Xenotyphlops

Xenotyphlops is a genus of snakes, the only genus of the family Xenotyphlopidae, comprising two species found only in Madagascar.^[1] These snakes are also known as the Malagasy blind snake.^[2]

Xenotyphlops
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Squamata
Suborder:	Serpentes
Infraorder:	Scolecophidia
Superfamily:	Typhlopoidea
Family:	Xenotyphlopidae Vidal, Vences, Branch & Hedges, 2010
Genus:	Xenotyphlops Wallach & Ineich, 1996
Species
Two species, see text

Evolution

Xenotyphlops is an ancient group that diverged from other blind snakes during the Cretaceous, following the separation of Madagascar from India. On the newly-isolated Madagascar, the ancestral Xenotyphlopidae and Typhlopidae diverged from one another; Typhlopidae dispersed worldwide from Madagascar while leaving behind a single Malagasy genus (Madatyphlops), while the Xenotyphlopidae remained restricted to Madagascar. Xenotyphlops, Madatyphlops, and the Madagascan big-headed turtle are the only Malagasy terrestrial vertebrates whose isolation on Madagascar is due to Gondwanan vicariance.^[3]

Physical characteristics

The family Xenotyphlopidae is composed of small blind snakes.^[2] These members lack cranial infrared receptors in pits or durface indentations.^[2] It is thought that these snakes used to have eyes but lost use of them over time.^[4] Members of the genus Xenotyphlops are distinguishable externally from the Typhlopidae by possessing a greatly enlarged and nearly circular rostral shield and a single enlarged anal shield.^[2] This shield is nearly vertical in a lateral aspect; as a result, the two species have a "bulldozer" appearance. Xenotyphlops get no larger than an earthworm and have translucent pink scales.^[4] Xenotyphlops species are internally unique in that they lack a tracheal lung and possess an unexpanded tracheal membrane.^[5] Like many other snake families they are assumed to be oviparous.^[2] Both species are completely terrestrial.^[6]

Geographic range

Snakes of the genus Xenotyphlops are endemic to the island of Madagascar. Xenotyphlops burrow in the softer sandy soil of Madagascar's coastline forest and shrubland.^[4] For over 100 years the genus was known only from the type locality, which was "Madagascar", and only from the type specimens.^[7] These snakes presumably live in colonies of subterranean social insects.^[2]

Conservation status

According to the IUCN Red List, X. grandidieri are considered to be critically endangered and X. mocquardi are data deficient.^[6] The two biggest threats to these species are Energy production (via mining/quarrying) and biological resource use (via logging and unintentional effects).^[6]

Species

• Xenotyphlops grandidieri (Mocquard, 1905)
• Xenotyphlops mocquardi Wallach, Mercurio & Andreone, 2007

Nota bene: A binomial authority in parentheses indicates that the species was originally described in a genus other than Xenotyphlops.

Etymology

The specific name, grandidieri, is in honor of French naturalist Alfred Grandidier.^[8]

The specific name, mocquardi, is in honor of French herpetologist François Mocquard.^[8]

Taxonomy

In 2013, after examining several newly collected specimens, Wegener et al. concluded that X. mocquardi falls within the range of variation of X. grandidieri, and they proposed that X. mocquardi be considered a synonym of X. grandidieri. This change would make Xenotyphlops a monotypic genus in a monotypic family.^[9] The Xenotyphlipidae's sister taxon are the Typhlopidae.^[2]

References

1. "Xenotyphlops ". Integrated Taxonomic Information System. Retrieved 29 August 2007.
2. Vitt, Laurie J.; Caldwell, Janalee P. (2013). Herpetology: An Introductory Biology of Amphibians and Reptiles, Fourth Edition. Cambridge, Massachusetts: Academic Press. ISBN 0-12-386919-6. OCLC 934973974.
3. Ali, Jason R.; Hedges, S. Blair (2023-05-04). "The colonisation of Madagascar by land‐bound vertebrates". Biological Reviews. doi:10.1111/brv.12966. ISSN 1464-7931.
4. "Madagascar blind snake | Xenotyphlops grandidieri ". EDGE of Existence. Retrieved 2020-05-12.
5. Species Xenotyphlops grandidieri at The Reptile Database . Retrieved 27 May 2019.
6. "The IUCN Red List of Threatened Species". IUCN Red List of Threatened Species. Retrieved 2020-05-12.
7. McDiarmid RW, Campbell JA, Touré TA (1999). Snake Species of the World: A Taxonomic and Geographic Reference, Volume 1. Washington, District of Columbia: Herpetologists’ League. 511 pp.
8. Beolens, Bo; Watkins, Michael; Grayson, Michael (2011). The Eponym Dictionary of Reptiles. Baltimore: Johns Hopkins University Press. xiii + 296 pp. ISBN 978-1-4214-0135-5. (Xenotyphlops grandidieri, pp. 105-106; X. mocquardi, p. 181).
9. Wegener JE, Swoboda S, Hawlitschek O, Franzen M, Wallach V, Vences M, Nagy ZT, Hedges SB, Köhler J, Glaw F (2013). "Morphological variation and taxonomic reassessment of the endemic Malagasy blind snake family Xenotyphlopidae (Serpentes, Scolecophidia)". Spixiana 36 (2): 269-282.

Further reading

• Mocquard F (1905). "Note préliminaire sur une collection de Reptiles et de Batraciens offerte au Muséum par M. Maurice de Rothschild ". Bulletin du Muséum National d'Histoire Naturelle 11 (5): 285–288. (Typhlops grandidieri, new species, p. 287). (in French).
• Wallach V, Ineich I (1996). "Redescription of a Rare Malagasy Blind Snake, Typhlops grandidieri Mocquard, with Placement in a New Genus (Serpentes: Typhlopidae)". Journal of Herpetology 30 (3): 367–376. (Xenotyphlops, new genus).
• Wallach V, Mercurio V, Andreone F (2007). "Rediscovery of the enigmatic blind snake genus Xenotyphlops in northern Madagascar, with description of a new species (Serpentes: Typhlopidae)". Zootaxa 1402: 59–68. (Xenotyphlops mocquardi, new species).

External links

• Xenotyphlops at the Reptarium.cz Reptile Database