Distorsio habei is the most common Distorsio species in the MNHN/ORSTOM collections reported here, which reflects the intensity of deep-water sampling around New Caledonia and the Loyalty Islands, as D. habei is among the least common of Distorsio species in collections from the Philippine Islands. This abundance of material allows a better appreciation of the characters and variation of D. habei than previously has been possible, as well as more satisfactory comparison with D. euconstricta and D. graceiellae.
An important character is that no specimens of D. habei, of whatever size or degree of apertural secretion, have the basal constricting ridge inside the outer lip separated from the columellar base by only a narrow slit, that characterises D. euconstricta and D. graceiellae. Apart from this difference, small specimens of D. habei resemble adult D. graceiellae in a number of characters: (1) the very marked coiling distortion is brought about by the very enlarged, excentric bulge to the left of the aperture (in conventional apertural view), a raised zone of four narrow, closely spaced cords producing a particularly elevated, wide peripheral protrusion; (2) a narrow constricted /one without prominent spiral sculpture follows below the peripheral raised zone; (3) five narrow, finely nodulous, relatively closely spaced spiral cords occupy the rest of the base, and are separated from the cords on the anterior canal by another narrow constricted zone lacking obvious sculpture. D. habei differs from D. graceiellae in its less horizontal and less markedly concave sutural ramp, in its very straight, narrow, elevated basal columellar ridge bearing unusually short transverse nodules, separated from the columellar by a much more strongly concave smooth area than in all other Distorsio species, in its wide, flattened lower area of the outer lip, bearing long, narrow transverse ridges, and in the more prominent, more obviously nodulous spiral ridge in the centre of the mid-columellar embayment.
DISTRIBUTION. — Distorsio habei occurs uncommonly throughout the western Pacific, from BOSO Peninsula. Honshu. Japan, south to New Caledonia and Vanuatu, and to southern Queensland. Australia, and eastwards to Hawaii (BEU. 1987: figs 146, 150). Most material seen is from the Philippine Islands. DIMENSIONS. — LARGEST New Caledonian specimen: H 58.9. D 35.1.