Rhinobatos typus and Rhynchobatus djiddensis were collected from Heron Island, Australia and examined for monocotylid parasites. Specimens of Neoheterocotyle rhinobatidis (Young, 1967) Chisholm, 1994 and N. rhynchobatis (Tripathi, 1959) Chisholm, 1994 were collected from the gills of Rhinobatos typus. This represents both a new host and new locality record for N. rhynchobatis. Neoheterocotyle bychowskyi (Timofeeva, 1981) Chisholm, 1994, N. nagibinae (Timofeeva, 1981) Chisholm, 1994 and N. rhinobatis (Pillai & Pillai, 1976) n. comb. were identified from the gills of Rhynchobatus djiddensis from Australia and are all new locality records. We consider N. djiddensis (Pillai & Pillai, 1976) n. comb. a species inquirenda and synonymise N. trilobata Timofeeva, 1981 with N. rhinobatis. Therefore, there are 7 valid species in the genus, including N. bychowskyi, N. forficata, N. inpristi, N. nagibinae, N. rhinobatidis, N. rhinobatis and N. rhynchobatis. The larvae of N. rhinobatis and N. rhynchobatis are described and the anterior glands of the larvae are related to those of the adults. The development of the male copulatory organ of N. rhinobatidis is described. Host-specificity and geographic range of the genus are also discussed and a key to species is provided.