Ophiura (Ophiuroglypha) verrucosa, Mcknight, Donald G., 2003

Mcknight, Donald G., 2003, New brittle­stars (Echinodermata: Ophiuroidea) from New Zealand waters, Zootaxa 352, pp. 1-36 : 26-27

Ophiura (Ophiuroglypha) verrucosa n.sp. Fig. 3 : E, F.

Material examined: NIWA Stns P940 (2); U226 (11).

Depth Distribution: 2092–2421 m.

Geographic Distribution: This species is recorded only from the Tasman Basin, near the western margin of the Lord Howe Rise,

Description: Holotype, NIWA Stn U226: disc diameter 17 mm, arms broken, longest at about 38 mm. Disc pentagonal in outline, inflated above, especially at arm bases, flat below. Dorsal surface of disc covered with distinct plates slightly spaced apart; they are irregular in shape, mostly flat­topped and with angular outlines, the surface very finely rugose; some smaller plates almost tubercular. Centrodorsal evident, rounded­pentagonal; probable radial plates present at about 1/2 disc radius. Radial shields a little lower than other plates, somewhat longer than wide, slightly divergent and with rounded margins. Shields extend usually with 1–3 swollen areas or broad low tubercles near distal end inwards for about 1/3 disc radius, separated by 3 plates proximally, one distally. Usually no enlarged plate at or on interradial margin. Surface of disc between plates is finely rugose. Ventral interradii with similar small scales, most convex and imbricating. The genital scale narrow throughout. Genital clefts extend nearly from distal margin of oral shield to margin, interradial border with a continuous series of low, block­like papillae, becoming longer distally; dorsally forming an inconspicuous armcomb of flat, blunt short spines; combs of opposite sides quite widely separated. Oral shields wider than long, with an obtuse proximal point and a slightly convex distal margin, lateral margins are almost parallel, slightly constricted near distal margin at start of genital cleft. Adoral shields meet within, extending distally to lateral angles of oral shield, separating it from first lateral armplates, shields slightly widened distally. Adoral shields may rarely be in 2 pieces, outer much the smaller. A small transverse plate (?ventral end of dental plate) is present at the tip of the oral plates. Oral plates with 7–8 oral papillae; proximal is usually pointed, others flat and blunt­tipped, distal 1–2 slightly enlarged. A single pointed, flat apical papilla at tip of jaw; teeth blunt­tipped. Second oral tentacle­pore opens outside oral slit, 6–7 flat, blunt papillae on outer margin, 9–11 on inner, almost confluent with oral papillae, distalmost enlarged.

Arms distinctly higher than wide at base, carinate throughout. Dorsal armplates in contact throughout, wider than long from fourth or fifth; outline of plates is that of a truncate triangle, widest distally; plates are carinate, with a keel and with distal margin flaring and thickened in large specimens; occasional plates are shorter and irregular; in lateral profile arms are strongly serrate. Lateral armplates with slightly swollen upper margin; first lateral armplate with 2 short, bluntly pointed spines, second with 3, both segments are within disc and spines are adjacent to tentacle scales; beyond disc usually 3 short spines, upper near dorsal margin of plate, lower 2, near tentacle­scale; distal margin of plate is usually convex between upper and lower spines; more distal middle armspines become curved, forming a slight though distinct hook.

Ventral armplates separated and wider than long from about disc margin, the fourth or fifth plate; first and second plate are truncate proximally, third to fifth have a distinct proximal point, with concave margins, and broadly rounded distally; on more distal joints the proximal point becomes small, and plates have marked sharp lateral angles. First 3–4 tentacle­pores large and conspicuous, fifth is smaller, beyond they appear to be absent; larger pores have 5 short, flat blunt­tipped scales on outer margin, 3–4 shorter scales on inner margin; inner scales disappear by third pore; outer scales are more or less aligned with lower armspines, but are clearly shorter and flatter. At distal margin of large tentacle­pores is an enlarged tentacle­scale, extending from ventral to lateral armplate. Beyond fifth to seventh arm segment, where tentacle­pores are absent or minute, there is 1, sometimes 2 very small flat scales adjacent to lowest armspine and supplementary scale is absent.

Colour: (preserved specimen) Uniform creamy­white above and below.

Etymology: verrucosa , referring to the warty dorsal disc surface.

Holotype: Deposited in the NIWA collection, Wellington No. H­826 (Stn U226).

Paratypes: Deposited in the NIWA collection, Wellington No. P­1378 (Stn U226).

Remarks: In having abruptly raised dorsal disc plates this species is similar to O. rugosa (Lyman) , but differs in having a serrate arm profile and entirely separated radial shields, even in the smallest specimens with disc diameters of 7 and 9 mm; and has numerous disc plates; both O. carinifera (Koehler) and O. lymani (Ljungman) have carinate arms, though scarcely serrate in profile, and they lack raised disc plates separated by deep grooves. The other species referred to the genus have relatively smooth dorsal disc surfaces and rounded arms.

Figures

FIGURE 3: Amphiophiura bakeri n. sp. holotype, disc diameter 9.5 mm. A: dorsal, B: ventral; paratype, C: dorsal (SEM), D: ventral (SEM). Ophiura (Ophiuroglypha) verrucosa n. sp. holotype, disc diameter 17 mm, E: dorsal, F: ventral.