Madagasikara johnsoni 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Mollusca Gastropoda Sorbeoconcha Pachychilidae

Scientific Name: Madagasikara johnsoni (E.A. Smith, 1882)
Melanatria johnsoni E.A. Smith, 1882

Assessment Information [top]

Red List Category & Criteria: Endangered B1ab(i,ii,iii)+2ab(i,ii,iii) ver 3.1
Year Published: 2016
Date Assessed: 2016-05-23
Assessor(s): Van Damme, D.
Reviewer(s): Cumberlidge, N., Ranaivoson, C.H., Randrianasolo, H. & Rasamy, J.
Facilitator/Compiler(s): Sayer, C.
The species is confined to a part of the Mahajamba river system in Madagascar. Considering the small number of specimens collected, it seems to be rare and localised. Habitat destruction along the river, for example due to mining, has severely increased turbidity caused by erosion during the rainy season. Continuing declines in the extent of occurrence (EOO), area of occupancy (AOO) and habitat quality may hence be assumed. There are up to five locations, the AOO is currently estimated at 250 km² and the EOO at 500 km². However, these may be overestimates and the species could already be Critically Endangered or Extinct. This species is assessed as Endangered.

Geographic Range [top]

Range Description:Madagasikara johnsoni is restricted to the Kamoro river drainage (Mahajamba river system) in Mahajanga Province, northwest Madagascar (Köhler and Glaubrecht 2010). This drainage consists of five rivers but it is unknown how many of these rivers the species occurs in.
Countries occurrence:
Additional data:
Estimated area of occupancy (AOO) - km2:250
Number of Locations:1-5
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:No data are available on the subpopulations, population dynamics or generation length. However, considering the small number of specimens collected, it seems to be rare and localised.
Current Population Trend:Unknown
Additional data:

Habitat and Ecology [top]

Habitat and Ecology:The species inhabits rivers but is also cited from some artificial ponds in a tourist centre.

Use and Trade [top]

Use and Trade: This species is not used.

Threats [top]

Major Threat(s): Habitat destruction in the highland parts, for example due to mining, causing erosion and increasing turbidity in the middle and lower part of the river are cited by de Rham and Nourissat (2004) as important threats. As everywhere in Madagascar, pollution from the growing urban centres is also on the rise.

Conservation Actions [top]

Conservation Actions: No conservation measures have been implemented or are planned. The river drainage where it occurs is close to the Ankarafantsika National Park but it is unknown whether the species occurs here.

Citation: Van Damme, D. 2016. Madagasikara johnsoni. The IUCN Red List of Threatened Species 2016: e.T91353263A91353273. . Downloaded on 19 August 2018.
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