First Molecular Characterization of Adult Physaloptera praeputialis von Linstow, 1889, Infecting African Lion (Panthera leo) in Tanzania

Résumé fourni par la source

Physalopterid nematodes are common gastric parasites of carnivorous mammals, yet their diversity, host associations, and evolutionary relationships in African wildlife remain poorly understood. The present study aimed to investigate the adult Physaloptera specimens recovered from African lions (Panthera leo) in the Serengeti National Park in the Mara region, Tanzania, using morphological and molecular techniques. Seven non-captive lions comprising three males and four females were opportunistically necropsied between 2023 and 2025. The sampled lions included two subadults (4-5 years), three prime adults (6-9 years), and two older individuals (10-14 years). A total of 157 adult spirurid nematodes were recovered from three infected hosts with infection intensities ranging from 48 to 57 worms per host. Morphometric characterizations, such as cephalic collarette structures, marked unequal spicules, well-developed caudal alae in males, and an anterior positioned vulva in females, together with typical eggs, were consistent with Physaloptera praeputialis. Nuclear 18S rRNA sequences showed high similarity of 98-99.5% to P. praeputialis reference sequences. In contrast, mitochondrial cytochrome c oxidase subunit I (Cox1) sequences formed a distinct lineage, exhibiting approximately 12% divergence from available P. praeputialis sequences retrieved from the GenBank database at the time of analysis. A molecularly characterized record of adult Physaloptera from an African lion in Tanzania is presented, revealing previously unrecognized genetic diversity among African physalopterids. Findings highlight the role of apex predators as indicator hosts in trophic parasite transmission and emphasize the importance of multilocus approaches for resolving spirurid taxonomy, parasite biogeography, and host–parasite associations in wildlife ecosystems.

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