Satondella azonata new species

(Figures 10–11)

Chresonymy. Scissurella ? sp.: Spencer et al., 2009: 202.

Type material. Holotype (NMNZ M.174835: Fig. 10). 0.63 × 0.36 mm. Paratypes from type locality (NMNZ M.301398, 4: Fig. 11 A–B; NMNZ M.174825, 5: Fig. 11 C).

Type locality. Wanganella Bank summit, West Norfolk Ridge, W of Cape Maria van Diemen, New Zealand, 32.543˚S, 167.487˚E, 133 m, 29 Jan. 1981, RV Tangaroa, rhodolith gravel and red algae.

Etymology. A-, Latin prefix for without, -zonata referring to the selenizone. It describes the lack of a selenizone in this species. Adjective.

Description. Shell small (to 0.63 mm: Figs 10–11), trochiform depressed, apex sunken in. Protoconch of 1 whorl, fine irregular axial cords on outer portion, apical cap and inner portion of whorl smooth; no apertural varix, apertural margin sinusoid. Teleoconch I of 1.125 whorls; suture impressed; 12–16 axials, low cords at onset of teleoconch I gradually rising to strong lamellae, onset of lamellae shifting from suture to position of foramen on shoulder, from suture to mid base on underside; interstices with fine irregular growth lines. Teleoconch II of 0.125 whorl. Shoulder flat, sculpture consisting of only fine irregular growth lines. Base with 2–3 strong axial lamellae as on teleoconch I. Umbilicus wide, distinct funiculus, underside of protoconch visible. No selenizone; foramen oblong, raised to chimney. Aperture subquadrate, peristome thickened. Animal unknown.

Distribution. West Norfolk Ridge and northern New Zealand, 33– 805 m.

Specimen records. Wanganella Bank,West Norfolk Ridge. 32.536˚S, 167.512˚E, 113 m (NMNZ M.257269, 1); summit, 32.543˚S, 167.487˚E, 133 m (NMNZ M.301398, 4; NMNZ M.174835, 1); summit, 32.653˚S, 167.528˚E, 133 m (NMNZ M.174826, 1); summit, 32.666˚S, 167.560˚E, 133 m (NMNZ M.174825, 5). New Zealand. Three Kings Islands: Three Kings Trough, 34.000˚S, 171.917˚E, 805 m (NMNZ M. 160302, 1); N of Great Island, 34.016˚S, 172.117˚E, 622 m (NMNZ M.034601, 2); Middlesex Bank, 34.033˚S, 171.733˚E, 246–291 m (NMNZ M.148570, 1); reef between Great Island and Farmer Rocks, 34.150˚S, 172.167˚E, 33 m (NMNZ M. 160303, 1).

Remarks. The thickening of the peristome resembles the condition seen in Liotiidae and is a clear sign of fully grown specimens. Accordingly, the absence of a selenizone is not an indication of juvenile specimens, but is a distinct, species-specific character.

Satondella minuta from the Indo-Pacific has a smooth protoconch, has a selenizone, and has distinct spirals over the entire teleoconch. Satondella bicristata n. sp. from New Zealand has twice as many but lower axial cords/ lamellae and has distinct spirals particularly on the base. Satondella dantarti Luque, Geiger & Rolán, 2011, has a selenizone, distinct spiral sculpture on the teleoconch as well as axial lamellae on the shoulder.