Mycale (Naviculina) mascarenensis, Van & Aryasari & De, 2021

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 : 154-156

publication ID 10.11646/zootaxa.4912.1.1

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Mycale (Naviculina) mascarenensis

sp. nov.

Mycale (Naviculina) mascarenensis View in CoL sp.nov.

Figs 99 View FIGURE 99 a–c, 100a–d, 101a–e

Material examined. Holotype RMNH Por. 11689, Rodrigues, Mourouk Ebony, Castel Rock , 19.7648°S S 63.4626E, 18 m depth, SCUBA, coll. N.J. de Voogd, field nr. ROG 103, 19 October 2016 (orange-brown). GoogleMaps

Paratype RMNH Por. 11723, Rodrigues , Passe Grenade, 19.675S 63.4842E, 8 m depth GoogleMaps , SCUBA, coll. N.J. de Voogd, field nr. ROG 140, 21 October 2016 (orange-brown) .

Description ( Figs 99 View FIGURE 99 a–c, 100a–b). Massively encrusting on dead corals and rocks ( Figs 99 View FIGURE 99 a–c), also consolidating coral rubble ( Figs 100 View FIGURE 100 a–b). Color orange-brown, faintly punctate ( Fig. 99c View FIGURE 99 ), surface not clearly reticulate. On deck, color turns more reddish orange. In preserved condition the specimens are collapsed and fragmented, and beige colored. The detachable skin is transparent and becomes largely loose from the pulpy choanosomal tisse. Size up to 5 x 3 x 2 cm (preserved holotype). Consistency soft.

Skeleton ( Figs 100 View FIGURE 100 c-d). Choanosomal skeleton cavernous, with a basal spongin-rich spicule mass enveloping coral debris, from which issue comparatively thin spicule tracts, 50–150 µm in diameter, further thinning out near the surface to carry the ectosomal skeleton. The detachable tangential skeleton is parchment-like and consists of the usual aegogropila-type reticulation of intercrossing spicule tracts ( Fig. 100c View FIGURE 100 ). These are comparatively thin, 15–35 µm, consisting of up to 4 spicules in cross section, meshes up to 300 µm in widest dimension. Rosettes of anisochelae, 70–100 µm in diameter ( Figs 100 View FIGURE 100 c–d), as well as single anisochelae II and less frequent flagellated sigmas ( Fig. 99d View FIGURE 99 ) are scattered between the sutface tracts.

Spicules ( Figs 101 View FIGURE 101 a–e). Mycalostyles, three categories of anisochelae, flagellated sigmas (no ‘normal’ sigmas, no toxas).

Mycalostyles ( Figs 101a,a View FIGURE 101 1 View FIGURE 1 ), straight, slim, with elongated, barely developed heads and pointed opposite ends, 318– 355.8 –399 x 3– 5.2 – 7 µm.

Anisochelae I ( Fig. 101b View FIGURE 101 ), ‘normal’ shaped, with well-developed alae, upper median alae extended outward, free part of the shaft about 40% of spicule length, 33– 36.3 – 39 µm.

Anisochelae II ( Fig. 101c View FIGURE 101 ), naviculichelae, squarish in outline, central plate leaving only small open spaces between the upper and lower alae, rims smooth or with slight upper bump, but not provided with spines, both sides slightly different, 24– 27.3 – 30 µm.

Anisochelae III ( Fig. 101d View FIGURE 101 ), naviculichelae, oval in outline, 15– 17.1 – 19 µm.

Flagellated sigmas ( Figs 101e View FIGURE 101 ), strongly curved, asymmetrical endings (reminding strongly of Mycale (Naviculina) diversisigmata Van Soest, 1984 ) (cf. Van Soest 2017: fig. 2), 47– 122.3 –201 x 36– 101.2 – 156 µm. No ‘normal’ sigmas I and II.

Distribution and ecology. Rodrigues, Mascarene Islands (dependency of Mauritius), on reefs, 8–18 m depth.

Etymology. Named after the island group of the Mascarenes to which the type locality Rodrigues belongs.

Remarks. So far, the new species appears to be endemic to the island of Rodrigues. It is obviously closely related to M. (N.) cleistochela , which shares the possession of flagellated sigmas as well as the ‘normal’ anisochelae I and naviculichelae II and III. The two specimens described here differ clearly from M. (N.) cleistochela in lacking toxas and ‘normal’ sigmas. Also the in situ shapes and surface characters are clearly different (cf. Figs 93 View FIGURE 93 and 99 View FIGURE 99 ).


National Museum of Natural History, Naturalis













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