Hidden in historical sources: Rediscovering the thorny oyster (Spondylus gaederopus Linnaeus, 1758) in art, archives, and cultural knowledge.

The thorny oyster (Spondylus gaederopus), a Mediterranean bivalve prised during prehistoric times for its distinctive spiny purple shell, has since been overlooked in cultural and scientific records. Frequently depicted in Early Modern still-life paintings, particularly in Italian works of the seventeenth century, its representations were historically misidentified as scallops or common oysters. This participated in obscuring the visual evidence of occurrence and human use of this species during this period. Here, we adopt an interdisciplinary approach combining art historical analysis, taxonomic verification, archival research, and ethnobiological investigation to reconstruct the cultural and ecological history of S. gaederopus in Italy. We identify the species in 43 paintings dated between 1635 and 1750, predominantly by members of the Neapolitan Recco family, revealing its former abundance in coastal markets. Complementary historical documents, local knowledge, and oral testimonies confirm its culinary and cultural significance across Italy from the Early Modern period to the twentieth and twentieth-first century. Comparative measurements indicate a decline in average shell size since the seventeenth century, consistent with a potential harvesting pressure. Our findings demonstrate that unconventional sources including visual art, archival records, and oral testimonies can provide rich ecological and cultural insights, recovering lost biodiversity references and revealing human-marine interactions over centuries. Integrating such interdisciplinary evidence not only sheds light on the forgotten history of S. gaederopus but also highlights the potential of combining cultural heritage and scientific research to inform contemporary conservation strategies.