Larochea spirata, 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 : 29-31

Larochea spirata new species

( Figures 23–25 )

Type material. Holotype ( NMNZ M.172130: Fig. 23 ). 1.35 × 1.54 mm. Paratypes from type locality ( NMNZ M.172127, 36: Figs 24–25 ).

Type locality. West Norfolk Ridge, W of Cape Reinga, New Zealand, 34.285˚S, 168.430˚E, 785–800 m, 2 June 2003, RV Tangaroa , comminuted coral and bryozoans.

Etymology. Spira, Latin for the spire, referring to the pronounced spire compared to other species in the genus.

Description. Shell medium size (to 1.5 mm. Figs 23–25 ), trochiform, elevated, up to 20% taller than wide (NMNZ M.172127: tallest specimen not shown). Protoconch of 0.75 whorl, flocculent sculpture with 3 indistinct spiral cords, no apertural varix, apertural margin straight. Teleoconch of up to 1.8 whorls, suture moderately impressed. Early teleoconch with shoulder showing approximately 20–22 indistinct axial cords, becoming more distinct with growth; spirals about ½ strength of axials, first spiral commencing after 0.33–0.5 whorl, approximately 25 at apertural margin; spirals running over axials forming minute elevated points. Axials becoming less distinct from suture towards base, sometimes vanishing entirely. Spirals transitioning at periphery from cords on shoulder to low steps on base of same density as on shoulder; axials barely perceptible on base. Anomphalous. Aperture oval, roof overhanging.

Animal unknown.

Distribution. West Norfolk Ridge, 785– 800 m.

Remarks. The elevated shell shape of large specimens immediately distinguishes this species from any other Larochea species. Additionally among New Zealand species, La. secunda Powell, 1937 lacks the spiral sculpture on the protoconch, while La. scitula Marshall, 1993 , from Wanganella Bank , West Norfolk Ridge has much stronger, more elevated axial cords, and La. miranda Finlay, 1927 lacks distinct axial sculpture.

Figures

FIGURE 23. Larochea spirata new species. Holotype West Norfolk Ridge, W of Cape Reinga, New Zealand, 785 – 800 m (NMNZ M. 172130). Scale bar shell = 1 mm. Scale bars protoconch = 100 µm.

FIGURE 24. Larochea spirata new species. Paratypes West Norfolk Ridge, W of Cape Reinga, New Zealand, 785 – 800 m (NMNZ M. 172127). Scale bars shell A – B = 1 mm. Scale bars shell C = 0.5 mm. Scale bars protoconch = 100 µm.

FIGURE 25. Larochea spirata new species. Paratypes (NMNZ M. 172127). West Norfolk Ridge, W of Cape Reinga, New Zealand, 785 – 800 m. Scale bars shell A – B = 1 mm. Scale bars shell C = 0.5 mm. Scale bars protoconch = 100 µm.