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Environ Biol Fish (2014) 97:967979 DOI 10.1007/s10641-014-0261-8
Interrelationships of the durophagous stingrays (Batoidea: Myliobatidae)
Neil C. Aschliman
Received: 5 August 2013 /Accepted: 17 March 2014 /Published online: 3 April 2014 # Springer Science+Business Media Dordrecht 2014
Abstract In the last few years, estimates of the patterns and timing of the evolution of the pelagic, durophagous stingrays (Myliobatidae) have improved through new comparative data from morphology, the fossil record, and DNA sequences. These recent studies are here reviewed and a conservative summary of myliobatid diversification and origins is presented. The interrelationships and morphological evolution of the durophagous stingrays are discussed, including the nature of devil rays as derived myliobatids. An exploration of myliobatid origins includes estimates of the timing of their diversification and an assessment of gymnurids as a possible sister group. The prevailing signal suggests that the most recent common ancestor of extant myliobatids was a Late Cretaceous oscillating swimmer with a pavement-like dentition. The devil ray lineage began the transition to planktivory by at least the Oligocene, with dentition gradually reduced from grinding plates of interlocking elements to long rows of homodont teeth. Finally, the validity of the genera Manta (Bancroft, 1829) and Pteromylaeus (Garman, 1913) are called into question.
Keywords Myliobatidae . Batoidea . Comparative morphology. Molecularsystematics .Fossils .Paraphyly
Introduction
Myliobatidae is a derived family in the stingray order Myliobatiformes (Chondrichthyes: Batoidea). Often called pelagic rays, the members of this family exhibit a highly derived mode of swimming in which the wing-like pectoral fins of the laterally expanded disc oscillate up and down, akin to underwater flight (Webb 1984; Compagno 2003). These fishes occupy the continental and insular shelves to offshore waters in tropical and warm temperate marine areas worldwide (Nelson 2006). Myliobatidae comprises three subfamilies: Myliobatinae (eagle rays, Aetobatus, Aetomylaeus, Myliobatis, and Pteromylaeus; over 20 species), Rhinopterinae (cownose rays, Rhinoptera; at least seven species), and Mobulinae (devil rays, Manta and Mobula, about 11 species). The eagle rays and cownose rays are durophagous, grinding hard-shelled prey with pavement-like plates of interlocking dental elements. The devil rays, including the massive Manta birostris at up to 7 m in width, are planktivorous. A pair of mobile cephalic fins assist in feeding, making this subfamily the only extant group of vertebrates with three pairs of functional...