Differential Distribution of Minerals in the Proboscis Hooks of Corynosoma paraevae (Acanthocephala, Polymorphidae) Juveniles from Notothenia coriiceps off Argentine Islands, West Antarctica

Abstract

Excysted cystacanths of Corynosoma paraevae Amin et al., 2025 (Polymorphidae) were described as a cryptic species from the body cavity of Notothenia coriiceps Richardson, 1844 collected off Galindez Island, Argentine Islands. This description included its molecular analysis, SEM images, and Energy Dispersive X-ray Analysis (EDXA) for the first time which demonstrated highest levels of calcium in all hooks and hook roots compared to sulphur and phosphorus. We report here for the first time a new aspect of elemental analysis of hooks demonstrating the differential distribution of sulphur , phosphorous, calcium, and magnesium at the center and margins of anterior, middle and posterior hooks, and hook roots. In this study, Calcium was found to be the most prevalent element in roots (root edge and root middle) and the center of middle hooks. Phosphorous was also common but not as prevalent as calcium and was highest in the center of the roots and also the middle of all hooks. Interestingly, phosphorous was consistent in all hook roots but was lowest in the center of posterior hooks and roots. Sulphur was negligible or absent in root center of anterior and middle hooks, pronounced in posterior hook root and most prevalent in the edges of all hook tips as well as the edge of the middle hook. The biological importance of this pattern is discussed in terms relevance to hook strength and flexibility, species identity and comparative systematics. This EDXA profile of C. paraevae was distinctly differentiated from that of the morphologically closely related species Corynosoma pseudohamanni Zdzitowiecki, 1984.