Xestospongia arenosa van Soest & de Weerdt, 2001

Ugalde, Diana, Fernandez, Julio C. C., Gómez, Patricia, Lôbo-Hajdu, Gisele & Simões, Nuno, 2021, An update on the diversity of marine sponges in the southern Gulf of Mexico coral reefs, Zootaxa 5031 (1), pp. 1-112 : 44

Xestospongia arenosa van Soest & de Weerdt, 2001

Tables 6, 7; Figs. 37A–C

Synonymy and references: Xestospongia arenosa van Soest & de Weerdt (2001: 110) , Rützler et al. (2014: 14), Pérez et al., (2017: 10), and Silva & Zea (2017: 120).

Type locality. Curaçao .

Material examined. CNPGG-2237, Triangulos Oeste reef (20.9622°N, - 92.3112°W), 15 m depth, coll. Gabriel Cervantes, 08 September 2017 ; CNPGG-2245, Triangulos Oeste reef (20.9517°N, - 92.3096°W), 23 m depth, coll. Oscar Bocardo, 09 September 2017 .

Description. Slightly encrusting habit. Specimen CNPGG-2245 is fragmented and excavating the coral rubble. The encrusting specimen’s size is 3.5 × 2.5 × 1 cm. Surface microhispid and undulated. Oscules are scattered. Color in vivo white, light-beige preserved in ethanol. The consistency is brittle, easily broken.

Skeleton. Ectosome is detachable, and the tangential skeleton shows unispicular reticulation ( Fig. 37A ), enclosing meshes 150–270 µm in diameter. An isotropic reticulation conforms the choanosomal skeleton from ill-defined tracts, traversed single-spicules ( Fig. 37B ), and rounded meshes 350–500 µm in diameter. The skeleton that goes close to the surface is confused and vague.

Spicules. Megascleres: Oxeas to styles, slightly curved, with a wide range in size ( Fig.37C ); 250– 375 (50.1)– 420/8.5– 14.3 (3.3)–19 µm.

Distribution. Mexico (current records), Curaçao ( van Soest & Weerdt de 2001), Belize ( Rützler et al. 2014), Colombia, and Martinique ( Silva & Zea 2017).

Remarks. Our material of Xestospongia arenosa constitutes the first record of the species for the GoM. The present material’s overall features are similar to those from the original description, distinguished from other Xestospongia species by its loose reticulation, mainly of single spicules. Our specimens were inside the coral rubble with only a portion of their body exposed on the surface, contrasting to the massive morphology of specimens from van Soest & de Weerdt (2001) and Silva & Zea (2017). Characteristics matching our specimens and those described in van Soest & de Weerdt (2001) and Silva & Zea (2017) are the ectosomal skeleton with a unispicular isotropic reticulation, the triangular meshes, and the loose choanosomal skeleton with a reticulation of ascending primary spicule tracts. The length of spicules in our specimens were slightly smaller (250– 375 (50.1)–420/8.5– 14.3 (3.3)–19 µm) than in specimens recorded by van Soest & de Weerdt (2001): 342–431.2–508 × 7–10.1–14 µm, and Silva & Zea (2017): 300–436–508 × 16–19–29.2 µm. This difference in the spicules proportions could be due to the lower amounts of silica available in the GoM compared to other regions in the Atlantic ocean ( Lanza-Espino de la & Gómez-Rojas 2004).

Figures

FIGURE 37. Xestospongia arenosa van Soest & de Weerdt, 2001 (CNPGG-2237), skeleton and spicules: A. tangential section of the skeleton of the ectosomal region; B. transversal section of the skeleton; C. oxeas. Scale bars: A–B = 250 µm; C = 200 µm.