title: Observations on the micromorphology of the tropical rat mite Ornithonyssus bacoti (Hirst) as revealed by scanning electron microscopy.
abstract: Ornithonyssus bacoti (Hirst) is an important parasite of rodents. The characteristic shape of the dorsal and sternal shields and gnathosoma used as taxonomic characteristics was confirmed by scanning electron microscopy. The anal plate is distinctly pear-shaped with a pair of adanal setae lateral to the anal valves, a single postanal seta and a distinct dentate cribrum formed by peg-like projections. In the adult mites a peritreme extends anteriorly to the 1st coxa from the spiracle situated laterally between the 3rd and 4th coxa. The peritreme is an open canal protected by an overhanging dorsal ridge and lined with short peg-like aciculae. The gnathosoma includes a pair of pedipalps, a pair of protrusile chelicerae retracted into the hypostoma, and a serrate tritosternum ventrally. A unique feature to the normal setae of the pedipalps is a golf club-shaped seta which is found medially on the palp genu. A distinctive double-bladed 'palpal claw' or apotele is directed medially from the palp tibia. The pincer-like chela consists of a spear-like prong forming the moveable digit and a curved stylus-like fixed digit used to pierce the skin. Each leg ends with a pair of hooked tarsal claws and a pair of lateral comblike pretarsal appendages adjacent to the pulvillus. The pulvillus may be retracted, allowing the pretarsal operculum to function as a 'clasping organ' that enables the mite to clasp the hairs of the host during feeding.
authors.affiliation: Department of Veterinary Anatomy, Faculty of Veterinary Science, Medical University of Southern Africa, Medunsa, South Africa.
authors.forename: E D
authors.initials: ED
authors.lastname: Green
authors.forename: C
authors.initials: C
authors.lastname: Baker
mesh_terms: D000818:Animals; D005260:Female; D008297:Male; D008855:Microscopy, Electron, Scanning / Q000662:veterinary; D008925:Mites / Q000033:anatomy & histology* / Q000145:classification