ABSTRACT
Intertidal populations of small, six-rayed sea stars belonging to the Leptasterias hexactis complex along the Pacific coast of North America have a complex genetic structure and an uncertain taxonomic status. We studied 1,085 sea stars from 37 intertidal locations between Shemya, Alaska and San Simeon, California. The sea stars were identified using morphological and genetic criteria to four nominal species: Leptasterias epichlora (Brandt, 1835), L. hexactis (Stimpson, 1862), L. aequalis (Stimpson, 1862) and L. aspera Fisher, 1930. A maximum of two species was found at any particular intertidal location, and hybridization occurred rarely when two species were sympatric (10/1,085 or 0.9% of the total were identified as hybrid individuals). All species were similar genetically and morphologically, but could usually be recognized by at least one diagnostic allozyme locus separating each pair of species. Southern populations of L. hexactis showed genetic and morphological differences within single collections, consistent with the existence of a second, sympatric species (probably L. pusilla Fisher, 1930) at certain sites in central California.
