''Sagmatias'' was a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

dolphins A dolphin is an aquatic mammal within the infraorder Cetacea. Dolphin species belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontoporiidae (t ...

, defined in 1866 by

Edward Drinker Cope Edward Drinker Cope (July 28, 1840 – April 12, 1897) was an American zoologist, paleontologist, comparative anatomist, herpetologist, and ichthyologist. Born to a wealthy Quaker family, Cope distinguished himself as a child prodigy interested ...

with

Peale's dolphin Peale's dolphin (''Lagenorhynchus australis'') is a small dolphin found in the waters around Tierra del Fuego at the foot of South America. It is also commonly known as the black-chinned dolphin or even Peale's black-chinned dolphin. However, si ...

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

, described as ''Sagmatias amblodon''. It has been proposed to resurrect the genus to include four species of

oceanic dolphins Oceanic dolphins or Delphinidae are a widely distributed family of dolphins that live in the sea. Close to forty extant species are recognised. They include several big species whose common names contain "whale" rather than "dolphin", such as the ...

currently classified in the genus ''Lagenorhynchus''.

Mitochondrial DNA Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial D ...

studies have indicated that

Pacific white-sided dolphin The Pacific white-sided dolphin (''Lagenorhynchus obliquidens''), also known as the hookfin porpoise, is an active dolphin found in the cool or temperate waters of the North Pacific Ocean. Taxonomy The Pacific white-sided dolphin was named by Sm ...

dusky dolphin The dusky dolphin (''Lagenorhynchus obscurus'') is a dolphin found in coastal waters in the Southern Hemisphere. Its specific epithet is Latin for "dark" or "dim". It is very closely genetically related to the Pacific white-sided dolphin, b ...

and

hourglass dolphin The hourglass dolphin (''Lagenorhynchus cruciger'') is a small dolphin in the family Delphinidae that inhabits offshore Antarctic and sub-Antarctic waters. It is commonly seen from ships crossing the Drake Passage, but has a circumpolar distribu ...

are more closely related to dolphins in the

Lissodelphininae Oceanic dolphins or Delphinidae are a widely distributed family of dolphins that live in the sea. Close to forty extant species are recognised. They include several big species whose common names contain "whale" rather than "dolphin", such as the ...

subfamily, than to the two other members of the genus:

Atlantic white-sided dolphin The Atlantic white-sided dolphin (''Lagenorhynchus acutus'') is a distinctively coloured dolphin found in the cool to temperate waters of the North Atlantic Ocean. Description The dolphin is slightly larger than most other oceanic dolphins. It ...

and

white-beaked dolphin The white-beaked dolphin (''Lagenorhynchus albirostris'') is a marine mammal belonging to the family Delphinidae (oceanic dolphins) in the suborder Odontoceti (toothed whales). Taxonomy The species was first described by the British taxonomist ...

. This phylogenetic relationship is further supported by cladistic analysis of morphological characters. However, resurrection of the genus ''Sagmatias'' has not been accepted by the

Society for Marine Mammalogy The Society for Marine Mammalogy was founded in 1981 and is the largest international association of marine mammal scientists in the world. Mission The mission of the Society for Marine Mammalogy (SMM) is to promote the global advancement of mari ...

's taxonomic Committee, because the finer details of the phylogenetic relationships between the four species in the proposed ''Sagmatias'' genus and the four species of dolphins in the genus ''

Cephalorhynchus ''Cephalorhynchus'' is a genus in the dolphin family Delphinidae. Extant species It consists of four species: The species have similar physical features—they are small, generally playful, blunt-nosed dolphins—but they are found in distin ...

'' remains to be resolved. Genetic and bioacoustical evidence suggest that Peale's dolphin and hourglass dolphin are closer related to the ''Cephalorhynchus'' species than to the Pacific white-sided dolphin and dusky dolphin, which, if true, would make the genus ''Sagmatias''

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

References

{{Reflist, 30em Taxa named by Edward Drinker Cope Oceanic dolphins