Stryphnus ariena Kelly & Sim-Smith, 2012, sp. nov.

Stryphnus ariena sp. nov.

(Fig. 2 F, 7L–P, 8)

Asteropus simplex (Carter 1879), Dendy (1924: 306).

Asteropus simplex, Bergquist, (1968: 32–33, Pl. 4b, 11d). Asteropus sp. nov. 4 Carvalho, 2008: 199 –203, Fig. 37.

Material examined. Holotype ― NIWA 57285: NIWA Stn TAN0906/225, RV Tanagaroa, continental shelf off Doubtless Bay, Northland, 34.853° S, 173.609° E, 100 m, 18 Jul 2009. P aratype ― NIWA 62049: 2 miles northwest of North Cape, 34.381° S, 172.015° E, 51–80 m, RV Kaharoa, 18 Apr 1999, additional vouchers of this paratype are in the CRRF reference collection (0 CDN 6657-U) and at the USNM (USNM 1182998); NIWA 44559: NZOI Stn W438, Mernoo Bank, Chatham Rise, 43.238° S, 175.442° E, 78–83 m, 21 Feb 1995; NIWA 44459: NZOI Stn B93, Three Kings Islands, 34.000° S, 172.500° E, 55 m, 22 Sep 1958. Other material. NIWA 73688: NIWA Stn TAN1105/104, North Taranaki Bight, 38.294° S, 173.454° E, 187- 168 m, 2 Apr 2011; Asteropus simplex sensu Dendy (1924) — NHMUK 1923.10.1.237, NHMUK 1923.10.1.238, NHMUK 1923.10.1.239, NHMUK 1923.10.1.240: Terra Nova Stn 96, 7 miles east of North Cape, 128 m, British Antarctic (Terra Nova) Expedition, 1910, 16 Jul –24 Sep 1911, microscope slides from R. N. XXXII.11. Asteropus simplex, Dendy <XREF>(1916): NHMUK 1920.12.9.162, NHMUK 1925.11.1.147a, Okhamandal Sponges, Dendy Collection, microscope slides from R. N. V. 2.

Type locality. North Cape, New Zealand.

Distribution. Northern New Zealand, Three Kings Islands, Chatham Rise.

Description. Massive base, 80 x 130 mm, giving rise to tall stout curved digits with rounded ends, about 130 mm high and 50 mm diameter (Fig. 2 F). Small oscules, 5–8 mm diameter, are situated at the apex of each digit. Surface almost completely invested with a 1 mm thick layer of Desmacella dendyi, except around the apex of the digits, which are bare. Texture compressible, surface smooth, granular to the touch, interior is very harsh. Colour in life grey, interior cream to tan, colour in ethanol dark brown.

Skeleton. Ectosome 1000–1250 µm deep, translucent, cavernous, very lightly permeated with fibrillar collagen, with numerous darkly pigmented cells that give the ectosome a spotted appearance. Amphisanidasters and sanidasters are common throughout the ectosome but are not sufficiently dense at the surface to be called a ‘crust’. The choanosome is uniformly pigmented and denser than the ectosome, with oxyasters and other microscleres scattered in moderate abundance. Oxeas are abundant and without orientation in the choanosome, extending into the ectosome and beyond. Dichotriaenes are very rare; only one was found in the ectosome, in a histological section of the holotype, and only seven were found in the spicule preparation of this specimen.

Spicules. Megascleres (Fig. 7 L–M) are oxeas (Fig. 7 L), large, stout, fusiform, slightly curved with sharply pointed tips, 1873 (1290–2542) x 46 (30–64) µm, with many smaller and thinner growth stages present; plagiotriaenes (Fig. 7 M), small and slender with gently recurved clads that project forward at an angle of 45°, rhabdome 344 (285–445) µm long, clads 153 (128–173) µm long, cladome width 275 (200–330) µm (n=9), rare.

Microscleres (Fig. 7 N–P) are oxyasters (Fig. 7 N), large with numerous long, slender, smooth rays, 28 (16–40) µm diameter; amphisanidasters and sanidasters (Fig. 7 O, P), moderately densely acanthose spicules with relatively long, blunt spines, 13 (10–17) µm.

Substrate, depth range, and ecology. Attached to rocky substrate, collected between 51– 128 m.

Etymology. Named for banana-shaped morphology of the curved tapering digits (ariena = banana in Latin).

Remarks. Dendy (1924) identified a specimen from the vicinity of North Cape as Asteropus simplex, a species originally described from Western Australia, and subsequently recorded from the Indian Ocean (Pulitzer-Finali 1993) and Hong Kong (Uriz 2002; van Soest 1982). Bergquist (1968) followed Dendy in also placing her Three Kings specimens in Asteropus, due to the apparent lack of triaenes, a characteristic of the genus Asteropus. While Bergquist did not record any triaenes, Dendy (1924) did, commenting on the presence of “a very few triaenes and triaene-derivatives, viz. one plagiotriaenes, one mesotriaene, and one curious hexact form, all seem to belong to the sponge, but they cannot be regarded as normal constituents of the spiculation”. In revising the genus Asteropus in her PhD thesis, Carvalho (2008), also failed to find triaenes in Bergquist’s (1968) specimen of Asteropus simplex, renaming the Three Kings species Asteropus sp. nov. 4. While they are very rare, the plagiotriaenes examined in this work are clearly natural, as they have the same morphology and dimensions in all specimens. Moreover, the skeletal architecture is quite characteristic of other species of New Zealand Stryphnus.

There are a number of differences between Dendy’s specimen and the type specimen of A. simplex, a massive, convex, lobate sponge with no discernible ectosome and moderately sized oxeas (1316 x 28 µm). Dendy described his specimen as consisting of “two, stout, digitiform sponges, united below and torn off from at the base”. He also noted a “strongly developed” 1 mm thick ectosome, “very numerous, large, oval, vesicular cells containing a dark pigment in the form of well defined, coarse granules,” exactly as in the holotype of S. ariena sp. nov. and other specimens examined here. The oxeas in all New Zealand specimens are at least twice the length of those of A. simplex (2500 x 68 µm). We consider the Dendy and Bergquist specimens to be one and the same S. ariena sp. nov.

While S. ariena sp. nov. and S. levis sp. nov. have a similar form, the lobes of the latter species are broader, shorter and uncurved. The spicule complements separate the two species quite clearly; S. levis sp. nov. has dichotriaenes rather than plagiotriaenes, albeit, both are quite rare in the specimens, and S. levis sp. nov. lacks amphisanidasters.