Ophioderma bonaudoae, Martínez, Sergio & Del, Claudia J., 2008

Martínez, Sergio & Del, Claudia J., 2008, A new, first fossil species of Ophioderma MHller and Troschel, 1842 (Echinodermata: Ophiuroidea) (Late Miocene, Argentina), Zootaxa 1841, pp. 43-52 : 47-48

Ophioderma bonaudoae new species

Plate 1, figs. A–G

Diagnosis. Large Ophioderma with proximal dorsal arm plates arched, entire or irregularly fragmented in two or three parts; lateral arm plates with four or five short, flat spines of similar length with a finger-like outline.

Description. Disk outline pentagonal, interbrachial outline straight. Ventral surface not fully preserved. Dorsal surface with very small scales, larger distally, covered by small rounded granules. Radial shields ovate, granules do not cover them but taking into account the preservation, radial shields could have been covered. Arms broadly rounded near the disk, more rounded distally; ventrally flat, and with dorsal midline angular to rather sharply angular proximally, becoming flatter distally. At base, arm diameter is around 1/4 of disk diameter, and taper gently. Proximal dorsal plates sometimes irregularly fragmented in two or three parts. Ventral arm plates pentagonal, wider proximally (visible as hexagons) than distally (visible as quadrangles). Convex lateral plates bear five (four distally) small, not reaching the next distal joint, flattened, addpressed spines, with a finger-like outline. Spines are of similar length, or the dorsal one is a little smaller. Two flat tentacle scales, the ventral one largest. Buccal elements not preserved, except the hemi-mandibles and an oral shield (paratype). The oral shield is broadly rounded, the lateral margins converge gently to the mouth, and the proximal side is nearly straight.

Dimensions. Holotype, disk diameter: 29 mm, arm base diameter: 7 mm; Paratype, disk diameter: 24 mm, arm base diameter: 6 mm.

Type material: Holotype CNP-PIIc 00233, Paratype CNP-PIIc 00234

Etymology. Dedicated to María Sol Bonaudo, who collected both specimens.

PLATE 1. Ophioderma bonaudoae n.sp. A. Dorsal view of Holotype CNP-PIIc 00233.. Scale bar: 10 mm. B. Arm base of Holotype CNP-PIIc 00233. Scale bar: 10 mm C. Lateral view of arm of Holotype CNP-PIIc 00233. Scale bar: 1 mm. D. Arm base Holotype CNP-PIIc 00233. Scale bar: 10 mm. E. Ventral view of Holotype CNP-PIIc 00233. Scale bar: 10 mm F. Dorsal view of Paratype CNP-PIIc 00234 Scale bar: 10 mm. G. Ventral view of Paratype CNP-PIIc 00234. Scale bar: 10 mm.