Description
Holotype: USNM 20418, collected by Dr. W.L. Abbott, Mahé, between April 1890 and August 1892.

Paratype: USNM 20404, collected by Prof. Léon Vaillant (may not be G. alternans).

Generally less than 330 mm in total length; total number of teeth not exceeding 50 in any dental series (8-9 premaxillary teeth, 13-17 maxillary teeth); choanae moderate, with visible valves; tongue with a pair of narial plugs; splenials present; secondaries numerous; tentacle farther from the eye than from the nostrils in transformed specimens, thus located near the border of the lip; snout projecting beyond the mouth; gill-slit present at dorsolateral point on the second nuchal groove; in the holotype, anterior part of head is yellowish-gray and the body is purplish-black above and below (modified from Taylor 1968).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Seychelles

	View distribution map in BerkeleyMapper.
	View Bd and Bsal data (2 records).

Seychelles Islands: Mahé, Silhouette, Praslin, La Digue, Frégate.

Typically all Grandisonia species are fossorial and can be found under leaves, stones, decaying wood, and in wet soil. Known from sea-level to at least 750 m. Distribution is thought to be limited to the availability of moist habitat rather than elevation.

Life History, Abundance, Activity, and Special Behaviors
All species of Grandisonia are believed to be oviparous. G. alternans females are known to coil around egg clutches. This species also has a larval stage. These larvae have one pair of gill slits in line with the second nuchal groove and a small tail is present with one or two folds posterior to the anus.

Grandisonia alternans is the most abundant of the Grandisonia species and found in many different habitats on the large granitic Seychelles Islands.

Trends and Threats
A permit is required for their collection. They are potentially endangered by habitat destruction.

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities

References

Nussbaum, R. A. (1984). ''Amphibians of the Seychelles.'' Biogeography and Ecology of the Seychelles Islands. D.R. Stoddart , eds., Dr. W. Junk Publishers, Boston, 379-415.

Taylor, E.H. (1968). The Caecilians of the World. A Taxonomic Review. University of Kansas Press, Lawrence, Kansas.

Wake, M.H. (1977). ''The reproductive biology of caecilians: an evolutionary perspective.'' Reproductive Biology of Amphibians. D.H. Taylor and S.I. Guttman, eds., Plenum Press, New York., 73-101.

Species Account Citation: AmphibiaWeb 2021 Grandisonia alternans <https://amphibiaweb.org/species/1889> University of California, Berkeley, CA, USA. Accessed Apr 19, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 19 Apr 2024.

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