Radiella endeavourensis Austin, Ott, Reiswig, Romagosa & G, 2014, n. sp.

Radiella endeavourensis n. sp.

Fig. 11 A–H

Etymology. The species is named after Endeavour Ridge, the site of hydrothermal vent systems off Washington and British Columbia, where the holotype was collected.

Material examined. Holotype: RBCM 009-00052-001, sta, A1448, Endeavour Ridge, BC /Washington, (approx. 47° 42′N, 129° 13′W), 2500 m depth, May 4, 1984, coll. V. Tunnicliffe, 1 specimen.

Description. Macroscopic features. (Fig. 11 A, B). Sponge size 11.1 x 7 x 6 mm high. Form: subspherical, upper surface convex, lower surface concave. Three or more conical fistulae range from 0.2–1 mm in diameter and 0.2–1.5 mm in height. Spicule tracts radiate to and along the fistulae. Main body of the sponge hispid with spicules extending beyond the surface 0.5–0.9 mm. Preserved sponge firm but compressible. Colour in life unknown; colour in alcohol variegated brown with white papillae and a white fringe around the base.

Microscopic features (Fig. 11 C, D). Ectosome up to 2 mm thick. Low density portion up to 1 mm thick adjacent to the choanosome; largely supported by relatively few spicules (fusiform tylostyle type II) with no particular orientation. Periodically multispicular tracts 0.2–0.3 mm in diameter with tangentially aligned (sub)tylostyles I radiate from the choanosome to a layer of short fusiform tylostyles II which form a palisade at right angles to the surface, and are disposed randomly throughout the sponge. Some subtylostyles extend beyond the surface as noted above. A layer of straight, thin subtylostyles radiates out from the center of the lower surface where it forms a thatch.

Spicules. Spicules are composed of three types: 1) Principal tylostyles (I) fusiform, bent on the long axis, typically tylote but may be subtylote with ovoid heads; 2) Smaller fusiform tylostyles (II); 3) Straight, thin subtylostyles up to 2.6 mm long (many broken and could have been longer). Only 10 unbroken subtylostyles were found.

Holotype RBCM 009-00052-001 Remarks. Our sponge fits the diagnosis for Radiella (synonym Trichostemma) (Boury-Esnault 2002). Given that Radiella spp. are deep water, we compared our specimen with known species from all oceans (Table 8). Character sets are based on: R. sarsii (Plotkin 2004, Uriz & Rosell 1990); R. sol. (Boury-Esnault 2002); R. hemisphaericum (Koltun 1966, Plotkin 2004); R. straticularis (Wilson 1925); R. irregularis (Ridley & Dendy 1887); R. antarctica (Plotkin & Janussen 2008); R. endeavourensis n. sp. (Austin et al.) this paper.

Table 8 compares Radiella species. Not included in Table 8 are: Radiella conica (Hansen 1885) and R. alvea (Hansen 1885) as there is insufficient information about them (Atlantic Arctic).

In comparing our specimen from Endeavour Seamount with other species we note the following:

• Our multi-oscular specimen differs from two species with a single osculum: R. sarsii and R. antarctica. • Our specimen has minimum size ectosomal tylostyles of 360 Μm compared to minimal sizes ranging from 125–290 Μm in four other species where there are measurements (R. antarctica, R. hemisphaericum, R. sarsii, and R. sol).

• Our specimen has spicules both randomly arranged and clearly radially arranged in the choanosome compared to only randomly arranged in two other species (R. sarsii, R. irregularis).

• Our specimen has only two layers in the ectosome compared to three layers in R. straticularis.

Conclusion. The four features noted in our specimen are not found together in any other adequately described species. Ideally more specimens would help to identify infraspecies variability. Also, more characters could be assessed by looking at types for several species which were poorly described in the 1880s. However, at this time we propose that our specimen be considered a new species, R. endeavourensis.

Bathymetric range. 2500 m depth.

Geographic distribution. Endeavour Ridge, 47° 42′N, 129° 13′W. This constitutes the first record for a Radiella sp. from the NE Pacific.

Ecology. There is no substrate information on the single specimen we examined. The sponge was not attached to anything when collected.