Glyphodiscus pentagonalis, Mah, 2005

Mah, Christopher, 2005, A phylogeny of Iconaster and Glyphodiscus (Echinodermata, Asteroidea, Valvatida, Goniasteridae) with descriptions of four new species, Zoosystema 27 (1), pp. 137-161 : 148-150

Glyphodiscus pentagonalis n. sp.

( Fig. 3D, E )

HOLOTYPE. — South Pacific Ocean. SMIB 8 , banc Éponge (mont B), stn DW 146, 24°55.2’S, 168°21.7’E, 514-522 m, 27.I.1993, 1 specimen dry, R = 1.6 cm, r = 1.3 cm ( MNHN EcAs 11688).

PARATYPES. — New Caledonia. LITHIST, banc Stylaster, stn DW 01, 23°37.4’S, 167°42.1’E, 440 m, 10.VIII.1999, 1 specimen dry, R = 2.2 cm, r = 1.5 cm ( MNHN EcAs 11690). — SMIB 3, stn DW 05, 24°55’S, 168°22’E, 502-512 m, 21. V.1987, 1 specimen dry, R = 1.6 cm, r = 1.3 cm ( MNHN EcAs 11689). — BERYX 11, stn DW 27, 23°37’S, 167°41’E, 460-470 m, 18.X.1992, 1 specimen dry, R = 1.7 cm, r = 1.4 cm ( MNHN EcAs 11687). — SMIB 8, banc Éponge (mont B), stn DW 147, 24°54.9’S, 168°21.8’E, 508-532 m, 27.I.1993, 2 specimens dry, R = 1.4 cm, r = 1.2 cm, R = 1.2 cm, r = 1.1 cm ( MNHN EcAs 11694). — BATHUS 3, stn DW 819, 23 °45’S, 168°16’E, 478-486 m, 28 XI.1993, 1 specimen dry, R = 1.5 cm, r = 1.3 cm ( MNHN EcAs 11695).

ETYMOLOGY. — This species is named for its distinctive pentagonal shape.

DISTRIBUTION. — Currently known only from New

Caledonia. 460- 532 m.

Phylogeny of Iconaster and Glyphodiscus ( Echinodermata, Asteroidea)

Mah C.

DIAGNOSIS. — Pentagonal body with few, smooth marginal plates (≈ 4-6) in each interadii. Superomarginal plates at each arm tip triangular in outline, and directly abutting across arm.

APOMORPHY LIST. — 12, marginal plates elongate. 13, enlarged basal superomarginals. 27, arms short.

DESCRIPTION

Disk pentagonal. interradial arcs linear. Arms, short and stubby. Body, stout and flat.

Disk area pentagonal. Plates bare, flat. Surface ornamentation absent. Surfaces smooth. Plates more convex on papular regions along radii than on interradial regions of disk. Papular regions composed of six plates surrounding a single seventh plate in the center. Plates flanked at corners by papulae. Abactinals hexagonal to polygonal in shape, especially those around disk center. Plates more elongate, angular at contact between abactinal plates and superomarginal plates. Primary circlet plates at disk center enlarged, plates adjacent to contact with superomarginals smaller. Two enlarged heptagonal plates in each interradius. All plates with complete peripheral border of c. 20-60 granularrectangular plates. Plates adjacent to superomarginal surface with scattered pedicellariae. Madreporite triangular, flanked by three plates.

Approximately six marginals in smaller specimens (R = 1.0 cm) vs approximately eight superomarginal plates (R = 2.4 cm) in larger specimens. Typically about two superomarginals per interradius in specimens above R = 1.0 cm. Marginal plates smooth, devoid of surface ornamentation. Plates flat, largely smooth.

Superomarginals at base of arm enlarged and in direct contact. Shape, asymmetrically pentagonal. Enlarged plates approximately 1.5 times those of the interradial superomarginal plates. Superomarginal plates along arm are four-sided but roughly triangular in shape. No enlarged inferomarginals. Inferomarginals are roughly triangular in shape. All marginal plates bordered by a complete ring of rectangular accessories/granules similar to those of the abactinal and actinal surfaces. Inferomarginals smooth, flat.

Figures

FIG. 3. — A-C, Glyphodiscus magnificus n. sp., New Caledonia, paratype, dry (MNHN EcAs 11682); A, abactinal view; B, superomarginal plate shape; C, oral and adambulacral regions; D, E, Glyphodiscus pentagonalis n. sp., New Caledonia, holotype, dry (MNHN EcAs 11688); D, abactinal view; E, oral and adambulacral regions. Scale bars: A, 5.0 mm; B, D, 3.0 mm; C, 2.0 mm;