Belongs within: Naticidae.
Sinum is a genus of moon snails with an ear-shaped shell and reduced, horny operculum.
Characters (from Oldroyd 1927): Shell ear-shaped, with minute spire and very large aperture, externally with revolving striae, colour usually white, sometimes with a thin corneous epidermis. Operculum minute, horny, subspiral.
<==Sinum Röding 1798 BR05 (see below for synonymy)
|--*S. haliotoideum (Linnaeus 1758)BR17 (see below for synonymy)
|--‘Sigaretus’ australis Dunker 1871H09
|--S. bifasciatum (Récluz 1851)LB12
|--S. californicum Oldroyd 1917O27
|--S. concavum (Lamarck 1822) [=Sigaretus concavus]BB64
|--‘Sigaretus’ coriaceus Broderip & Sowerby 1829BS29
|--S. debile Gould 1852O27 [=Sigaretus debilisC64]
|--S. eximium (Reeve 1864)W93 [=Sigaretus eximiusH09]
|--‘Sigaretus’ filicatus Mighels 1845J49
|--S. fornicatumA27
|--S. grayi (Deshayes 1843)BC01 [=Sigaretus grayiBB64; incl. Sinum cortezi Burch & Burch 1964BC01]
|--S. incisum (Reeve 1864)W93 [incl. Sigaretus undulatus Lischke 1872F27, W93, F27]
|--S. javanicum Gray in Griffith & Pidgeon 1834W93
|--S. keratium Dall 1919O27
|--S. laevigatus Lamarck 1822W93
|--S. maculatum (Say 1831)S11
|--S. martini Finlay 1927 (see below for synonymy)F27
|--S. neritoides [=Sigaretus neritoides]O27
|--S. pazianum Dall 1919O27
|--S. perspectivum (Say 1831)S11
|--S. sanctijohannis (Pilsbry & Lowe 1932)PP78
|--‘Sigaretus’ subglobosusH86
`--S. zonale (Quoy & Gaimard 1833)W93 [=Ectosinum zonaleWG71; incl. *E. pauloconvexum Iredale 1931W93]
Sinum Röding 1798BR05 [=Sigaretus Lamarck 1799BR05; incl. Cryptostoma Blainville 1818W93, Ectosinum Iredale 1931W93; Adeloderma, Cryptocochlides, Schismatobranchia, Sigaretidae, Sigaretinae]
*Sinum haliotoideum (Linnaeus 1758)BR17 [=Helix haliotoideaBR17, *Sigaretus haliotoideusBR17, Velutina haliotoideaJ64; incl. Si. planulatus Récluz 1843H09, W93]
Sinum martini Finlay 1927 [=Sigaretus undulatus Martin 1885 nec Lischke 1872 nec Hutton 1885; incl. Natica (Ampullina) laevis Hutton 1885 non N. laevis Weerth 1884]F27
*Type species of generic name indicated
References
[A27] Allan, R. S. 1927. The geology and palaeontology of the Lower Waihao Basin, south Canterbury, New Zealand. Transactions and Proceedings of the New Zealand Institute 57: 265–309.
[BR05] Bouchet, P., & J.-P. Rocroi. 2005. Classification and nomenclator of gastropod families. Malacologia 47 (1–2): 1–397.
[BR17] Bouchet, P., J.-P. Rocroi, B. Hausdorf, A. Kaim, Y. Kano, A. Nützel, P. Parkhaev, M. Schrödl & E. E. Strong. 2017. Revised classification, nomenclator and typification of gastropod and monoplacophoran families. Malacologia 61 (1–2): 1–526.
[BC01] Boyko, C. B., & J. R. Cordeiro. 2001. Catalog of Recent type specimens in the Division of Invertebrate Zoology, American Museum of Natural History. V. Mollusca, part 2 (class Gastropoda [exclusive of Opisthobranchia and Pulmonata], with supplements to Gastropoda [Opisthobranchia], and Bivalvia). Bulletin of the American Museum of Natural History 262: 1–170.
[BS29] Broderip, W. J., & G. B. Sowerby. 1829. Observations on new or interesting Mollusca contained, for the most part, in the Museum of the Zoological Society. Zoological Journal 4: 359–379, pl. 9.
[BB64] Burch, J. Q., & R. L. Burch. 1964. A new species of Sinum from the Gulf of California. Nautilus 77 (4): 109–110.
[C64] Carpenter, P. P. 1864. Supplementary report on the present state of our knowledge with regard to the Mollusca of the west coast of North America. Report of the British Association for the Advancement of Science 33: 517–686.
[F27] Finlay, H. J. 1927. New specific names for austral Mollusca. Transactions and Proceedings of the New Zealand Institute 57: 488–533.
[H09] Hedley, C. 1909. The Marine Fauna of Queensland: Address by the President of Section D. Australasian Association for the Advancement of Science: Brisbane.
[H86] Hutton, F. W. 1886. The Mollusca of the Pareora and Oamaru systems of New Zealand. Proceedings of the Linnean Society of New South Wales, series 2, 1 (1): 205–237.
[J64] Jeffreys, J. G. 1864. The Upper Tertiary fossils at Uddevalla, in Sweden. Report of the British Association for the Advancement of Science 33 (Notices and Abstracts): 73–79.
[J49] Johnson, R. I. 1949. Jesse Wedgwood Mighels with a bibliography and a catalogue of his species. Occasional Papers on Mollusks 1 (14): 213-231.
[LB12] Luque, Á. A., A. Barrajón, J. M. Remón, D. Moreno & L. Moro. 2012. Marginella glabella (Mollusca: Gastropoda: Marginellidae): a new alien species from tropical West Africa established in southern Mediterranean Spain through a new introduction pathway. Marine Biodiversity Records 5: e17.
[O27] Oldroyd, I. S. 1927. The Marine Shells of the West Coast of North America vol. 2 pt 3. Stanford University Press: Stanford University (California).
[PP78] Poorman, F. L., & L. H. Poorman. 1978. Additional molluscan records from Bahía de Los Angeles, Baja California Norte. Veliger 20 (4): 369–374.
[S11] Simone, L. R. L. 2011. Phylogeny of the Caenogastropoda (Mollusca), based on comparative morphology. Arquivos de Zoologia 42 (4): 161–323.
[W93] Wilson, B. 1993. Australian Marine Shells vol. 1. Prosobranch Gastropods. Part One. Odyssey Publishing: Kallaroo (Western Australia).
[WG71] Wilson, B. R., & K. Gillett. 1971. Australian Shells: illustrating and describing 600 species of marine gastropods found in Australian waters. A. H. & A. W. Reed: Sydney.