Haliclona (Halichoclona) sonnae, 2019

Kelly, Michelle & Rowden, Ashley A., 2019, New sponge species from hydrothermal vent and cold seep sites off New Zealand, Zootaxa 4576 (3), pp. 401-438 : 415-417

Haliclona (Halichoclona) sonnae sp. nov.

( Figs 1 , 2 , 5 , 6 ; Table 2, 4)

Material examined. Calypso hydrothermal vent field (Southern vent field), southwest of White Island, Bay of Plenty : Holotype — NIWA 52859 , IFM GEOMAR Stn SO 135/103, 37.695° S, 177.101° E, 179–181 m, collected by rock dredge, 10 Oct 1998. Paratype — NIWA 52897 , IFM GEOMAR Stn SO 135/108, 37.687° S, 177.121° E, 193 m, collected by submersible, 10 Oct 1998 .

Type location & distribution. Calypso hydrothermal vent field, Bay of Plenty, New Zealand, 179–193 m.

Description. S pherical to hemispherical, cushion-shaped sponge ( Fig. 2 , 5A, B ), about 30 mm high and wide,

with an irregular, lumpy surface from which may emerge short, fine, hollow fistular outgrowths. Surface faintly hispid, top 2–3 mm easily detached from the underlying skeleton in flakes ( Fig. 5B ); sponge is highly cavernous; the subsurface appears hollow out of water, reflecting the overlying tangential ectosome, from under which the preserving fluid drains from the substantial subectosomal spaces. Oscules uncommon, flush with the surface, about 2 mm diameter. Texture in life extremely fragile, crisp, brittle, delicate. Colour in life and preservative, pale cream with a translucent surface, reflecting the subdermal spaces beneath.

Skeleton. Choanosomal skeleton consists of a subisotropic to confused reticulation of oxeas, surrounding large spaces, rendering the interior highly cavernous ( Fig. 5C, D ). There is some organisation into rough uni- to multispicular tracts emerging towards the surface in the upper choanosome ( Fig. 5D ), criss-crossed roughly by multiple spicules, about 150–400 µm apart. The ectosomal skeleton is the same as the choanosome, the apical spicules of the primary lines project from the surface ( Fig. 5C ) and the whole is overlaid and interspersed with an irregular layer of oxeas in a more-or-less paratangential isodictyal reticulation that can be quite thick in places ( Fig. 5C ), giving the impression of a thick tangential skeleton that comes off in flakes, with subectosome attached. Choanosome is separated from the ectosome by quite large subdermal spaces ( Fig. 5C ). Nodal or fibre spongin not visible. Interstitial oxeas are abundant throughout.

Spicules. Megascleres ( Table 3; Fig. 6 ), oxeas with fine, fusiform tips, slightly curved, 158 (135–183) × 8 (5– 11) µm.

Substrate, depth range and ecology. Attached to volcaniclastic rock covered in sediment and associated with high densities of other sponges and an undescribed orange anemone, 177– 193 m.

Etymology. Named for the R.V. Sonne, the German research vessel from which most of the Calypso hydrothermal vent collections were made in 1998. The ship is named after the original German meaning for sun (sonne).

Remarks. Haliclona (Halichoclona) sonnae sp. nov. has a highly characteristic, distinguishing feature: an ectosome that is detachable in thick flakes. On preliminary examination, the holotype and paratype were assigned to the genus Adocia [now a synonym of Haliclona (Haliclona) ] because there appeared to be a distinct surface skeleton, easily separable from the underlying choanosome. However, on closer examination, histological sections revealed that the ectosome did not have the highly organised, tangential surface isodictyal reticulation of formerly Adocia species, which can be sliced cleanly from the crisp underlying choanosome with a scalpel blade. Rather, the skeletal arrangement is a thick ectosomal ‘subisodictyal crust,’ separated by abundant subdermal spaces, from a denser subisodictyal reticulation that shows some rough tract development. Combined with the cushion-shaped morphology, the presence of rare but relatively large oscules, the crisp, fragile consistency, the apparent absence of spongin, and the detachable flaky ectosome (de Weerdt 2002), the morphology and skeleton architecture of the new species is highly reminiscent of species in the Haliclona subgenus Halichoclona .

There is only one species of this subgenus recognised from New Zealand waters: Haliclona (Halichoclona) caminata ( Bergquist & Warne, 1980) ( Table 2), a massive, crisp, fragile sponge with a basal mat from which arises long, hollow, oscular fistules, a subectosomal region with primary tracts separated from a more confused choanosome by subdermal spaces, and oxeas around 130 (100–180) µm long. Although H. (Halichoclona) caminata is one of the deepest recorded species at 75 m (Mernoo Bank, South Island east coast), and is thus far restricted to the east coast of New Zealand, it has not been recorded to date as far north as the Bay of Plenty and not at the depth recorded for H. sonnae sp. nov. (177–193 m). Haliclona (Halichoclona) sonnae sp. nov. differs physically from H. (Halichoclona) caminata in the lack of abundant oscular tubes (although it may put up hollow, irregular tendrils) and the oxeas are larger on average [158 (135–183) µm long. While the subectosomal skeleton of H. (Halichoclona) sonnae sp. nov. is like that of H. (Halichoclona) caminata in that it has relatively dense primary tracts, those of H. (Halichoclona) caminata are much thicker (10–20 spicules wide) than in H. (Halichoclona) sonnae sp. nov. (1–2 spicules wide) and only extend to a depth of about 1200 µm as opposed to 2000–3000 µm deep in H. (Halichoclona) sonnae sp. nov.

Figures

FIGURE 1. Map showing type localities for new species described from the Calypso hydrothermal vent field in the Bay of Plenty and named seep sites on the Hikurangi Margin.

FIGURE 2. Photograph of seabed at Southern vent field of the Calypso hydrothermal vent field (NIWA Stn KAH1004/8: image 1119; 37.688° S, 177.123° E, 190 m), showing the three sponge species that dominate the epifauna assemblage at this site: Blue arrow—finely branched Haliclona (Soestella) battershilli sp. nov.; Red arrows—translucent white, cushion-shaped Haliclona (Halichoclona) sonnae sp. nov.; Green arrows—stubby fingered, peach-coloured Protosuberites novaezelandiae sp. nov. The orange anemone is undescribed. Image captured by NIWA’s DTIS (Deep Towed Imaging System) deployed from RV Kaharoa.

FIGURE 5. Haliclona (Halichoclona) sonnae sp. nov.: A. Encrusting, cushion-shaped specimens in situ (red arrows) intermingled with Haliclona (Soestella) battershilli sp. nov., at Southern vent field of the Calypso hydrothermal vent field (NIWA Stn KAH1004/8: image 1113; 37.688° S, 177.123° E, 190 m); B. Preserved holotype, NIWA 52859, showing cavernous interior and thick, flaky ectosome; C. Histological section of holotype showing the thick ectosome, dominated by an irregular, ladder-like reticulation, overlaid at the surface with a thin layer of paratangential oxeas. Also showing the highly cavernous subectosomal region separating the outer ectosome from the deeper choanosome; D. Histological section of the deep choanosome showing the loose, irregular, subisotropic to confused reticulation of oxeas in the choanosome, interrupted by large subdermal canals and spaces. Image in 4A captured by NIWA’s DTIS (Deep Towed Imaging System) deployed from RV Kaharoa.

FIGURE 6. Haliclona (Halichoclona) sonnae sp. nov., holotype NIWA 52859, spicules: A, B. Oxea megascleres with fine, fusiform tips, slightly curved.