Ophiomidas aurum, Mcknight, Donald G., 2003

Mcknight, Donald G., 2003, New brittle­stars (Echinodermata: Ophiuroidea) from New Zealand waters, Zootaxa 352, pp. 1-36 : 29

Ophiomidas aurum n.sp. Fig. 5 : C, D.

Material examined: NIWA Stn I25 (1).

Depth Distribution: 675 m.

Geographic Distribution: This species is recorded from off the east coast of northern New Zealand.

Description: Disc diameter 4.5 mm, maximum arm length 7.5 mm. Disc round, margin vertical, disc flat above and below. Dorsal surface covered by thin, imbricating plates, variable in shape and size, primaries not prominent. Radial shields longer than wide, extending inwards for almost 1/3 disc radius, with rounded inner and outer ends; separated throughout by 2–3 plates in a single row, these decreasing in size distally, so that distal ends of the shields are almost in contact; shields of two pairs are equal, in another one is larger, and in the other two one shield is in 2 pieces. A large plate lies at the interradial margin and has a few small, scattered granules in it; granules may extend to the outer corners of the radial shields. Ventral interradial area small, with a few small thin plates, and with scattered small granules. Oral shield relatively large, 4­sided and longer than wide, widest just proximal to mid­length, pointed proximally and laterally, distal margin straight. Adoral shields lie more or less proximal to oral shields, short and do not taper. Oral plates with a single pointed apical papilla at jaw tip and 5–6 oral papillae on side of jaw; inner pointed, smaller than apical papilla, rest increasingly rounded or leaf­like, and becoming slightly larger distally. The genital clefts short, on ventral surface, lying under enlarged first lateral armplate, which conceals them from view.

Arms wider than high, very gently tapering. First dorsal armplate straight proximally, distal border rounded; rest triangular, acutely pointed proximally, and longer than wide, increasingly separated form the third or fourth. Lateral armplates prominent in dorsal view, with 3 short stubby slightly appressed armspines, about equal to 1/2 an arm segment in length. First lateral armplate is broadened and is longer than the others, visible only in ventral view, truncate distally and projects slightly to more or less embrace the oral shield but does not cover the entire interradius. Ventral armplates triangular, first is truncate proximally, others are increasingly separated from the third, becoming very small distally. Tentacle­pores quite prominent, with a single rounded tentacle­scale on proximal margin; pore is spaced from the lowest armspine.

Colour: (Preserved specimen) uniform creamy­white above and below.

Etymology: aurum , the metal King Midas desired.

Holotype: Deposited in the NIWA collections, Wellington No. H­828 (Stn I25).

Remarks: This species, the third known, can be distinguished from both O. alatum Koehler and O. reductum Koehler in having small granules at the margin and ventrally, a four­sided oral shield and in having 3 armspines.

Figures

FIGURE 5: Ophiocten cryptum n. sp. holotype, disc diameter 7.5 mm. A: dorsal, B: ventral. Ophiomidas aurum, n. sp. holotype, disc diameter 4.5 mm. C: dorsal, D: ventral. Ophiophyllum teplium n. sp, holotype, disc diameter 7 mm. E: dorsal, F: ventral.