Poecillastra macquariensis Kelly & Cardenas, sp. nov.

Poecillastra macquariensis Kelly & Cárdenas sp. nov.

urn:lsid:zoobank.org:act: 78B12A37-93E0-4CA9-9317-81F835B112FE

Fig. 5

Etymology

Named for the type location of this species, the Macquarie Ridge.

Type material

Holotype NEW ZEALAND • Subantarctic region of New Zealand, Seamount 5, Macquarie Ridge, NIWA Station TAN0803/48; 51.096° S, 161.976° E; depth 462–524 m; 4 Apr. 2008; NIWA 52640 leg.; epibenthic sled; NIWA.

Description

Solid stalk of sponge of unknown morphology, 15 mm in diameter, 20 mm high, expanding on the broken, upper surface, sides of stalk sculpted, attachment base contains patches of substrate (Fig. 5A). Surface hispid and scratchy to the touch; texture firm, incompressible. Colour in preservative tan.

Skeleton

Stalk composed of huge swathes of contort oxeas and triaenes between which are abundant microscleres.

Spicules

MEGASCLERES (Fig. 5 D–E)

Abundant contort to sinuous oxeas (Fig. 5D) with slightly rounded tips, 3725(2125‾5750) × 53(30‾70) µm; medium-shafted triaenes (Fig. 5E), rhabd slightly curved, tapering to a sharp tip, 852(550‾1225) µm, clads of slightly uneven length, slightly curved downwards, 578(450‾680) µm, overall cladome width, about 900‾1360 µm long, ranging to pseudocalthrops. Broken true oxeas are evident but unmeasurable.

MICROSCLERES (Fig. 5 B–C, F–G)

Microxeas (Fig. 5 B–C), straight to slightly curved, roughened, abundant, 332(260‾420) × 7(5‾8) µm, n = 20; plesiasters (Fig. 5F), with 3‾5 microspined blunt-tipped rays, overall 67(50‾100), ray length 37(25‾60) µm, n = 10; metaster- to amphiaster- to spiraster-like streptasters (Fig. 5G), with long, microspined rays, abundant, 19(15‾20) µm long.

Distribution

Macquarie Ridge.

Substrate, depth range and ecology

Attached to rock substrate; depth 462– 524 m.

Remarks

The specimen is the attachment base of a sponge of unknown morphology, but it clearly differs from the holotype of Poecillastra ducitriaena sp. nov. in having a very hispid, crisp, scratchy surface, indicating a reduction of the ectosomal crust of microscleres, and the abundance of large megascleres. It is similar to Poecillastra ducitriaena sp. nov. in the possession of abundant contort oxeas in the stalk, but differs in the lack of straight oxeas in the stalk and the much larger dimensions of all the spicules: the contort oxeas are up to 2000 µm longer, on average, in Poecillastra macquariensis sp. nov., and the triaenes are about double the size of those in Poecillastra ducitriaena sp. nov., and much more abundant, the microxeas are about ten times larger, and the sponge contains plesiasters, absent in Poecillastra ducitriaena sp. nov.

Because our knowledge of Poecillastra in the New Zealand region is reasonable (see above), we have made the decision to record and name this second Poecillastra species, despite our lack of information on the body shape, and because surface texture, spicule types and dimensions are so different from those of Poecillastra ducitriaena sp. nov.