Species assessed as Data Deficient

Of the 54 species of western African decapods assessed, 13 (24%) were judged to be Data Deficient (four crabs and nine shrimps), indicating the need for further research on these species and their conservation status.

6.2.5.1 Data Deficient crabs

Afrithelphusa gerhildae (DD)

This species is known only from a single locality in Guinea.

It is listed here as Data Deficient in view of the absence of further information on its distribution, ecological requirements, population size and trends A. gerhildae is known only from three specimens all collected from a single locality in Guinea (Kindia), and it is of concern that that no new specimens have come to light since then. There are potential threats from increased habitat destruction relating to expanding human populations and more intensive agriculture in this part of Guinea. However, there is not enough known about this species to make a thorough assessment at this time and surveys are urgently required (Cumberlidge & Daniels, 2020b). As a consequence, the conservation status of this species was changed recently from CR to DD but if the threats to the locality of this species increase then a reassessment of the status of this species should be carried out.

Potamonautes senegalensis (DD)

This species is known only from two specimens collected in 1960 from an unspecified locality in the dry savannah zone of northern Senegal associated with the Senegal River. Given that freshwater crabs are never found in saltwater habitats, it seems likely that this species was collected upstream of the saltwater influence in this river in the freshwater zone upstream of Podor. Potamonautes senegalensis is listed as Data Deficient in view of the absence of further information on its distribution, ecological requirements, population size, and population trends (Cumberlidge & Daniels, 2020k). It is of concern that this species was last collected in 1960, and that no new specimens have come to light since then.

Potamonautes lipkei (DD)

This species has a relatively restricted range and is known from fewer than five specimens from two localities in Niokolo Koba National Park, Senegal collected in 2010 (Dˇuriš & Koch, 2010). Within the Park it has been recorded on Mount Assirik

slope at 151 m asl and at the Gambia River embankment at Smenti (tourist centre) at 34 m asl. The Mount Assisik specimens were collected from burrows in the banks of small seasonally dry streams with large pools that flow through a valley covered by a gallery forest. One of the specimens was collected from the banks of the Gambia River which flows year round and does not dry up seasonally. There is no information on population size or trends, or on potential threats to the species (Cumberlidge & Daniels, 2020i).

Additional surveys are needed to better understand the distribution of this species. Further research may support the adoption of the existing Parc National du Niokolo-Koba KBA for this species (see Chapter 9).

Sudanonautes nigeria (DD)

This species is known only from a single locality and was last collected in 1973 in the rainforests of southeastern Nigeria in the western part of the Lower Guinea forest block. There have been no recent attempts to recollect the species. It is listed as Data Deficient in view of the absence of further information on its distribution, ecological requirements, population size, population trends, and long-term threats.

6.2.5.2 Data Deficient shrimps

Caridina ebuneus (DD)

The species was described in 2009 (Richard & Clark, 2009) from samples collected between 1946 and 1954 from various locations in Côte d’Ivoire. The exact ecological requirements of this species are not known, as no habitat information is specified in Richard & Clark (2009). As such, the species is considered Data Deficient.

Caridina ghanensis (DD)

The species was recently described from two samples, both collected in 1949, from “Pond Vume”, Ghana and La Sio, near Lomé, Togo (Richard & Clark, 2009). Neither locations could be georeferenced, but is seems likely that “Pond Vume”

refers to a pond in the town of Vume. As the exact distribution of the species is not known due to this uncertainty, nor its exact ecological requirements and no specific threats could be identified, the species is considered as Data Deficient.

Caridina messofluminis (DD)

This species was recently described on the basis of 14 specimens collected in “Mess stream”, Cameroon (Richard

& Clark, 2009). As this location cannot be traced nor georeferenced, the species is considered as Data Deficient.

Caridina okiamnis (DD)

This species was recently described (Richard & Clark, 2009) on the basis of 14 specimens collected in “Okia stream”, Cameroon. As this location could not be traced nor georeferenced, the species is considered as Data Deficient.

Euryrhynchoides holthuisi (DD)

The species is only known from the type series collected before 1976, from a single site in Sierra Leone. The type description mentions the species was collected from the River Taja at Njala, a location in the south of Sierra Leone.

It also provides a georeference (8°06’N 12°04’W), which is in the north of the country. In view of this uncertainty, the species is considered as Data Deficient.

Macrobrachium felicinum (DD)

Due to extensive confusion with other West African taxa, the species is only known with certainty from two sites, one in Ghana and one in Angola. As the further distribution of the species is not known and no specific threats could be identified, the species is considered as Data Deficient.

Macrobrachium raridens (DD)

This poorly known species has been recorded from the northern part of tropical West Africa (Holthuis, 1951), from Guinea to Nigeria. The majority of records pre-date 1947 and although the species has been mentioned in more recent literature, the identifications are not certain. As the species is so poorly known, it is considered to be Data Deficient.

Macrobrachium thysi (DD)

The species is only known from the type series, collected in 1966–1968 from two sites near Banco, Côte d’Ivoire, both within the Banco National Park. As the wider distribution of the species is not known and no specific threats could be identified, the species is considered as Data Deficient.

Euryrhynchina puteola (DD)

The species is only known from the type series (seven specimens), collected in 2012 (described in 2017) from a small, drinking water well in Mbanga City, Littoral province, Cameroon (De Grave et al., 2017). As the potentially wider distribution of this species is not known and in view of its very recent description, and as no threats could be identified, this species is considered to be Data Deficient.

6.3 Patterns of species richness

There is a clear centre of diversity around the Cross River / Oyono in southeastern Nigeria and the Meme River in neighbouring Cameroon, with up to 14 species co-occurring in each of these river catchments. There are secondary centres of diversity in the Ochi-Nakwa River basin in Ghana and the Cavally and St Paul Rivers in Liberia, each with up to 11 species. Of the 26 crab species assessed, 19 (73%) are endemic to the western Africa region based on their mapped ranges, and the 12 species threatened with extinction are all endemic to the western Africa region.

Figure 6.4 Species richness of freshwater decapods in western Africa based on Red List range maps. Source: Compiled by the report authors using data from the IUCN Red List (2021).

Figure 6.5. Species richness of threatened freshwater decapods in western Africa based on Red List range maps. Source:

Compiled by the report authors using data from the IUCN Red List (2021).

Figure 6.7. Species richness of regionally endemic freshwater decapods in western Africa based on Red List range maps. Source:

Compiled by the report authors using data from the IUCN Red List (2021).

Figure 6.6. Species richness of Data Deficient freshwater decapods in western Africa based on Red List range maps. Source:

Compiled by the report authors using data from the IUCN Red List (2021).