Mycale (Mycale) dendyi

Mycale (Mycale) dendyi (Row, 1911)

Figs 74 a–c, 75a–d, 76a–h, 77, Table 5

Esperella dendyi Row, 1911: 332, fig. 15.

Mycale sulcata Hentschel, 1911: 307, fig. 11; Lévi 1963: 11, Pl. IB, text-fig. 4.

? Mycale sulcata var. minor Hentschel, 1911: 310, fig. 12.

Mycale sulcata var. aruensis Hentschel, 1912: 340.

? Mycale (Mycale) sulcata; Burton 1959: 238.

Mycale (Mycale) aruensis; Hajdu 1995: 101.

Mycale (Mycale) dendyi; Hajdu 1995: 101.

Mycale (Mycale) minor; Hajdu, 1995: 104.

Material examined. SMF983, holotype of Mycale sulcata var. aruensi s, Indonesia, Aru Islands, N of Penembulai, depth 8 m, coll. Merton Expedition, stat. 10, 2 April 1908.

BMNH 1936.3.4.587, Mycale sulcata, Murray collection stat. 24, Gulf of Aden, 11.895°N 51.22°E, depth 73– 220 m, 9 October 1933.

ZMA Por. 07964, Indonesia, Nusa Tenggara, Sumba, NE coast, E of Melolo, 9.9167°S 120.75°E, gently sloping reef flat, depth 1–4 m, snorkeling, coll. R. W.M. van Soest, Indonesian-Dutch Snellius II Expedition stat. 052, field nr. 052/ II/03, 13 September 1984 (orange); ZMA Por. 08935, Indonesia, Indonesia, Sulawesi, SE 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. IOP-E 169/ IV/03, 30 September 1984 (yellow); ZMA Por.P. 11920 (slide only), Indonesia, Sulawesi, SE Sulawesi, Take Bone Rate, S of Pulau Tarupa Kecil, 6.535°S 121.15°E, depth 59 m, coll. Indonesian-Dutch Snellius II Expedition stat. 4.232, 16 October 1984; ZMA Por. 11124, Seychelles, Mahé, N of Aride Island, 4.2°S 55.6833°E, depth 40 m, rectangular dredge, coll. R. W.M. van Soest, Netherlands Indian Ocean Expedition stat. 715, field nr. IOP-E 715/12A, 19 December 1992 (orange); ZMA Por. 11447a, Mahé, N of Aride Island, 4.2°S 55.6833°E, depth 40 m, rectangular dredge, coll. R. W.M. van Soest, Netherlands Indian Ocean Expedition stat. 715, field nr. IOP-E 715/12, 19 December 1992 (orange); ZMA Por. 15216, Indonesia, Sulawesi, SW Sulawesi, Spermonde Archipelago, Lae-lae, 5.134°S 119.338°E, coll. B.W. Hoeksema, field nr. 240503, 24 May 1997 (orange); ZMA Por.P. 27690–27693 (thick sections and spicule mounts, slides only), South Africa, Port Elizabeth region, coll. A. van Schie, field nr. UPE 96–133–134, March 1996; RMNH Por. 2180, Indonesia, Bali, Sanur, Bangsai Point, slowly declining reef slope, 8.6706°S 115.2644°E, depth 6 m, SCUBA, coll. N.J. de Voogd, Bali-Lombok Strait Expedition 2001 stat.06, field nr. BAL06/020401/024, 2 April 2001 (orange); RMNH Por. 2582, Singapore. Pulau Hantu Besar, W side, 1.2264°N 103.7463°E, depth 6 m, SCUBA, coll. N.J. de Voogd, field nr. SIN.19/020406/144, 2 April 2006 (orange); RMNH Por. 5226, Indonesia, Sulawesi, North Sulawesi, Manado, Tua South Negen, 1.625°N 124.7056°E, depth 12 m, SCUBA, coll. N.J. de Voogd, field nr. MD08 /150501/051, 15 May 2001; RMNH Por. 5837, Sulawesi, SW Sulawesi, Spermonde Archipelago, Karanrang, 4.8556°S 119.3769°E, depth 12 m, SCUBA, coll. N.J. de Voogd, field nr. UPG011/200810/037, 20 August 2008 (yellow); RMNH Por. 11767, Indonesia, Sulawesi, SW Sulawesi, Spermonde Archipelago, Karanrang, 4.8556°S 119.3769°E, depth 10 m, SCUBA, coll. N.J. de Voogd, field nr. CEL094, 27 April 2018 (orange); RMNH Por. 11768, Indonesia, Sulawesi, SW Sulawesi, Spermonde Archipelago, Karanrang, 4.8556°S 119.3769°E, depth 12 m, SCUBA, coll. N.J. de Voogd, field nr. CEL116, 27 April 2018.

Description (Figs 74 a–c, 76a). Massively encrusting sponge growing among corals, with coarsely grooved irregular surface, often encrusted with sediment (Fig. 74a). The grooves meander over the surface (Fig. 74b) forming characteristic polygonal ‘islands’ of thick surface flakes. Oscules in life large (1–2 cm in diameter) and composite, but they may contract in preservation. Small openings are found in the grooves (Fig. 74c). Size may be considerable, up 12 cm in lateral expansion, up to 10 cm in thickness, but much smaller thinly encrusting specimens are also found. Color in life bright orange, in preservation becoming shades of brown, the surface regions darker brown, the inner and lower parts of specimens lighter brown or beige. Consistency rather soft and compressible, coarsely fibrous.

Skeleton (Figs 75 a–d). Plumoreticulate skeleton of thick spicule tracts (Fig. 75a), deep in the choanosome being 300–400 µm in diameter, gradually subdividing towards the surface into thinner tracts, ending up subectosomally into tracts of 50 µm or less which carry the surface crust. The ectosomal skeleton (Fig. 75b) is a thick (100 µm), dense layer of tangentially arranged individual megascleres. Inbetween the intercrossing megascleres there is a dense mass of trichodragmas and individual raphides. In the subectosomal region numerous rosettes of anisochelae I are found (Fig. 75 c–d), in a large size variation, 60–210 µm in diameter; the smaller rosettes appear to be of small anisochelae I (Fig. 75d).

Spicules (Figs 76 b–h). Mycalostyles, three categories of anisochelae, a single category of sigmas, trichodragmas.

Mycalostyles (Fig. 76b,b 1), robust, straight, elongately fusiform with barely developed heads, in a large size variation, possibly regionally determined, 318– 484.6 –781 x 3– 10.4 – 16 µm.

Anisochelae I (Fig. 76c), mostly arranged in globular rosettes, robust, strongly curved, free part of the shaft about 40% of total spicule length, with short rounded upper alae and squarish lower alae, in a large size range, 48– 62.9 – 75 µm.

Anisochelae II (Fig. 76d), of normal shape, with well-developed upper and lower alae, free part of the shaft about 25%, 16– 22.3 – 30 µm.

Anisochelae III (Fig. 76e), dominated by well-developed upper alae, lower alae complicated, irregularly divided (not clearly visible in light microscopy, only properly observed with SEM), with basal spur, 11– 13.9 – 18 µm. In one of our specimens no anisochelae III were found, in most specimens they were rare or moderately rare.

Sigmas (Fig. 76f), predominantly thin, symmetrical, occasionally with slightly incurved endings, frequency variable in various specimens, size usually 13– 21.8 – 34 µm, but a few—possibly foreign—larger sigmas have been found, 48–60 µm.

Trichodragmas, very common, especially the larger sizes; in many specimens there are distinctly larger trichodragmata (I, Fig. 76g), 61– 84.9 –144 x 5– 10.7 – 16 µm, and smaller (II, Figs 76h), 12– 22.3 –35 x 5–7 µm. In two of our specimens, trichodragmas II were rare or absent.

Distribution and ecology (Fig. 77). Indonesia, Singapore, Seychelles, Red Sea, West Australia, Gulf of Aden, Maldives, South Africa, possibly South Korea, from shallow water reefs down to 59–73 m, possibly deeper down to 220 m.

Remarks. We follow Hajdu (1995) in considering Mycale sulcata Hentschel, 1911 synonymous with Mycale (Mycale) dendyi (Row, 1911). Hajdu examined type material of Row and found that the differences on paper between the two descriptions were non-existent, e.g. Row’s material did contain sigmas and two sizes of trichodragmas. As Hajdu (1995) (p. 101) pointed out, the publication date of Esperella dendyi Row, 1911 was printed to be November 30, 1911, whereas Hentschel’s publication of Mycale sulcata bears no print information other than the year 1911. According to the ICZN (art. 21.3.2), the printed date of the latter is then determined to be December 31, 1911. Accordingly, if both are the same species as assumed here, the name Mycale (Mycale) dendyi (Row, 1911) has priority. Hajdu (1995) listed specimens of this species from Korea, which need further examination.

Mycale sulcata var. minor Hentschel, 1911 was listed as Mycale minor in Hajdu (1995: 104), but he did not study it and he did not comment on it. Hentschel (1911: 311) stated it was a reduced form (hence the varietal name minor), but he also suggested a similarity with his Mycale parasitica var. arenosa considered now a junior synonym of Mycale (Grapelia) australis (cf. above). The specimen was dried and thus could have been macerated and lost part of its spicule complement. In the absence of further information we consider it a member of the present species, but it needs to be further studied.

We examined a microscopic slide of Mycale sulcata var. aruensis Hentschel, 1912 from the Aru Islands, raised to species status by Hajdu (1995) without discussion. We found that it conformed to the typical variety from Western Australia. Differences between the two noted by Hentschel (1912) were clearly the result of a difference in frequency of occurrence of anisochelae II and III and sigmas. These were observed in both ‘varieties’, thus removing their differences.

One of our specimens (RMNH Por. 5226), appeared to have two distinct rosette sizes (140–180 µm vs. 60–70 µm), the smaller of which contained smaller than usual anisochelae I (less than 45 µm). Other features of the specimen did not differ from the characters of M. (M.) dendyi, so we refrained from attaching taxonomic significance to this.

Burton’s (1959) material from the Indian Ocean of this species (as Mycale sulcata) consists of several fragments with thick surface crust and irregular skeleton, similar to the Sulawesi specimen ZMA Por. 15216 (cf. Fig. 63a), but it contained large sigmas up to 86 µm. That sigma size exceeds those of all our specimens, so it is uncertain whether Burton’s material could be conspecific with M. (M.) dendyi. Hajdu (1995) proposed part of the sample to be a separate species, his Mycale (Mycale) sp. 4. Proper redescription of the sample is necessary.

Mycale (Mycale) myriasclera Lévi & Lévi, 1983 shares the shape of the anisochelae I with the present species, but differs clearly in lacking anisochelae III and sigmas (cf. below).

Outside our target region, Mycale (Mycale) novaezealandiae Dendy, 1924 (see also Bergquist & Fromont 1988), possesses a similar spicule complement, including curved anisochelae I. Thanks to Eduardo Hajdu’s thesis work, we were able to examine a spicule suspension made from the type specimen BMNH 1923.10.1.102, which revealed two size categories of mycalostyles (972– 1116 x 23–30 µm and 511–678 x 10–23 µm), and anisochelae I 81–92 µm, clearly larger than those of the present species, confirming that the species differs from M. (M.) dendyi. See for further details also below.

The shape of anisochelae I of this species reminds rather strongly of those found in Mycale (Grapelia) burtoni Hajdu, 1995, a deviating Grapelia because of the absence of unguiferous upper alae. In combination with the peculiar anisochelae III in the present species showing strongly indented lower alae, it would seem possible that M. dendyi is also a Grapelia, and not a member of the subgenus Mycale. That would then also apply to Antarctic Mycale (Mycale) tridens Hentschel, 1914, which is even more Grapelia -like as its upper alae are pointed and could be termed ‘unguiferate’ (cf. Hentschel 1914: pl. V fig. 6; Ríos 2006: fig. 191). Elsewhere, several other Mycale (Mycale) species have such strongly curved anisochelae I, further complicating eventual close affiliations between subgenera Mycale and Grapelia. We will have to await molecular support.

We compared spicule size data from Indo-West Pacific and Western Indian Ocean specimens assigned to this species (cf. Table 5), but no clear differences were found.