A maximum-likelihood (ML) tree based on concatenated sequences of two mitochondrial [16S rRNA (16S; 380 bp) and cytochrome c oxidase subunit I (COI; 626 bp)] and three nuclear gene markers [18S rRNA (18S; 1738 bp), 28S rRNA (28S; 505 bp), and histone H3 (H3; 329 bp)]. Numbers near each node are support values generated by a separate partitioned ML bootstrap analysis with 1000 replicates. Country names of each species sampling location are abbreviated as follows: CA = Canada, JP = Japan, RU = Russia, USA = United States of America, and VE = Venezuela.