Occurrence, Taxonomy, And Phenotypic Variation Of Angel Sharks In The Eastern Pacific Ocean

Angel sharks are a primarily benthic group comprising the monotypic genus Squatina. Distinguishing the numerous individual species within this genus proves very difficult due to the general morphological homogeneity they exhibit. In the Eastern Pacific region the Squatina genus appears to have an anti-tropical distribution. In the North Eastern Pacific (NEP) described species Squatina californica occurs from off the coasts of southern Alaska to Mexico. In the South Eastern Pacific (SEP) described species Squatina armata occurs off the coasts of Ecuador down to southern Chile. It is not currently known if more distinct species occur and remain yet described throughout both these areas, particularly the understudied SEP. Even in the more studied NEP, previous studies suggest that a sub-population in the partially isolated Gulf of California may constitute a third distinct species. Throughout the entire range the degree of phenotypic variation exhibited by sub-populations has not been previously noted. Here the morphology of multiple sharks from across the Eastern Pacific region were measured and compared across varying degrees of geographic distances. Samples specimens were measured using a newly refined morphometric protocol specifically designed for angel sharks unique body plan. Groups of samples from the NEP and SEP were subsequently compared with the corresponding original species description for each area. Results indicate the presence of at least four distinct morphologies of the Squatina genus throughout the entire Eastern Pacific region.