Tympanotonos Schumacher, 1817

Islamoğğlu, Yeşşim, Dominio, Stefano & Kowalke, Thorsten, 2011, Early Eocene Caenogastropods (Mollusca, Gastropoda) from Haymana-Polatl Basin, Central Anatolia (Turkey): taxonomy and palaeoecology, Geodiversitas 33 (2), pp. 303-330 : 319

Genus Tympanotonos Schumacher, 1817

TYPE SPECIES. — Murex fuscatus Linnaeus, 1758 . Extant: W Africa.

The genus is based on the only living species Tympanotonos fuscatus (Linnaeus, 1758) from West African tropical shores. The type species is characterized by three spiral ribs strongly beaded by axial folds on each spiral whorl, with one riblet intercalated between the two anterior ribs, another riblet between anterior rib and suture, and the shoulder rib typically enlarged and sometimes spinose. Previous authors included several fossil species in the genus (e.g., Cossmann & Pissarro 1910, 1911), such as the middle Eocene Tympanotonos calcaratus ( Brongniart, 1823) from the Western Tethys. The latter shows the variability of the living species, particularly regarding the number and type of spiral and axial elements, resulting in a granulate, tuberculate or spinose sculpture, sometimes changing within the same specimen ( Plaziat 1970; Kowalke 2001). Bearing this variability in mind Kowalke (2001) included within Tympanotonos genera or subgenera such as Eotympanotonos, Ptychopotamides and Potamidopsis . Among Eocene potamidid genera, Campanilopsis Chavan, 1849 was considered a possible synonym of Telescopium Montfort, 1810 . On the other hand, Reid et al. (2008) have lately assigned all Eocene “ Tympanotonos ”, incuding Eotympanotonos and Ptychopotamides , to the genus typified by the Oligocene species Potamides lamarkii Brongniart, 1810 . These authors attribute to Potamides the large variability of rib sculpture shown by Eocene species. Here the traditional solution reviewed by Kowalke (2001) is preferred, leaving Potamides for smaller-sized potamidids with rounded whorls that appeared in the Oligocene of the Tethys having a characteristic sculptural development of the protoconch and the early teleoconch, well distinguished from Potamides .