Pristionchus kravanhensis n. sp., the first Pristionchus species reported from Cambodia

Summary A new Pristionchus species, P. kravanhensis n. sp. (Nematoda: Diplogastridae), from Cambodia is described. It was isolated from a melolonthine beetle in the Cardamom Mountains, has a gonochoristic mode of reproduction, and falls into the triformis group of Pristionchus species using a phylogeny based on orthologous proteins. Pristionchus kravanhensis n. sp. is sister to all other species in its group and most closely related to P. yamagatae and P. magnoliae . The new species is characterised by the arrangement of male genital papillae, ⟨v1, v2, v3d/v4, ad, ph, (v5, v6, v7, pd)⟩, where v2, v3d, co and v4 and v5, v6, v7, pd are close to each other, the distance v1-v2 is generally shorter than v2-v4, and v5-7 and pd overlap. The stomatal morphology is also used to distinguish P. kravanhensis n. sp. from other species in the triformis group. It has anteriorly split cheilostomatal plates, which rarely occur in eurystomatous form, and has only two alternative mouth forms (stenostomatous and one type of eurystomatous forms), while others have three (stenostomatous and two types of eurystomatous forms). Hence, this new species represents an interesting biological entity to study the molecular basis underlying the transition from dimorphism to triformism.