Heliacus is a genus of gastropods belonging to the family Architectonicidae.MolluscaBase eds. (2025). MolluscaBase. Heliacus A. d'Orbigny, 1842. Accessed through: World Register of Marine Species at: https://www.marinespecies.org/aphia.php?p=taxdetails&id=137663 on 2025-11-13
General characteristics (Original description in French) The operculum is corneous and conical, increasing in diameter from the apex to the base; its inner side is smooth with a central point; all the rest is composed of spirally coiled lamellae which decrease in diameter and are always fringed at their circumference. The shell is usually higher than the other sundials, with a narrower umbilicus.Orbigny, A. d'. (1841-1853). Mollusques. In: R. de la Sagra (ed.). Histoire physique, politique et naturelle de l'Ile de Cuba. Arthus Bertrand, Paris.
(Described as Gyriscus in Latin) The shell is turbinate, conico-turreted, and umbilicate; the apex is blunt, with the tip involuted; the whorls are rounded and transversely girdled; the aperture is subcircular, with the margins sharp and joined by a callus, the columellar lip being reflected. The operculum is corneous (horny), multispiral on the upper part, and provided with a stylet-like process on the lower part.
Distribution The Heliacus species are typically found in warm-temperate to tropical waters globally, from the intertidal zone down to the subtidal and occasionally deeper.
Species
† Heliacus albertinae (Sacco, 1892) Heliacus anaglyptus † Heliacus angularis Makiyama, 1927 † Heliacus antu S. N. Nielsen & Frassinetti, 2007 Heliacus areola Heliacus asteleformis † Heliacus bahamondei Frassinetti & Covacevich, 1981 †Heliacus berthae (O. Boettger, 1902) Heliacus bisulcatus Heliacus caelatus Heliacus cerdaleus † Heliacus chonos S. N. Nielsen & Frassinetti, 2007 Heliacus corallinus Heliacus costatus Heliacus cylindricus † Heliacus darraghi † Heliacus deningeri (K. Martin, 1914) Heliacus discoideus Heliacus enoshimensis Heliacus fallaciosus Heliacus fenestratus Heliacus geminus † Heliacus globosus Harzhauser & Landau, 2023 Heliacus hyperionis Heliacus imperfectus Heliacus implexus Heliacus infundibuliformis Heliacus jeffreysianus † Heliacus lowei Durham, 1950 Heliacus madurensis Heliacus malani Heliacus mazatlanicus Heliacus mighelsi Heliacus miser † Heliacus morningtonensis Garrard, 1978 Heliacus nereidis Heliacus oceanitis † Heliacus otwayanus Garrard, 1978 Heliacus otwayanus Heliacus planispira Heliacus ponderi Heliacus proteus † Heliacus radiatus (Borson, 1821) † Heliacus reticulatus Dockery, 1993 † Heliacus robertsae Durham, 1950 Heliacus reticulatus Heliacus rotula Heliacus splendidus Poppe & Tagaro, 2026 † Heliacus stefanmeszarosi Biskupič, 2024 Heliacus sterkii Heliacus stramineus † Heliacus taverai Heliacus trochoides Heliacus turritus Heliacus variegatus Heliacus verdensis Heliacus virgatus † Heliacus wannonensis (Tenison Woods, 1879) Heliacus willianseverii Heliacus worsfoldi
References
SeaLifeBase Powell A. W. B., New Zealand Mollusca, William Collins Publishers Ltd, Auckland, New Zealand 1979 Bieler, R. (1987). Die Gattungen der Architectonicidae (Gastropoda: Allogastropoda). Teil 4: Heliacus (Pyrgoheliacus) n. subgen. und Architectonica (Adelphotectonica) n. subgen. Archiv für Molluskenkunde. 117 (4/6): 203-215, pls. 1-2 Bieler, R. (1993). Architectonicidae of the Indo-Pacific (Mollusca, Gastropoda). Abhandlungen des Naturwissenschaftlichen Vereins in Hamburg. NF. 30: 1-376
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