Aulospongus trirhabdostylus, Cavalcanti & Santos & Pinheiro, 2014

Cavalcanti, Thaynã, Santos, George Garcia & Pinheiro, Ulisses, 2014, Two new species of Aulospongus Norman, 1878 with a key to the Atlantic species (Poecilosclerida; Demospongiae; Porifera), Zootaxa 3827 (2), pp. 282-292 : 284-288

Aulospongus trirhabdostylus sp. nov.

( Figures 1–3 , Table 1–2)

Type locality. Brazil, Rio Grande do Norte State, Potiguar Basin .

Type specimens. Holotype. UFPEPOR 1517, Bacia Potiguar (04º 44.8945' S; 036º 25.4571' W), Rio Grande do Norte State, Brazil, depth 108 m, trawl, Bombona 39, col. Petrobras, (23/05/2011) . Paratypes: UFPEPOR 1519, UFPEPOR 1520 and MNRJ 17487 (collected together with the holotype); UFPEPOR 1521, Bacia Potiguar (04º 36.7198' S; 036º 46.7554' W), Rio Grande do Norte State, Brazil, depth 140 m, trawl, Bombona 29, col. Petrobras, (22/05/2011) .

Diagnosis. Aulospongus trirhabdostylus sp. nov. is the only Aulospongus in Atlantic with three categories of rhabdostyles.

External morphology ( Fig. 2A–D ). Massive–arborescent with digitiform projections, 6 x 5.5 x 5 cm (length x height x width) ( Fig. 2A ). Small oscules (0.8–1 mm) are observed on the sides or on the tips of the projections ( Fig. 2A , arrows). Surface with bouquets of spicules irregularly distributed ( Fig. 2B ). Fibre-bundles are inter-connected by a thin layer of spongin ( Fig. 2B–C ). Consistency is elastic, not easily torn. Colour in life is unknown and brownish-purple in ethanol. However, the specimens were collected in the same drag as Aiolochroia crassa ( Hyatt, 1875) and stored in the same container. It is possible that the Aiolochroia crassa pigments painted the Aulospongus specimens.

Skeleton ( Fig. 2C–E ). Ectosomal skeleton composed of bouquets of anisoxeas forming irregularly distributed projections ( Fig. 2C ). Choanosomal skeleton relatively thick, dominated by spongin fibres predominantly formed by plumo-reticulate bundles composed by rhabdostyles ( Fig. 2D ). Each perpendicular column arising from the choanosome consists of several bundles of fibres. Fibres-bundles and tracts cored and echinated by rhabdostyles with no recognizable distribution of the three categories ( Fig. 2E ).

Spicules ( Fig. 3A–H ). Ectosomal auxiliary anisoxeas (399– 473.3 –547 / 3– 4.0 – 6 µm): long, thin, smooth, straight to slightly curved, with distinct tips (one sharply pointed and the other styloid) ( Fig. 3A, E , E’); Choanosomal principal rhabdostyles (rhabdostyles I) (127– 199.5 –287 / 7– 11.1 – 14 µm): robust, slightly curved next to the basal region (rhabd), smooth base to a few spines (1–2), on the medium region to the tip composed of curved spines (hook-shaped) directed to the base, the spines near the tips are smaller and fewer than in the smaller rhabdostyles ( Fig. 3B, F ); Echinating rhabdostyles (rhabdostyles II) (90– 116.7 –155 / 3– 6.5 – 13 µm): small, completely microspined, straight to slightly curved ( Fig. 3C, G ); Auxiliary rhabdostyles (rhabdostyles III) (171– 217.6 –277 / 2– 6.3 – 9 µm): thin, with a slight curvature towards the end (slightly rhabdose base) and microspined (small granular spines) from the medium to the apical region ( Fig. 3D, H ).

Distribution ( Fig. 1 ). Brazil: Northeastern Region: Rio Grande do Norte State: off Bacia Potiguar.

Depth. 108–140 m.

Etymology. The species name refers to the presence of three categories of rhabdostyles.

Remarks. Aulospongus trirhabdostylus sp. nov. belongs the genus by the presence of three categories of rhabdostyles, plumose choanosomal skeleton with fibres ascending to the periphery. In comparison with the species from Atlantic, Aulospongus trirhabdostylus sp. nov. differs from A. monticularis by its massive bulbousencrusting growth form, rhabdostyles I (completely smooth) and subectosomal extra-axial styles. Aulospongus phakelloides is a fan-shaped sponge, with two categories of echinating rhabdostyles and absence of anisoxeas. Aulospongus samariensis is club-shaped sponge, with one category of echinating rhabdostyles and the presence of styles. Aulospongus spinosus is a bulbous–erect sponge, with two categories of rhabdostyles (completely smooth), while A. trirhabdostylus sp. nov. has massive-arborescent growth form, three categories of rhabdostyles (all with spines) and presence of anisoxeas (see Table 2, Fig. 3 ). The most similar species to A. trirhabdostylus sp. nov. is A. gardineri ( Dendy, 1922) from the Indian Ocean which also has three categories of rhabdostyles, but differs morphology of sponges, and in the morphology of rhabdostyles III (completely smooth in A. gardineri ), presence of extra-axial styles, and spicules size (see Table 2). Finally, A. gardineri is known only from the Indian Ocean, making conspecificity highly improbable.

Figures

FIGURE 1. Location of the studied area, Potiguar Basin, and the collection sites of Aulospongus trirhabdostylus sp. nov. (1) (3) and Aulospongus mandela sp. nov. (1) (2) (3). Collection depths: (1) 108 m; (2) 143 m; (3) 140 m.

FIGURE 2. Aulospongus trirhabdostylus sp. nov. (UFPEPOR 1517, holotype). A, preserved specimen showing oscules (arrows); B, surface details; C, detail of thick section showing brushes; D, thick section showing the ectosome and choanosome; E, detail of polyspicular tracts of echinating spicules. Scale bars: A = 1 cm; B = 500 µm; C–E = 300 µm.

FIGURE 3. Spicule composition of Aulospongus trirhabdostylus sp. nov. (UFPEPOR 1517, holotype) in SEM. A, ectosomal auxiliary anisoxea; B, choanosomal principal rhabdostyles; C, echinating rhabdostyles; D, auxiliary rhabdostyles; E–H, details of respectively A–D. Scale bars: A = 40 µm; B = 20 µm; C = 10 µm; D = 20 µm; E–H = 2 µm; E’= 4 µm.