Cerithioidea

Cerithioidea View in CoL

Varices appear to have originated four times independently in the Cerithioidea , because the basal-most cerithioideans do not have varices ( Strong et al., 2011). Rounded, unsynchronized varices that extend up the spire evolved once in Potamididae (Turonian-Recent) ( Saul & Squires, 2003; Reid et al., 2008) and once in the clade including Cerithiidae , Litiopidae ( Alaba and Gibbarissoia), and Diastomatidae (Paleocene-Recent) ( Houbrick, 1981; Strong et al., 2011). In many cases, these varices are lighter in colour compared to rest of the shell. The third origin is in the Batillariidae and the fourth in Faunus ater (L. 1758) ( Pachychilidae ).

Broad, lateral, subterminal varices are also found in many species of Potamididae , Cerithiidae (not Alabininae), Pachychilidae ( Faunus ), and Battilariidae ( Fig. 2E–G View Figure 2 ). A few cerithiines, including Clypeomorus , can also have a dorsal subterminal varix ( Houbrick, 1985, 1991; Ozawa et al., 2009; Strong et al., 2011).

Many Mesozoic cerithioids are difficult to assign to specific families, so varix origins in these families are unclear. The earliest potamidid with a ventrolateral varix is Cedrosia pacifica Saul & Squires, 2003 (Late Cretaceous), although many Mesozoic potamidids are also avaricate ( Saul & Squires, 2003). The earliest batillariid found was Pyrazus partschi ( Zekeli, 1852) from the Late Cretaceous, while the first without varices?Echinobathra is mid-late Cretaceous ( Ozawa et al., 2009). In the paraphyletic cerithiidae ( Ozawa et al., 2009), Cryptaulax is found in the Triassic without varices, while the varicate taxon Hemicerithium ? interlinea (Cragin, 1893) occurs in the Cenomanian (Early Late Cretaceous) ( Stephenson, 1952; Sälgeback & Savazzi, 2006).

Faunus ater View in CoL has a subtle ventrolateral varix not mentioned by Houbrick (1991). Faunus View in CoL is reconstructed as the basal genus, as well as the sole brackish water representative of the freshwater Pachychilidae ( Köhler & Glaubrecht, 2010) View in CoL . Earlier fossil pachychilids, including other Faunus View in CoL , do not show varices, so this may be a separate and Recent origin of varices ( Pacaud & Harzhauser, 2012).