Cladaster kiko, Mah, 2024

Mah, Christopher L., 2024, New genera and species of deep-sea Goniasteridae (Asteroidea) from the North Pacific, Zootaxa 5543 (4), pp. 451-500 : 470-472

Cladaster kiko n. sp.

FIGURE 6A–F

Etymology

The species epithet is named for the word kiko , the Hawaiian word for “point or tip” alluding to the elongate and pointed furrow spines.

Diagnosis

Cladaster with two long curved and flattened furrow spines and an enlarged, thickened subambulacral spine.

Superomarginals 13–14, inferomarginal plates 19, distalmost superomarginals abutted, pre-terminal superomarginal and inferomarginal plates, strongly convex.

Comments

Cladaster kiko n. sp. differs most markedly from C. rudis and C. katafractarius which both have multiple pairs of superomarginal plates abutted along the arm, three in the former, four in the latter. C. katafractarius also has four furrow spines as opposed to the two in C. kiko n. sp.

Cladaster analogous and the North Pacific C. validus share several characters with Cladaster kiko n. sp. including the presence of an enlarged single subambulacral spine and two or three furrow spines. C. analogous has three thick, blunt furrow spines proximally becoming two distally whereas C. validus has two spatulate furrow spines through the series on its arm. However both of these species have raised platform like regions on their superomarginal plate surfaces whereas those on C. kiko n. sp. are flat with no raised areas. Furrow spines on C. kiko are also curved and have a narrowed and pointed tip whereas those in C. validus are blunt and thickened.

Cladaster kiko n. sp. is among the most deeply occurring of the known Cladaster species, which are known primarily from between 100– 600 m. C. analogus has been collected from 1647–2044 m (Mah 2011).

Occurrence

North Pacific, 1199 m.

Description

Body stout, stellate/weakly stellate ( R /r=1.96), interradial arcs curved, armtip pointed ( Fig. 6A, E ).

Abactinal plates round, oval to irregularly round or even triangular in shape, each plate weakly convex, shallow fasciolar grooves ( Fig. 6D ). Plates larger proximally, becoming smaller distally adjacent to the superomarginal contact. Abactinal plates on disk and on arms up to abutted pre-terminal superomarginal plates. Each plate covered with distinctly, round granules, 10–20 ( Fig. 6D ). Peripheral granules with pointed tips, bullet-shaped, even and widely spaced, 3 to 7 per side. Granules on central plate surface more rounded, without tip, 1 to 8, widely spaced. Abactinal plate surface otherwise smooth, bare. Granules readily abraded, when removed leaving convexity on plate surface. Papulae present only on most abactinal surface approximately six around each plate, with approximately two or three single papulae per side. Madreporite triangular, flanked by three plates, well-developed sulci. No pedicellariae.

Superomarginals 13 to 14, inferomarginals 19, interradial marginal plates with 1:1 association, but offset distally along arms. Individual superomarginal plates wide (W>L), with convex surface, rounded dorsolateral edge. Inferomarginal plates more flattened but with rounded actinolateral edge. Superomarginals with cylindrical to pointed easily abraded granules 20–40, mostly 15–20, widely spaced on smooth surface with convexities on plate surface ( Fig. 6C, D ). Granules producing a superficial spiny layer over the abactinal/marginal plate surface. Pre-terminal superomarginal plates abutted over midline, strongly convex. Inferomarginal plates adjacent to the terminal plates much more convex than those along the arm, interradially. Granules most abundant on dorsolateral-lateral surface with proximal surface with fewer granules. Peripheral granules, 40, 10–15 per side, each round in shape, widely spaced. Shallow fasciolar groove present between marginal plates. Inferomarginal plates surface with 30–40 abundant, round granules, widely spaced. Peripheral granules 40–60, approximately 10 per side.

No pedicellariae. Terminal plate spherical with 2 to 4 granules on surface adjacent to pre-terminal.

Actinal surface with 1 to 2 full series with some irregular plates present distally adjacent to inferomarginal contact. Individual plates round variably oval to more oblong. weakly developed fasciolar grooves. Actinal plates covered with 6 to 20 pointed bullet-like granules, but easily abraded, leaving shallow convexities on actinal plate wall. Granules widely spaced. Peripheral granules also bullet-like close to widely spaced, approximately 3 to 6 per side. A single pedicellariae one to three present in three of the four actinal intermediate regions.

Adambulacral plates with three to four furrow spines, two with flattened, elongate, distinctly curved, blade-shaped furrow spines with the remaining spines, much shorter, approximately 10% of the length of the elongate spines ( Fig. 6F ). One or two large subambulacral spines, blunt, the largest was twice as thick as the furrow spines, elongate equal in length to the furrow spines. Remaining subambulacral surface with 6 to 8 granules, rounded to pointed in shape; two to three large pointed spines, three times as thick as the furrow spines but similar in size/shape to the granules on the actinal surface. Oral plates with three flattened, elongate blade-shaped furrow spines with the longest elongate spine projecting into the mouth. Four enlarged, elongate spines present on the oral plate surface (these equivalent to the subambulacral spines), with six to seven pointed granules present along the side of the fossae present between the two halves of the oral plate.

Living color was white ( Fig. 6B ).

Material Examined

Holotype. MCZ 162797 North Pacific Ocean , 32.572876 ° -175.059768 °, 1199 m. Coll. E/V Nautilus , 14 April 2022. 1 wet spec. R=5.5 r= 2.8 cm .

Figures

FIGURE 6. Cladaster kiko n. sp. MCZ 162797. Holotype. A. Abactinal B. In situ observation. C. Abactinal-lateral view. D. Abactinal-lateral view showing abactinal and superomarginal surface. E. Actinal F. Adambulacral plates showing large furrow spines. Scale bar=10.0 mm, A, E; Scale bar=5.0 mm: C, D; Scale bar=1.0 mm: F.