Geodia pocillum, Van, Rob W. M., 2017

Van, Rob W. M., 2017, Sponges of the Guyana Shelf, Zootaxa 1, pp. 1-225 : 95-97

Geodia pocillum sp. nov.

Figures 59 a–k

Material examined. Holotype RMNH Por. 10547, Guyana, ‘Luymes’ Guyana Shelf Expedition, station 50, 7.7167°N 57.0833°W, depth 96 m, rectangular dredge, bottom sandy mud, 30 August 1970 .

Paratypes RMNH Por. 9796, two specimens with same data as the holotype .

Description. The holotype ( Fig. 59 a) is the middle-sized of three inverted cone-shaped individuals. The paratypes ( Fig. 59 a1) are the largest and the smallest of the three, respectively 5 cm high and 4 cm in diameter, and the smallest 2.5 cm in diameter; the latter paratype is more globular. The upper side of each has a shallow central depression, 3 cm wide in the largest individual, on the bottom of which are concentrated uniporal oscules ( Fig. 59 a2). Color in alcohol beige or pale-orange. Surface smooth. Consistency hard.

Skeleton. The cortex consists of a mass of sterrasters with scattered small oxeas and strongylospherasters, 1–1.5 mm in thickness, carried by radially arranged triaenes. The choanosome remains largely radial, with bundles of rhabdomes of the triaenes and oxeas.

Spicules. ( Figs 59 b–k) Oxeas in three categories, orthotriaenes, anatriaenes, protriaenes, sterrasters, oxyasters in two categories, strongylospherasters.

Long thin oxeas ( Figs 59 b,b1), curved, occasionally wispy, gradually tapering to sharp points, usually broken, the few entire ones (n=4) measure 2938–6600 x 13–16 µm.

Fusiform oxeas ( Figs 59 c,c1), straight or slightly curved, 2445– 3367 –4935 x 29– 42 –57 µm.

Orthotriaenes ( Figs 59 d,d1d2), with rhabdomes thinly tapering and often curved, in a large size range but not divisible in size categories; rhabdomes 1640– 2997 –3960 x 30– 57 –72 µm, cladomes 175– 538 –780 µm, cladi 102– 282 –390 x 30– 43 –57 µm.

Anatriaenes ( Figs 59 e,e1), straight, rhabdomes thinly tapering, cladi short and curved evenly, in a large size range but no size categories; rhabdomes 700– 2020 –2730 x 7– 20 –29 µm, cladomes 57– 132 –240 µm, cladi 20– 82 –202 x 6– 17 –23 µm.

Protriaenes ( Figs 59 f,f1), verging toward plagiotriaenes, not common, rhabdomes straight, thinly tapering, in a wide size range but no obvious categories; rhabdomes 810– 1514 –3442 x 7 – 12.3 –16 µm, cladomes 75– 141 –230 µm, cladi 48– 110 –208 x 6 – 9.0 –14 µm.

Small (cortical) oxeas ( Fig. 59 g), straight or slightly curved, 258– 306 –331 x 5.5– 6.6 –7.5 µm.

Sterrasters ( Figs 59 h,h1), oval, uniform in shape and size, 82– 87.4 –93 x 66 – 72.2 –78 µm. Rosettes are warty and have 3–5 conical rays.

Large oxyasters ( Fig. 59 i), thin-rayed, spined entirely except near the centre, 38– 49.3 –63 µm, ray number 7–10.

Small oxyasters ( Fig. 59 j), rays more conical, spined apically but smooth in the lower half, smooth in the center, 19– 24.6 –29 µm, ray number 9–16.

Strongylospherasters ( Fig. 59 k), with smooth center and stunted rays spined apically, 9– 11.6 –15 µm, ray number 10–20.

Distribution and ecology. Guyana Shelf, sand bottom at 96 m depth.

Etymology. Pocillum (noun) (L.) = a small goblet or cup, referring to the shape of the sponge.

Remarks. The combination of shape, oval sterrasters and the diversity of triaenes and euasters are distinct among the many described Geodia species of the Central West Atlantic.

Apart from the above treated Geodia gibberosa , tropical Central West Atlantic waters (Greater Caribbean and NE Brazilian regions), contain the following fourteen additional Geodia species (from Van Soest et al. 2016): G. apiarum ( Schmidt, 1870) , G. corticostylifera Hajdu, Custodio, Russo & Peixinho, 1992 (including G. vosmaeri sensu Boury-Esnault, 1973 ), G. cribrata Rützler, Piantoni, Van Soest & Díaz, 2014 , G. cumulus Schmidt, 1870 , G. curacaoensis Van Soest, Meesters & Becking, 2014 , G. glariosa ( Sollas, 1886) , G. neptuni ( Sollas, 1886) , G. papyracea Hechtel, 1965 , G. spherastrea Lévi, 1964 , G. stromatodes ( Uliczka, 1929) , G. thomsonii Schmidt, 1870 , G. tumulosa ( Bowerbank, 1872) . G. tylastra Boury-Esnault, 1973 , and G. vosmaeri ( Sollas, 1886) . Of these, only G. curacaoensis matches most of the features of the present specimens. The holotype of that species is similar in shape to one of the two present paratypes. However, there are a number of differences: (1) no protriaenes were found in that species, (2) oxeas were not differentiated into separated long-thin and fusiform-thick oxeas, (3) the cladomes and cladi of the orthotriaenes are considerably shorter (cladomes 320–550 µm, cladi 160–270 µm as opposed to 175–780 µm and 102–390 µm), (4) cortical oxeas were longer (320–480 µm vs 258–331 µm) and slightly asymmetrical, (5) the size of large oxyasters is only half of that of the present species. Together these differences are here taken as sufficient evidence for specific distinction. See the discussion in Van Soest et al. (2014) for the features differing in the other twelve tropical Central West Atlantic Geodia species. It may turn out that the Barbados specimen Geodia cf. megastrella sensu Van Soest & Stentoft (1988) fits better with G. pocillum sp. nov. than with G. curacaoensis , as previously suggested by Van Soest et al. (2014).

Figures

FIGURE 59. Geodia pocillum sp. nov., a, habitus of holotype RMNH Por. 10547 (scale bar = 1 cm), a 1, habitus of the two paratypes RMNH Por. 9796 (scale bar = 1 cm), a 2, concentrated uniporal oscules in the small globular paratype, b – k, SEM images of spicules, b, long thin oxea, b 1, detail of apex of b, c, fusiform oxea, c 1, detail of apex of c, d, orthotriaene, d 1, cladome of d, d 2, cladome of a smaller orthotriaene, e, anatriaene, e 1, cladome of anatriaene, f, protriaene, f 1, cladome of protriaene, g, small cortical oxea, h, sterraster, h, detail of surface of sterraster, i, large oxyaster, j, small oxyaster, k, strongylospheraster.