''Pantherophis'' is 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 ...

of non

venom Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved ''venom apparatus'', such as fangs or a sti ...

ous

colubrid Colubridae (, commonly known as colubrids , from la, coluber, 'snake') is a family of snakes. With 249 genera, it is the largest snake family. The earliest species of the family date back to the Oligocene epoch. Colubrid snakes are found on ever ...

snakes Snakes are elongated, limbless, carnivorous reptiles of the suborder Serpentes . Like all other squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales. Many species of snakes have skulls with several more joi ...

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to central and eastern regions of

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

. It consists of the North American ratsnakes, the foxsnakes, and the cornsnakes. The genus, which contains 10 recognized species, first appeared in the fossil record in the

Middle Miocene The Middle Miocene is a sub-epoch of the Miocene Epoch made up of two stages: the Langhian and Serravallian stages. The Middle Miocene is preceded by the Early Miocene. The sub-epoch lasted from 15.97 ± 0.05 Ma to 11.608 ± 0.005 Ma (million y ...

around 16.3 million years ago. They are a large terrestrial snake genus that lack subocular scales. Originally classified in the genus ''

Elaphe ''Elaphe'' is a genus of snakes in the family Colubridae. ''Elaphe'' is one of the main genera of the rat snakes, which are found in many regions of the northern hemisphere. ''Elaphe'' species are medium to large constrictors by nature. Althoug ...

'', phylogenetic studies have found this taxon to be closely related to ''

Pituophis ''Pituophis'' is a genus of nonvenomous colubrid snakes, commonly referred to as gopher snakes, pine snakes, and bullsnakes, which are endemic to North America. Geographic range Species and subspecies within the genus ''Pituophis'' are found ...

''. As with all snakes ''Pantherophis'' is an obligate

faunivore A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other ...

with a diet that consists of small

mammals Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

birds Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...

, reptiles and amphibians, and even insects. While many species conservation status is categorized as "least concern", many local populations in some species have declined where some places have them listed as federally protected. The corn snake (''P. guttatus'') is a popular pet reptile, due to the availability of captive-bred animals, their low maintenance and calm disposition, and the variety of color morphs. There are other species of ''Pantherophis'' that are in the pet trade, though are not as popular as the corn snake.

Field Characteristics

Member species in the genus ''Pantherophis'' are large terrestrial snakes, built for constriction. ''Pantherophis'' is characterized by having a divided Anal scale, cloacal plate. The dorsal scales are arranged in more than 30 rows around the body, and at least some of these are Keeled scales, keeled, albeit faintly. All species lack Ocular scales, subocular scales. Each of the ten or so species can be further distinguished based on subtle characteristics, such as color markings, scale nuances, and geographic range.

Systematics and Paleontology

Taxonomy

The taxonomy of ''Pantherophis'' has been a complicated area of research. The genus was named by the Austrian zoologist Leopold Fitzinger in 1843, with the type species being ''Pantherophis guttatus''. Shortly after, the genus was then considered to be a junior synonym of the otherwise Old World genus ''

''. However the morphology of the Hemipenis, hemipenes, the dentition, and the squamatization found the New World species to be closer to the genus ''Pituophis'' (gopher snakes, pine snakes, and bullsnakes). Soon subsequent molecular studies have found support of the sister grouping between ''Pituophis'' and the North American ''Elaphe'' species, which resulted in the resurrection of the genus ''Pantherophis''. These two genera, along with several other North American endemic taxa like ''Lampropeltis'' belong to the tribe Lampropeltini. There are currently four Subgenus, subgenera of ''Pantherophis'' with three extant and one extinct: ''Scotophis'' Spencer Fullerton Baird, Baird & Charles Frédéric Girard, Girard, 1853, for the ratsnakes; †''Palaeoelaphe'' species:Charles Whitney Gilmore, Gilmore, 1938, for a Miocene fossil species; ''Mintonius'' Joseph T. Collins, Collins & species:Travis William Taggart, Taggart, 2008, for the foxsnakes; and ''Pantherophis'' for the cornsnake complex. There are a few studies that suggested the possibility that ''Pantherophis'' is paraphyletic in respect to ''Pituophis''. To maintain taxonomic stability, some of the aforementioned subgenera are reevaluated into proper genera. This, however, has not been supported by larger scale molecular trees concerning the relationships of various snake taxa.

Phylogeny

The interspecies relationships of ''Pantherophis'' usually has the subgenera ''Pantherophis'' and ''Mintonius'' being sister taxa, with ''Scotophis'' at the root of the genus. Below is the widely supported phylogenetic tree of the species in the genus.

Extant Species

Below is the list of valid species with their geographic distributions.''Pantherophis''
The Reptile Database. www.reptile-database.org. ''Nota bene'': In this list, a Binomial nomenclature, binomial authority in parentheses indicates that the species was originally described in a genus other than ''Pantherophis''.

Fossil Remains

The fossil record of ''Pantherophis'' is the

to Upper Pleistocene. In addition to fossil remains of some of the extant species, there are fragmentary ''Pantherophis'' remains throughout the second half of the Cenozoic in North America. Only three fossil species have been described from more complete remains. The Early Pliocene ''P. buisi'' which might be a basal species in the ''Scotophis'' subgenus, and ''P. kansensis'' which is the sole species in the subgenus of ''Palaeoelaphe'', the trunk vertebrae similar to ''Mintonius'' subgenus. ''P. nebraskensis'' was another valid species, but it is considered to be a junior synonym of ''P. kansensis''.

References

External links

''Pantherophis''
SSARHerps
''Pantherophis''
The Reptile Database {{Taxonbar, from=Q134803 Rat snakes Colubrids Snake genera Taxa named by Leopold Fitzinger