Boa sigma

Boa sigma, known commonly as the Mexican west coast boa, is a species of snake in the family Boidae. The species is endemic to western Mexico. Boa sigma has previously been regarded as conspecific with Boa constrictor, and later with Boa imperator; however, in 2016, it was suggested on genetic grounds that Boa sigma should be regarded as a separate species.

Boa sigma
CITES Appendix II (CITES)[1]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Boidae
Genus: Boa
Species:
B. sigma
Binomial name
Boa sigma
(Smith, 1943)
Distribution range for Boa sigma
Synonyms[2]
  • Constrictor constrictor sigma Smith, 1943

Taxonomy

Boa sigma was originally described as Constrictor constrictor sigma by Hobart Muir Smith in 1943.[3][4] The subspecies only included snakes from the Islas Marías, and it did not receive wide recognition; instead, it was synonymized with the mainland subspecies Boa constrictor imperator by many authors.[4][5][6]

In the 21st century, genetic studies revealed that Boa constrictor is a species complex. First, Boa constrictor imperator was elevated to species level, but it was soon recognized that there was another species nested within the new species Boa imperator. According to Card et al. (2016), the name Boa sigma is available for this third species.[4] However, further research is needed because the genetic study of Card et al. didn't include samples from the Islas Marías, from where the holotype and the paratypes were collected.[4][7][8] Despite this uncertainty, Boa sigma has been widely accepted as a valid species.[2][9]

Phylogeny

Suárez-Atilano et al. (2014) identified two lineages of Boa imperator with a divergence date of about 5.2 Ma.[10] However, Card et al. (2016) found the divergence date of these lineages, which they recognized as Boa imperator and Boa sigma, to be around 14 Ma.[4] Both divergence dates could be explained with the rise of biogeographical barriers.[11]

Distribution and habitat

Boa sigma is distributed along the Pacific Coast of Mexico west of the Isthmus of Tehuantepec.[12] The northernmost records are from Sonora,[13] where the species can reach altitudes of 1,420 metres (4,659 ft).[14] Within the distribution range of Boa sigma, the three islands of the Islas Marías are included: María Madre, María Magdalena and María Cleofas.[12]

Based on species distribution modelling, Boa sigma lives mainly within the tropical dry forest ecoregion, whereas Boa imperator seems to prefer areas with more precipitation.[11] In Oaxaca, there is a contact zone between these two species, but it is unclear whether or not hybridization occurs there.[2][11]

Folklore

In eastern and southern Sonora, it is widely believed that Boa sigma, locally known as corúa, corúga, corúva, culebrón or limacoa, is the guardian of water (guardiana del agua). Unlike other snakes, Boa sigma is protected by rural Sonorans, because it is thought that killing the boa would cause the spring (aguaje) to dry up.[15][16][17]

References
  1. "Appendices". CITES. Retrieved 2022-01-14.
  2. Uetz, P.; Freed, P.; Aguilar, R.; Hošek, J., eds. (2022). "Boa sigma". The Reptile Database. Retrieved 2022-03-28.
  3. Smith, Hobart M. (1943). "Summary of the collections of snakes and crocodilians made in Mexico under the Walter Rathbone Bacon Traveling Scholarship". Proceedings of the United States National Museum. 93 (3169): 393–504. doi:10.5479/si.00963801.93-3169.393. Retrieved 2022-03-28.
  4. Card, Daren C.; Schield, Drew R.; Adams, Richard H.; Corbin, Andrew B.; Perry, Blair W.; Andrew, Audra L.; Pasquesi, Giulia I.M.; Smith, Eric N.; Jezkova, Tereza; Boback, Scott M.; Booth, Warren (September 2016). "Phylogeographic and population genetic analyses reveal multiple species of Boa and independent origins of insular dwarfism" (PDF). Molecular Phylogenetics and Evolution. 102: 104–116. doi:10.1016/j.ympev.2016.05.034. PMC 5894333. PMID 27241629. Retrieved 2022-03-28.
  5. Lindemann, Laurel (2009). "Boa constrictor". Animal Diversity Web. Retrieved 2022-03-28.
  6. "Hog Island Boa". BioLib. Retrieved 2022-03-28.
  7. Nolasco-Luna, Jose Rafael; Barraza-Soltero, Ilse K.; López-Montes, Manuel A.; Moreno-López, Jesús A.; Escobedo-Galván, Armando H. (2022-02-28). "An updated checklist of the herpetofauna from Isla María Cleofas, Mexico". Check List. Pensoft Publishers. 18 (1): 241–252. doi:10.15560/18.1.241. ISSN 1809-127X. S2CID 247178452. Retrieved 2022-03-28.
  8. Loc-Barragán, Jesús A.; Ramírez-Silva, Juan Pablo; Woolrich-Piña, Guillermo A. (December 2016). "Boa sigma (Smith, 1943). Diet". Mesoamerican Herpetology. 3 (4): 1015–1017. Retrieved 2022-03-28.
  9. Uetz, P.; Freed, P.; Aguilar, R.; Hošek, J., eds. (2022). "Boa imperator". The Reptile Database. Retrieved 2022-03-28.
  10. Suárez-Atilano, Marco; Burbrink, Frank; Vázquez-Domínguez, Ella (December 2014). Riddle, Brett (ed.). "Phylogeographical structure within Boa constrictor imperator across the lowlands and mountains of Central America and Mexico". Journal of Biogeography. 41 (12): 2371–2384. doi:10.1111/jbi.12372. S2CID 84956217. Retrieved 2022-05-27.
  11. Suárez-Atilano, Marco; Rojas-Soto, Octavio; Parra, Juan L.; Vázquez-Domínguez, Ella (September 2017). "The role of the environment on the genetic divergence between two Boa imperator lineages". Journal of Biogeography. John Wiley & Sons, Ltd. 44 (9): 2045–2056. doi:10.1111/jbi.13006. ISSN 0305-0270. S2CID 90091483. Retrieved 2022-03-28.
  12. Reynolds, R. Graham; Henderson, Robert W. (September 2018). "Boas of the World (Superfamily Booidae): A Checklist With Systematic, Taxonomic, and Conservation Assessments". Bulletin of the Museum of Comparative Zoology. Museum of Comparative Zoology, Harvard University. 162 (1): 1–58. doi:10.3099/MCZ48.1. S2CID 91781892.
  13. Van Devender, Thomas R.; et al. (2020). "Distribution and Ecology of the Northernmost Mexican West Coast Boa Constrictor (Boa sigma)". Herpetological Review. 51 (3): 433–438. Retrieved 2022-03-28.
  14. Sky, Jacobs (2018). "Boa sigma" (PDF). Herpetological Review. 49 (2): 287. Retrieved 2022-03-28.
  15. Van Devender, Thomas R.; Reina-Guerrero, Ana Lilia (March 2022). "In the shadow of Picacho de Bacoachi: the Tribes of Basaitequi" (PDF). Sonoran Herpetologist. 35 (1): 30–37. ISSN 2333-8075. Retrieved 2022-04-09.
  16. Van Devender, Thomas R. "Research in the Sierra Madre Occidental of Eastern Sonora, Mexico: Wide-ranging Tropical Animals". Arizona-Sonora Desert Museum. Retrieved 2022-04-09.
  17. Turner, Dale S.; et al. (June 2022). "Amphibians and Reptiles of Rancho Las Playitas area, Sonora, Mexico" (PDF). Sonoran Herpetologist. 35 (2): 62–71. ISSN 2333-8075. Retrieved 2022-07-08.
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