype BMNH 1887.5.2.189 of Esperella fusca Ridley & Dendy, 1886 considered synonymous with M.(M.) laevis), in Hajdu’s (1995) chapter 5 and fig. 5.41, and in Hajdu & R̹tzler‘s (1998) fig. 15d. In these cases the anisochelae were treated as ‘robust’ versions of anisochelae III, which in majority have the stick-like condition as in M.(M.) crassissima. In contrast, we postulate here that the spurred anisochelae with broadly developed lower fronal alae in M. (M.) laevis in reality are anisochelae II, not previously recognized in this species.

Sigma categories are not obvious because the shape and thickness of the larger and the smaller sigmas are largely similar. For that reason they were not distinguished by some authors (Dendy 1905; Hentschel 1912; Calcinai et al. 2013), but from the size ranges provided by these authors it is likely that they were present. We believe the two sigma size categories are shared with related species (e.g. Mycale (Mycale) grandis, cf. below), so it is important to distinguish them as separate spicule types.

Trichodragmas are predominantly small (20–30 µm long), but some specimens (six of our 25 specimens) have a wider size range, up to 75 µm. We could not find a correlation with other features of the sponges.

Calcinai et al. (2013) report the presence of very small smooth microxeas (2.5 µm, apparently visible only with SEM) in the type specimen BMNH 1907.12.1.56 and in their own specimen from Vietnam. Although very small rod-like grains or debris is often present in our specimens, we failed to consistently find sufficient numbers of such tiny objects.

Colors reported for this species are so varied, that taxonomic diversity could be presumed. However, no correlation was evident between colors (the more yellow-red colored vs the more green or blueish green specimens) and spicule measurements and frequency of occurrence of the various spicule types. Color variation (greenish blue and orange) was also reported by Pulitzer-Finali (1993), so we must accept at this stage of our knowledge that color is not a consistent feature of the species.

Regional differences in spicule size data are also not clear (cf. Table 4), although most Seychelles specimens (except ZMA Por. 12705) have shorter mycalostyles and shorter anisochelae I than those of Indonesian specimens. Skeletal tracts of Seychelles specimens on average appear thinner (50–100 µm with 6–10 spicules in cross section) than Indonesian specimens (60–180 µm with 8–14 spicules in cross section).

The name M. (M.) crassissima Dendy, 1905 is threatened by M. (M.) gelatinosa (Ridley, 1884), which may turn out to be a senior synonym (see also below). Ridley’s description of the skeleton and the spicules appears to overlap with the data provided above. The only clear distinction is the shape of the smallest anisochelae, which would lack the spur. This can be distinguished with certainty by SEM. We were unable to reexamine Ridley’s material, so this remains to be established definitively.

The description of Mycale (Mycale) digitata Bergquist & Tizard, 1967 (as Mycale (Carmia), reported also by Kelly-Borges & Bergquist (1988) as Aegogropila digitata, reminds of the present species, but short trichodragmas are apparently not present in that species (see also below).