Phorcus Risso, 1826

Harzhauser, Mathias, 2021, The Cainozoic to present-day record of Circum-Mediterranean, NE Atlantic and North Sea Cantharidinae and Trochinae (Trochoidea, Gastropoda) - a synopsis, Zootaxa 4902 (1), pp. 1-81 : 50

Subgenus Phorcus Risso, 1826

Type species. Phorcus margaritaceus Risso, 1826 [= Phorcus richardi (Payraudeau, 1826) ], SD (Bucquoy et al. 1885: 399). Present-day, Mediterranean Sea.

Diagnosis. Subtriangular, turbiniform shells with moderately convex teleoconch whorls and convex base. Umbilicus initially open, narrowing during ontogeny; usually minute or fully sealed, but open in few species. Shell surface either smooth or with low, broad spiral cords (see also Affenzeller et al. 2017).

Remarks. The oldest occurrences are documented from the Late Miocene of the NE Atlantic ( Landau et al. 2017; Martín-González et al. 2018). Mediterranean records all post-date the Messinian Salinity Crisis, suggesting an immigration with Atlantic faunas during the early Pliocene. The generic placement of extant species follows Donald et al. (2012).

= Neptheusa Leach in Gray, 1852; type species: Trochus crassus Pulteney, 1799 , by monotypy. Present-day, British Isles.

= Umbiculus Nordsieck, 1982; type species Trochus richardi var. pallida Bucquoy, Dautzenberg & Dollfus, 1884 [= Phorcus richardi (Payraudeau, 1826) ], OD (Nordsieck 1982: 26). Present-day, Mediterranean Sea. Introduced as “Sektion” (= section) of Gibbula (Gibbula) , which makes it an available name according to ICZN Article 10.4. ( A uninominal name proposed for a genus-group division of a genus, even if proposed for a secondary (or further) subdivision, is deemed to be a subgeneric name even if the division is denoted by a term such as “section” or “division).

= Mutilastra Nordsieck, 1974 ; type species Trochus mutabilis Philippi, 1851 , OD ( Nordsieck 1974: 21). Present-day: NE Atlantic ( Portugal); Mediterranean Sea.