''Pantherophis'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

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 st ...

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 ev ...

snakes

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 else ...

to central and eastern regions of North America. 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 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. Altho ...

'', phylogenetic studies have found this taxon to be closely related to '' Pituophis''. As with all snakes ''Pantherophis'' is an obligate faunivore 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 o ...

, birds, reptiles and amphibians, and even

insects Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of j ...

. 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 cloacal plate. The

dorsal scales In snakes, the dorsal scales are the longitudinal series of plates that encircle the body, but do not include the ventral scales In snakes, the ventral scales or gastrosteges are the enlarged and transversely elongated scales that extend down t ...

are arranged in more than 30 rows around the body, and at least some of these are keeled, albeit faintly. All species lack 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 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 specime ...

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 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 Lampropeltini is a tribe of colubrid snake endemic to New World. These include the kingsnakes, milk snake, corn snake, gopher snakes, pine snakes, and bullsnakes. At least 51 species have been recognized and the group have been heavily studied ...

. There are currently four subgenera of ''Pantherophis'' with three extant and one extinct: ''Scotophis'' Baird & Girard, 1853, for the ratsnakes; †''Palaeoelaphe'' Gilmore, 1938, for a

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

fossil species; ''Mintonius'' Collins &

Taggart ''Taggart'' is a Scottish detective fiction television programme created by Glenn Chandler, who wrote many of the episodes, and made by STV Studios for the ITV network. It originally ran as the miniseries "Killer" from 6 until 20 Septembe ...

, 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 (, or ; plural form ) is a Latin phrase meaning "note well". It is often abbreviated as NB, n.b., or with the ligature and first appeared in English writing . In Modern English, it is used, particularly in legal papers, to draw the atten ...

'': In this list, a

binomial authority In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

in parentheses indicates that the species was originally described in a genus other than ''Pantherophis''.

Fossil Remains

The fossil record of ''Pantherophis'' is the Middle Miocene to

Upper Pleistocene The Late Pleistocene is an unofficial age in the international geologic timescale in chronostratigraphy, also known as Upper Pleistocene from a stratigraphic perspective. It is intended to be the fourth division of the Pleistocene Epoch within ...

. 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 Early may refer to: History * The beginning or oldest part of a defined historical period, as opposed to middle or late periods, e.g.: ** Early Christianity ** Early modern Europe Places in the United States * Early, Iowa * Early, Texas * Early ...

''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