In this part of the series, giving a systematic account of the Gastropoda of the Lower Pliocene (Zanclean) deposits of Estepona, province of Málaga, Spain, the Nassariidae are described and discussed. The study area has been expanded to include other major Iberian Pliocene deposits, those of the Mondego basin of central-west Portugal, the Guadalquivir basin of southern Atlantic Spain and the Alt Empordà (Girona), Baix Llobregat (Barcelona) and Baix Ebre (Tarragona), all northern Mediterranean Spain. The faunal composition is compared with that present in the Atlantic, North Sea Basin and Mediterranean Miocene to Recent times. The diversity of Nassariidae in the Iberian assemblages is comparable in number of species and composition to that found in the Italian Pliocene.
Sixty species are described and discussed, with particular emphasis on protoconch morphology. Ten species are new to science, Nassarius iberoclathratus nov. sp., Nassarius patnuttalli nov nom., Nassarius dinizi nov. sp., Nassarius plioholsaticus nov. sp., Nassarius manuelmolinai nov. sp., Nassarius cotteri nov. sp., Nassarius lusitanicus nov. sp., Nassarius mondegoensis nov. sp., Demoulia zbyszewskii nov. sp. and Cyllenina amaldiformis nov. sp. One further species we consider new, Nassarius sp. indet. an nov sp., but do not name formally due to lack of well-preserved specimens.
Several new subjective synonymies are suggested; Nassa olivii Bellardi, 1882 junior synonym of Nassarius semistriatus (Brocchi, 1814); Nassa semistriata var. restitutiana Fontannes, 1873, Nassa semistriata var. cabrierensis Fischer & Tournouer, 1873, Nassa dertonensis Bellardi, 1882, Buccinum (Caesia) inconstans Hoernes & Auinger, 1882, Nassa (Amyclina) dertonensis italicistria Ruggieri, 1949, Nassa (Amyclina) dertonensis neogigas Ruggieri, 1949 and Hinia (Hinia) pseudocostulata Venzo & Pelosio, 1963 junior synonyms of Nassarius striatulus striatulus (Eichwald, 1829); Buccinum cuvierii Payaudeau, 1826 and Nassa atava Bellardi, 1882 junior synonyms of Nassarius corrugatus (Brocchi, 1814); Nassa pinnata Bellardi, 1882, Nassa neglecta Bellardi, 1882 and Nassa catalaunica Almera & Bofill, 1898 junior synonyms of Nassarius elatus (Gould, 1845); Nassa crebricostulata Bellardi, 1882, Nassa subecostata Bellardi, 1882 and Nassa nova Bellardi, 1882 junior synonyms of Nassarius elabratus (Doderlein, 1862); Nassa pyrenaica var. compacta Fontannes, 1879, Nassa tersa Bellardi, 1882, Nassa heynemanni von Maltzan, 1884 and Nassa tersa var. abbreviatula Sacco, 1904 junior synonyms of Nassarius pyrenaicus (Fontannes, 1879); Nassa semperi Bellardi, 1882 and Nassa longa Bellardi, 1882 junior synonyms of Nassarius aldrovandii (Bellardi, 1882); Nassa planicostata Bellardi, 1882 junior synonym of Nassarius angulatus (Brocchi, 1814); Nassa (Hima) rozieri Peyrot, 1925 junior synonym of Nassarius serraticosta (Bronn, 1831); Nassa andonae Bellardi, 1882 junior synonym of Nassarius productus (Bellardi, 1882); Buccinum carcassonni De Serres, 1829, Nassa eurosta Fontannes, 1879, Nassa d・fanconae Bellardi, 1882, Nassa forestii Bellardi, 1882, Nassa interposita Bellardi, 1882, Nassa inaequicostata Bellardi, 1882 and Nassa fallax (Michelotti) in Bellardi, 1882 junior synonyms of Nassarius turritus (Borson, 1820); Eione affinis Cocconi, 1873 junior synonym of Nassarius circumcinctus (A. Adams, 1852); Buccinum lampas Brocchi, 1814, Nassa (Desmoulaea [sic]) conglobata var. subobsoletecostata Sacco, 1904 and Nassa (Desmoulea) conglobata altavillensis Ruggieri et al., 1959 junior synonyms of Demoulia conglobata (Brocchi, 1814); Nassa (Desmoulaea [sic]) conglobata var. subobsoletecostata Sacco, 1904 junior synonym of Demoulia pupa (Brocchi, 1814).
The Italian Late Miocene and Pliocene shells identified in the literature as Nassarius tumidus (Eichwald, 1830) are shown not to be conspecific with this Middle Miocene Paratethyan taxon, and are considered a distinct taxon, Nassarius tauroprimus (Sacco, 1904).
The fossil and Recent populations of Nassarius gibbosulus (Linnaeus, 1758) are considered distinct based on morphometric analysis of their shells, the fossil shells are considered a chronosubspecies of the Recent population, the first available name for the fossil form being Nassarius gibbosulus pliopergibbosus (Sacco, 1904). The Iberian assemblages fall within two groups; one with a group of species akin to that found in the Pliocene central Mediterranean, the north-east Spanish, Estepona Basin and Guadalquivir Basin assemblages, and the other with a significant percentage of distinct taxa, the Mondego Basin assemblage. Although the family is still well represented in the Mediterranean fauna, since Pliocene times there has been a major extinction and turnover of species. Of the 60 species recorded, only eight (13.3%) survived into the Recent faunas. The palaeobiogeography of the Pliocene to Recent European Nassariidae is discussed, and the strongly thermophilic character of many of the taxa highlighted by the rapid increase in specific and generic diversity southwards with increasing SSTs. A strong endemicity amongst the nassariids within both Pliocene and Recent biogeographical provinces is demonstrated, and the southward increasing number of specific and generic taxa found in the North-East Atlantic Pliocene biogeographical provinces follows the general pattern of Molluscan distribution dictated by the equatorward increasing of SSTs.