Thelastoma vanwaerebekei n. sp. (Oxyurida: Thelastomatidae) a parasite of Gymnetis litigiosa (Coleoptera: Scarabaeidae) from Uruguay.

Thelastoma vanwaerebekei n. sp. was extracted from the hindgut of Gymnetis litigiosa. The new species is included in the group of species with females having the excretory pore at the same level as the pharyngeal basal bulb (or slightly anteriorly), long tail length (approximately 30% of total body length) and males without spicules. Females of T. vanwaerebekei n. sp. differ from those of T. madecassum in tail shape (filiform and conical, respectively). They differ from T. basiri, T. imphalensis and T. dessetae in the morphology of the anterior region. In females, pharyngeal length is shorter than in T. depressum. In males, T. vanwaerebekei n. sp. differs from T. blabericola in the tail length, and from T. raoi in the number of caudal papillae. The partial 18S SSU and 28S LSU rRNA gene regions were amplified.

Morphological and molecular characterisation of an isolate of Steinernema diaprepesi Nguyen & Duncan, 2002 (Rhabditida: Steinernematidae) from Argentina and identification of its bacterial symbiont.

Entomopathogenic nematodes of the families Heterorhabditidae Poinar, 1976 and Steinernematidae Chitwood & Chitwood, 1937 are used for biological control of insect pests. An isolate of Steinernema diaprepesi Nguyen & Duncan, 2002 was recovered from a carrot field in the locality of Santa Rosa de Calchines (Santa Fe Province, Argentina). These nematodes were characterised based on morphological, morphometric and molecular studies. Their symbiotic bacterium was identified as Xenorhabdus doucetiae Tailliez, Pagès, Ginibre & Boemare, 2006 by sequencing the 16S rRNA gene. The isolate of S. diaprepesi studied exhibits some morphometric differences with the original description, especially in the first generation adults. This is the first description of the species in Argentina.

Morphological and molecular characterisation of the entomoparasitic nematode Hammerschmidtiella diesingi (Nematoda, Oxyurida, Thelastomatidae).

A population of Hammerschmidtiella diesingi was detected in specimens of Periplaneta americana collected in Córdoba city (Argentina) was studied. Nematodes were characterized based on morphological, morphometric and genetic (D2-D3 expansion segment) analyses. New data are provided, especially on particular morphological characters that were a matter of controversy in previous studies. H. diesingi is reported in Argentina for the first time.