Limited morphological differences between genetically identified cryptic species within the Leptasterias species complex (Echinodermata: Asteroidea)

Sea stars of the Leptasterias species complex are common members of the rocky intertidal community of the temperate and subarctic North American Pacific coast. Variation in 53 morphological characters was studied in 645 Leptasterias spp. collected at 13 intertidal locations from the Aleutian Islands to Oregon. The sea stars were also examined for restriction-site polymorphisms in polymerase chain reaction amplified DNA representing the putative mitochondrial DNA (mtDNA) control region and flanking sequences; these polymorphisms have recently been shown to discriminate among Leptasterias species in the Puget Sound region and southern Alaska. Ten mtDNA haplotypes were identified (designated A-J); five of these (D, E, H, I, and J) had not been reported in earlier surveys and were found at single locations only. Canonical discriminant analysis of morphological variation could partially separate nine of the haplotypes (A-I), but there was some overlap in canonical variable scores between most pairs of haplotypes. Morphologically, the haplotypes formed three major clusters based on canonical variable scores, composed of haplotypes A/C/D, B/E/F/G/H, and I.