Stelletta ovalae Tanita 1965

Stelletta ovalae Tanita 1965

(Fig. 2)

Material examined. ZSM 20140112, specimen in ethanol, collected by Robert Stone with a camera array towed from the FV Sea Storm; 8 August 2012, 177 m depth, 4 km NNE of Bishop Point, Unalaska Island, eastern Aleutian Islands, Bering Sea (54°00.499” N, 166°56.136” W). Attached to a large cobble. Bottom water temperature = 4.2 °C.

Description. Globular, in life and in ethanol creamy white sponge (32 mm x 29 mm x 28 mm) with a strongly hispid surface due to long spicules, protruding up to 13 mm above the surface (Fig. 2A, right). Spicules and spicule mat are light brown in color possibly due to sediment and biofoulants (Fig. 2A). A large patch of the upper surface is without protruding spicules (Fig. 2A), probably lost due to abrasion during collection. Consistency is hard, there are no oscules or surface pores visible. Conical, polyspicular tracts of triaenes and oxeas start with the narrow end in the choanosome, getting broader towards the surface. They protrude through the cortex and reach above the surface with the clads of the triaenes facing out. The cortex appears brown under the microscope and is a thin membrane, 15–40 µm in diameter with oxyasters distributed within the membrane. Spicules consist of dichotriaenes, straight rhabds, 4500–5600 x 180–230 µm, clads 380–525 x 180–225 µm per ray; long oxeas 8000–10,500 x 18–38 µm, large oxyasters with conical, blunt rays 18–24 µm in diameter and small oxyasters, 9–12 µm in diameter. The basal part of the sponge with long, thin anatriaenes among the protruding spicules, rhabds, 2300– 6400 x 40 –70 µm, clads 35–78 x 34 –56 µm.

Discussion. Tanita 1965 reported only one category of oxyasters, 14–18 µm in diameter but Tanita & Hoshino 1989 report two categories, 20–25 µm and 10 µm in diameter. The description and measurements of Tanita & Hoshino, 1989 fit very well to the specimen we describe here (Table 1). This species was previously known only from the Sea of Japan at a depth of 70 m. This is the first record of the species from Alaskan waters and a range extension of more than 4600 km.