Neopetrosia eurystomata, Van Soest & Meesters & Becking, 2014

Van Soest, Rob W. M., Meesters, Erik H. W. G. & Becking, Leontine E., 2014, Deep-water sponges (Porifera) from Bonaire and Klein Curaçao, Southern Caribbean, Zootaxa 3878 (5), pp. 401-443 : 430-432

Neopetrosia eurystomata new species

Figures 19a–f , 20a–c

Xestospongia cf. proxima sensu Van Soest & Stentoft, 1988: 132 , pl. 12 fig. 4, text-fig. 64 (not: Thalysias proxima Duchassaing & Michelotti, 1864 ).

Material examined. Holotype: RMNH Por. 9239, Caribbean Netherlands, Bonaire, Kralendijk Pier (Dive 2), 12.1469°N 68.2821°W, on sandy rubble at 108 m, coll. L.E. Becking & E. Meesters, field nr. BON1/ BDR008 , 30 May 2013.

Paratypes: RMNH Por. 9242, Caribbean Netherlands, Bonaire, Kralendijk Pier (Dive 2), 12.1469°N 68.2821°W, on sandy rubble at 111 m, coll. L.E. Becking & E. Meesters, field nr. BON1 / BDR013 , 30 May 2013 . RMNH Por. 9250, Caribbean Netherlands, Bonaire, Curoil Dock, (Dive 3), 12.137°N 68.286°W, in the sand at 88 m, coll. L.E. Becking & E. Meesters, field nr. BON3 / BDR037 , 31 May 2013 .

Description. Vase shaped ( Figs. 19a–d ), larger specimens with wide, flaring walls, some specimens may look similar to barrel sponges [ Xestospongia muta ( Schmidt, 1870) ]. Size of largest specimen 30 cm high, 18 cm wide, wall thickness 1.5–2 cm. The preserved holotype consist of two fragments, one 4.5 x 2.5 x 1 cm, the other 3 x 2 x 1.5 cm. The paratypes consists of two (RMNH 9242) and one (RMNH 9250) fragments, each approximately 4 x 2 x 2 cm. External color of live specimen is pink and white, inner color dark red or brownish ( Fig. 20a ). Consistency firm and crumbly, but slightly compressible. Surface ( Fig. 20a ) with vague stellar sunken groups of pores on both the outer and the inner surface. Outer surface often infested with red zoanthids.

Skeleton. The surface skeleton ( Fig. 19e ) is a vague tangential reticulation of single spicules or two or three aligned spicules. Underneath there are regularly distributed subdermal spaces of 200–400 µm diameter. The choanosomal skeleton ( Fig. 19f ) is isotropic but with a superimposed anisotropic orientation as is typical for many Neopetrosia species. There is little or no visible spongin.

Spicules. Oxeas.

Oxeas ( Fig. 20b–c ), smooth, robust, sharply pointed, lightly curved, in a fairly large size range, but not divisible in size categories, 160– 187 –200 x 5– 9 – 10 µm.

Ecology and distribution. In the mesophotic zone at or around the 100 m mark, off the SW coast of Bonaire; at 120 m off Barbados.

Etymology. Eury- (Gr.) means wide, -stoma (G.) means mouth, referring to the wide, often flaring, opening of the vase-like sponge.

Remarks. The species was reported by Van Soest & Stentoft (1988: 132) as Xestospongia cf. proxima . It is not the encrusting Neopetrosia proxima (see above). At first glance it appears close to the common shallow-water sponge Xestospongia muta in habit. However, the spicules of our new species are definitely significantly shorter and thinner than those of X. muta . Van Soest (1980: 68) compared spicule sizes of shallow-water populations of X. muta in several Greater Caribbean localities: Curaçao specimens measured 360–345 x 11–16 µm, Puerto Rico specimens 303–412 x 14–23 µm, and Bahamas specimens 290–430 x 3.5–12 µm. The spicules of our deep-water specimens do not exceed 200 µm in length. Although the shallow-water specimens of X. muta have predominantly oxea spicules, there is always a good proportion of strongyle forms. In the present deep-water material there are no strongyles, all spicules are sharply pointed oxeas. Finally, the skeletal structure of X. muta specimens is more loosely organized, and does not have the superimposed anistropic arrangement of spicules and meshes. No other Neopetrosia species in the Central West Atlantic have a vase-shaped habit.

The niphatid Cribrochalina vasculum (Lamarck, 1814) shares the vase-shaped habit with N. eurystomata n. sp., but it is different in color (brown) and the spicules include forms as small as 50 µm and up to 300 µm or more. The skeleton is also radically different with an emphasis on ascending spicule tracts separated by large spaces in which only loose spicules occur, with few interconnecting tracts ( Wiedenmayer 1977: 119; Zea 1987: 91).

Figures

FIGURE 19. Neopetrosia eurystomata n. sp., a. holotype RMNH Por. 9239 in situ, b. paratype RMNH Por. 9242 in situ, c. holotype after collection, d. paratype RMNH Por. 9242, after collection, e. tangential view of ectosomal skeleton of holotype, f. cross section of peripheral skeleton of holotype.

FIGURE 20. Neopetrosia eurystomata n. sp., a. fragment of paratype RMNH Por. 9250 after collection, b–c. SEM images of spicules of holotype RMNH 9239, b. larger oxea, b1. details of apex of larger oxea, c. smaller oxea.