Diadophis punctatus (Linnaeus, 1766)
Key Characters: Yellow or cream-colored ring around the neck; dorsal scales smooth; anal plate divided.
Similar Species: No other small snake in Illinois has a ring on the neck and smooth scales. See the Key to Illinois Snakes for help with identification.
Subspecies: Twelve subspecies are currently recognized, with three subspecies generally acknowledged as being in Illinois: Prairie Ring-necked Snake, D. p. arnyi Kennicott, 1859; Northern Ring-necked Snake, D. p. edwardsii (Merrem,1820); Mississippi Ring-necked Snake, D. p. stictogenys Cope, 1860.
Description: A small (up to 40 cm TL), wormlike, burrowing snake with a blue-gray to black back. The belly is yellow or orange, possibly scattered with black spots or bands. Juvenile may be darker above than adult. The three subspecies differ in the extent and location of ventral spots: the prairie ringneck has numerous irregularly placed spots, the Mississippi ringneck has paired dark spots down the middle of the belly, and the northern ringneck’s belly has a few black dots or is unmarked.
Habitat: Hill prairies, bluffs, and open forests.
Natural History: Usually found under rocks or debris. Mating may take place in spring or fall with eggs laid in June. Clutch size is normally 3-4 eggs and hatching takes place in August or September. Hatchlings range from 8 to 11 cm TL. Ring-necks feed on earthworms, small insects, and salamanders. The main predators are other snakes and birds.
Status: Locally abundant in the Shawnee Hills and along the southern Mississippi River bluffs.
Etymology: Diadophis – diadem (Greek) meaning headband; ophios (Greek) meaning serpent, reptile; punctatus – punctum (Latin) meaning ‘small hole’, spot. For Prairie Ring-necked Snake, arnyi is a patronym for Samuel Arny. For Northern Ring-necked Snake, edwardsi is a patronym for George Edwards (1694-1773). For Mississippi Ring-necked Snake, stictogenys, Gr. stiktos dotted and Gr. genys cheek or under jaw.
Original Description: Linnaeus, C. 1766. Systema Naturae per Regina tri Naturae secundum Classes, Ordines, Genera, Species, cum Characteribus, Differentiis, Synonymis, Locis. 12th ed. Salvii, Stockholm.
Type Specimen: None designated. For Prairie Ring-necked Snake, ? For Northern Ring-necked Snake, ? For Mississippi Ring-necked Snake, not designated.
Type Locality: Not stated. For Prairie Ring-necked Snake, “Hyatt, Anderson County, Kansas”. For Northern Ring-necked Snake, “Pennsylvania”. For Mississippi Ring-necked Snake, unknown.
Original Name: Coluber punctatus Linnaeus, 1766. For Prairie Ring-necked Snake, D. arnyi Kennicott,1859. For Northern Ring-necked Snake, Coluber edwardsii Merrem, 1820. For Mississippi Ring-necked Snake, D. punctatus stictogenys Cope, 1860.
Nomenclatural History: With so many subspecies recognized, it is no surprise that the history of names applied to this species is extensive and sometimes confusing. Concerning the Illinois literature, the Davis & Rice list (see here) contains D. arnyi, D. p. punctatus, and D. p. amabilis Baird & Girard, 1853. The latter is surprising given that it is the Pacific Ring-necked Snake. Julius Hurter listed D. regalis arnyi in his list of species inhabiting the Illinois counties bordering Missouri. See “History of Illinois Herpetology” for more details.