Systematics of myliobatoid elasmobranchs: with emphasis on the phylogeny and historical biogeography of neotropical freshwater stingrays (Potamotrygonidae: Rajiformes)

Abstract

The neotropical freshwater family Potamotrygonidae appears to be the only stingray group that has radiated in a non‐marine environment. To assess the affinities of potamotrygonids to other rays, a phylogenetic analysis was undertaken using 39 morphological characters from 18 stingray groups. The single tree produced (CI = 0.80, RI = 0.88) suggests that neotropical freshwater rays are a monophyletic group, and that within Potamotrygonidae, Paratrygon is basal to a clade composed of Plesiotrygon and Potamotrygon. The sister group to potamotrygonids was determined to be amphi‐American Himantura—these taxa share synapomorphies of the ventral mandibular musculature and the hyomandibular/mandibular articulation. The topology suggests that potamotrygonids are derived from a freshwater‐invading ancestor that was distributed along the northern coast of South America (Pacific and Caribbean) prior to the emergence of the isthmus of Panama. This hypothesis conflicts with parasite‐based biogeographic scenarios of a stricdy Pacific origin for potamotrygonids. General systematic results concerning urolophids, dasyatids, and pelagic myliobatoid stingrays are also discussed.

A dated molecular phylogeny of manta and devil rays (Mobulidae) based on mitogenome and nuclear sequences

“…Fossil, morphological and molecular data support the hypothesis that mobulids are one of the most derived groups of elasmobranchs and closely related to rhinopterids (cownose rays, genus Rhinoptera) within a polyphyletic clade of Myliobatidae Aschliman et al, 2012a;Claeson et al, 2010;De Carvalho et al, 2004;Dunn et al, 2003;Lovejoy, 1996;McEachran and Aschliman, 2004;McEachran et al, 1996;Nishida, 1990;Shirai, 1996). However, a sister-clade relationship to a myliobatid-rhinopterid clade has also been proposed (Gonzalez-Isais and Dominguez, 2004) solely based on morphological data.…”

A test of the utility of DNA barcoding in the radiation of the freshwater stingray genus Potamotrygon (Potamotrygonidae, Myliobatiformes)

“…Initial phylogenetic studies of Rosa (1985), Lovejoy (1996), Lovejoy et al (1998), andMarques (2000) aimed to test the monophyly of this family, to infer the phylogenetic relationships among its three described genera, and to establish its sister group. These studies supported the monophyly of the Potamotrygonidae and most of them concluded that colonization of fresh water in South America is the result of a single colonization event.…”

“…As outgroup, we included the shark Heterodontus francisci (GenBank# AJ310141), and the Myliobatiformes stingray species Hexatrygon bickelli (GenBank# AY597334), and Himantura pacifica. The genus Himantura is considered the most likely sister taxon of Potamotrygonidae (Lovejoy, 1996;McEachran et al, 1996;Lovejoy et al, 1998;Dunn et al, 2003).…”

Testicular structure and spermatogenesis of Amazonian freshwater cururu stingray Potamotrygon cf. histrix

“…The family Potamotrygonidae (Elasmobranchii: Myliobatiformes) is the only living chondrichthyan family restricted to freshwater habitats (Lovejoy, 1996) and they are distributed throughout most of the major river systems of South America. The Amazon Basin contains the greatest number of valid species of freshwater stingrays and Brazil is the country with the highest diversity of species (approximately 18 species) (Rosa, 1985;Compagno & Cook, 1995;Charvet-Almeida et al, 2002;Carvalho et al, 2003).…”