Class Gastropoda

Family Cassidae Latreille, 1825

Genus Semicassis Mörch, 1852

Species Semicassis laevigata (Defrance, 1817)

Semicassis laevigata (Defrance, 1817) (Mollusca – Gastropoda – Cassidae) is a species belonging to the subfamily Phalinae Beu, 1981, quite common in the Italian Pliocene, locally abundant. Some authors consider it to be synonymous with the present Semicassis saburon (Bruguière, 1792). Average height 60/70 mm.

Original description / Descrizione originale:

Cassis laevigata

Casque lisse, Cassis laevigata, Nob. Coquille ovale, composée de cinq à six tours, dont les quatres premiers sont striés transversalement. L’intérieur du bord droit, ainsi que la columelle, sont légèrement dentés. Longueur, 54 millimètres (2 pouces).

from page 210 di Defrance J.L.M. (1817). [Mineralogie et Geologie] In: Dictionnaire des Sciences Naturelles dans lequel on traite méthodiquement des diffrents êtres de la nature (par plusieurs professeurs du Jardin du Roi …, F[rédéric] Cuvier, ed.). Paris. Vol. 7.

Distribution

Paratethys: reported from Miocene to Present-day how S. saburon (Bruguière, 1792). The spiral ornamentation on the Pliocene specimens consists in only 2-3 cords near the adapical suture.

Bibliographic references and some more common synonyms

1817 Cassis laevigata Defrance, p. 210.

1974 Semicassis (Semicassis) laevigata (Defrance) – Malatesta, p. 253, pl. 19, fig. 8

1995 Semicassis (Semicassis) miolaevigata – Baluk, p.203, Pl. 16, figs 1–4.

2004 Semicassis laevigata – Landau al., Pl. 3, figs. 1–2 (cum syn.)

2008 Semicassis saburon (Bruguière) – Chirli, p. 85, pl. 31, figs 10-16

2009 Semicassis laevigata – Landau et al., p. 67, pl. 4, figs 1-2.

Remarks

As discussed by LANDAU et al. (2004), these Paratethyan Miocene shells have usually been identified as Semicassis miocenica SACCO, 1890. Whilst the shells in the NHMW collection tend to be broader and thicker than typical Pliocene Mediterranean shells of Semicassis laevigata(DEFRANCE, 1817), with a more thickened labral varix, a whole range of variability can be observed within the Paratethyan specimens, and they intergrade with typical Pliocene S. laevigata. (Landau et al., 2009: p. 68).

References

Baluk W. (1995). Middle Miocene (Badenian) gastropods from Korytnica, Poland. Part II. Acta Geologica Polonica, 45(3-4):1-255.

Chirli C., 2008. Malacofauna Pliocenica Toscana. Vol. 6. Neotaenioglossa. Carlo Chirli Ed., Tavarnelle, pp. 128, 38 pls.

Defrance J.L.M., 1817. [Mineralogie et Geologie] In: Dictionnaire des Sciences Naturelles dans lequel on traite méthodiquement des diffrents êtres de la nature (par plusieurs professeurs du Jardin du Roi …, F[rédéric] Cuvier, ed.). Paris. Vol. 7.

Landau B., Harzhauser M. & Beu A. (2009). A Revision of the Tonnoidea (Caenogastropoda, Gastropoda) from the Miocene Paratethys and their Palaeobiogeographic Implications. Jahrbuch der  Geologischen Bundesanstalt, 149 (1): 61-109.

Malatesta A., 1974. Malacofauna Pliocenica Umbra. Memorie per servire alla Descrizione della Carta geologica d’Italia, 13, 498 pp., 32 pls. Tipografia U. Pinto, Roma.

We thank our friend Massimo Cresti for the execution and use of the photos.

Ringraziamo per l’esecuzione e l’uso delle foto, l’amico Massimo Cresti.