The presence of Pseudunio auricularius (Spengler, 1793) in Italy from the Pleistocene to the 20th century

The purpose of this research is to gather and review all historical and recent information regarding the distribution of Pseudunio auricularius (Spengler, 1793) in Italy, and organize them in a comprehensive framework. The lack of data in the European literature concerning the presence of this freshwater bivalve species in the Italian territory prompted a critical review of information from 19th century authors to the present, as well as data related to specimens of P. auricularius found in private collections and various Italian and foreign museums. Nearly fifty collection sites are considered, most of them concentrated in Northern Italy (Lombardy, Veneto, Emilia-Romagna) and Central Italy (Umbria, Lazio). The presence of the taxon in Italy dates from the Early Pleistocene to the 20th century. Several subfossil valves have been collected after the 19th century, particularly from the Cagnola Canal (Padua, Veneto) in 1991, and from the Chiusello Canal, Chiese, and Oglio rivers (Mantua and Cremona, Lombardy) in 1929, 1980, 2022, and 2024, where it is now considered extinct. However, a collection from the Tiber River (Lazio) in 1973 suggests the existence of living individuals at least until the 20th century. Our study clarifies uncertain or incorrect aspects related to specific sites where P. auricularius had been reported, such as Castel Goffredo (Mantua, Lombardy), Via de’ Castellani (Florence), Porto Conte (Alghero, Sardinia), and the Bronze Age site of Gorzano (Modena, Emilia-Romagna). Iconographic material includes both historical documents and a large number of mostly unpublished photographs of valves from the described sites.