Figure 1. Trees resulting from cladistic analyses using maximum parsimony of conchologic characters for tropical America Neogene corbulid genera. Characters polarized using Corbula as an outgroup. Each node is labeled with its Bremer decay index. 1.1 One most parsimonious tree derived from analysis of a 70-character matrix (tree length = 203; consistency index (CI) = 0.5959; and retention index (RI) = 0.5738). 1.2 Strict consensus of two most parsimonious trees derived from analysis of a 73-character matrix (tree length = 208; CI = 0.5758; and RI = 0.5579). After Anderson and Roopnarine (2003).