Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Amphibia Anura Sooglossidae

Scientific Name: Sooglossus thomasseti
Species Authority: (Boulenger, 1909)
Common Name(s):
English Thomasset's Frog, Thomasset's Seychelles Frog
Nesomantis thomasseti Boulenger, 1909
Taxonomic Source(s): Frost, D.R. 2013. Amphibian Species of the World: an Online Reference. Version 5.6 (9 January 2013). Electronic Database. American Museum of Natural History, New York, USA. Available at:

Assessment Information [top]

Red List Category & Criteria: Critically Endangered B1ab(ii,iii) ver 3.1
Year Published: 2013
Date Assessed: 2012-04-10
Assessor(s): IUCN SSC Amphibian Specialist Group,
Reviewer(s): Catenazzi, A.
Contributor(s): Gerlach, J. & Nussbaum, R.
Facilitator/Compiler(s): Angulo, A.
Listed as Critically Endangered given that its extent of occurrence (EOO) is estimated to be 67 km2, its population is considered to be severely fragmented, and there is a continuing decline in its area of occupancy (AOO) and quality of its habitat due to projected changes in rainfall patterns in the Seychelles.
Previously published Red List assessments:
2004 Vulnerable (VU)
1996 Endangered (EN)
1994 Rare (R)
1990 Rare (R)
1988 Rare (R)
1986 Indeterminate (I)

Geographic Range [top]

Range Description: This species is restricted to Mahé and Silhouette Islands in the Seychelles, occurring between 150-991 m asl, though one individual was found at 95 m asl. Its extent of occurrence (EOO) is estimated to be 67 km2 with an upper limit of 100 km2, while its area of occupancy (AOO) is estimated at 22 km2 based on area polygons for occupied habitat for each mapped subpopulation (J. Gerlach pers. comm. March 2012). It is known from four subpopulations (J. Gerlach pers. comm. March 2012) representing  two threat-defined locations: one location in Silhouette comprising one subpopulation, and one locations in Mahé comprising two subpopulations (J. Gerlach pers. comm. March 2012).
Countries occurrence:
Estimated area of occupancy (AOO) - km2: 21.9
Continuing decline in area of occupancy (AOO): Yes
Estimated extent of occurrence (EOO) - km2: 67
Number of Locations: 2
Lower elevation limit (metres): 95
Upper elevation limit (metres): 991
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: It is less common than other members of the family Sooglossidae. The global population is considered to be severely fragmented i.e., it occurs in fragmented habitat patches, the species has poor dispersal ability, such that it is not possible for animals to move between fragments, and it is believed that 50% or more of its individuals occur in isolated and fragmented habitat patches (J. Gerlach pers. comm. March 2012).
Current Population Trend: Unknown
Additional data:
Population severely fragmented: No

Habitat and Ecology [top]

Habitat and Ecology: It is restricted to relatively undisturbed habitat in wet rocky areas along streams or dry streambeds. It is associated with areas that have high levels of mist and cloud cover (Gerlach 2011). The recent low-altitude records were from secondary forest, but it shows a strong preference for higher altitudes and undisturbed habitats. It breeds by direct development, the eggs being laid among rocks.
Systems: Terrestrial; Freshwater
Continuing decline in area, extent and/or quality of habitat: Yes

Use and Trade [top]

Use and Trade: There are no reports of this species being utilized.

Threats [top]

Major Threat(s): The main threats are habitat degradation and climate change. Habitats are deteriorating mainly due to increased fire and invasive species, principally the tree Cinnamomum verum (J. Gerlach pers. comm. March 2012). Climate change is projected to lead to a 7% decline in area of occupancy within ten years, and a decline of 65% by 2100 (J. Gerlach pers. comm. March 2012).

Conservation Actions [top]

Conservation Actions: It occurs in Morne Seychellois and Silhouette National Parks (J. Gerlach pers. comm. March 2012). There is a need for close monitoring of the population status of this species; this was initiated in 1996 but was forcibly terminated in 2011 (J. Gerlach pers. comm. March 2012). Captive colonies have been successfully maintained, although successful captive breeding has yet to be recorded for this species (J. Gerlach pers. comm. March 2012). The development of captive breeding techniques is recommended for this species, as well as improved habitat management to minimize the impact of invasive species (J. Gerlach pers. comm. March 2012).

Citation: IUCN SSC Amphibian Specialist Group,. 2013. Sooglossus thomasseti. The IUCN Red List of Threatened Species 2013: e.T14663A15493219. . Downloaded on 09 October 2015.
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