Mycale (Carmia) tubiporicola sp.nov.

Figs 49 a–b, 50a–c, 44a–c

Mycale spec. Van Soest & Verseveldt 1987: 28, figs 1–3; Erhardt & Baensch 2000: 52; Van Soest & Hajdu 2002: 680.

Material examined. Holotype ZMA Por. 09261, Indonesia, Nusa Tenggara, Komodo, NE cape, 8.4833°S 119.5683°E, coastal reef with sandy bottom, depth 1–4 m, snorkeling, coll. R. W.M. van Soest, Indonesia-Dutch Snellius II Expedition stat. 096, field nr. 096/ II/19, 20 September 1984.

Paratype ZMA Por. 08009, Indonesia, Nusa Tenggara, E of Komodo, Teluk Slawi, 8.6°S 119.52°E, coastal reef with sandy bottom, depth 1–4 m, snorkeling, coll . R. W.M. van Soest, Indonesia-Dutch Snellius II Expedition stat. 069, field nr. 069 / II/16, 17 September 1984; paratype ZMA Por. 09280, Indonesia, Nusa Tenggara, Komodo, NE cape, 8.4833°S 119.5683°E, coastal reef with sandy bottom, depth 1–4 m, snorkeling, coll . R. W.M. van Soest, Indonesia-Dutch Snellius II Expedition stat. 096, field nr. 096 / II/19, 20 September 1984; paratype ZMA Por. 09281, Indonesia, Nusa Tenggara, Komodo, NE cape, 8.4833°S 119.5683°E, coastal reef with sandy bottom, depth 1–4 m, snorkeling, coll . R. W.M. van Soest, Indonesia-Dutch Snellius II Expedition stat. 096, field nr. 096 / II/19, 20 September 1984; paratype ZMA Por. 09283, Indonesia, Nusa Tenggara, Komodo, NE cape, 8.4833°S 119.5683°E, coastal reef with sandy bottom, depth 1–4 m, snorkeling, coll . R. W.M. van Soest, Indonesia-Dutch Snellius II Expedition stat. 096, field nr. 096 / II/19, 20 September 1984; paratype ZMA Por. 09315, Indonesia, Nusa Tenggara, E of Komodo, Teluk Slawi, 8.6°S 119.52°E, coastal reef with sandy bottom, depth 1–4 m, snorkeling, coll . R. W.M. van Soest, Indonesia-Dutch Snellius II Expedition stat. 069, field nr. 069 / II/16, 17 September 1984 .

Not type material: ZMA Por. 09282, Indonesia, Nusa Tenggara, Komodo, NE cape, 8.4833°S 119.5683°E, coastal reef with sandy bottom, depth 1–4 m, snorkeling, coll. R. W.M. van Soest, Indonesia-Dutch Snellius II Expedition stat. 096, field nr. 096/ II/19, 20 September 1984 (dried) ; ZMA Por. 16695, Indonesia, Sulawesi, SW Sulawesi, Spermonde Archipelago, Kapoposang, 5.1338°S 119.3381°E, SCUBA, coll. N.J. de Voogd, field nr. NV/ KP/020900/120, 2 September 2000 ; ZMA Por. 22224, Indonesia, Nusa Tenggara, Komodo, NE cape, 8.4833°S 119.5683°E, coastal reef with sandy bottom, depth 1–4 m, snorkeling, coll. R. W.M. van Soest, Indonesia-Dutch Snellius II Expedition stat. 096, field nr. 096/ II/19, 20 September 1984 (dried) ; RMNH Por. 5310, Indonesia, Halmahera, Tidore Desa Tahua, 4.75275°N 127.39203°E, depth 3 m, SCUBA, coll. B.Hoeksema, Ternate-Halmahera Expedition stat. TER.07, field nr. TER07/281009/061, 28 October 2009 .

Description (Figs 49 a–b, 50a–c). The pale-white tissues and skeleton of the present Mycale specimens are intimately intertwined with specimens of the octocoral Tubipora musica L., forming tube-like structures not found in free T. musica individuals. Apparently, the sponge has caused the octocoral to form these tubes, an obvious advantageous growth form for an otherwise encrusting sponge without elaborate supporting skeleton. Van Soest & Verseveldt (1987) gave an extensive description of the present symbiotic association with Tubipora musica, including drawings made from histological sections, reproduced here in Fig. 50c. We refer to this paper for more details, confining ourselves to measurements and illustrations of the spicule complement.

Skeleton (Fig. 50b). Not clearly developed. Megascleres in vague bundles or scattered singly in low density. Microscleres abundant, rosettes of anisochelae not clearly developed, but clustered anisochelae are not uncommon.

Spicules (Figs 51 a–c). Mycalostyles, anisochelae, sigmas.

Mycalostyles (Figs 51a,a 1), comparatively robust, straight, with prominent heads and pointed opposite endings, 202– 237.8 –262 x 4– 5.1 – 6 µm.

Anisochelae I (Figs 51b), usually solitary but one rosette-like cluster was found in ZMA Por. 09280; shape of individual spicule narrow, median alae parallel and close to the shaft, lower median alae with upwards extended finger-shaped lobe, free part of the shaft 20% of spicule length, 16– 24.2 – 27 µm.

Sigmas (Fig. 51c), robust, thickness 2.5–3 µm, often symmetrical, comparatively narrow, 84– 95.2 – 119 µm. A few thin small sigmas (20–30 µm) were found in one of the specimens (paratype ZMA Por. 08009), but it is uncertain whether they were proper.

Distribution and ecology. Indonesia, particularly common around the island of Komodo, also found off SW Sulawesi and Halmahera; sandy bottom in bays and lagoons, down to 4 m.

Etymology. The name means ‘dwelling on Tubipora ’ referring to the likely symbiosis of the sponge with its ‘host’ Tubipora musica .

Remarks. The features of this new species, apart from its co-habitation with Tubipora musica are the large symmetrical sigmas in combination with a single category of narrow-shaped anisochelae and straight comparatively robust mycalostyles. Earlier speculation (Van Soest & Verseveldt 1987) that this species could be free-living elsewhere in Indonesia has so far been demonstrated as unproven. No Mycale (Carmia) species with similar skeletal characters was found among the many specimens studied from the region. This confirms its hypothesized symbiotic nature.