A comparative assessment of the morphology of Profilicollis altmani (Acanthocephala, Polymorphidae) from crustaceans and shore birds in Peru, with special notes on hook elemental analysis (EDXA), SEM imaging, histopathology, and molecular profile.

The morphology of cystacanths and adults of Profilicollis altmani (Perry, 1942) Van Cleave, 1947 (Polymorphidae) were studied from the Pacific mole crab Emerita analoga (Stimpson) (Crustacea, Hippidae) and Belcher's gull Larus belcheri (Vigors) (Aves, Laridae), respectively, in Peru. Comparative morphometrics with accounts of other populations of P. altmani from elsewhere off the Pacific and Atlantic coasts of North and South America revealed marked intraspecific population variations. We report scanning electron micrographs (SEM) of new features, not before noted or captured in line drawings by earlier observers. We further present microscope images that reveal internal details not previously reported or possible to see with SEM. Energy dispersive X-ray analysis (EDXA) revealed unusual patterns in the chemistry of proboscis hooks especially the high sulfur and diminished phosphorous and calcium in hook tips and low sulfur and high levels of phosphorous and calcium at mid hooks. The size and shape of all hooks of the cystacanths are reported for the first time. Histopathological studies in L. belcheri from Peru are also included. Cystacanths of P. altmani from California were also analyzed for molecular patterns and compared with other sequences reported from other locations. The molecular data and the analysis of our new sequences of cytochrome oxidase I (COI) showed that haplotypes of P. altmani had low genetic variation; the species is not geographically structured, and within its clade no monophyletic group is formed.