Onustus plioextensus (Sacco 1896) (Gastropoda: Caenogastropoda): a Mediterranean Pliocene xenophorid with Western Atlantic relationships?

Submitted by admin on Sun, 20/11/2011 18:55
G. MANGANELLI
V. SPADINI
(2010)
Volume
40
Part
3
Page from
333

Onustus plioextensus (Sacco 1896) is a Mediterranean Pliocene xenophorid characterized by a large fragile shell with wide thin peripheral flange, porcellanous below. It is only known from the Piacenzian (Middle Pliocene) of central northern Italy and is very similar to the west Atlantic Onustus longleyi (Bartsch 1931). If the morphological similarity between these two xenophorids is not a result of convergent evolution and testifies to real affinity, then they constitute a group of closely related species with amphi-Atlantic distribution, a biogeographical pattern suggested for certain gastropod species mainly belonging to the tonnoideans.

Keywords
Xenophorids
Onustus plioextensus
taxonomy
palaeontology
biogeography
Pliocene