Mycale (Zygomycale) angulosa (Duchassaing & Michelotti, 1864)

Figures 101 a–j

Restricted synonymy:

Pandaros angulosa Duchassaing & Michelotti, 1864: 89, pl. IX fig. 4.

Zygomycale parishi; De Laubenfeld 1956: 3 (Not: Rhaphiodesma parishi Bowerbank, 1875) Mycale (Aegogropila) angulosa; Van Soest 1984: 16, pl. I figs 5–6, text-fig. 3 (with additional synonyms). Mycale (Zygomycale) angulosa; Van Soest & Hajdu 2002: 688; Muricy et al. 2011: 158.

Material examined. RMNH Por. 9947, Suriname, ‘ Snellius O.C.P.S. ’ Guyana Shelf Expedition, station F46, 6.312°N 56.57°W, depth 25–29 m, bottom sand, 7 May 1966 .

Description. Irregularly ramose (Fig. 101 a), with shorter or longer partially creeping branches, 3 cm or more in length, 0.5–1 cm in diameter, forming masses of up to 4 x 4 x 2 cm. Color in alcohol pale brown. Surface irregular, covered with small lobes occasionally bearing small oscules (<1 mm). Consistency soft to slightly firm.

Skeleton. The surface skeleton (Fig. 101 b) is of the Aegogropila type, with tangentially intercrossing spicule tracts of 30–90 µm in diameter containing 7–12 spicules in cross section. Anisochelae I form rosettes. Choanosomal skeleton irregularly reticulate, with strong spicule tracts of 150–200 µm in diameter.

Spicules. (Figs 101 c–j) Styles, anisochelae, isochelae, sigmas, toxas, trichodragmas.

Styles (Figs 101 c,c1), fusiform, tapering gradually to rounded and pointed opposite ends, no obvious constriction or tyle, size 294– 316 –342 x 8 – 9.3 –11 µm.

Anisochelae, in two distinct size categories, (1) anisochelae I (Fig. 101 d), robust, with long free shaft and short lower alae, 47– 51.1 –59 µm, and (2) anisochelae II (Fig. 101 e), robust, with short free shaft and long upper alae, 18– 21.7 –26 µm.

Isochelae (Fig. 101 f), uniform in shape and size, thin, elongate, 11– 12.2 –14 µm.

Sigmas in two size categories, (1) large, robust (Fig. 101 g), 74– 82.2 –92 µm, and (2) small, thin (rare) (Fig. 101 h), 30– 34.0 –36 µm.

Toxas (Fig. 101 i), with shallow curve and upturned apices, occurring in toxodragmas (Fig. 101 i1), length 25– 63.8 –84 µm, dragmas 5–7 µm in thickness.

Trichodragmas (Fig. 101 j), 24– 33.1 – 42 x 6 – 7.7 –9 µm.

Distribution and ecology. Guyana Shelf, Virgin Islands, Cuba, Jamaica, Curaçao, NE Brazil, in mangroves, bays and on soft bottoms at 1–58 m depth (Guyana Shelf 25–29 m).

Remarks. Shape and spicule sizes match closely with previous descriptions of this common species. A similar sister species, M. (Z.) sierraleonensis Van Soest, Beglinger & De Voogd, 2014, was recently described from Sierra Leone in the East Atlantic. It spicules are almost identical in shape and size, but it has a third size category of sigmas. The present specimen confirms this difference.