Revisiting Acanthocephalus dirus (Van Cleave, 1931) (Acanthocephala: Echinorhynchidae) Using SEM and Energy Dispersive X-Ray Analysis (EDXA) for the First Time

Abstract

Acanthocephalus dirus (Van Cleave, 1931) Van Cleave and Townsend, 1936 is the most widely distributed and studied species of acanthocephalans in North America. Acanthocephalus jacksoni Bullock, 1962 from New England and Acanthocephalus parksidei Amin, 1975 from Wisconsin are junior synonyms. Line drawings were used in these and all subsequent descriptive accounts since. We are reporting SEM images of A. dirus for the first time from 2 Wisconsin populations from Catostomus commersoni Lacépède showing new details that could not have been seen only with optical microscopy. The new SEM observations include new features that were not previously reported such as apical sensory pores, micropores variably distributed on the trunk and on the proboscis and hooks, hooks of variable size, and bursa with 2 circles of sensory papillae and 2 pedunculated suckers. We are also providing a detailed elemental analysis of middle hooks using Energy Dispersive x-ray analysis (EDXA) showing high levels of sulfur in all samples especially hook tips.