Falcaustra vietnamensis n. sp. is described from the small intestine of Physignathus cocincinus from north-central Vietnam. The new species is characterized by the large male worms (20.2-28.8 mm in length and 557-724 μm in width) relative to known members of the genus, 2 sharply pointed alate spicules of equal length (1,128-1,256 μm in length), gubernaculum including 2 separate pieces, 1 ventral with a pointed distal end and 1 dorsal with a blunt distal end (164-192 μm and 155-172 μm in length, respectively), and 12 pairs of caudal papillae. Female worms are larger than male worms (24.2-34.1 mm in length and 532-735 μm in width), with the vulva situated in the posterior half of body, and elliptical eggs, 60-70 μm long by 42-47 μm wide. Falcaustra vietnamensis n. sp. represents the 38th species assigned to the genus and the third species recorded from a lizard host in the Oriental biogeographical region. Partial sequences of the 18S ribosomal RNA gene (rDNA), internal transcribed spacer regions (ITS), and cytochrome c oxidase subunit 1 (COI) are provided for the new species. The molecular phylogenetic position of the genus Falcaustra is briefly discussed.
Keywords: Falcaustra vietnamensis n. sp.; Physignathus cocincinus; Agamidae; Nematoda; Squamata; Vietnam.
© American Society of Parasitologists 2021.