Kampylaster tumulus n. sp.

FIGURE 8A–E

Etymology

The species epithet tumulus is taken from the Latin for “mound” alluding to this species’ mound-like resemblance.

Diagnosis

Body thick, broadly mound-shaped, weakly stellate (R/r=1.3–1.6). Surface covered by coarse, round granules, approximately 3 counted along a 1.0 mm line (Fig. 8A). Granules, enlarged cylindrical (bullet) shaped, 3 to 4 at R>1.0 cm, along edge of the inferomarginal plates (Fig. 8D, E). Transverse furrow spine series, 3 to 6, spines widely spaced. Most showing 4 to 5 but approaching 6 spines in larger individuals (R=1.6) (Fig. 8E).

Comments

This species shares several characters, including the bullet-shaped granules on the marginals, a more angular actinolateral edge, and furrow spine number, with Kampylaster claireae suggesting closer relationship between the deep-water species than with the shallower Kampylaster incurvatus .

Occurrence

South Atlantic Ocean (−63.05, −14.53), 1000–2000 m.

Description

Individuals weakly stellate (R/r=1.2–1.4), interradial arcs acute, Body thick and strongly arched (Fig. 8A).

Abactinal plates flattened, imbricate, round to polygonal proximally becoming more scale-like distally (Fig. 8A, B). Primary plates flat to weakly convex. Abactinal plates largest proximally smaller and more numerous distally, especially around arm tips. Transition in size between disk and arms abrupt. Granules round, coarse present as continuous cover over abactinal surface, obscuring plate boundaries in uncleaned specimens. At R=1.1, approximately 3 granules are counted along a 1.0 mm line, smaller individuals with smaller granules. Madreporite covered and obscured by granules, weakly defined with a single sinusoidal sulcus. No papulae observed.

Marginal plates approximately 12 to 14 per interradius (arm tip to arm tip) at R= 1.1 cm, up to 16 per interradius at R= 1.6 cm. Each plate block-like in shape (Fig. 8B), thick forming approximately 20% of distance between center of oral surface and interradial edge. Observed externally, marginal outline is broadly quadrate, corners rounded. Largest interradially, decreasing in size distally. Superomarginals in direct 1:1 correspondence with inferomarginals, superomarginals larger than inferomarginals. Granules cover both marginal plate series, obscuring plate boundaries up to actinolateral edge. Inferomarginals each with 3 to 5 bullet-shaped granules forming a distinct series along the actinal edge of the inferomarginal plate (Fig. 8D, E). Granules abruptly absent at actinolateral edge of inferomarginal plate.

Granules absent from actinal surface, actinal surface composed of plates embedded in dermis at relatively small sizes (R=1.3). When tissue is hydrated one or two plates are observable at center of actinal intermediate region. At larger sizes (R>2.0) actinal plates more prominent with 1 to 3 spines per plate (Fig. 8C, E).

Furrow spines, separate (no web), elongate and blunt, 3 to 7 in transverse palmate arrangement at oblique angle to furrow (Fig. 8D, E). Mostly 4 to 5 at R= 1.1 cm, 6 in larger individuals (R= 1.6 cm). Oral plates with 3 to 4 furrow spines or a single or absent spine on its surface.

Material Examined

Holotype. USNM 1662075, South Atlantic Ocean, −63.05, −14.53, 1000–2000 m. Coll. R/V Eltanin, USAP, 23 Feb. 1966. 1 dry specs. R=1.9 r=1.6.

Paratypes: USNM 1122407, South Atlantic Ocean, −63.05, −14.53, 1000–2000 m. Coll. R/V Eltanin, USAP, 23 Feb. 1966. 3 dry specs. R=2.2 r=1.5, R=1.3 r=1.0.

USNM 1082897, Antipodes Island, New Zealand, South Pacific Ocean . −49.85, −178.575, 2010–2100 m. Coll. R/V Eltanin, 26 Feb. 1968. 1 dry spec. R=0.9 r=0.8 .