Sonoran lyre snake (Trimorphodon lambda)
The Sonoran lyre snake is a snake in the family Colubridae with a mild venom for its prey, not dangerous to people. GBIF holds 451 licensed U.S. records of it; it reaches our listing threshold in 4 states, most of all Arizona (422), Nevada (21) and Utah (5). Its observation records peak in July.
Trimorphodon lambda, the Sonoran lyre snake, is a species of rear-fanged snake in the family Colubridae. Native to the southwestern United States and northwestern Mexico, the species is best known for the distinctive V-shaped or lyre-like marking on the top of its head. Previously classified as a subspecies of the western lyre snake (Trimorphodon biscutatus), it is now widely recognized as a distinct species.
From Wikipedia: Trimorphodon lambda, text under CC BY-SA 4.0.
Is the Sonoran lyre snake poisonous or venomous?
Mildly venomous but not dangerous: the Sonoran lyre snake has enlarged rear teeth and a mild venom for its prey, and a bite causes at most local swelling, which is why many sources simply call it harmless. It is not a pit viper or coral snake, the only U.S. land snakes with medically dangerous venom. Clean any bite like a small wound.
Which states have the Sonoran lyre snake?
The Sonoran lyre snake's U.S. record is concentrated: Arizona alone holds 94% of licensed records. It is listed in 4 states in all; the next are Nevada (21), Utah (5) and New Mexico (3).
The count includes 121 records filed under the older name Trimorphodon biscutatus in Arizona (103), Nevada (15) and Utah (3).
| # | State | Records | Share of state snakes | Rank in state |
|---|---|---|---|---|
| 1 | Arizona | 422 | 2.0% | 15th of 60 |
| 2 | Nevada | 21 | 0.5% | 21st of 27 |
| 3 | Utah | 5 | 0.2% | 25th of 28 |
| 4 | New Mexico | 3 | 0.0% | 53rd of 56 |
When is the Sonoran lyre snake seen?
Across the U.S., observation records of the Sonoran lyre snake run mostly March through September, peaking in July with 22% of them. Winter (December to February) holds 2% of them.
How recent are the Sonoran lyre snake records?
The Sonoran lyre snake record leans on older material: only 16% of dated U.S. records come from 2017–2026, and the median record is from 1985. The oldest dated record is from 1892; the busiest year was 1968, with 11 records.
| Decade | Records | Share |
|---|---|---|
| 1890s | 1 | 0.4% |
| 1900s | 1 | 0.4% |
| 1930s | 7 | 2.8% |
| 1940s | 5 | 2.0% |
| 1950s | 17 | 6.9% |
| 1960s | 46 | 18.5% |
| 1970s | 34 | 13.7% |
| 1980s | 32 | 12.9% |
| 1990s | 15 | 6.0% |
| 2000s | 38 | 15.3% |
| 2010s | 24 | 9.7% |
| 2020s | 28 | 11.3% |
Species recorded in the same counties
Of the 13 counties where the Sonoran lyre snake is most recorded, 13 are also top counties for each of the eight snakes in the table below; no other snake shares more. Venomous species among its neighbors: the Mohave rattlesnake, the Sonoran coralsnake and the western diamondback rattlesnake.
| Species | Shared counties |
|---|---|
| Glossy snake | 13 |
| Gopher snake | 13 |
| Long-nosed snake | 13 |
| Mohave rattlesnake venomous | 13 |
| Ring-necked snake | 13 |
| Sonoran coralsnake venomous | 13 |
| Southwestern blackhead snake | 13 |
| Western diamondback rattlesnake venomous | 13 |
Related species in the U.S.
Other members of the family Colubridae with profiles here: Western terrestrial garter snake, Common garter snake, Gopher snake, Ring-necked snake, Northern water snake and Eastern racer.
GBIF records read 2026-09-29. Listed: any license. Counted: CC0/CC BY only. How we count.