Endangered Species Monday: Afrithelphusa monodosa
Warning: Extinction is now Inevitable
This Mondays (E.S.P) -Endangered Species watch Post I focus on a species of fresh water crab that’s rarely spoken about within the theater of conservation, or animal rights forums. Identified by Mr Bott from which I know little on and about this particular species of marsh crab is currently listed as endangered. Rarely do I document on a species of animal that I and other conservationists know will be extinct within the next five years. My aim for this Monday’s endangered species column is to raise awareness about the plight of this little creature, in a way I hope will force Cites and the Guinea government to now implement emergency evasive action to halt extinction immediately. (Image: Purple Marsh Crab, photographer unknown)
I must also point out that one must not confuse the [common name] of this species [above], identified back in 1959, to that of the United States [Purple Marsh Crab]. Professor Linnaeus created the nomenclature system for a reason, and yet again I am seeing two species of animals that hold the same common names being confused with one-another. Sesarma reticulatum is not under any circumstances related to the Afrithelphusa monodosa pictured above and below.
Endemic to Guinea the species was listed back in 1996 as [critically endangered]. However since the last census was conducted back in  the Purple Marsh Crab has since been submitted into the category of [endangered]. Unfortunately as yet there remains no current documentation on population size, furthermore from the 1996 census, marine conservation reports suggest that no fewer than twenty specimens have been collected from the wild. To date the ‘estimated’ population size stands at a mere 2.500 mature individuals.
Back in 1959 Mr Bott identified the specimen as Globonautes monodosus however from 1999 the species was re-named as Afrithelphusa monodosa. The Purple Marsh Crab is one of only five species in the two genera of which belong to a very rare group of fresh water crabs that are still endemic to the Guinea forests within the block of Western Africa. All five specimens within the two genera are listed as either [endangered or critically endangered], and as such its quite likely that all five specimens will become extinct within the next five to eight years, or possibly even sooner. It is without a doubt that one of the next species on the planet to go extinct will be the Purple Marsh Crab.
Allegedly new specimens have been discovered since  however these reports are somewhat sketchy. When I last documented on the specimen back in 2010 there were no conservation efforts or any projects in the planning process that would help preserve the crabs future survival. We are now in 2015 and I have yet to witness any conservation projects planned or taking place, which I find rather frustrating. As explained the species will be extinct within a matter of years of which the Convention on International Trade of Endangered Species (Cites) should be protecting.
A. monodosa lives within the Guinea swamps and all year round wetland habitat within the 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. 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 pseudol.
Image: Credited to Piotr Naskrecki. Purple Marsh Crab.
To be truthfully honest I feel documenting on the current threats is in reality a waste of my time because both the Guinea government and Cites have known of these threats for many years. Yet little if any actions are being taken to suppress these threats. Either way I will document on them in the hope that someone will push for protection or whip into action a protective project sooner rather than later.
To date the species hasn’t been listed on either Cites (I-II) Appendix’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.
International Animal Rescue Foundation Africa propose the following actions to be undertaken immediately:
- Up to date assessment of population size and location of any new and old habitats documented.
- Surveys to asses diets, predators, diseases and behavior.
- Investigations to locate new subspecies.
- Protection zones established within the highest populated zones.
- Liaising the Guinea government for funding of conservation projects.
- Listing of the species in (I Appendix) Cites.
- Community education and awareness programs.
- Removal of healthy and gene strong species for captive breeding programs.
Crabs Role within the Eco-System
Crabs are one of the major decomposes in the naval environment. In other terms, Crabs help in cleaning up the bottom of the sea and rivers by collecting decaying plant and animal substance. Many fish, birds and sea mammals rely on crabs for a food source. Regardless of if this is one species with low individual populations or not, extinction will only harm other animals. Furthermore will reduce other species food sources. The video below depicts the [Marsh Crabs] and their normal natural environment. The species in question which is identical to the Guinea Purple Marsh Crab is not included within the video but is related to the five genera.
Thank you for reading.
Dr Jose C. Depre
Environmental and Botanical Scientist.