Virginia to Sao Paulo, Caribbean; western Africa; Madeira to central Mediterranean. Lower photic zone to bathyal depths, often on coralligenous bottoms.
Original taxon: Bifrontia zanclaea.
Synonyms: actoni, nobilis.
450m deep, Estepona, Málaga, Andalucia, S. Spain. 9mm.
Original pictures provided by J. M. Martin (ES).
– (CC BY-NC-SA) –
« Testa supra planata, subtus latissime umbilicata, anfractibus bicarinatis, tetraquetris, carinis lineolis elevatis radiantibus crispatis; apertura subrotundo elliptica, transversa. […] Anfractus fere exacte tetraquetri; pagina superior plana; laevis; externa utrinque versus angulum filo elevato ornata; infera laevis; interna cum anfractibus anterioribus maxima ex parte connata. » – R. A. Philippi: Enumeratio molluscorum Siciliae… vol. II, Berlin 1844, p. 225.
« Torinia zanclea, Phil. — Shell minute, planorbiform; whorls quadrangular, periphery broad, with a rib above and another below; colour fulvous, clouded with alternate light and dark; umbilicus very wide; aperture nearly square. Operculum as in typical Torinia. Mediterranean. » – G. W. Tryon: op. cit. p. 23.
« Omalaxis nobilis, Verril. — Shell planorbiform, upper surface nearly flat, base very concave; whorls 5, nearly quadrangular, the two peripheral angles strongly granosely carinate, peripheral area spirally ribbed, surface of the shell with radiating, elevated growth-lines; color pale chestnut, irregularly and indistinctly banded with whitish chestnut; base spirally striated; aperture trapezoidal with the outer corners angular and the inner corners rounded. Operculum thin, horny, multispiral, slightly concave. Chesapeake Bay. » – G. W. Tryon: op. cit. p. 24.
« Omalaxis nobilis, Verril. — Shell planorbiform, upper surface nearly flat, base very concave; whorls 5, nearly quadrangular, the two peripheral angles strongly granosely carinate, peripheral area spirally ribbed, surface of the shell with radiating, elevated growth-lines; color pale chestnut, irregularly and indistinctly banded with whitish chestnut; base spirally striated; aperture trapezoidal with the outer corners angular and the inner corners rounded. Operculum thin, horny, multispiral, slightly concave. Chesapeake Bay. » – G. W. Tryon: op. cit. p. 24.