Terrestrial and lacustrine gastropods from the Priabonian (upper Eocene) of the Sultanate of Oman.

Abstract

Terrestrial and aquatic gastropods from the upper Eocene (Priabonian) Zalumah Formation in the Salalah region of the Sultanate of Oman are described. The assemblages reflect the composition of the continental mollusc fauna of the Palaeogene of Arabia, which, at that time, formed parts of the southeastern Tethys coast. Several similarities with European faunas are observed at the family level, but are rarer at the genus level. These similarities point to an Eocene (Priabonian) rather than to a Rupelian age, although the latter correlation cannot be entirely excluded. At the species level, the Omani assemblages lack any relations to coeval faunas. This suggests the possible presence of a distinct biogeographic province during the Palaeogene or may simply reflect the extremely sparse non-marine fossil record of the Eocene in the Tethys region. The occurrence of the genera Lanistes, Pila, and Gulella along with some pomatiids, probably related to extant genera, suggests that the modern African–Arabian continental faunas can be partly traced back to Eocene times and reflect very old autochthonous developments. In contrast, the diverse Vidaliellidae went extinct, and the morphologically comparable Neogene Achatinidae may have occupied the equivalent niches in extant environments. Carnevalea Harzhauser and Neubauer nov. gen., Arabiella Kadolsky, Harzhauser and Neubauer nov. gen., Pyrgulella Harzhauser, Kadolsky and Neubauer nov. gen., Salalahia Kadolsky, Harzhauser and Neubauer nov. gen., Omanitopsis Harzhauser and Neubauer nov. gen., Arabicolaria Harzhauser and Neubauer nov. gen., Pacaudiella Harzhauser and Neubauer nov. gen., Goniodomulus Harzhauser and Neubauer nov. gen., Eoquickia Harzhauser and Neubauer nov. gen., Omanillya H. Nordsieck nov. gen. and Omanifera H. Nordsieck nov. gen. are introduced as new genera. Pila neuberti Harzhauser and Neubauer nov. sp., Arabiella arabica Kadolsky, Harzhauser and Neubauer nov. sp., Pyrgulella parva Harzhauser, Kadolsky and Neubauer nov. sp., Salalahia thaytinitiensis Kadolsky, Harzhauser and Neubauer nov. sp., Omanitopsis vandammei Harzhauser and Neubauer nov. sp., Procyclotopsis eocenica Harzhauser and Neubauer nov. sp., Palaeocyclotus kuehschelmi Harzhauser and Neubauer nov. sp., Arabicolaria arabica Harzhauser and Neubauer nov. sp., Pacaudiella omanica Harzhauser and Neubauer nov. sp., Pacaudiella flammulata Harzhauser and Neubauer nov. sp., Goniodomulus solaniformis Harzhauser and Neubauer nov. sp., Cerastus hyznyi Harzhauser and Neubauer nov. sp., Omanillya lunellifera H. Nordsieck nov. sp., Omanillya costellata H. Nordsieck nov. sp., and Omanifera euclista H. Nordsieck nov. sp. are described as new species.