In this paper 20 taxa of the genus Nassarius s. l., often classified by the authors under the sub-genus Uzita H. et A. Adams, 1853, are described and discussed. The specimens are preserved in the zoological and paleontological collections of the « Institut Royal des Sciences Naturelles » in Brussels. They are either fossils from European and North-African Neogene strata, or recent species from the Mediterranean, Lusitanian and West-African regions. However from the British Museam of Natural History and from the « Museo Civico di Storia naturale di Milano » we have obtained photographs of the original matrial of N. denticulatis (A. Adams, 1852) and of N. prismaticus (Brocchi, 1814) and so have been able to designate lectotypes for both these species. For practical reasons only, this species-group could be named the N. clathratus (Born, 1778)-« group », after its first described member. Several of these taxa are still frequently misinterpreted, especially N. denticulatis, N. limatus (Deshayes in Lamarck, 1844) and N. prismaticus. So we have restricted the synonymy to the quotations whose correctness we could verify. We arranged the taxa according to their morphological affinities, as far as it was possible to do so uniserially. This seems to correspond, at least partly, with their actual relationship. For each taxon we mentioned the geograhical and stratigraphical distribution of the studied specimens, and also some of the chief numerical data. We describe three new species: N. sperlingensis n.sp., from the Pleistocene of Sicily; N. pseudoserratus n.sp., from the Mediterranean Pliocene; N. scaldisianus n.sp., from the Atlantic Pliocene. During the Miocene the « group » is poorly represented. We only mention N. contortus (Dujardin, 1837) in the Helvetian. N. brugnonis (Bellardi, 1882), in direct lineage with N. denticulatus, in the Tortonian. N. spectabilis (Nyst, 1843 = N. elegans (Dujardin non Sowerby) in the Helvetian-Tortonian-Redonian. This last species has often been mistaken for N. limatus and extends to the Scaldisian with its form vandewouweri (Glibert, 1959). During the Pliocene this species group expanded widely and rapidely, mainly in the Mediterranean province, but also in the Atlantic province: in Belgium, France, Great Britain and the Netherlands. Most of the species studied here belong to this geological period. During the Pleistocene the « group » decreased rapidely and today, in the same regions, only N. denticulatus, with no known fossil record, N. limatus, restricted to the Mediterranean and dating from the Upper Pliocene, and N. prismaticus mentioned already by G. Brocchi, in 1814, from the Adriatic Sea, but apparently very rare, can be mentioned.We have got further evidence of two opinions expressed in a previous work about the « group » of N. semistriatus (Brocchi, 1814) (Adam, W. et Glibert, M., 1974): the size and shape of the protoconch are essential characteristics, too often neglected, for the specific identification of those shells. Also in the present case the structure of the columellar callus and the sculpture of the siphonal canal should be taken into account; the subgeneric division commonly used for the classification of the species of Nassarius are mostly missing factual basis.Of general interest are: supplementary evidence of viviparity in some fossil and recent species of Nassarius: in N. ficaratiensis (Monterosato, 1891), from the Sicilian and in N. Limatus; changes in the shell, due to preservation, can bring very great changes in sculpture and may thus lead to inaccurate descriptions. A typical example is N. anomalus (Harmer, 1914). We wish to express our appreciation and sincere gratitude to the persons who have kindly assisted us in the course of our work: Mrs. K.M. Way (British Museum Natural History, London), Dr. Giovanni Pinna (Museo Civico di Storia Naturale, Milano) and Dr. O. Priolo (Catania). |
