A new species of trypanorhynch cestode is described from two species of stingrays, the Panamic stingray Urotrygon aspidura (Jordan & Gilbert) and the Pacific chupare Himantura pacifica (Beebe & Tee-Van) collected in the Golfo de Montijo in the Eastern Pacific Ocean off the coast of Panama. Shirleyrhynchus panamensis n. sp. represents an important addition to the family, which until now consisted of two monotypic genera. The new species is characterised by an elongate scolex with four, ovate bothria, presence of prebulbar organs, absence of gland cells within the muscular bulbs and an oncotaxy with a typical heteroacanthous, heteromorphous tentacular armature, a characteristic basal armature and the presence of a slight basal swelling. It is readily distinguished from its congeners by a smaller scolex and features of the oncotaxy, such as dissimilar hooks on opposing principle rows, a commencement of hook rows from the bothrial to the antibothrial surface and a much shorter basal armature. Although described only on the basis of immature worms lacking a strobila, the new species adds information on features of the oncotaxy within Shirleyrhynchus Beveridge & Campbell, 1988. Observation of the holotype of Shirleyrhynchus aetobatidis (Shipley & Hornell, 1906) revealed apparent differences from Australian specimens that have been described as Shirleyrhynchus butlerae Beveridge & Campbell, 1988 but which were later synonymised. Observations of type-specimens of S. butlerae also revealed differences from the original description and some morphological characteristics are amended. Shirleyrhynchus butlerae is herein resurrected and an amended generic diagnosis and a key to the identification of species are provided. The molecular voucher specimen of 'S. aetobatidis' utilised in previous molecular phylogenetic studies was re-observed which revealed a misidentification of the specimen with Parachristianella indonesiensis Palm, 2004.