Spilotes pullatus
Spilotes pullatus, commonly known as the chicken snake or tropical rat snake, is a large, nonvenomous colubrid snake species endemic to the Neotropical region, characterized by its slender body, distinct head, and striking coloration featuring a predominantly black dorsal surface with yellow to orange crossbands, spots, or net-like patterns that vary by locality.[1] Adults can reach total lengths of up to 3 meters.[1] This diurnal, semi-arboreal species is known for its active foraging behavior, primarily on the ground or in low vegetation, and its ability to constrict larger prey items.[2] Native to a broad range spanning southern Mexico (from Veracruz and Chiapas southward) through Central America (including Belize, Costa Rica, and Panama) to northern and central South America (encompassing countries such as Brazil, Ecuador, Peru, Bolivia, Guyana, and Argentina as far south as Misiones), S. pullatus also occurs on the islands of Trinidad and Tobago.[3] It primarily inhabits lowland tropical forests at elevations up to 200 meters, often near water bodies or wetlands, but demonstrates notable adaptability by persisting in disturbed environments like agricultural plantations and secondary forests.[2] The species is oviparous, with females laying clutches of 5–11 eggs (mean 8.6) during the rainy season (October–November in southeastern Brazil), and hatchlings emerge 73–76 days later; reproduction is seasonal, tied to vitellogenesis from June to November.[2] The diet of Spilotes pullatus consists mainly of small mammals (such as rodents, comprising about 90% of prey records) and birds, with occasional bats, eggs, amphibians, or reptiles; prey size represents 0.36–7.37% of the snake's body mass, subdued through constriction or direct biting.[2] Behaviorally, it exhibits territoriality, with males engaging in ritual combat involving upright coiling and pushing during the mating season (August–October), and it defends itself against threats by inflating the neck, nodding the head, and rattling the tail, potentially escalating to biting.[2] Classified as Least Concern by the IUCN as of 2019 due to its wide distribution, tolerance of habitat alteration, and stable populations,[4] S. pullatus faces no major global threats but may be locally impacted by deforestation in some regions.Taxonomy and Classification
Etymology and Synonyms
The genus name Spilotes is derived from the Greek word spilos, meaning "stain" or "spot," alluding to the spotted or patterned dorsal coloration observed in species of this genus.[5] The specific epithet pullatus originates from the Latin term meaning "clothed in dark garments," a reference to the snake's dark, banded or blotched appearance that resembles dark clothing over a lighter base.[3] Spilotes pullatus was originally described by Carl Linnaeus in 1758 as Coluber pullatus in his Systema Naturae, based on specimens from tropical America.[3] The species was subsequently transferred to the genus Spilotes by Johann Georg Wagler in 1830, with Coluber pullatus (via the junior synonym Coluber coronatus Laurenti 1768) designated as the type species of the genus.[3] Throughout its taxonomic history, S. pullatus has accumulated numerous synonyms due to revisions and regional descriptions, reflecting early uncertainties in colubrid classifications. Key historical synonyms include:- Cerastes coronatus Laurenti 1768
- Cerastes mexicanus Laurenti 1768
- Coluber novae Hispaniae Gmelin 1789
- Coluber variabilis Merrem 1790
- Coluber plutonius Daudin 1803
- Coluber (Natrix) Caninana Merrem 1820
- Coluber variabilis var. Kuhlii Wied 1825
- Spilotes variabilis Duméril & Bibron 1854
- Herpetodryas incertus Jan 1863
- Spilotes pullatus var. anomalepis Bocourt 1888
- Spilotes pullatus maculatus Amaral 1929
- Spilotes pullatus mexicanus Amaral 1929
Subspecies
Spilotes pullatus is traditionally divided into six subspecies, reflecting regional variations in coloration and pattern, though recent taxonomic revisions have questioned their distinctiveness, often treating them as clinal morphs within the species.[3] These subspecies are primarily distinguished by differences in dorsal scale patterns, such as the shape, regularity, and arrangement of yellow spots on a black background, with limited variation in scale counts across the group (typically 16-18 dorsal scale rows at midbody).[3] The nominotypical subspecies, S. p. pullatus (Linnaeus, 1758), is described from "America meridionalis" (originally erroneous as "Asia"), restricted to Espírito Santo, Brazil (Araçatiba, Viana), and features bold, transverse yellow bands that may fuse into spots posteriorly.[3] S. p. anomalepis (Bocourt, 1888), with type locality in Roraima, Brazil, exhibits irregular, often broken or fragmented yellow spots that lack uniformity.[3] S. p. argusiformis (Amaral, 1929), originating from Honduras, displays a pattern of more rounded, eye-like yellow spots reminiscent of an argus pheasant, though specific scale metrics remain similar to the nominate form.[3] S. p. maculatus (Amaral, 1929), type locality in southern Brazil, is characterized by regular, subrectangular transverse spots that form distinct crossbands, differing from the irregularity in anomalepis.[3] S. p. auribundus (Cope, 1861), with type locality in Mirador, Veracruz, Mexico, is characterized by prominent golden-yellow crossbands.[3] Finally, S. p. mexicanus (Laurenti, 1768, originally as Cerastes mexicanus), from regions including Veracruz and San Luis Potosí in Mexico, shows larger, more elongated yellow markings that can appear as stripes in some individuals.[3]| Subspecies | Describer & Year | Type Locality | Key Morphological Traits |
|---|---|---|---|
| S. p. pullatus | Linnaeus, 1758 | Espírito Santo, Brazil | Bold transverse yellow bands fusing to spots |
| S. p. anomalepis | Bocourt, 1888 | Roraima, Brazil | Irregular, broken yellow spots |
| S. p. argusiformis | Amaral, 1929 | Honduras | Rounded, eye-like yellow spots |
| S. p. maculatus | Amaral, 1929 | Southern Brazil | Regular subrectangular transverse spots |
| S. p. auribundus | Cope, 1861 | Mirador, Veracruz, Mexico | Prominent golden-yellow crossbands |
| S. p. mexicanus | Laurenti, 1768 | Veracruz, Mexico | Elongated yellow markings, stripe-like |