Ophiophycis johni, Mcknight, Donald G., 2003

Mcknight, Donald G., 2003, New brittle­stars (Echinodermata: Ophiuroidea) from New Zealand waters, Zootaxa 352, pp. 1-36 : 18-19

Ophiophycis johni n. sp. Fig. 4 : C, D, F.

Material examined: NIWA Stns R435 (11); R439 (1).

Depth Distribution: 985–1000 m.

Geographic Distribution: This species is only known from off Hawke Bay, on the east coast, North Island, New Zealand.

Description: Holotype, NIWA Stn R435: disc diameter 5.5 mm, arms broken, longest at about 4 mm. Disc pentagonal, inflated dorsally, flat ventrally.

Dorsal surface of disc covered by 16 plates; most are swollen or almost tubercular, especially at their distal ends. Centrodorsal more or less stellate, with a tubercle at centre, and 5 radiating swollen interradial ridges; surrounding centrodorsal are 5 more or less spearhead­shaped radial plates about as wide as long or slightly longer, pointed proximally, distal margin swollen with 3 tubercles, higher than succeeding plates, the central tubercle separating proximal ends of radial shields. Radial shields blunt proximally and distally, longer than wide, each pair united for most of length and swollen along union; each shield may be swollen along midline. Two interradial plates lie outside the ring of radial plates; first is longer than wide, spear­head shaped and widest proximally, with concave lateral margins, rarely plate is divided into 2; marginal plate ovoid, much wider than long, spanning most of interradius, swollen and conspicuous. Ventral surface of disc with 3 plates distal to oral shield; 2 elongate plates just behind shield, and a small plate, pointed proximally, rounded distally that extends to margin, flat on outer end which projects between armspines of the second lateral armplates. This plate at margin appears to be ventral surface of dorsal marginal interradial plate. Oral shields small, more or less triangular; adoral shields larger, meet broadly within. Oral plates with a low ridge of fused papillae along most of oral slit, with a separate small, pointed papilla proximally; a slightly larger apical papilla at tip of jaw; teeth not visible.

Arms wider than high at base, flattened, tapering abruptly from base. Dorsal armplates present throughout broken arm, first 2 contiguous, others separated; first dorsal armplate separates outer ends of radial shields, and is swollen, almost tubercular; second plate is subrectangular, wider than long, first 2 plates together form a triangle, a little wider than long; third plate is a truncate triangle, with base distal, separated from second; other plates are small and broadly triangular, well separated. One specimen has 12 free arm segments, with dorsal armplates present on the proximal 9. First lateral armplate confined to ventral side of disc, second pair just meet proximal to third dorsal armplate, widest at outer margin; others meet broadly on dorsal surface of arm; plates have 3 (sometimes only 2) flattened armspines; plates of arms with 3, then 2 very short, pointed, rounded armspines. On ventral surface, first lateral armplate nears margin but does not reach it, and has 2 small, flattened spines whose outer ends extend just past distal ends of interradial plates; other plates reach margin, the fifth pair of laterals are the first united for more than 1/2 length on ventral midline. Ventral armplates separated throughout, decreasing in size from the first, and are minute triangles from the seventh; proximal 6 plates are longer than wide, pointed proximally and distally, laterally excavate besides tentacle­pore; plates become wider distally from the second. Tentacle­pores conspicuous, present by 7 basal ventral plates, tentacle­scale single, flattened, slightly pointed distally.

Colour: (Preserved specimens) uniform white, on both dorsal and ventral surfaces.

Etymology: This species is named for Mr John Mitchell, NIWA, for introducing me to seamount mapping.

Holotype: Deposited in the NIWA collection, Wellington No. H­823 (Stn R435).

Paratypes: Deposited in the NIWA collection, Wellington No. P­1375 (Stn R435).

Remarks: O. johni differs from all others in the genus in having the disc plates swollen, the centrodorsal stellate, with the rays swollen. The radials are pointed proximally and have a distal tubercular region. Almost all plates have a finely granular appearance due to glassy inclusions in the plates and the sutures are commonly difficult to see.

Figures

FIGURE 4: Ophiophycis richardi n. sp. holotype, disc diameter 4 mm. A: dorsal, B: ventral, E: armbase (SEM). Ophiophycis johni n. sp. holotype, disc diameter 5.5 mm. C: dorsal, D: ventral, F: armbase (SEM).