Comparative study of three cryptic species of the genus Eucephalobus Steiner, 1936 with conoid-elongate tail and its relationship with the genus Pseudacrobeles Steiner, 1938

Three cryptic species of the genus Eucephalobus, collected from coastal dunes of Spain and wet areas of California and Vietnam, are studied. The objective of this study is the differentiation of those species of the genus Eucephalobus with a long tail, which can be confused with each other and especially with Eucephalobus oxyuroides. These species are E. compsus, E. hooperi and E. panaxi. Furthermore, Pseudacrobeles unguicolis, which is also confused with these species, has been studied. This study provides detailed morphological and morphometrical characterisation for the three species of Eucephalobus, including light and scanning electron microscopy illustrations. Molecular characterisation of E. hooperi, E. mucronatus, E. striatus and Pseudacrobeles unguicolis is also presented.