Is the Southern Cantil venomous?

Yes. The Southern Cantil (Agkistrodon howardgloydi) is venomous and belongs to the Viperidae family (copperhead/cottonmouth). Its bite is considered moderate-high risk to people. Treat any bite as a medical emergency.

Is the Southern Cantil poisonous?

Snakes are venomous, not poisonous. "Poisonous" means harmful to eat or touch; "venomous" means injecting toxins through a bite. The Southern Cantil is venomous, delivering venom through a bite.

Where does the Southern Cantil live?

The Southern Cantil has verified records in 3 countries, including Nicaragua, Costa Rica, Honduras. See the distribution section below for its full range.

How do I identify the Southern Cantil?

Heavy body, triangular head, vertical pupils, and a heat-sensing pit between each eye and nostril.

How big does the Southern Cantil get?

Usually 2–4 ft, heavy-bodied.

What does the Southern Cantil eat?

Fish, frogs, lizards, birds, eggs, and rodents were identified in the diet of A. howardgloydi in one Nicaraguan publication. A study conducted early in the rainy season of 1994 in Costa Rica found some age related variation in the diet: neonates ( 50 cm.) contained lizards (Ctenosaura), mice (Liomys), and rats (Sigmodon), suggesting an ontogenetic shift in diet from ectotherm prey in juveniles, to endotherm prey in…

Copperhead / Cottonmouth

Southern Cantil

Venomous

Agkistrodon howardgloydi

The Southern Cantil (Agkistrodon howardgloydi) is a venomous snake in the Viperidae family, recorded in 3 countries.

If you are bitten

Copperhead and cottonmouth bites are painful and need medical care but are rarely fatal with prompt treatment (cottonmouth venom is the more potent of the two). Stay calm, keep the limb still, remove tight items, and go to an emergency room. Do not use a tourniquet or cut the wound. Call Poison Control at 1-800-222-1222 or 911 in the US, or your local emergency number. (Source: CDC.)

Also called: Copperhead / Cottonmouth
Family: Viperidae
Size: Usually 2–4 ft, heavy-bodied.
Habitat: Copperheads favor forests and rocky hillsides; cottonmouths favor swamps, marshes, and slow water.
Behavior: Pit vipers that often hold their ground; cottonmouths gape to flash a white mouth lining when threatened.
Identify: Heavy body, triangular head, vertical pupils, and a heat-sensing pit between each eye and nostril.
Danger: moderate-high

About the Southern Cantil

Agkistrodon howardgloydi is a species of venomous snake, a pit viper in the subfamily Crotalinae of the family Viperidae. The species is endemic to Central America. It is most commonly called castellana, but it has also been called the southern cantil, Gloyd's moccasin, and a number of other colloquial names. It is a rare species with a relatively small geographic distribution in the tropical dry forest on the Pacific coast of Honduras, Nicaragua, and extreme northwest Costa Rica. A. howardgloydi is a stout, medium-sized snake with a maximum total length (including tail) of 96 cm (38 in). It is a viviparous species, with females giving birth in the rainy season from May to August. No clinical reports on envenomation had been published (as of 1999), but laboratory tests and analysis indicate the venom is highly toxic and similar to its close relative Agkistrodon bilineatus, and potentially lethal.

Etymology

Roger Conant's original description states: "This subspecies is named for the late Howard K. Gloyd, my close friend, colleague, and expert on pit vipers, especially the rattlesnakes. Gloyd worked for decades on the genus Agkistrodon (sensu lato), and he had predicted that a new race of A. bilineatus would eventually be described from lower Central America."

The common name castellana is the feminine form of the Spanish adjective castellano, translating to Castilian or Spaniard, but it is not entirely clear how this name came to be applied to A. howardgloydi. It has been speculated that it is something of an analogy, with the snake and the conquistadores being equally feared, or the snake and the conquistadores both being alert and ready to strike in a confrontation.

Taxonomy and Phylogenetics

The molecular evidence indicates the genus Agkistrodon is a monophyletic group, with the copperheads, (A. contortrix and A. laticinctus) the most basal (ancestral) lineage of the genus, the cottonmouths (A. piscivorus) basal to the four cantil species, Taylor's cantil (A. taylori) basal to the common cantil (A. bilineatus), which is basal to the Yucatecan cantil (A. russeolus) and the castellaana (A. howardgloydi). Both molecular and morphological evidence indicate that Agkistrodon howardgloydi and Agkistrodon russeolus are more closely related to each other (sister taxa) than Agkistrodon bilineatus or Agkistrodon taylori.

In 1984, while preparing a monograph on the genus Agkistrodon, and after examining virtually all museum specimens of Agkistrodon from Central America known at that time, Roger Conant described Agkistrodon bilineatus howardgloydi as a subspecies of the common cantil (Agkistrodon bilineatus). In the following 30 years, subsequent accounts supported recognition of the subspecies. In a 2013 taxonomic reevaluation, all three subspecies of Agkistrodon bilineatus were elevated to full species (Agkistrodon bilineatus, Agkistrodon russeolus, and Agkistrodon howardgloydi) based on morphology, biogeography, and consideration of previous DNA-based studies.

Description

Adapted from Wikipedia, available under CC BY-SA.

Frequently asked: Southern Cantil

Is the Southern Cantil venomous?: Yes. The Southern Cantil (Agkistrodon howardgloydi) is venomous and belongs to the Viperidae family (copperhead/cottonmouth). Its bite is considered moderate-high risk to people. Treat any bite as a medical emergency.
Is the Southern Cantil poisonous?: Snakes are venomous, not poisonous. "Poisonous" means harmful to eat or touch; "venomous" means injecting toxins through a bite. The Southern Cantil is venomous, delivering venom through a bite.
Is the Southern Cantil dangerous?: Copperhead and cottonmouth bites are painful and need medical care but are rarely fatal with prompt treatment (cottonmouth venom is the more potent of the two). Stay calm, keep the limb still, remove tight items, and go to an emergency room. Do not use a tourniquet or cut the wound. Call Poison Control at 1-800-222-1222 or 911 in the US, or your local emergency number. (Source: CDC.)
Where does the Southern Cantil live?: The Southern Cantil has verified records in 3 countries, including Nicaragua, Costa Rica, Honduras. See the distribution section below for its full range.
How do I identify the Southern Cantil?: Heavy body, triangular head, vertical pupils, and a heat-sensing pit between each eye and nostril.
How big does the Southern Cantil get?: Usually 2–4 ft, heavy-bodied.
What does the Southern Cantil eat?: Fish, frogs, lizards, birds, eggs, and rodents were identified in the diet of A. howardgloydi in one Nicaraguan publication. A study conducted early in the rainy season of 1994 in Costa Rica found some age related variation in the diet: neonates (<38 cm.) contained frogs (Hypopachus) and lizards (Marisora, Holcosus); juveniles (38–50 cm.) contained frogs (Leptodactylus), lizards (Ctenosaura), and mice (Liomys); adults (>50 cm.) contained lizards (Ctenosaura), mice (Liomys), and rats (Sigmodon), suggesting an ontogenetic shift in diet from ectotherm prey in juveniles, to endotherm prey in…
Why is it called the Southern Cantil?: Roger Conant's original description states: "This subspecies is named for the late Howard K. Gloyd, my close friend, colleague, and expert on pit vipers, especially the rattlesnakes. Gloyd worked for decades on the genus Agkistrodon (sensu lato), and he had predicted that a new race of A. bilineatus would eventually be described from lower Central America." The common name castellana is the feminine form of the Spanish adjective castellano, translating to Castilian or Spaniard, but it is not entirely clear how this name came to be applied to A. howardgloydi.

If you are bitten by the Southern Cantil

A venomous snakebite is a medical emergency. Call your local emergency number immediately. In the US, dial 911 or Poison Control at 1-800-222-1222.

Get away from the snake and stay calm. Most bites worsen when people panic or try again to handle the snake.
Call 911 or Poison Control (1-800-222-1222) right away. Antivenom works best when given early.
Note the time of the bite and, from a safe distance, the snake's color and pattern, a phone photo is enough. Do not chase it.
Keep the bitten limb still and at roughly heart level. Sit or lie down and limit movement.
Remove rings, watches, and tight clothing near the bite before swelling starts.
Gently wash the bite with soap and water and cover it with a clean, dry dressing.

Do not

Do not cut the wound or try to suck out the venom.
Do not apply a tourniquet or ice.
Do not drink alcohol or caffeine.
Do not take aspirin or ibuprofen, they can worsen bleeding. Acetaminophen is safer for pain.
Do not try to catch or kill the snake. A dead snake can still bite by reflex.

First-aid guidance adapted from the U.S. Centers for Disease Control and Prevention (CDC NIOSH), Venomous Snakes. Educational only; always follow the instructions of emergency responders.

Where it is found

Nicaragua Costa Rica Honduras

More Viperidae snakes

Classification

How scientists group this snake, from the broadest category down to the exact species. Each step narrows to its closest relatives.

OrderThe broad group of scaled reptiles: all snakes and lizards: Squamata
FamilyA group of related snakes that share key traits: Viperidae
GenusA close-knit group of very similar species: Agkistrodon
SpeciesThis exact snake, named in the two-part scientific name: Agkistrodon howardgloydi

Keep learning

Distribution from GBIF & iNaturalist. Venom status per CDC. Background: Wikipedia. Informational only. Never handle a snake to identify it.