Circeaster kristinae, Mah, 2006

Mah, Christopher L., 2006, Phylogeny and biogeography of the deep-sea goniasterid Circeaster (Echinodermata, Asteroidea, Goniasteridae) including descriptions of six new species, Zoosystema 28 (4), pp. 917-954 : 936-938

Circeaster kristinae n. sp.

( Fig. 5 D-F)

HOLOTYPE. — Timor Sea/ Indian Ocean. NW Slope, 115 nautical miles NNW of Dampier , WA (Western Australia), 18°46’S, 116°24’E, no depth recorded, 1 dry spec, R = 12.1 cm, r = 3.4 cm ( WAM Z20711).

PARATYPES. — Timor Sea/Indian Ocean. Off Port Hedland, WA, 149 nautical miles NW, on mud, 18°43’S, 116°35’E to 18°43’S, 116°33’E, 612- 610 m, 7.IV.1982, 1 dry spec., R = 13.1 cm, r = 4.2 cm ( WAM Z20672). — 18°38’S, 116°52’E to 18°38’S, 116°54’E, 600- 594 m, 7.IV.1982, 1 dry spec., R = 12.3 cm, r = 3.9 cm ( WAM Z20694). — W of Roebuck Bay, WA on muddy bottom, 18°04’S, 118°14’E to 18°00’S, 118°19’E, 400- 396 m, 24.II.1984, 1 dry spec., R = 13.1 cm, r = 3.9 cm ( WAM Z20707). — NW of York Sound, WA, 12°54.4’S, 123°0.2’E to 12°50.6’S, 123°0.4’E, 452- 462 m, 15.II.1984, 1 dry spec., R = 13.3 cm, r = 4.2 cm ( WAM Z20708). — NW of York Sound, WA, mud bottom, 12°48.1’S, 122°56.7’E to 12°50.6’S, 122°55.2’E, 496-504 m, 15.II.1984, 1 dry spec., R = 14.5 cm, r = 3.4 cm ( WAM Z20709). — NW of Augustus Island, WA, on soft bottom, 13°17’S, 122°37.4’E to 13°18’S, 122°35.8’E, 494- 484 m, 15.II.1984, 1 dry spec., R = 10.1 cm, r = 3.3 cm ( WAM Z20712). — Off Port Hedland, WA, 124 nautical miles NNW, 18°20’S, 118°00’E to 18°19’S, 118°00’E, 320 m, 10.IV.1982, 1 dry spec., R ≈ 8.0 cm (arm broken), r = 3.2 cm ( WAM Z20713). — C. 123 nautical miles NNW of Dampier, 18°52’S, 116°00’E, 550 m, 14.III.1992, 3 dry specs, R = 12.3 cm, r = 3.3 cm, R = 11.4 cm, r = 4.6 cm, R = 12.9 cm, r = 3.6 cm ( WAM Z20722). — C. 123 nautical miles NNW of Dampier, WA, 18°48’S, 116°07’E, 555 m, 17.III.1992, 1 dry spec., R = 10.6 cm, r = 3.3 cm ( WAM Z20723). — C. 23 nautical miles NNW of Dampier, 18°52’S, 116°00’E, 550 m, 14.III.1992, 3 dry specs, R = 11.0 cm, r = 3.5 cm, R = 10.6 cm, r = 3.4 cm, R = 12.6 cm, r = 3.6 cm ( WAM Z20724). — C. 123 nautical miles NNW of Dampier, WA, 18°48’S, 116°07’E, 555 m, 17.III.1992, 1 dry spec., R = 11.1 cm, r = 3.6 cm ( WAM Z20725). — C. 150 nautical miles WNW of Port Hedland,WA, 18°00’S, 118°09’E, 545 m, 28.II.1992, 1 dry spec., R = 11.1 cm, r = 3.6 cm ( WAM Z20726).

ETYMOLOGY. — This species is posthumously named in honour of Dr Kristina Louie, UCLA.

DISTRIBUTION. — Central Pacific (Timor Sea) to Indian Ocean. 320- 610 m.

DIAGNOSIS. — R/r ≥ 4.0. Abactinal arm plates, enlarged, bare.Transition abrupt between arm, disk plates. Abactinal plates extend to arm tip. Marginal plates with scattered, rounded granules. Actinal plates with rounded granules, small paddle-like pedicellariae with sharp teeth. One to several subambulacral spines present between furrow spines and adambulacral pedicellariae.

APOMORPHY LIST. — Nodes 21 to 20: 2.1, SM granules present; 2.2, IM granules present; 3.1, actinal granules present; 3.2, actinal accessories angular; 6.3, interradial arcs, linear.

Nodes 21 to Circeaster kristinae n. sp.: 4.1, row of enlarged subambulacral spines.

DESCRIPTION

Body moderately thickened, disk small. Interradial arcs linear. Abactinal plates polygonal to round. Plates smaller centrally on disk; carinal series wide, enlarged, becoming 1.5-3 times size of central disk plates. Plates smaller, more polygonal with equal dimensions interradially, especially adjacent to superomarginal contact with disk surface. Plate surface convex to flattened.One to 30 coarse, hemispherical granules present on each plate. Granules smaller with greater abundance, larger with fewer abundance. Individual granules nearly tubercle-like in size. Granule abundance lowest (1-10 granules) on disk center, increasing at disk edge and base of arms (10-30 granules). Granules absent on distal abactinal arm plates but can extend midway on arm (c. 12 marginal plates from terminal). Arm plates enlarged, three to four times the size of central disk plates. Two or three series of plates on arm base, gradually decreasing to single series distally. Arm plates wide to quadrate. Some plates more irregularly polygonal. Some arm plates resemble disk plates in size. Most arm plates flattened, enlarged, some specimens (e.g., WAM Z20722) with one to six convex, wart, like carinal plates, often with large number of small granules (c. 20-30) relative to abundance of granules on other arm plates (approximately one to five).

Madreporite polygonal, low, convex, flanked by 8-10 abactinal plates.

Marginal plates, 50-70 (arm tip to arm tip), widest, most enlarged interradially, decreasing in size distally. Both series with blunt, curved dorsolateral edge. Both plate series with 40-90 bead-like to angular peripheral granules forming evenly spaced border around each plate. Straight to zigzag border between superomarginal, inferomarginal plate series.

Superomarginal plates low-convex in cross-section, corners, rounded to angular. Contact boundary with abactinal disk plates, straight to low-curved. Granules, coarse 1-40, typically 20-35, scattered, covering superomarginal plate surface. Granule abundance highest interradially, decreasing distally. Granules absent from 6-15th plates adjacent to terminal plate. Granules on superomarginal plate center, periphery of plate bare. Pedicellariae single, small, paddle-shaped, on lateral surface of superomarginal plate adjacent to inferomarginal contact. This area otherwise bare.

Inferomarginal edge rounded, plates low, convex. Contact boundary with actinal intermediate region, straight to low-curved. Granules, 1-55, typically 30-40, identical to those on superomarginals, scattered, covering inferomarginal plate surface. Inferomarginal granules densely packed with greatest abundance interradially, decreasing distally. Greater numbers of granules on interradial inferomarginals (c. 50 granules) compared to corresponding superomarginals (c. 35 granules). Granules absent from six to 15th plates adjacent to terminal plate. One or two paddle-like pedicellariae identical to those on superomarginal plates on periphery of inferomarginal plate adjacent to actinal intermediate region.

Actinal region composed of six or seven chevrons. Actinal plates rounded-polygonal, largest on chevron adjacent to adambulacral plate series, decreasing in size closer to actinal/inferomarginal boundary. Grooves shallow. Actinal plate surfaces covered by 2-12 scattered, hemispherical granules and/or single, large bivalve pedicellariae with three or four teeth. Actinal regions otherwise bare. Granule density increases closer to inferomarginal plate contact, replaced by pedicellariae closer to mouth plates. Five to 25 angular to polygonal granules forming discrete, well-spaced boundary around each plate.

Furrow spines, six to nine, flattened, polygonal to angular in cross-section. Furrow spines decrease in number distally. Peripheral granules and furrow spines with roughened furrow tips. Discrete gap located between furrow spines and individual, large bivalve pedicellariae. One or two enlarged subambulacral spine present adjacent to furrow spines and pedicellariae. Adambulacral plate covered by 5-20 angular granules some with roughened tips cover remainder of adambulacral plate, forming border around adambulacral plate. Furrow spines on mouth plate, 15-25 flattened, polygonal to angular in cross-section. Spines on mouth plate tip triangular in cross-section. Pedicellariae, large, identical to those on adambulacrals, one or two, on mouth plates. Mouth plate surface and peripheral border covered by 12-25 angular, polygonal granules with roughened or jagged tips. Granules enlarged angular 8-10, with tips roughened, form border along mouth plate suture.

Figures

FIG. 5. — A-C, Circeaster arandae n. sp. (MNHN EcAs 11727); A, abactinal surface; B, actinal surface; C, abactinal arm disk surface; D-F, Circeaster kristinae n. sp. (WAM Z20694); D, abactinal surface; E, abactinal arm-disk surface; F, actinal surface. Scale bars: A-E, 1.0 cm; F, 0.5 cm.