Plakortis angulospiculatus (Carter, 1879)

Van, Rob W. M., 2017, Sponges of the Guyana Shelf, Zootaxa 1, pp. 1-225 : 192-193

Plakortis angulospiculatus (Carter, 1879)

Figures 121 a–d

Suberites angulospiculatus Carter, 1879a: 346 , pl. XXVIII figs 8a–b.

Plakortis angulospiculatus ; Van Soest 1981: 3; Zea 1987: 222, fig. 81, Pl. 13 figs 6–7; Moraes & Muricy 2003: 386, fig. 2; Rützler et al. 2014: 16 .

Material examined. RMNH Por. 9918, Suriname, ‘ Luymes O.C.P.S. II’ Guyana Shelf Expedition, station M97, 7.3083°N 54.1667°W, depth 130 m, bottom coarse sand, 16 April 1969 .

Description. ( Fig. 121 a) Pale beige (in alcohol), massive fragments, size of largest 5 x 3 x 2 cm. The fragments are overgrown by a crust with digitations of Haliclona (Gellius) aff. flagellifera , which likely affected color and surface characteristics. No apparent oscules. Consistency firm.

Skeleton. Surface skeleton consists of a tangential crust pierced by regularly distributed pores, 80–250 µm in diameter.

Spicules. ( Figs 121 b–d) Diods, triods.

Diods robust, in a large size variation ( Figs 121 b–c), but no clear size categories, 57– 134 –202 x 2 – 5.1 – 8 m.

Triods ( Fig. 121 d), both equiangular and Y-shaped forms, actines 21– 44.1 – 72 x 1 – 3.4 –5 µm (‘cladomes’ 39– 69.5 –123 µm).

Distribution and ecology. Guyana Shelf, Jamaica, Curaçao, Colombia, Belize, from shallow water down to 130 m.

Remarks. In the key to the Central West Atlantic Plakortis species provided by Ereskovsky et al. 2014 (pp. 303–304) the present specimen keys out as Plakortis angulospiculatus ( Carter, 1879a) . Few other species of Plakortis have diods larger than 200 µm as found in my specimen.

Several more species have been described from NE Brazil (Domingos et al. 2013), but all these have distinctly smaller diods. Brazilian records of Plakortis angulospiculatus (cf. Muricy et al. 2011) may belong to one of these new species, at least it is likely that not all belong to P. angulospiculatus , so their presence is here left undecided.

We noticed a few small spheres (7–10 µm diameter), the significance of which is unclear. Muricy (2011) was the first to report the presence of these spicules in Australian Plakortis species, and subsequently also found them in Brazilian species (Domingos et al. 2013). It remains to be decided if the presence of these, usually uncommon, spheres has taxonomic significance, as there is a distinct possibility that they are a product of high environmental silica content, or more simple spicular reduction (in this case reduced diods).

Figures

FIGURE 121. Plakortis angulospiculatus (Carter, 1879), a, habitus of RMNH Por. 9918 (scale bar = 1 cm), b – d, SEM figures of the spicules, b, larger diods, c, smaller diods, d, triod.