Neopodospongia exilis, Sim-Smith, Carina & Kelly, Michelle, 2011

Sim-Smith, Carina & Kelly, Michelle, 2011, Two new genera in the family Podospongiidae (Demospongiae: Poecilosclerida) with eight new Western Pacific species, Zootaxa 2976, pp. 32-54 : 45-46

Neopodospongia exilis gen. nov. sp. nov.

( Fig. 1 D, 4N–R)

Material examined. Holotype ― NIWA 52579: RV Kaharoa Stn KAH0204/9, Cavalli Seamounts, 34.111° S, 174.138° E, 562–600 m, 14 Apr 2002.

Type location. Cavalli Seamounts, off N New Zealand.

Distribution. Known only from type location.

Description. Thinly encrusting sponge, 10 mm long x 10 mm wide x 1 mm thick, attached to a piece of coral rubble ( Fig. 1 D). Surface is smooth, granular, easily detached from underlying choanosome, slightly wrinkled. Oscules are not visible but tiny pores, 25–100 μm in diameter, can be seen under magnification. Texture of ectosome is tough and translucent like cellophane. Choanosome is soft, fragile. Colour in ethanol opaque white, interior creamy yellow.

Skeleton. Ectosome a thin collagenous layer of aciculospinorhabds that are densely packed in a vertical arrangement with the apical spine pointing away from the surface. Choanosomal skeleton composed of dense radiating brushes of megascleres that emerge from the base of the sponge radiating towards the ectosome. The orientation of the brushes in the holotype is messy and generally oblique to the surface as a result of desiccation. Aciculospinorhabd microscleres are also scattered throughout the choanosome.

Megascleres ( Fig. 4 N, Table 2)― Strongyloxeas with central thickening and polytylote swellings, faintly subtylostylote, occasionally curved; 596 (483–680) x 8 (7–9) μm.

Microscleres ( Fig. 4 O–R, Table 2)― Aciculospinorhabds I ( Fig. 4 O & R); large, stout, compact. Basal whorl typically with four stout directly opposed spines extending obliquely away from the shaft towards the base of the spicule, the median whorl is located slightly off centre along the shaft and has eight stout spines arranged in diverging pairs. Apical whorl composed of up to eight spines in diverging pairs, each with bifurcate tips, one branch frequently being longer than the other, extending obliquely away from the shaft towards the apical spine. Apex expanded and extended into a spire of four directly opposed and merged blades with serrated edges; 70 (56–76) x 40 (34–46) μm. Aciculospinorhabds II ( Fig. 4 P–Q, Table 2); small, slender, heavily spined. Basal and apical whorls are very similar in the possession of four long irregularly disposed spines that emerge obliquely from both base and apex. Median whorl is relatively regular with numerous spines arranged in diverging pairs. The apex may consist of a single long spine ( Fig. 4 P), or several long spines ( Fig. 4 Q); 45 (25–59) x 21 (13–27) μm. The protoaciculospinorhabd is sigmoidal in shape ( Fig. 4 R).

Substrate, depth range, and ecology. Attached to dead coral rubble between 562 and 600 m depth.

Etymology. Named for the morphology of the sponge, being small, thin, and meagre in proportions ( exilis = Latin for meagre).

Remarks. Neopodospongia exilis gen. nov. sp. nov. differs primarily from the shallow water species N. pagei gen. nov. sp. nov. and N. bergquistae gen. nov. sp. nov. in having much larger megascleres and microscleres. While the aciculospinorhabds of the two latter species are more similar to each other in terms of structure and ornamentation, those of N. exilis gen. nov. sp. nov. are quite different, with strongly sculpted and spired forms compared to the other species ( Fig 4 ). Neopodospongia exilis gen. nov. sp. nov. also has two quite discrete forms of aciculospinorhabds as in N. pagei gen. nov. sp. nov. Neopodospongia exilis gen. nov. sp. nov. is rare; the holotype was the only specimen collected from New Zealand waters, despite numerous recent voyages. It is a deep-water species, having been collected between 500 and 600 m whereas the other two Neopodospongia gen. nov. species are from comparatively shallow waters.

Neopodospongia exilis gen. nov. is similar to an informally named shallow water Chilean species, Sigmosceptrella tupecomareni , illustrated in Willenz et al. (2009). The key difference between this species and the New Zealand species is in the ornamentation of the larger aciculorhabd of S. tupecomareni , in which the apical whorl is merged with the apex forming a large bushy structure, unlike in N. exilis in which the apical whorl is quite separate ( Fig. 4 O). The smaller aciculospinorhabds of S. tupecomareni have much shorter spines that are themselves diversely spined, unlike those of N. exilis ; which have long smooth spines.

Figures

FIGURE 1. New genera and species of Podospongiidae from New Zealand, Australian, and Indonesian waters: A. Podospongia virga, holotype NIWA 52692, Cape Reinga, New Zealand; B. Podospongia colini, holotype USNM 1154618, Sulawesi, Indonesia; C. Neopodospongia pagei, holotype NIWA 52580, Three Kings Islands, New Zealand; D. Neopodospongia exilis, holotype NIWA 52579, Cavalli seamounts, New Zealand; E. Neopodospongia bergquistae, holotype NIWA 62016, Poor Knights Islands, New Zealand; F. Diplopodospongia teliformis, holotype NIWA 35005, Hikurangi Channel, New Zealand; G. Diplopodospongia rara, holotype NIWA 52693, Campbell Plateau, New Zealand; H. Diplopodospongia macquariensis, holotype QM G 331915, Seamount 8, Macquarie Ridge, Australia. Scale = 10 mm for all images.

FIGURE 4. Megascleres and microscleres of Neopodospongia gen. nov. spp. nov: Neopodospongia pagei, holotype NIWA 52580, A. strongyloxea, scale = 100 µm; B. aciculospinorhabd I; C, D. immature forms of aciculospinorhabd I; E. sigmoidal protoaciculospinorhabd I; F. aciculospinorhabd II; G. immature aciculospinorhabd II, scale B – G = 20 µm; H. top down view of the apical whorl and spire of aciculospinorhabd, scale = 5 µm. Neopodospongia bergquistae, holotype NIWA 62016, I. strongyloxea, scale = 100 µm; J. aciculospinorhabd; K. immature aciculospinorhabd; L. sigmoidal protoaciculospinorhabd, scale J – L = 20 µm; M. top down view of the apical whorl and spire of aciculospinorhabd, scale = 5 µm. Neopodospongia exilis, holotype NIWA 52579, N. polytylote style with subtylostylote modification, scale = 100 µm; O. ectosomal aciculospinorhabd; P, Q. choanosomal aciculospinorhabds, scale = 20 µm; R. sigmoidal protoaciculospinorhabd, scale O – R = 20 µm.