Spongia (Heterofibria) cooki, Samaai & Pillay & Janson, 2019

Samaai, Toufiek, Pillay, Ruwen & Janson, Liesl, 2019, Shallow-water Demospongiae (Porifera) from Sodwana Bay, iSimangaliso Wetland Park, South Africa, Zootaxa 4587 (1), pp. 1-85 : 69

Spongia (Heterofibria) cooki sp. nov.

( Fig. 31 A–E)

Material examined. Holotype. SAMC–A24791 (cross-reference TS 871 & Saf 03-Sod 46), Gotham reef, Sodwana Bay (27.4916°S, 32.7022°E), South Africa, 0 5 November 2003, collected by T. Samaai, depth 34 m.

Type locality. Gotham reef, Sodwana Bay, east coast of South Africa .

Description. Massive, digitate, 160 × 100 × 80 mm diameter, with an interconnecting network of blades that terminate with emergent fibres ( Fig. 31A ). Surface smooth, with a pinacoderm stretched over the sponge (secondarily lost upon collection and fixation in preservative), giving the sponge a slightly glossy sheen. Large oscules visible 2–5 mm in diameter, but not visible in preserved specimen. Upper part of the cartilaginous-like blades consists of exposed skeletal fibres, while the lower half is bare. Interconnecting network of the cartilaginous-like blades forms the oscula canals. Texture firm, fairly hard, rather cartilaginous, barely compressible, difficult to tear. Colour in life dark-grey; in preservative dark-brown.

Skeleton ( Fig. 31 B–E). Choanosomal skeleton consists of homogenous primary and secondary fibres. Primary fibres irregularly, spares, cored with foreign material, more frequent near the surface; secondary fibres are uncored and dominate the skeleton. Fibre network increases in density towards the surface and primary fibres branch before they emerge at the surface. Secondary fibre meshes are irregular polygonal. Pseudo-tertiary fibre network observed within polygonal meshes and interconnect with adjacent secondary fibres. Primary fibres, 65 (55–89) µm in diameter, secondary fibres, 28 (23–37) µm in diameter, and pseudo-tertiary fibres, 16 (12–18) µm in diameter. Fibres are yellow-orange in colour. There are regular collagen deposits within the mesohyl, and an uneven layer, 255–400 µm, at the surface.

Substratum, depth range and ecology. This sponge was found on rocky shaded walls or under overhangs in moderate to exposed locations at a depth of 34 m.

Etymology. Named after Dr. Steve Cook, sponge taxonomist in recognition for the contribution he has made to our knowledge of dictyoceratid sponges.

Remarks. The genus Spongia is characterized as unarmoured, somewhat lacunose, with simple primary fibres that are without distinct laminations and the choanosome dominated by sub-primary skeletal fibres ( Cook & Bergquist 2002). The sponge belongs in the subgenus Spongia (Heterofibria) . Cook & Bergquist (2001) in a revision of Spongia from New Zealand described five species from the area. Initially, this was the only known locality of this subgenus. However, Mothes et al (2006) described a new species, Spongia (Heterofibria) catarinensis , off the coast of Brazil. The subgenus is fairly new with a total of 6 described species. There are no Spongia (Heterofibria) species described from the WIO. The discovery of a species in South Africa could indicate that subgenus has a Southern Hemisphere, tropical to subtropical distribution. Spongia (Heterofibria) cooki sp. nov. has a skeleton similar to S. (H) cristata ( Cook & Bergquist, 2001) from New Zealand. However, there are differences between the two species including S. (H) cristata possessing an external morphology of upright lobes with tufts of coalescent fibres, a heavier coring of fibres and no dermal layer of collagen at the surface. Spongia (H) catarinensis differs from S. (H) cooki sp. nov. with a low encrusting morphology, translucent fibres with smaller dimensions (primary fibres, 60–100 µm; secondary fibres, 11–69 µm) and an absent dermal layer of collagen. The formation of primary fibres from secondary fibres and the presence of fascicules have been observed in S. (H) manipulatus described by Cook & Bergquist (2001). All the species in the subgenus have a bathymetry of 10–20 m with the exception of S. (H) cooki sp. nov., which was found at 34 m.

Key diagnostic characters.

• Sponge massive digitate.

• Pinacoderm stretched over the sponge.

• Large oscules visible.

• Secondary fibre meshes are irregular polygonal interconnected with pseudo-tertiary fibre network.

• Dermal layer of collagen at the surface.

Figures

FIGURE 31. Spongia (Heterofibria) cooki sp. nov. A. In situ; B-E. Skeletal architecture (B, x5; C, x5; D, x10; E, x10)