The first morphological and molecular identification of Quilonia sp. (Nematoda: Strongylidae) from wild Asian elephant (Elephas maximus) in China.

The Asian elephant (Elephas maximus) is classified as an endangered species on the IUCN Red List of Threatened Species. In China, approximately 300 individuals remain in the wild. Parasitic infections are significant concerns both human and animal medicine, especially within wildlife. However, there are currently no photomicrographs and genetic data available for parasites from wild Asian elephants in China. In order to preliminarily investigate parasitic infections of the wild Asian elephants in China, we collected faecal samples from a wild, vagrant male elephant for this study. Here, we provided photomicrographs with larval Quilonia sp.. Concurrently, the partial ITS (internal transcribed spacer) gene of Quilonia sp. was cloned, sequenced using PCR (polymerase chain reaction) technique, and subjected to bioinformatic analysis. Morphological identification of Quilonia sp. was conducted, revealing a rod-like anterior structure, short esophagus, tapered tail, thick cuticle, and a length exceeding 500 μm. Phylogenetic analysis suggests that BND-ITS (ITS gene of the specimen) belongs to the Quilonia sp.. The present study also will enhance the current understanding of the taxonomy of Quilonia sp., support long-term health monitoring of Asian elephants in China, and contribute to future genomic studies.