\u3ci\u3eReticulotaenia\u3c/i\u3e n. gen. for \u3ci\u3eLateriporus australis\u3c/i\u3e Jones and Williams, 1967, and \u3ci\u3eLateriporus mawsoni\u3c/i\u3e Prudhoe, 1969 (Cestoda: Dilepididae), from Sheathbills, \u3ci\u3eChionis\u3c/i\u3e spp., in Antarctica, with a Consideration of Infraspecific Variation and Speciation

Reticulotaenia n. gen. was established in the family Dilepididae for two species of cestodes, formerly referred to Lateriporus Fuhrmann, 1907, that are characteristic helminths in sheathbills, Chionis spp., in Antarctica. The new genus was most similar to Lateriporus and Dilepis Weinland, 1858, but was easily distinguished from these and other genera of Dilepidinae having a unilateral genital pore. The salient features of Reticulotaenia were a rostellum armed with a single row of 10 hooks, a vaginal sphincter, and a reticulate ovary and uterus. Reticulotaenia australis (Jones and Williams, 1967) n. comb. was redescribed on the basis of specimens from Chionis alba (Gmelin) collected near Palmer Station, Antarctica. Morphological variation in this species of cestode was evaluated in specimens from the South Orkney Islands (type locality) and South Georgia. In addition, R. mawsoni (Prudhoe, 1969) n. comb. from Chionis minor Hartlaub was distinguished from its congener. The present host and geographic distribution of R. australis and R. mawsoni appeared to represent a result of host-parasite cospeciation