Morphological and molecular characterization of Brevimulticaecum sinensis sp. nov. (Nematoda: Ascaridoidea) from Alligator sinensis (Crocodilian: Alligatoridae)

<i>Brevimulticaecum sinensis</i> sp. nov. is a novel species belonging to the genus <i>Brevimulticaecum</i> (Nematoda: Heterocheilidae). It was detected in the stomach of a carcass of a Chinese alligator (<i>Alligator sinensis</i> Fauvel, 1879; Crocodilian: Alligatoridae) at the National Nature Reserve of China Alligator, Anhui Province, China. This study investigated the morphological and molecular characteristics of the isolated <i>B. sinensis</i> sp. nov. Herein, light and scanning electron microscopy, DNA sequencing, and histological analyses were performed for <i>B. sinensis</i> sp. nov. Notably, microscopy revealed novel taxonomic features of <i>B. sinensis</i> sp. nov. Additionally, the sequences of the internal transcribed spacer (ITS), cytochrome oxidase I (COI), and small subunit DNA (18S) segments of <i>B. sinensis</i> sp. nov. were 892, 655, and 885 bp, respectively. To the best of our knowledge, this is the first study providing molecular data showing the affiliation of this <i>Brevimulticaecum</i> species with the family Heterocheilidae. The histological analysis revealed the pathology of <i>B. sinensis</i> sp. nov. infection in <i>A. sinensis</i>. Overall, the findings of this study provide novel geographic and infection records of <i>B. sinensis</i> sp. nov., with it being added to nematode species that infect crocodiles.