LAUSR

In this study, we present a morphological description of immature and adult specimens of Ornithodoros saraivai n. sp., a tick associated with the frog Cycloramphus boraceiensis (Cycloramphidae) at São Sebastião island, located in the São Paulo state seaboard, Brazil. While larvae of O. saraivai are ecologically related to Ornithodoros faccinii, another soft tick associated with cycloramphids, the combination of 7 sternal pairs, 16 dorsal pairs, a pyriform dorsal plate and a partially toothed hypostome constitute unique characters of the O. saraivai larvae. One undetermined nymphal instar and adults of O. saraivai are similar to mature specimens of the Ornithodoros talaje species group; however, the O. saraivai specimens can be recognized by the presence of a robust bean-shaped spiracle with a large spiracular plate and more than two long seta in palpal article I. Identical partial sequences of the mitochondrial 16S rDNA gene confirmed the identity for all collected stages and for two cohorts of laboratory-reared larvae of O. saraivai. A Bayesian and Maximum Parsimony inferred phylogenetic trees support the position of O. saraivai in a clade with O. faccinii, suggesting the existence of an Ornithodoros lineage that evolved in association with amphibians.