Central Galápagos Racer

Reptiles of Ecuador | Serpentes | Colubridae | Pseudalsophis | Pseudalsophis dorsalis

English common names: Central Galápagos Racer, Santa Cruz Racer.

Spanish common names: Culebra central de Galápagos, culebra de Santa Cruz, serpiente corredora de Santa Cruz.

Spanish common name: Culebra central de Galápagos.

Recognition: ♂♂ 102.5 cm ♀♀ 95 cm. Pseudalsophis dorsalis is the only snake known to occur on Santa Fe Island, Edén Islet, and Venecia Islet and is one of two species occurring on Baltra and Seymour Norte islands (previously also on Santa Cruz Island). The other species is the Painted Racer (P. steindachneri), a smaller snake that has golden speckled lateral black bands.

Natural history: Frequent. Pseudalsophis dorsalis is a diurnal snake inhabiting volcanic rock areas, dry shrublands, dry grasslands, deciduous forests, and rural gardens.1,2 Central Galápagos Racers are active on soil, rocks, and dry stream beds during the daytime and sometimes at night, but usually not during hot midday hours.1 Individuals of P. dorsalis are mildly venomous, which means their bite is dangerous to small prey, but not to humans.3 They are foraging predators that feed on Santa Fe Leaf-toed Geckos (Phyllodactylus barringtonensis), lava lizards (Microlophus barringtonensis and M. indefatigabilis), juvenile Marine Iguanas (Amblyrhynchus cristatus) and Galápagos Land-Iguanas (Conolophus subcristatus), and the eggs of Galápagos doves.1,4,5 Central Galápagos Racers are preyed upon by owls,6 and attacked by mockingbirds.7


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Conservation: Near Threatened. We consider Pseudalsophis dorsalis to be in this category following IUCN criteria.8 Although the species has been extirpated from one island corresponding to over 88% of its historical extent of occurrence (probably as a result of the introduction of cats and rats), the five remaining populations are, presumably, not undergoing population declines nor facing major immediate threats of extirpation. The remaining localities are free of exotic predators and are protected within the Galápagos National Park.2

Distribution: Pseudalsophis dorsalis was historically endemic to an estimated 428 km2 area on four islands and two islets in central Galápagos. Today, Central Galápagos Racers persist in an estimated 47 km2 area on Baltra, Seymour Norte, and Santa Fe islands as well as on Edén and Venecia islets. However, they have been extirpated from Santa Cruz Island. Galápagos, Ecuador.

Distribution of Pseudalsophis dorsalis Distribution of Pseudalsophis dorsalis in and around Santa Cruz Island Distribution of Pseudalsophis dorsalis in Santa Fe Island

Etymology: The generic name Pseudalsophis, which comes from the Greek words pseudo (meaning “false”) and Alsophis (a genus of Caribbean snakes), refers to the similarity between snakes of the two genera.9 The specific epithet dorsalis, which comes from the Latin words dorsum (meaning “back”) and -alis (meaning “pertaining to”),10 is probably a reference to the bold dorsal stripe present in some individuals of this species.11

See it in the wild: Like most snakes in Galápagos, Central Galápagos Racers are secretive animals, but, with some luck, they can be seen with ~20% certainty during tourism day trips to Santa Fe and Seymour Norte islands. On Seymour Norte, snakes of this species are more frequently observed in sea bird nesting areas. The best time to look for the racers is during the first hours after sunrise or right before sunset.

Authors: Alejandro ArteagaaAffiliation: Tropical Herping (TH), Quito, Ecuador. and Juan M GuayasaminbAffiliation: Laboratorio de Biología Evolutiva, Universidad San Francisco de Quito (USFQ), Quito, Ecuador.,cAffiliation: Galapagos Science Center, Galápagos, Ecuador.,dAffiliation: Centro de Investigación de la Biodiversidad y Cambio Climático, Universidad Tecnológica Indoamérica, Quito, Ecuador.

Academic reviewers: Robert A Thomas and Luis Ortiz-Catedral.

Photographers: Alejandro ArteagaaAffiliation: Tropical Herping (TH), Quito, Ecuador. and Jose VieiraaAffiliation: Tropical Herping (TH), Quito, Ecuador.,eAffiliation: ExSitu, Quito, Ecuador.

How to cite? Arteaga A, Guayasamin JM (2020) Pseudalsophis dorsalis. In: Arteaga A, Bustamante L, Vieira J, Guayasamin JM (Eds) Reptiles of Ecuador: Life in the middle of the world. Available from: www.tropicalherping.com

Klebba's Minifund logoThis species account of the Central Galápagos Racer (Pseudalsophis dorsalis) is available for free online thanks to the support of Klebba's Minifund.

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Literature cited:

  1. Tropical Herping field notes.
  2. Márquez C, Cisneros-Heredia DF, Yánez-Muñoz M (2016) Pseudalsophis dorsalis. The IUCN red list of threatened species. Available from: www.iucnredlist.org
  3. Thomas RA (1997) Galápagos terrestrial snakes: biogeography and systematics. Herpetological Natural History 5: 19–40.
  4. Washington Tapia, unpublished data.
  5. Ortiz-Catedral L, Christian E, Skirrow MJA, Rueda D, Sevilla C, Kumar K, Reyes EMR, Daltry JC (2019) Diet of six species of Galapagos terrestrial snakes (Pseudalsophis spp.) inferred from faecal samples. Herpetology Notes 12: 701–704.
  6. Steadman DW (1982) Fossil birds, reptiles, and mammals from isla Floreana, Galápagos Archipelago. PhD Thesis, Tucson, United States, The University of Arizona.
  7. Van Denburgh J (1912) Expedition of the California Academy of Sciences to the Galápagos Islands, 1905-1906. IV. The snakes of the Galápagos Islands. Proceedings of the California Academy of Sciences 1: 323–374.
  8. IUCN (2001) IUCN Red List categories and criteria: Version 3.1. IUCN Species Survival Commission, Gland and Cambridge, 30 pp.
  9. Zaher H, Grazziotin FG, Cadle JE, Murphy RW, Moura-Leite JC, Bonatto SL (2009) Molecular phylogeny of advanced snakes (Serpentes, Caenophidia) with an emphasis on South American Xenodontines: a revised classification and descriptions of new taxa. Papéis Avulsos de Zoologia 49: 115–153.
  10. Brown RW (1956) Composition of scientific words. Smithsonian Books, Washington, 882 pp.
  11. Steindachner F (1876) Die Schlangen und Eidechsen der Galápagos-Inseln. Verhandlungen der Zoologisch-Botanischen Gesellschaft in Wien 1876: 303–329.