Redescription and new record of () (Nematoda: Trichuroidea) in the monocled cobra from central Thailand: morphological and molecular insights.

The parasitic nematode () De, 1998, found in the Indian cobra is redescribed and re-illustrated in the present study. The monocled cobra was discovered to be a new host for this parasite in central Thailand. A comprehensive description extending the morphological and molecular characteristics of the parasites is provided to aid species recognition in future studies. The morphometric characters of 41 parasites collected from 5 cobra specimens are compared with those described in the original studies. Phylogenetic analyses using mitochondrial cytochrome c oxidase subunit 1 and nuclear 18S ribosomal RNA genes were performed to provide novel information on the systematics of . Similar characteristics were observed in the examined nematode samples, despite being found in different hosts, confirming their identity as . The molecular genetic results support the species status of , indicating is well defined and separated from other related nematode species in the family Capillariidae. Morphological descriptions, genetic sequences, evolutionary relationships among capillariids and new host and distribution records of are discussed. specimens found in the Thai cobra had some morphological variation, and sexual size dimorphism was also indicated. was found to infect various cobra host species and appeared to be common throughout the Oriental regions, consistent with its hosts' distribution.