Ornithodoros cerradoensis n. sp. (Acari: Argasidae), a member of the Ornithodoros talaje (Guérin-Méneville, 1849) group, parasite of rodents in the Brazilian Savannah

Abstract

Ornithodoros cerradoensis n. sp. is described from field-collected and laboratory reared nymphs, males, females,and larvae parasitizing the rodents Cavia aperea and Thrichomys sp. in the Brazilian Savannah. This new species ismorphologically and genetically related with the Ornithodoros talaje group and can be separated from otherNeotropical species using the following combination of characters: larva with 18 pairs of setae on dorsum (sevenanterolateral, four central and seven posterolateral), hypostome with median dentition 2/2; adults provided withlarge mammillae; dorsal disks surrounded by bulked marginal ridges delimiting barely pebbled areas; three disksin the anterolateral file, and median disk not merging with the posteromedian file. Feeding assays in the laboratorydemonstrated that (1) larvae of O. cerradoensis are slow-feeders (∼6 days), (2) first nymphal instar (N1)molts to second instar (N2) without feeding, and (3) N2 and third nymphal instar (N3) engorge rapidly (minutes).With the exception of Ornithodoros hasei nymphs that depict flattened bodies, O. cerradoensis N1, N2, andN3 highly resemble homologous instars of other species in O. talaje sensu lato, therefore are not suitable formorphological comparisons within the group. In addition to morphological signature of larvae and adults thatseparate this new species; results of cross-mating attempts between O. cerradoensis and Ornithodoros guaporensis amorphologically and phylogenetically closely related species that also parasitizes rodents in the BrazilianSavannah; a Principal Component Analysis using larval characters; and a phylogenetic analysis using mitochondrialmarkers, support O. cerradoensis as an independent lineage within the Ornithodorinae.