Dendromonocotyle species (Monogenea: Monocotylidae) are the only monocotylids to parasitize the skin of chondrichthyan hosts. Currently 11 species are recorded from the skin of ray species in the Dasyatidae, Myliobatidae and Urolophidae. There have been increasing reports of Dendromonocotyle outbreaks on rays kept in public aquaria. This paper provides a broad review of Dendromonocotyle that should assist taxonomists and aquarists with species identification and help decisions on potential control methods for Dendromonocotyle infections. The taxonomy and host-specificity of Dendromonocotyle are discussed and a key to current species is provided. We summarise what little is known about the biology of Dendromonocotyle including egg embryonation and hatching, feeding, camouflage and reproduction. The efficacy of freshwater baths, chemical treatments and biological control measures such as the use of cleaner fish for Dendromonocotyle is also discussed. We demonstrate that effective control of Dendromonocotyle on captive rays is hampered by the lack of basic biological data on the life cycle of the parasites. A case history is provided outlining the success of a public aquarium (Underwater World, Mooloolaba, Queensland, Australia) in managing D. pipinna infections on captive Taeniura meyeni without chemical intervention simply by taking measures to reduce host stress.
Dendromonocotyle lotteri sp. n. is described from the dorsal skin surface of the stingray Himantura gerrardi (Gray) on exhibit in the public aquarium at the Atlantis resort in Dubai. It is differentiated from all other Dendromonocotyle species by the unique morphology of the distal portion of the sclerotised male copulatory organ. Dendromonocotyle lotteri is the second representative in the genus with 56 marginal haptoral papillae having a papillae to loculus association represented numerically as 6-6-8-8. We found Dendromonocotyle colorni Chisholm, Whittington et Kearn, 2001 on the same host specimens at the Atlantis resort public aquarium and Dendromonocotyle kuhlii Young, 1967 on Neotrygon kuhlii (Müller et Henle) kept at Burgers' Zoo Aquarium in Arnhem, The Netherlands. Supplemental information is provided for both D. colorni and D. kuhlii. The presence of Dendromonocotyle infections in public aquaria and host specificity are discussed. A key to the 17 species of Dendromonocotyle is also provided.