Maps
Locality Map
Locality map for Pantherophis obsoletus (Western Ratsnake).
Map created 15 April 2026.
County Map
County map for Pantherophis obsoletus (Western Ratsnake).
Map created 15 April 2026.
Historical Locality Map
Historical locality map for Pantherophis obsoletus (Western Ratsnake). Black circles ( 
) represent records after 1986, blue squares ( 
) represent records between 1966 and 1986, orange triangles ( 
) represent records prior to 1966. Note that more recent records might conceal underlying older records.
Map created 15 April 2026.
Historical County Map
Historical county map for Pantherophis obsoletus (Western Ratsnake). Black circles ( ) represent records after 1986, blue squares ( ) represent records between 1966 and 1986, orange triangles ( ) represent records prior to 1966. Note that only the most recent county record for each county is shown.
Map created 15 April 2026.
Ecological Drainage Locality Map
Ecological Drainage Units locality map for Pantherophis obsoletus (Western Ratsnake).
Map created 15 April 2026.
Natural Divisions Locality Map
Natural Divisions and Sections locality map for Pantherophis obsoletus (Western Ratsnake).
Map created 15 April 2026.
Major Watersheds Locality Map
Major Watersheds locality map for Pantherophis obsoletus (Western Ratsnake).
Map created 15 April 2026.
Level I Ecoregion Locality Map
Level I Ecoregion locality map for Pantherophis obsoletus (Western Ratsnake).
Map created 15 April 2026.
Level II Ecoregion Locality Map
Level II Ecoregion locality map for Pantherophis obsoletus (Western Ratsnake).
Map created 15 April 2026.
Level III Ecoregion Locality Map
Level III Ecoregion locality map for Pantherophis obsoletus (Western Ratsnake).
Map created 15 April 2026.
Level IV Ecoregion Locality Map
Level IV Ecoregion locality map for Pantherophis obsoletus (Western Ratsnake).
Map created 15 April 2026.
Native Status
Pantherophis obsoletus (Western Ratsnake) is native to Missouri.
Collection Summary
Pantherophis obsoletus (Western Ratsnake) has a total of 644 valid, non-duplicated collections representing 111 counties and 528 localities. There are a total of 201 collectors and 476 collection dates for the species. This results in a total of 507 expeditions for the species, a measure of unique date / collector(s) combinations. The earliest collection year for the species in Missouri is 1889 and its most recent collection year is 2025. The earliest and latest collection dates (independent of earliest and most recent collection years) are January 4 and November 28, respectively. If you have a new record to report, read the New Records section of the FAQ.
Collection Summary by County
| County | Localities | Collections | Collectors | Dates | Expeditions | Earliest Year | Latest Year | |
|---|---|---|---|---|---|---|---|---|
 | Adair | 3 | 3 | 4 | 3 | 3 | 1939 | 1961 |
| Andrew | 2 | 2 | 2 | 2 | 2 | 1959 | 2017 |
| Atchison | 1 | 1 | 1 | 1 | 1 | 1968 | 1968 |
| Audrain | 3 | 3 | 2 | 3 | 3 | 1939 | 2000 |
| Barry | 4 | 5 | 8 | 5 | 5 | 1937 | 2004 |
| Barton | 7 | 7 | 6 | 7 | 7 | 1987 | 2022 |
| Bates | 3 | 3 | 2 | 3 | 3 | 1958 | 2007 |
| Benton | 3 | 3 | 3 | 3 | 3 | 1958 | 2004 |
| Bollinger | 4 | 5 | 5 | 5 | 5 | 1969 | 2019 |
| Boone | 11 | 16 | 9 | 15 | 16 | 1940 | 2024 |
| Buchanan | 1 | 1 | 1 | 1 | 1 | 1982 | 1982 |
| Butler | 5 | 7 | 6 | 6 | 6 | 1956 | 1995 |
| Caldwell | 3 | 3 | 2 | 3 | 3 | 1954 | 2017 |
| Callaway | 3 | 3 | 1 | 3 | 3 | 1998 | 2023 |
| Camden | 5 | 6 | 4 | 4 | 4 | 1938 | 2006 |
| Cape Girardeau | 7 | 10 | 9 | 8 | 9 | 1923 | 1996 |
| Carroll | 2 | 2 | 2 | 2 | 2 | 1961 | 1983 |
| Carter | 6 | 8 | 9 | 7 | 7 | 1930 | 2002 |
| Cass | 4 | 4 | 3 | 4 | 4 | 1948 | 2014 |
| Cedar | 3 | 3 | 2 | 3 | 3 | 1990 | 2018 |
| Chariton | 7 | 8 | 3 | 7 | 7 | 1999 | 2020 |
| Christian | 1 | 1 | 1 | 1 | 1 | 1967 | 1967 |
| Clark | 2 | 2 | 2 | 2 | 2 | 1979 | 2005 |
| Clay | 4 | 4 | 4 | 4 | 4 | 1939 | 2024 |
| Clinton | 1 | 3 | 1 | 3 | 3 | 1961 | 1961 |
| Cole | 3 | 3 | 3 | 3 | 3 | 1938 | 2006 |
| Cooper | 2 | 2 | 2 | 2 | 2 | 1991 | 2013 |
| Crawford | 4 | 4 | 3 | 4 | 4 | 1934 | 2003 |
| Dade | 5 | 5 | 5 | 5 | 5 | 1983 | 2021 |
| Dallas | 6 | 8 | 8 | 6 | 6 | 2000 | 2019 |
| Daviess | 2 | 2 | 3 | 2 | 2 | 2001 | 2015 |
| De Kalb | 1 | 1 | 1 | 1 | 1 | 2020 | 2020 |
| Dent | 2 | 5 | 6 | 4 | 4 | 1909 | 2013 |
| Douglas | 2 | 2 | 3 | 2 | 2 | 1978 | 2024 |
| Dunklin | 6 | 8 | 6 | 8 | 8 | 1936 | 1995 |
| Franklin | 5 | 9 | 5 | 6 | 6 | 1933 | 1999 |
| Gasconade | 2 | 2 | 2 | 2 | 2 | 1934 | 2007 |
| Gentry | 3 | 4 | 4 | 3 | 3 | 1997 | 2019 |
| Greene | 54 | 65 | 15 | 53 | 53 | 1957 | 2025 |
| Grundy | 9 | 9 | 5 | 6 | 6 | 1964 | 2010 |
| Harrison | 1 | 1 | 1 | 1 | 1 | 1992 | 1992 |
| Henry | 4 | 4 | 11 | 4 | 4 | 1962 | 2007 |
| Hickory | 3 | 3 | 4 | 3 | 3 | 1950 | 2018 |
| Holt | 8 | 9 | 5 | 7 | 7 | 1953 | 2024 |
| Howard | 5 | 5 | 2 | 5 | 5 | 1999 | 2015 |
| Howell | 1 | 1 | 1 | 1 | 1 | 1973 | 1973 |
| Iron | 4 | 4 | 6 | 4 | 4 | 1991 | 2020 |
| Jackson | 23 | 35 | 7 | 26 | 29 | 1932 | 1983 |
| Jasper | 4 | 4 | 3 | 4 | 4 | 1982 | 2018 |
| Jefferson | 11 | 14 | 3 | 6 | 6 | 1900 | 1998 |
| Johnson | 11 | 18 | 12 | 13 | 13 | 1961 | 2008 |
| Knox | 2 | 2 | 2 | 2 | 2 | 1961 | 2012 |
| Laclede | 7 | 7 | 9 | 7 | 7 | 1999 | 2020 |
| Lafayette | 2 | 2 | 4 | 2 | 2 | 1990 | 2014 |
| Lawrence | 5 | 5 | 3 | 5 | 5 | 1994 | 2015 |
| Lewis | 2 | 2 | 2 | 2 | 2 | 1940 | 2013 |
| Lincoln | 4 | 5 | 3 | 4 | 4 | 1963 | 2013 |
| Linn | 3 | 4 | 3 | 4 | 4 | 1980 | 2005 |
| Livingston | 3 | 3 | 3 | 3 | 3 | 1961 | 2020 |
| Macon | 2 | 2 | 2 | 2 | 2 | 1961 | 2023 |
| Madison | 3 | 3 | 5 | 3 | 3 | 1982 | 2020 |
| Maries | 2 | 2 | 3 | 2 | 2 | 2000 | 2001 |
| McDonald | 3 | 4 | 3 | 4 | 4 | 1930 | 2002 |
| Mercer | 1 | 1 | 1 | 1 | 1 | 1983 | 1983 |
| Miller | 3 | 3 | 5 | 3 | 3 | 1973 | 2020 |
| Mississippi | 5 | 5 | 5 | 5 | 5 | 1984 | 2011 |
| Moniteau | 3 | 3 | 2 | 3 | 3 | 1966 | 2015 |
| Monroe | 2 | 2 | 2 | 2 | 2 | 1933 | 2001 |
| Montgomery | 3 | 5 | 5 | 5 | 5 | 1901 | 2024 |
| Morgan | 4 | 4 | 2 | 3 | 3 | 2015 | 2019 |
| New Madrid | 2 | 2 | 4 | 2 | 2 | 1995 | 2008 |
| Newton | 6 | 7 | 8 | 6 | 6 | 1992 | 2002 |
| Nodaway | 7 | 7 | 4 | 5 | 5 | 1966 | 2015 |
| Oregon | 9 | 9 | 6 | 8 | 8 | 1950 | 2017 |
| Osage | 4 | 4 | 3 | 4 | 4 | 1991 | 2010 |
| Ozark | 4 | 4 | 5 | 4 | 4 | 1986 | 2020 |
| Pemiscot | 4 | 5 | 3 | 3 | 4 | 1923 | 1963 |
| Perry | 7 | 8 | 5 | 5 | 7 | 1923 | 2017 |
| Pettis | 6 | 8 | 3 | 5 | 5 | 1939 | 2021 |
| Phelps | 6 | 6 | 7 | 6 | 6 | 2001 | 2022 |
| Pike | 9 | 9 | 8 | 9 | 9 | 1971 | 2013 |
| Platte | 2 | 2 | 1 | 2 | 2 | 1983 | 1983 |
| Polk | 10 | 10 | 5 | 10 | 10 | 1961 | 2023 |
| Pulaski | 1 | 1 | 1 | 1 | 1 | 1957 | 1957 |
| Putnam | 1 | 1 | 1 | 1 | 1 | 2016 | 2016 |
| Ralls | 2 | 2 | 1 | 2 | 2 | 2002 | 2002 |
| Randolph | 6 | 6 | 3 | 6 | 6 | 2000 | 2025 |
| Ray | 2 | 16 | 2 | 7 | 7 | 1951 | 1953 |
| Reynolds | 4 | 4 | 5 | 4 | 4 | 1933 | 2020 |
| Ripley | 2 | 2 | 3 | 2 | 2 | 2001 | 2007 |
| Saint Charles | 7 | 9 | 5 | 8 | 8 | 1958 | 2010 |
| Saint Clair | 5 | 6 | 5 | 6 | 6 | 1931 | 2007 |
| Sainte Genevieve | 3 | 3 | 4 | 2 | 2 | 1988 | 2010 |
| Saint Francois | 3 | 3 | 3 | 3 | 3 | 1929 | 1950 |
| Saint Louis | 6 | 15 | 7 | 13 | 15 | 1889 | 2017 |
| Saline | 1 | 1 | 1 | 1 | 1 | 2015 | 2015 |
| Scott | 4 | 5 | 5 | 4 | 5 | 1923 | 2015 |
| Shannon | 8 | 9 | 13 | 8 | 8 | 1941 | 2008 |
| Shelby | 3 | 3 | 2 | 3 | 3 | 1961 | 1961 |
| Stoddard | 12 | 17 | 11 | 11 | 11 | 1937 | 2024 |
| Stone | 5 | 6 | 9 | 6 | 6 | 1906 | 2012 |
| Sullivan | 3 | 3 | 2 | 3 | 3 | 1961 | 2012 |
| Taney | 6 | 6 | 8 | 5 | 6 | 1933 | 2025 |
| Texas | 2 | 2 | 2 | 2 | 2 | 1989 | 2002 |
| Vernon | 5 | 5 | 4 | 5 | 5 | 1937 | 2018 |
| Warren | 1 | 1 | 1 | 1 | 1 | 2009 | 2009 |
| Washington | 1 | 4 | 1 | 2 | 2 | 1909 | 1909 |
| Wayne | 10 | 10 | 11 | 10 | 10 | 1935 | 2022 |
| Webster | 5 | 9 | 5 | 5 | 5 | 1959 | 2019 |
| Worth | 2 | 2 | 3 | 2 | 2 | 1982 | 2001 |
| Wright | 4 | 4 | 3 | 3 | 3 | 2003 | 2024 |
Potential County Records
| Likelihood | County | Rationale | Ecoregion / Watershed | |
|---|---|---|---|---|
 | 2 | Marion | Same Level IV ecoregion, within 5 miles | Claypan Prairie |
| 2 | Schuyler | Same Level IV ecoregion, within 5 miles | Loess Flats and Till Plains |
 | 6 | Scotland | Same Level IV ecoregion, within 20 miles | Loess Flats and Till Plains |
Linnaean Classification
- Kingdom:
- Animalia - Animals
- Phylum:
- Chordata - Chordates
- Subphylum:
- Vertebrata - Vertebrates
- Class:
- Reptilia Laurenti, 1768 - Reptiles
- Order:
- Squamata Oppel, 1811 - Lizards and Snakes
- Family:
- Colubridae Oppel, 1811 - Harmless Egg-laying Snakes
- Genus:
- Pantherophis Fitzinger, 1843 - North American Ratsnakes
- Species:
- Pantherophis obsoletus (Say in James, 1822) - Western Ratsnake
Recent Taxonomic Synonyms
- Elaphe obsoleta