Renetheo felli, Mcknight, Donald G., 2003

Mcknight, Donald G., 2003, New brittle­stars (Echinodermata: Ophiuroidea) from New Zealand waters, Zootaxa 352, pp. 1-36 : 7-9

Renetheo felli n.sp. Fig. 2 : A, B, C, D.

Material examined: NIWA Stns E864 (2); G1 (1); P1 (3); P2 (6); P5 (2); P6 (3 arms); P7 (13); Z9044 (6).

Distribution: This species is recorded from the Wanganella Bank and near the Kermadec Islands, to the north of New Zealand, 122– 307 m.

Description: Disc diameter about 1.2 mm, arms at least 25 mm long (surely much longer), usually coiled or twisted; disc flat above and below, interradii slightly concave. Disc covered by skin often with stubby, very thorny spinelets, though these may be sparse or absent on individual specimens. Ventral surface of disc very small, oral shield mainly marginal, small, pointed proximally, widened to a rounded distal margin, just longer than wide; madreporite larger and rounded or oval; adoral shields relatively large, curved, meeting within and extending to first lateral armplate. Oral plates elongate, the margins with 3 pointed, slightly spaced oral papillae and one similar papilla at tip of jaw. One specimen has uppermost tooth visible through dorsal disc membrane; it is elongate and narrow, scarcely tapering. Second oral­tentacle pore opens outside oral slit. Genital slits short, very inconspicuous, lying between adoral shields and first lateral armplate, at ventral disc margin.

Dorsal surface of arm skin­covered and flat for about half of length, with vertebrae visible beneath the skin; beyond and starting abruptly are thin, delicate, rounded­triangular dorsal armplates, slightly separated by the lateral plates, and just longer than wide. Rarely there is a line of minute granules along the dorsal midline of the arms, out to the start of the dorsal plates. First ventral armplate at outer end of oral slit is just longer than wide, proximal and distal margin more or less straight, lateral margins concave to accommodate tube­feet; next 8–10 arm segments with thin, delicate ventral plates present, firstly as a short wide plate with a distinct notch in distal margin; ventral plates then become small, ovoid and often in 2 lateral pieces; beyond about the tenth plate they are absent. Ventral armplates are absent before dorsal armplates appear. Lateral plates meet or almost meet on ventral midline, and the ventral plates when present lie distal to them; on dorsal surface lateral plates are widely separated proximally and do not meet until dorsal plates are present; they have a distinct spine­bearing ridge, with 6–8 glassy thorny armspines, the base slightly swollen; proximally the uppermost usually somewhat expanded at the tip, lying diagonally across the dorsal arm surface, though not enveloped by skin and not supporting the integument; the next 2 are the longest, equal to 2 arm segments; the others are smaller, lowest is just less than one segment in length, is flattened and scarcely thorny, apparently acting as a tentacle­scale, no true scale being present, and tentacle­pores are scarcely visible. Distally on the arm, where dorsal plates are present the uppermost spine tapers and is like the others but the number of armspines does not change. The vertebrae are zygospondylous, similar to those in Astrogymnotes .

Colour: (Preserved specimens) dorsal surface of disc and proximal half of arms light brown, sometimes with darker blotches, disc may be darker; ventral surface uniform, very light brown (dried specimens Stn Z9044).

Etymology: This species is named for the late Dr H.B. Fell, who added several species of Ophiuroidea to the New Zealand fauna.

Holotype: Deposited in the NIWA collection, Wellington No. H­819 (Stn Z9044).

Paratypes: Deposited in the NIWA collection, Wellington No. P­1370 (Stn Z9044); P­ 1371 (Stn P2).

Remarks: The first specimens were found on an unnamed antipatharian ( Antipathes sp.) collected from south of the Kermadec Islands (Stn Z9044); further specimens were then located on antipatharians from the Wanganella Bank area by my colleague Dr S. O’Shea. At Stn Z9044 the ophiuroid Astrogymnotes was also present. Collections from Stations P1 and P7 each include a 6­armed specimen. These specimens have equal arms and do not appear fissiparous.

Figures

FIGURE 2: Renetheo felli n. gen. et sp. holotype, disc diameter 1.2 mm. A: dorsal, B: ventral, C: cleaned vertebra (SEM), D: oral region (SEM).