Stelletta anthastra Lehnert & Stone, 2014, n. sp.

Stelletta anthastra n. sp.

(Fig. 3)

Material examined. Holotype, USNM 1231429, in 70% ethanol, fragment of the holotype (ZSM 20140114), in 70% ethanol. Collected by Brian Knoth with a research survey bottom trawl from the FV Ocean Explorer; 17 June 2012, 225 m depth, 19.8 km WNW of Carlisle Island in the Islands of Four Mountains, eastern Aleutian Islands, Bering Sea (52°58.542” N, 170°23.322” W). Attached to a mass of sand and pebbles. Bottom water temperature = 3.9 °C.

Description. Large, massive, whitish (in life), ovoid sponge, approximately 18.5 cm x 15 cm x 12 cm, hard, only slightly elastic consistency, no oscules visible. The surface is covered by many low elevations, similar to a cauliflower (Figs. 3A & B). Many small openings are visible under low magnification (16 X). We are not sure whether these openings are pores or oscules but they are ungrouped and scattered over the entire surface without any obvious pattern. In sections perpendicular to the surface the radial arrangement of polyspicular tracts, consisting of different triaenes and oxeas is visible with the unaided eye (Figs. 3B–D) as the tracts are 4–5 cm long. These tracts start in the interior with a diameter of 1 mm and fan out at the surface to a diameter of 4–10 mm and support the surface elevations which have the same diameters and height of 2–4 mm. The cortex is 8–10 mm below the surface (Fig. 3D). Spicules are ortho- to plagiotriaenes (Fig. 3E), straight rhabds, 680–910 x 112–115 µm, recurved clads, 480–500 x 90 –100 µm, occasionally with one or two reduced clads; very long, thin anatriaenes (Fig. 3F), up to 19,000 x 30 µm and a short cladome with clads, 180 x 20 µm, oxeas, 9500–11,900 x 50 –120 µm, oxyspherasters (Figs. 3G–H), the distal end looks inflated because of a concentration of spines there, 14–20 µm in diameter, and anthasters (Figs. 3I –J) with spiny ends of rays, 5–8 µm in diameter.

Discussion. Stelletta anthastra n. sp. differs from all other known species of Stelletta (Table 1) and differs from S. makushina n. sp. in having shorter triaenes, extremely long anatriaenes up to 19 mm in length, much longer oxeas, larger, differently shaped oxyasters and an additional category of anthasters. S. ovalae Tanita 1965 also has very long megascleres but it differs in having dichotriaenes lacking in S. anthastra and in the categories of asters. S. ovalae has two size categories of oxyasters while S. anthastra has one category each of oxyaster and anthaster. S. rhaphidiophora Hentschel 1929 (Table 1) also has very long megascleres but differs in having dichotriaenes, a second category of oxyasters instead of the anthasters present in S. anthastra, and in having bundles of rhaphids. S. splendens Tanita, 1965 is the only other species of Stelletta where “three-rayed” anthasters are described with spiny rays, 95 x 25 µm. These clearly differ in size and dimensions from the anthasters described here. We question whether the three-rayed anthasters described for S. splendens are indeed anthasters.

Etymology. Named after the beautiful anthasters that occur in this species.