A comparative morphometric analysis of Cancer borealis Stimpson, 1859 and Cancer irroratus Say, 1817 (Decapoda: Brachyura: Cancridae) in the northwest Atlantic Ocean

The distributions of Cancer borealis and Cancer irroratus were analyzed revealing important new records. Morphological characters of the carapace were tested with one-way analysis of variance (ANOVA) for differences across latitude and depth gradients. Northern (> 41°N) and southern (< 30°N) groups of C. borealis exhibited significant (P < 0.05) differences from mid-latitude groups in carapace and chelae character means. In C. irroratus, northern (> 38°N) and southern (< 32°N) groups exhibited significant (P < 0.05) differences from mid-latitude groups in carapace and chelae character means. Measurements for C. borealis from shallow water (< 10 meters) differed significantly (P < 0.05) compared to those from deeper water In C. irroratus, shallow water (< 10 meters) and deepwater (> 100 meters) specimens exhibited (P < 0.05) significantly different means from those of mid-depth waters. Discriminant function analysis of diagnostic characters proved effective at discriminating the two species.