Erylus trisphaerus

Ugalde, Diana, Gómez, Patricia & Simões, Nuno, 2015, Marine sponges (Porifera: Demospongiae) from the Gulf of México, new records and redescription of Erylus trisphaerus (de Laubenfels, 1953), Zootaxa 3911 (2), pp. 151-183 : 154-156

Erylus trisphaerus (de Laubenfels 1953)

( Figs. 3 A–F, 4A–E)

Selected synonymy: Unimia trisphaerus de Laubenfels, 1953:546; Alcolado 1976:7 (only cited).

Material examined. CNPGG –1183, CNPGG –1304, and CNPGG –1312 Alacranes reef (22°21'55.99”N, 89°40'20.79”W), depth 30 m 6/VIII/2013.

Description. Massive sponge with well-defined lobes, each provided with an apical oscule 3–5 mm in diameter ( Fig. 3 A). The sponge measures 3.5–8 cm in height and 3–5 cm in width, the lobes 2–3.5 cm in diameter. The surface is smooth, but when taken out of water it wrinkles as the sponge shrinks, and shows irregularly distributed ostia, 80–110 µm in diameter and slightly sunken in. Oscules on top of the lobes and some lateral ones are less than 1 mm in diameter, the latter type was surrounded by lighter color. Consistency is firmly compressible but easily frail. The color in vivo is dark brown with scattered beige tinges, in alcohol it is blackish brown on top and beige at the base.

Skeleton. The cortex consist of one layer, ca. 500 µm thick, of microxeas tangentially disposed, and below which another layer of aspidasters assembles. The choanosomal skeleton has a radial arrangement towards the surface formed by spicular tracts of oxeas and orthotriaenes going upward ( Fig. 3 B), and a confused arrangement in all directions towards the interior, among which microxeas, aspidasters and oxyasters are dispersed.

Spicules ( Figs. 3 C–F, 4A–E). Megascleres are fusiform oxeas slightly curved 620–750 × 9.1–12 µm, orthotriaenes with rays in an equidistant angle, probably in two size classes, rhabds 250–480 × 5.3–13 µm, clads 160–210 µm. Microscleres: trilobulate aspidaster 70–140 × 30–36 µm, centrotylote microxeas 52–72 × 2.6–3.9 µm, chiasters I with 5–6 rays with finely spined tips 24.6–57.2 µm in diameter, chiasters II 13.3–15.6 µm, and oxyasters with 9–16 micro-spined rays, 12.7–15.6 µm.

Distribution and ecology. Northeastern Gulf of Mexico: 12.5 m depth (de Laubenfels 1953), and north La Habana, Cuba ( Alcolado 1976). This is the first record for the species in Mexican waters of the southern GMx. As far as is known, the species inhabits reef environments.

Remarks. Erylus trisphaerus differs from its congeners in the West Indies by having trilobate aspidasters. The specimen herein reported has a massive shape with lobules, contrary to the spherical shape that de Laubenfels quote in the original description “…probably spherical, with a single central hollow indicating numerous smaller cavities…” this denotes the ease with which the body collapses when it is outside the water. Although Alcolado (1976) lists this species for North Cuba, he does not provide a description or other visual material that could be used to compare between specimens.

The species appears recorded in other northern localities from the Gulf of Mexico, however such references ( Little 1963; Rützler et al. 2009) just cite the registration given by de Laubenfels in 1953. The lack of records from E. trisphaerus around the West Indies makes it a possible endemic species to the Gulf of Mexico. This new record for the Mexican coasts is particularly noteworthy because it has not been reported since the original description by de Laubenfels (1953).

Figures

FIGURE 3. Erylus trisphaerus (de Laubenfels, 1953): A. Habit of specimen in alcohol. B. Perpendicular section of skeletal arrangement showing the cortex and radial spicular tracts. C. Orthotrienes and aspidasters in LM. D. Oxeas, aspidasters, and microxeas seen in SEM. E. Orthotriaene. F. Centrotylote microxea.