Paracrobeles mojavicus sp. n. (Nematoda: Cephalobidae) from the Mojave Desert, California.

Abstract

Paracrobeles mojavicus n. sp. from soil associated with creosote shrubs (Larrea tridentata), in the Mojave Desert, California, is the third species of Paracrobeles and the first described from the New World. The new species is differentiated from other species of the genus by a lower or higher number of total body annuli, a more posterior position of the excretory pore and vulva relative to total length, relatively short spicules, vagina oriented perpendicular to the body axis (versus at a sharp angle) and postvulval sac that extends far posterior to the tip of the ovary. The testis of P. mojavicus n. sp. is deeply reflexed relative to other species of the genus. Three large glands are ventral to the testis and open posteriorly near the spicules; re-examination of paratypes indicates the glands are present in other Paracrobeles but differ in shape and are larger in P. mojavicus n. sp. The phylogenetic significance of the enlarged bulbous posterior region of the corpus and the absence of tines on the probolae in defining the relationship of Paracrobeles to Acrobeles remains unresolved.