Figure 1. Maximum likelihood (ML) phylogram based on rDNA sequences. Taxa with ribbed shells have underlined names. Vertical lines labelled NZ (New Zealand), MAG (Magellanic) and Laq (laqueoid) mark the respective ingroup clades and the outgroup. ML tree constructed by heuristic search with tree bisection-reconnection branch exchange, rooted with laqueoid outgroups and using the Akaike information criterion-selected alignment-specific general time reversible ML model with gamma and invariant site corrections, gamma shape = 0.78 Pinvar = 0.80. With bootstrap support (%) based on 1000 pseudoreplicates using ML distances analysed by BioNJ. The maximum parsimony and ML trees had identical topology and similar bootstrap % (parsimony length = 1169, consistency index = 0.95, retention index = 0.84).