A new lecanicephalidean genus is erected for cestodes previously recognised as "New Genus 12" (Polypocephalidae) in a phylogenetic analysis of the interrelationship of members of this order. Examination of the cestode fauna of the mangrove whipray, Urogymnus granulatus (Macleay) (Myliobatiformes: Dasyatidae) from the Solomon Islands and northern Australia revealed the existence of specimens representing two new species, consistent in morphology with "New Genus 12." Corollapex gen. n. is unique among the 24 valid lecanicephalidean genera in its possession of an apical organ in the form of an external retractable central disk surrounded by eight concave muscular, membrane-bound pads and an internal heterogeneous glandular component. The two new species described herein, Corollapex cairae sp. n. (type species) and Corollapex tingoi sp. n., differ from one another in overall size and number of mature and immature proglottids, and are noted to demonstrate a differential distribution between mature and juvenile host individuals. Additional species diversity in the new genus, beyond C. cairae sp. n., C. tingoi sp. n., and "New Genus 12 n. sp. 1" of Jensen et al. (2016) is suggested. Corollapex gen. n. appears to be restricted to dasyatid hosts in the Indo-West Pacific region.
Keywords: Indo-West Pacific region; Lecanicephalidea; Polypocephalidae; apical organ; scanning electron microscopy.