Xestospongia purpurea, Rützler, Klaus, Piantoni, Carla, Van, Rob W. M. & Díaz, Cristina, 2014

Rützler, Klaus, Piantoni, Carla, Van, Rob W. M. & Díaz, Cristina, 2014, Diversity of sponges (Porifera) from cryptic habitats on the Belize barrier reef near Carrie Bow Cay, Zootaxa 3805 (1), pp. 1-129 : 92-93

Xestospongia purpurea new species

( Figures 4 f, 41)

Material. Holotype: USNM 1229140, Carrie Bow forereef cave, 18 m. K. Ruetzler col. 19 May 1979.

Paratype: USNM 1229141, Carrie Bow South reef, lower surface of rock slab, 1 m. K. Ruetzler col. 13 Mar 0 9.

Diagnosis. Encrusting to cushion-shaped, knobbed, purple Xestospongia , with dull-pointed oxeas and styloids of 385 x 19 Μm mean dimensions, accompanied by less common, shorter and thinner oxeas, 308 x 7 Μm, possibly developmental stages.

External morphology. A knob or knobby cushion, to 20 mm thick, covering up to 15 cm 2 area (holotype), with some scattered oscula (2–5 mm) on the top of the bumps. Firm and brittle consistency, bristly surface. Live color deep purple outside, whitish interior; preserved, light tan in alcohol.

Skeleton structure. A multispicular, choanosomal network of fiber tracts (60–90 Μm thick), which end in the ectosome and cause the bristly surface, alternating with an isodictyal, multispicular mesh. Loose, disorganized spicules throughout.

Spicules. Mostly curved oxeas, points ranging from sharp to dull; styloid modifications are common. In the holotype they measure 340–420 x 15–20 (383 x 17) Μm, in the paratype they are thicker, 370–400 x 18–24 (387 x 21) Μm. A smaller, thinner kind could be developmental; it has the same range and means in both specimens: 240–350 x 4–8 (316 x 6) Μm.

Ecology. Cryptic habitats on the forereef, 1– 18 m.

Distribution. Only known from the Belize barrier reef.

Etymology. The species is named for its purple color, purpurea (Latin) .

Comments. Of the 10 recognized Caribbean species of Xestospongia (van Soest et al., 2013b) and based on the important characteristics of growth form and color (van Soest & de Weerdt, 2001), X. purpurea compares best with X. bocatorensis Diaz, Thacker, Ruetzler & Piantoni. This species from Caribbean Panama is also encrusting and purple, but it occurs as much thinner crusts, with very small oscula (1–2 mm), and it is purple throughout and associated with endosymbiotic, filamentous cyanobacteria. Accordingly, it grows on shallow, light-exposed reef and mangrove substrata. It also differs from the present species by having smaller and more delicate oxeas, which are supplemented by sigmas.

Figures

FIGURE 4. In-situ photographs of new sponge species reported in this contribution (measurements in parentheses are picture widths): a, Wigginsia curlewensis (8 cm); b, Phorbas aurantiacus (10 cm); c, Myrmekioderma laminatum (12 cm); d, Niphates arenata (10 cm); e, Siphonodictyon occultum (10 cm); f, Xestospongia purpurea (8 cm); g, Aplysina sciophila (20 cm).