signum is a noun in apposition [meaning flag or banner] and does not agree in gender with the genus it is combined with
marine, brackish, fresh, terrestrial
(ofBuccinum signum Reeve, 1846)Reeve, L. A. (1846-1847). Monograph of the genus <i>Buccinum</i>. In: <i>Conchologia Iconica, or, illustrations of the shells of molluscous animals</i>, vol. 3, pl. 1-14 and unpaginated text. L. Reeve & Co., London. [stated dates: pl. 1-12, December 1846; pl. 13-14, February 1847]. , available online athttp://biodiversitylibrary.org/page/11118823 page(s): pl. 2, species no. 6 [details]
MolluscaBase eds. (2024). MolluscaBase. Siphonalia signum (Reeve, 1846). Accessed through: World Register of Marine Species at: https://www.marinespecies.org/aphia.php?p=taxdetails&id=491363 on 2024-05-18
original description(ofBuccinum signum Reeve, 1846)Reeve, L. A. (1846-1847). Monograph of the genus <i>Buccinum</i>. In: <i>Conchologia Iconica, or, illustrations of the shells of molluscous animals</i>, vol. 3, pl. 1-14 and unpaginated text. L. Reeve & Co., London. [stated dates: pl. 1-12, December 1846; pl. 13-14, February 1847]. , available online athttp://biodiversitylibrary.org/page/11118823 page(s): pl. 2, species no. 6 [details]
new combination referenceAdams, A. (1863). On the Japanese species of <i>Siphonalia</i>, a proposed new genus of gasteropodous Mollusca. <em>The Annals and Magazine of Natural History.</em> (3) 11: 202-206., available online athttps://www.biodiversitylibrary.org/page/22221656 page(s): 203 [details]