Only one spiral keel on the body whorls (« Ogni anfratto ha un solo ordine di spigoli » writes Monterosato), instead of two in A. pagodula (Bucquoy, Dautzenberg & Dollfus, 1884). Also, there are less axial ribs in spinosa, and the tubercles are stronger: « la scultura esagera i caratteri e diminuisce i dettagli. » Intertidal, Punta del Carnero, Algeciras. 2,8mm.

« Tringali (2001), based on actual specimens collected in Mediterranean shores of Morocco, claims that A. spinosa (Monterosato, 1890) sensu Pallary (1902, 1920) is a morphotype of A. tessellata, considering the great variability shown by the latter species. Such assumption was recently accepted by Gofas et al. (2011), although it was not reported in WoRMS (2020). » – Reitano, Cresti & Di Franco: “A new species of the Alvania pagodula group (Monterosato, 1890) from the Pliocene of Italy: A. agathae n. sp. (Gastropoda Rissoidae)”, Biodiversity journal vol. 11(4), Palermo 2020, p.996.

« Alvania spinosa s.s. is characterized by a single median keel bearing spines, while A. tessellata presents a second less developed keel with spines, located halfway between the median region and the suture. » – Ibid.