Phylogenetic tree based on 19 mitochondrial COI gene sequences of the eight Acrossus species and Nimbus affinis (outgroup). Branch values indicate bootstrap support in maximum likelihood (ML) and neighbor joining (NJ), respectively. Tree topology and branch lengths reflect the results of ML analysis. The tree is drawn to scale, with branch lengths (evolutionary distance) measured in the number of substitutions per site. Dashes (–) indicate support values of less than 50 or incongruent between ML and NJ.