title: Redescription of the females of Hystrignathus rigidus Leidy, 1850 (Nematoda: Hystrignathidae), parasites of Odontotaenius disjunctus (Coleoptera: Passalidae) from eastern USA.
abstract: The female of Hystrignathus rigidus Leidy, 1850 (Nematoda: Hystrignathidae) is redescribed on the basis of new material from Odontotaenius disjunctus (Coleoptera: Passalidae) from Athens, Georgia, USA; which also constitutes a new locality record. SEM images are provided for the first time for the species. It is also first shown that H. rigidus presents ridged-shelled eggs. A differential diagnosis is provided. H. rigidus can be differentiated from the rest of the species of this genus by having a short, non inflated first cephalic annule; spines that surpass the level of the oesophagus, an absence of lateral alae, ridged-shelled eggs and its length of the body and tail. The material from the present study differs from a previous redescription by Christie (1934) by its shorter body (2.125-2.950 vs. 2.130-4.200), first cephalic annule (0.003-0.005 vs. 0.012) and oesophagus (0.350-0.430 vs. 0.650-0.670).
authors.affiliation: Instituto de Ecología y Sistemática, Carretera Varona 11835 e/ Oriente y Lindero, La Habana 19, CP 11900, Calabazar, Boyeros, La Habana, Cuba; Email: jans@ecologia.cu.
authors.forename: Jans
authors.initials: J
authors.lastname: Morffe
authors.affiliation: Instituto de Ecología y Sistemática, Carretera Varona 11835 e/ Oriente y Lindero, La Habana 19, CP 11900, Calabazar, Boyeros, La Habana, Cuba; Email: unknown.
authors.forename: Nayla
authors.initials: N
authors.lastname: García
authors.affiliation: Odum School of Ecology, University of Georgia, Athens GA 30602; Email: unknown.
authors.forename: Andrew K
authors.initials: AK
authors.lastname: Davis
mesh_terms: D063147:Animal Distribution; D000825:Animal Structures / Q000033:anatomy & histology / Q000254:growth & development; D000818:Animals; D049628:Body Size; D001517:Coleoptera / Q000469:parasitology*; D005260:Female; D005845:Georgia; D008297:Male; D009348:Nematoda / Q000033:anatomy & histology* / Q000145:classification* / Q000254:growth & development; D009929:Organ Size