Pachnodus velutinus 


Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Mollusca Gastropoda Stylommatophora Cerastidae

Scientific Name: Pachnodus velutinus
Species Authority: (Pfeiffer, 1841)

Assessment Information [top]

Red List Category & Criteria: Extinct ver 3.1
Year Published: 2009
Date Assessed: 2006-01-11
Assessor(s): Gerlach, J.
Reviewer(s): Miller, R.M., Pollock, C.M. & Seddon, M.B.
Range contraction in this species has been recorded since 1972, following range expansion by Pachnodus niger which eventually led to hybridization. Hybrids exhibited a selective advantage in being tolerant of dry conditions; P. velutinus required constant humidity levels in excess of 90%. In 1994, no true P. velutinus could be located and since that date its range has been occupied exclusively by P. niger x velutinus hybrids.
Previously published Red List assessments:
2000 Extinct (EX)

Geographic Range [top]

Range Description:Endemic to the Seychelles, this extinct snail was found only on Mahé island.
Countries occurrence:
Regionally extinct:
Seychelles (Seychelles (main island group))
Range Map:Click here to open the map viewer and explore range.

Habitat and Ecology [top]

Habitat and Ecology:This snail once inhabited high forests, requiring constant humidity levels in excess of 90%. By the early 1990s, it was restricted to the dampest area of moss forests, and by 1994 it had become extinct.

Threats [top]

Major Threat(s): Being vulnerable to dessication, this species was historically threatened by habitat degradation and climatic changes. Hybridization with Pachnodus niger led to the extinction of this species in 1994.

Conservation Actions [top]

Conservation Actions: This snail was historically present in the Morne Seychellois National Park.

Classifications [top]

1. Forest -> 1.6. Forest - Subtropical/Tropical Moist Lowland
suitability: Suitable  major importance:Yes

In-Place Research, Monitoring and Planning
In-Place Land/Water Protection and Management
In-Place Species Management
In-Place Education
2. Agriculture & aquaculture -> 2.1. Annual & perennial non-timber crops -> 2.1.2. Small-holder farming
♦ timing: Past, Unlikely to Return ♦ scope: Minority (<50%) ♦ severity: Unknown ⇒ Impact score: Past Impact 
→ Stresses
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation

8. Invasive & other problematic species & genes -> 8.1. Invasive non-native/alien species -> 8.1.2. Named species (Pachnodus niger)
♦ timing: Past, Unlikely to Return ♦ scope: Whole (>90%) ♦ severity: Slow, Significant Declines ⇒ Impact score: Past Impact 
→ Stresses
  • 2. Species Stresses -> 2.3. Indirect species effects -> 2.3.1. Hybridisation

11. Climate change & severe weather -> 11.2. Droughts
♦ timing: Past, Unlikely to Return ♦ scope: Whole (>90%) ♦ severity: Rapid Declines ⇒ Impact score: Past Impact 

Bibliography [top]

Gerlach, J. 1996. Patterns of hybridization and extinction in a tropical land snail. Phelsuma 6: 27-42.

Gerlach, J. 2006. Terrestrial and Freshwater Mollusca of the Seychelles Islands. Backhuys, Leiden.

Gerlach, J., Matyot, P. and Samways, M.J. 2005. Developing strategies for invertebrate conservation, the case of the Seychelles islands. Phelsuma: 9-12.

IUCN. 2009. IUCN Red List of Threatened Species (ver. 2009.2). Available at: (Accessed: 3 November 2009).

Citation: Gerlach, J. 2009. Pachnodus velutinus. In: The IUCN Red List of Threatened Species 2009: e.T40091A10304648. . Downloaded on 26 November 2015.
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