Afrithelphusa monodosa 

Scope: Global, Western Africa & Pan-Africa
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Arthropoda Malacostraca Decapoda Potamonautidae

Scientific Name: Afrithelphusa monodosa (Bott, 1959)
Common Name(s):
English Purple Marsh Crab
Afrithelphusa monodosus (Bott, 1959) [orth. error]
Globonautes monodosus Bott, 1959
Taxonomic Notes: Bott (1959) described this species as Globonautes monodosus. Cumberlidge (1999) transferred this species to the genus Afrithelphusa Bott, 1969. This species is one of only five species in two genera that belong to a rare group of freshwater crabs endemic to the upper Guinea forest block of West Africa. This genus was recently transferred from the Gecarcinucidae and reassigned to the Potamonautidae: Deckeniinae: Deckeniini: Globonautina by Cumberlidge et al. (2007).

Assessment Information [top]

Red List Category & Criteria: Endangered B1ab(iii)+2ab(iii); C2a(i) ver 3.1
Year Published: 1996
Date Assessed: 2008-01-01
Assessor(s): Cumberlidge, N.
Reviewer(s): Clotilde-Ba, F.-L., Attipoe, F.Y.K. & Darwall, W. and McIvor, A.
Despite the recent discovery of a new population of this species, it is still currently known from only a few specimens and from only two localities in Guinea. It was previously known from a single specimen collected in Boke, Guinea in 1947. Because of this the extent of occurrence for this species is here revised upward to an estimated 5,000 sq km (EN B1a), with an estimated area of occupancy of less than 500 sq km (EN B2a) due to its restriction to year-round wetland areas in guinea savannah and altered rainforest. Because of the discovery of new populations of this species (and the promise of finding other populations), its conservation status is downgraded from CR to EN. Available information on population size and trends and on the number of mature individuals is insufficient to estimate actual population size (for criterion C), but the scarcity of specimens implies a small population size (estimated to be fewer than 2,500 mature individuals) with no subpopulation estimated to contain more than 250 individuals i.e. EN C2a(i). There is a likely trend towards declining numbers due to increased habitat destruction relating to expanding human populations and more intensive agriculture in northwest Guinea. No quantitative analysis of the probability of extinction has been carried out to assess the species under criterion E.
Previously published Red List assessments:

Geographic Range [top]

Range Description:Guinea: this species is known only from two localities in Guinea and is therefore endemic to that country.
Countries occurrence:
Additional data:
Number of Locations:2
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:This species is known from less than 20 specimens. There is no information available on the population size or abundance of this species.
Current Population Trend:Decreasing
Additional data:

Habitat and Ecology [top]

Habitat and Ecology:This species lives in swamps and year-round wetland habitats in the Guinea savannah zone of northwestern Guinea. The original vegetation cover found at the farmland near the village of Sarabaya where this species was recently collected lies in southern guinea savannah in the semi-deciduous moist forest zone  (Cumberlidge 2006). Specimens of A. monodosus were collected from cultivated land from burrows dug into permanently moist soil each with a shallow pool of water at the bottom. At the end of the dry season after a six-month period without rain the soil in this area nevertheless remains wet year round, so this locality either has an underground water table close to the surface, or a nearby spring. The natural habitat of A. monodosus is still unknown but presumably this cultivated land was originally a permanent freshwater marsh. There were no nearby sources of surface water and it is clear that these crabs do not need to be immersed in water (as do their relatives that live in streams and rivers), and that A. monodosus can meet its water requirements (such as keeping its respiratory membranes moist and osmoregulation of body fluids) with the small amount of muddy water that collects at the bottom of their burrow. This species is clearly a competent air-breather and has a pair of well-developed pseudolungs similar to those seen in the related West African endemic genus Globonautes.

Threats [top]

Major Threat(s): The major present and future threats to this species include habitat loss/degradation (human induced) due to human population increases, deforestation, and associated increased agriculture in northwest Guinea.

Conservation Actions [top]

Conservation Actions: No conservation measures are known to be in place for this species and it is not found in a protected area.

Citation: Cumberlidge, N. 1996. Afrithelphusa monodosa. The IUCN Red List of Threatened Species 1996: e.T595A13066274. . Downloaded on 19 August 2018.
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