''Drymobius margaritiferus'', commonly known as the speckled racer, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of nonvenomous

colubrid Colubridae (, commonly known as colubrids , from , 'snake') is a family of snakes. With 249 genera, it is the largest snake family. The earliest fossil species of the family date back to the Late Eocene epoch, with earlier origins suspected. Colu ...

snake Snakes are elongated limbless reptiles of the suborder Serpentes (). Cladistically squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales much like other members of the group. Many species of snakes have s ...

native to the

Americas The Americas, sometimes collectively called America, are a landmass comprising the totality of North America and South America.''Webster's New World College Dictionary'', 2010 by Wiley Publishing, Inc., Cleveland, Ohio. When viewed as a sing ...

. The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

, ''margaritiferus'', means "pearl-bearing" in Latin, referring to the pearl-like spots on the

dorsal scales In snakes, the dorsal scales are the longitudinal series of plates that encircle the body, but do not include the ventral scales. Campbell JA, Lamar WW (2004). ''The Venomous Reptiles of the Western Hemisphere''. Ithaca and London: Comstock Publis ...

Geographic range and habitat

This species ranges throughout

Central America Central America is a subregion of North America. Its political boundaries are defined as bordering Mexico to the north, Colombia to the southeast, the Caribbean to the east, and the Pacific Ocean to the southwest. Central America is usually ...

from the

Isthmus of Tehuantepec The Isthmus of Tehuantepec () is an isthmus in Mexico. It represents the shortest distance between the Gulf of Mexico and the Pacific Ocean. Before the opening of the Panama Canal, it was a major overland transport route known simply as the T ...

and

Yucatán Peninsula The Yucatán Peninsula ( , ; ) is a large peninsula in southeast Mexico and adjacent portions of Belize and Guatemala. The peninsula extends towards the northeast, separating the Gulf of Mexico to the north and west of the peninsula from the C ...

, southward to

Panama Panama, officially the Republic of Panama, is a country in Latin America at the southern end of Central America, bordering South America. It is bordered by Costa Rica to the west, Colombia to the southeast, the Caribbean Sea to the north, and ...

and adjacent areas of northwest

Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...

, occurring at elevations from sea level up to 4,750 feet (1,453 m). Northward, it is found in the coastal lowlands and lower exterior slopes of the Sierra Madres of

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

, up the west coast to

Sonora Sonora (), officially Estado Libre y Soberano de Sonora (), is one of the 31 states which, along with Mexico City, comprise the Administrative divisions of Mexico, Federal Entities of Mexico. The state is divided into Municipalities of Sonora, 72 ...

, and up the east coast to northern

Tamaulipas Tamaulipas, officially the Free and Sovereign State of Tamaulipas, is a state in Mexico; one of the 31 states which, along with Mexico City, comprise the 32 federal entities of Mexico. It is divided into 43 municipalities. It is located in nor ...

. The northern limit of its distribution ranges into extreme south

Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...

, USA, where it is uncommon to rare in a few of the southernmost counties of the state.Werler, John E. and James R. Dixon. 2000. Texas Snakes: Identification, Distribution, and Natural History. University of Texas Press. Austin, Texas. xv, 417 pp. Köhler, Gunther. 2008. Reptiles of Central America, 2nd. ed. Herpeton Verlag. Offenbach, Germany. 460 pp. Speckled racers occur in a wide variety of habitats, including: forest, forest edges and clearings,

secondary growth In botany, secondary growth is the growth that results from cell division in the cambia or lateral meristems and that causes the stems and roots to thicken, while primary growth is growth that occurs as a result of cell division at the tips ...

riparian zones A riparian zone or riparian area is the interface between land and a river or stream. In some regions, the terms riparian woodland, riparian forest, riparian buffer zone, riparian corridor, and riparian strip are used to characterize a ripari ...

savannahs A savanna or savannah is a mixed woodland-grassland (i.e. grassy woodland) biome and ecosystem characterised by the trees being sufficiently widely spaced so that the Canopy (forest), canopy does not close. The open canopy allows sufficient li ...

marshlands In ecology, a marsh is a wetland that is dominated by herbaceous plants rather than by woody plants.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p More in general ...

pastures Pasture (from the Latin ''pastus'', past participle of ''pascere'', "to feed") is land used for grazing. Types of pasture Pasture lands in the narrow sense are enclosed tracts of farmland, grazed by domesticated livestock, such as horses, c ...

, and roadsides.Savage, J. M. 2002. The Amphibians and Reptiles of Costa Rica, A Herpetofauna between Two Continents, between Two Seas. University of Chicago Press, Chicago, Illinois. xx, 934 pp. It is often said to favor humid and wet areas with permanent water sources.Lee, J. C. 1996. The Amphibians and Reptiles of the Yucatán Peninsula. Comstock Publishing Associates, Cornell University Press, Ithaca, New York. xii, 500 pp. However, these snakes have been found in areas where no water was apparent, and habitats include

tropical dry forests The tropical and subtropical dry broadleaf forest is a habitat type defined by the World Wide Fund for Nature and is located at tropical and subtropical latitudes. Though these forests occur in climates that are warm year-round, and may receive ...

and tropical arid forests.Wilson, Larry David, and John R. Meyer. 1985. The Snakes of Honduras, 2nd. ed. Milwaukee Public Museum. x, 150 pp. Farr, William L. and David Lazcano (2011). Natural History Notes: Drymobius margaritiferus, Thanatosis. Herpological Review, 42(4); 613.McCranie, J. R. 2011. The Snakes of Honduras: Systematics, Distribution, and Conservation.. Contributions to Herpetology, Vol. 26. Society for the Study of Amphibians and Reptiles. x, 714 pp. In

Costa Rica Costa Rica, officially the Republic of Costa Rica, is a country in Central America. It borders Nicaragua to the north, the Caribbean Sea to the northeast, Panama to the southeast, and the Pacific Ocean to the southwest, as well as Maritime bo ...

, it is described as "ubiquitous in ''all but'' the most humid lowland and pre-montane zones," including dry lowland forests.

Description

The speckled racer is typically black in color, with distinctive yellow and blue spotting, and one light-colored spot on each scale, 365 pp. (''Drymobius margaritiferus'', pp. 131-133, Figure 31.) which gives the snake an overall greenish hue. The labials are yellow, with black sutures. The underside is typically yellow to green. They average 30–40 in. (76–102 cm) in length, with a record specimen documented at 50 in. (127 cm). 429 pp. (paperback). (''Drymobius margaritiferus'', p. 186 + Plate 32 + Map 142.) The

, which are feebly keeled middorsally, but smooth on the flanks, are arranged in 17 rows. The

ventrals In snakes, the ventral scales or gastrosteges are the enlarged and transversely elongated scales that extend down the underside of the body from the neck to the anal scale. When counting them, the first is the anteriormost ventral scale that cont ...

number 142–168; the

subcaudals In snakes, the subcaudal scales are the enlarged plates on the underside of the tail. Wright AH, Wright AA (1957). ''Handbook of Snakes of the United States and Canada''. Comstock Publishing Associates, a Division of Cornell University Press. (7t ...

, 85–126.

Natural history

As the name "racer" implies, it is a fast and agile species that is predominantly diurnal. It has been described as a nervous species, and will not hesitate to bite in self-defense when restrained or handled. Death feigning behavior, or

thanatosis Apparent death is a behavior in which animals take on the appearance of being dead. It is an immobile state most often triggered by a predatory attack and can be found in a wide range of animals from insects and crustaceans to mammals, birds, r ...

, was reported for two out of seven (28.5%) specimens that were caught and handled during field surveys conducted in

, Mexico. They will consume a wide variety of prey, but primarily feed on

frog A frog is any member of a diverse and largely semiaquatic group of short-bodied, tailless amphibian vertebrates composing the order (biology), order Anura (coming from the Ancient Greek , literally 'without tail'). Frog species with rough ski ...

s and

toad Toad (also known as a hoptoad) is a common name for certain frogs, especially of the family Bufonidae, that are characterized by dry, leathery skin, short legs, and large bumps covering the parotoid glands. In popular culture (folk taxonomy ...

s. One study of 36 Guatemalan and Mexican specimens with food items in their stomachs found 86% had

anurans A frog is any member of a diverse and largely semiaquatic group of short-bodied, tailless amphibian vertebrates composing the order Anura (coming from the Ancient Greek , literally 'without tail'). Frog species with rough skin texture due to ...

(predominantly ''

Eleutherodactylus ''Eleutherodactylus'' is a genus of frogs in the family Eleutherodactylidae.Hedges, S. B., W. E. Duellman, and M. P. Heinicke . 2008. New World direct-developing frogs (Anura: Terrarana): molecular phylogeny, classification, biogeography, and c ...

''), 8% lizards, 4% reptile eggs, and 2% small mammals. Juveniles are known to eat

insects Insects (from Latin ') are hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of jointed ...

. They are

oviparous Oviparous animals are animals that reproduce by depositing fertilized zygotes outside the body (i.e., by laying or spawning) in metabolically independent incubation organs known as eggs, which nurture the embryo into moving offsprings kno ...

, typically laying eggs in the spring, although in southern areas, the species is known to deposit eggs as early as February and March. Clutch sizes range from two to eight eggs that are usually 1.5 inches (3.8 cm) in length. Incubation is typically eight to nine weeks, with hatchlings measuring 6 to 10½ inches (15.2–27.6 cm) long.

Subspecies

There are four recognized

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

of ''D. margaritiferus'': * ''Drymobius m. margaritiferus'' (

Schlegel Schlegel is a German occupational surname. Notable people with the surname include: * Anthony Schlegel (born 1981), American football player * August Wilhelm Schlegel (1767–1845), German poet, brother of Friedrich * Brad Schlegel (born 1968), C ...

, 1837), Northern speckled racer:Liner, Ernest A. and Gustavo Cass-Andreu. (2008). Standard Spanish, English and Scientific Names of the Amphibians and Reptiles of Mexico (2nd. ed.). Herpetological Circular No. 38. Society for the Study of Amphibians and Reptiles. iv, 162 pp. Atlantic versant, Texas to Colombia, and sections of Pacific in

Chiapas Chiapas, officially the Free and Sovereign State of Chiapas, is one of the states that make up the Political divisions of Mexico, 32 federal entities of Mexico. It comprises Municipalities of Chiapas, 124 municipalities and its capital and large ...

, Mexico and southern range. * ''Drymobius m. fistulosus'' ( H.M. Smith, 1942), Central American speckled racer: Pacific versant, from southern Sonora to the

. * ''Drymobius m. occidentalis'' (

Bocourt Marie Firmin Bocourt (19 April 1819 – 4 February 1904) was a French zoologist and artist. As a young man, he worked as a preparateur for the zoologist Gabriel Bibron (1805–1848), later serving as a museum artist. In 1861, he was sent to Thail ...

, 1890), Western speckled racer: Pacific versant, from eastern

, Mexico to

El Salvador El Salvador, officially the Republic of El Salvador, is a country in Central America. It is bordered on the northeast by Honduras, on the northwest by Guatemala, and on the south by the Pacific Ocean. El Salvador's capital and largest city is S ...

. * ''Drymobius m. maydis'' (

Villa A villa is a type of house that was originally an ancient Roman upper class country house that provided an escape from urban life. Since its origins in the Roman villa, the idea and function of a villa have evolved considerably. After the f ...

, 1968):

Corn Islands The Corn Islands are two islands about east of the Caribbean Sea, Caribbean coast of Nicaragua, constituting one of 12 Municipality, municipalities of the South Caribbean Coast Autonomous Region of Nicaragua. The official name of the municipalit ...

, Nicaragua.

Conservation status

The speckled racer is a

threatened species A threatened species is any species (including animals, plants and fungi) which is vulnerable to extinction in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of ''critical depensatio ...

in the state of Texas, USA, where it is uncommon to rare. In some regions of Mexico and Central America, it is a common species.

References

External links

* {{Taxonbar, from=Q973272 Drymobius Reptiles described in 1837 Reptiles of Central America Reptiles of Mexico Fauna of the Rio Grande valleys Reptiles of Guatemala Reptiles of Colombia Taxa named by Hermann Schlegel