Larocheopsis macrostoma, Geiger, Daniel L. & Marshall, Bruce A., 2012

Geiger, Daniel L. & Marshall, Bruce A., 2012, New species of Scissurellidae, Anatomidae, and Larocheidae (Mollusca: Gastropoda: Vetigastropoda) from New Zealand and beyond, Zootaxa 3344, pp. 1-33 : 32

Larocheopsis macrostoma new species

( Figure 26 )

Type material. Holotype ( NMNZ M.137435: Fig. 26 ). 1.22 × 0.79 mm.

Type locality. Seamount 130 km S of Esperance Rock, Kermadec Ridge, New Zealand, 32.472˚S, 179.265˚W, 538 m, 15 Apr. 1997, FV Santa Maria, hardground, foraminiferal sand, sponges and bryozoans.

Etymology. Macro-, Latin prefix for large, -stoma, Latin suffix for mouth or aperture, referring to the comparatively large aperture of the species (OD).

Description. Shell medium size (to 1.2 mm. Fig. 26 ), trochiform, depressed. Protoconch of 0.75 whorl, smooth, no apertural varix, apertural margin sinusoid. Teleoconch of 1.66 whorls, suture little impressed. Sculpture of first 1.5 whorls consisting of pits, shoulder of last portion with distinct commarginal axial cords, crossed by approximately 8 irregularly-spaced, indistinct spiral threads. Base from periphery to closed umbilicus with up to 16 low, spiral steps, starting after 0.66 teleoconch whorl. Umbilicus closed, covered by callus. Aperture elongate, Dshaped oval, roof overhanging. Animal unknown.

Distribution. Seamount 130 km S of Esperance Rock, Kermadec Ridge, New Zealand, 538 m.

Remarks. Larocheopsis amplexa Marshall, 1993 , from New Zealand shares a similar protoconch, the pitted early teleoconch and the spiral steps on the base with Ls. macrostoma , but Ls. macrostoma has a much broader shell, and shows distinct axial sculpture on the shoulder near the apertural margin.

Figures

FIGURE 26. Larocheopsis macrostoma new species. Holotype. Seamount 130 km S of Esperance Rock, Kermadec Ridge, New Zealand, 538 m (NMNZ M. 137435). Scale bar shell = 1 mm. Scale bar protoconch = 100 µm.