Platythelphusa

Taxonomic history

The first freshwater crab to be described from Lake Tanganyika, by Alphonse Milne-Edwards in 1887, was considered so distinct from the other crabs known up to that time that it was placed in a new genus, as Platythelphusa armata. Twelve years later, a second species was described by W. A. Cunnington, leader of the third Tanganyika Expedition, and was also placed in a separate genus, as Limnothelphusa maculata. The same author later described a third species, Platythelphusa conculata, and eventually realised that all three belonged to the same genus, reducing Limnothelphusa to a taxonomic synonym.

In 1952, Capart did not recognise the species P. conculcata, but added four new species, P. denticulata, P. echinata, P. polita and P. tuberculata. Since that time, P. conculcata has been restored, and two new species have been described, P. immaculata and P. praelongata.

Distribution

All nine species live in relatively shallow waters around the edge of Lake Tanganyika. While four countries border Lake Tanganyika (Burundi, Democratic Republic of the Congo, Tanzania and Zambia), only two species have been found in all four countries, P. armata and P. conculcata. One species, P. polita, has been found in all except Zambia; two (P. echinata and P. tuberculata) have been found in Burundi and Tanzania; one has been found in Tanzania and Zambia (P. maculata); one is only known from Zambia (P. praelongata) and two have only been seen in Tanzania (P. denticulata and P. immaculata). However, many of the species are poorly known, and their true distributions may be wider than is currently known.

Species

''Platythelphusa armata''

As the largest species in the genus (up to 6 cm in carapace width), Platythelphusa armata is subject to small-scale fishery. Adults live at depths of 5 -, while juveniles live at depths of 1 -, and often inhabit discarded Neothauma tanganyicense shells. The species is listed as Least Concern by the IUCN.

''Platythelphusa conculcata''

Platythelphusa conculcata is found at depths of 20 -, and is listed as Least Concern by the IUCN.

''Platythelphusa denticulata''

Platythelphusa denticulata is known from few sites, all in Tanzania. Though it may have a low population, there is no evidence of a decline and it is listed as Least Concern by the IUCN.

''Platythelphusa echinata''

Platythelphusa echinata is found at depths of 5 - on the Tanzanian and Burundian shores of Lake Tanganyika. It lives where the substrate is rocky or sandy, and occasionally uses old Neothauma shells.

''Platythelphusa immaculata''

Platythelphusa immaculata is known from only 25 specimens, but is listed as Least Concern, because there are no apparent threats to its survival.

''Platythelphusa maculata''

Platythelphusa maculata lives on sand and rocks, and occasionally in Neothauma shells, at depths of 1 -, and is listed as Least Concern.

''Platythelphusa polita''

Platythelphusa polita lives on sand and rocks, and occasionally in Neothauma shells, at depths of 5 -, and is listed as Least Concern.

''Platythelphusa praelongata''

Platythelphusa praelongata lives at the greatest depth of any Platythelphusa species, the single known specimen having been collected at 40 -, around Mbita Island, and is listed as Data Deficient.

''Platythelphusa tuberculata''

Platythelphusa tuberculata has longer legs than the other species, and lives at the northern end of Lake Tanganyika, on muddy substrates. It has been found in the stomachs of fish including Chrysichthys brachynema and Bathybagrus stappersii (formerly Chrysichthys stappersii).

References

References

1. Neil Cumberlidge, Richard M. von Sternberg & Savel R. Daniels. (2008). "A revision of the higher taxonomy of the Afrotropical freshwater crabs (Decapoda: Brachyura) with a discussion of their biogeography". [[Biological Journal of the Linnean Society]].
2. (2006). "Molecular evidence for recent divergence of Lake Tanganyika endemic crabs (Decapoda: Platythelphusidae)". [[Molecular Phylogenetics and Evolution]].
3. (2005). "Out of Tanganyika: Genesis, explosive speciation, key-innovations and phylogeography of the haplochromine cichlid fishes". [[BMC Evolutionary Biology]].
4. R. von Sternberg. (1999). "A cladistic analysis of ''Platythelphusa'' A. Milne-Edwards, 1887, from Lake Tanganyika, East Africa (Decapoda: Potamoidea: Platythelphusidae) with comments on the phylogenetic position of the group". [[Journal of Natural History]].
5. (2004). "Two new species of ''Platythelphusa'' A. Milne-Edwards, 1887 (Decapoda, Potamoidea, Platythelphusidae) and comments on the taxonomic position of ''P. denticulata'' Capart, 1952 from Lake Tanganyika, East Africa". [[Crustaceana]].
6. (1999). "A revision of the genus ''Platythelphusa'' A. Milne-Edwards, 1887 from Lake Tanganyika, East Africa (Decapoda: Potamoidea: Platythelphusidae)". [[Journal of Natural History]].
7. N. Cumberlidge & S. A. E. Marijnissen. (2008). "''Platythelphusa armata''".
8. N. Cumberlidge & S. A. E. Marijnissen. (2008). "''Platythelphusa conculcata''".
9. N. Cumberlidge & S. A. E. Marijnissen. (2008). "''Platythelphusa denticulata''".
10. N. Cumberlidge & S. A. E. Marijnissen. (2008). "''Platythelphusa echinata''".
11. N. Cumberlidge & S. A. E. Marijnissen. (2008). "''Platythelphusa immaculata''".
12. N. Cumberlidge & S. A. E. Marijnissen. (2008). "''Platythelphusa maculata''".
13. N. Cumberlidge & S. A. E. Marijnissen. (2008). "''Platythelphusa polita''".
14. N. Cumberlidge & S. A. E. Marijnissen. (2008). "''Platythelphusa praelongata''".
15. N. Cumberlidge & S. A. E. Marijnissen. (2008). "''Platythelphusa tuberculata''".