Afrithelphusa leonensis
Creators: name: Cumberlidge, Neil
name: Mvogo Ndongo, Pierre A.
name: Clark, Paul F.
name: Salieu, Sankoh
name: von Rintelen, Thomas
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Deckeniidae
Afrithelphusa
Afrithelphusa leonensis

description: Afrithelphusa leonensis (Cumberlidge, 1987)
(Figures 1, 2 (c), 3(c), 4(b,f,j), 5(e,f,k,o), 6(g,h,i,o), 7(b,d,f), 8; Tables 1–3)
Sierra Leone freshwater crab
Globonautes leonensis Cumberlidge, 1987:2210–2215,fig. 1e–h, 2 f–g,tables 1, 2; Cumberlidge 1996a: 693–694, table 1.
Afrithelphusa leonensis Cumberlidge 1999: 225–226, fig. 46D, 47D, 48C, 49D, 50D, 51D, 52C, 53CC, 54–57, 62D, 68E, table IX.
Material examined
Type material. Holotype: Sierra Leone: adult ♂ (CW 26.4 mm), Sugar Loaf Mountain, Western Area Peninsula National Park (8.410678°N, − 13.219825°W), coll. T. S. Jones, 7 October 1955 (NHM 1955.10.7.42–43). Paratypes: 2 adult females (CWs 27 mm, 21 mm), Sugar Loaf Mountain, Western Area Peninsula National Park (8.410678°N, − 13.219825°W), coll. T. S. Jones, 7 October 1955 (NHM 1955.10.7.42–43).
Other material. Sierra Leone: 5 subadult ♂♂ (CW 18.0, CL 14.5, CH 9.7, FW 5.6 mm; CW 17.8, CL 13.5, CH 9.7, FW 6.6 mm; CW 16.1, CL 13.6, CH 8.8, FW 5.1 mm; CW 15.1, CL 12.0, CH 8.2, FW 5.5 mm; CW 14.0, CL 11.3, CH 7.0, FW 3.9 mm); adult ♀, ovig. (CW 20.0, CL 15.0, CH 11.5, FW 6.6 mm); caught on land, 20–80 m from a permanent stream, in forest south-east of Guma Lake, in the Western Area Peninsula National Park (8.36225°N, − 13.192°W), 390 m ASL, approximately 10 km from type locality, coll. P. A. Mvogo Ndongo, 25–31 January 2021 (ZMB Crust. 34,606; ACCRHa-01); adult ♀ (CW = 27.0 mm), Sherbro island, Sierra Leone, coll. Dr C. H. Allen, 18 September 1922 (NHM 1922.9.18.8).
Diagnosis
Carapace outline transversely oval, highly arched (CH /FW = 1.6); pterygostomial region of carapace branchiostegite smooth, lacking setal patches (Figure 4 (b)). Mandibular palp composed of basis followed by two articles; terminal article (MPTA) bilobed, MPAL/ MPTA = 0.6 (Figure 4 (j); Table 3). Cheliped carpus texture roughened with granules, carinae (Figure 5 (k)); ambulatory legs P2–5 long, slender (ΣP2–5/CW = 6.5) (Figures 2 (c), 7(b,d), Table 3). G1TA medium length (G1TA/G1SA = 0.4), slim, straight, broadest proximally (Figure 6 (g,i), Table 3); G1SA with raised rounded shoulder on external margin near G1TA-G1SA junction (Figure 6 (g,i)); DM narrow (Figure 6 (i)). G2TA medium length (G2TA/ G2SA = 0.4), flagellum-like, ending in rounded tip (Figure 6 (h); Table 3). For a detailed description see Cumberlidge (1987, 1996a).
Size
The adult size range is CW 21–27 mm.
Colour
When alive, ambulatory legs orange, carapace purple, sternum and underside cream.
Distribution
The western Upper Guinea rainforest of West Africa in Sierra Leone. Afrithelphusa leonensis was rediscovered in a forest near Guma Lake, Western Peninsula National Park, Freetown, Western Area of Sierra Leone (Figure 1).
Habitat
This species is known from three Sierra Leone localities that are within the Northern Upper Guinea Ecoregion (FEOW 511). The new material was collected from the rainforest on Sugar Loaf Mountain, Western Area Peninsula National Park, which is a protected area.
Type locality
West Africa, Sierra Leone, Sugar Loaf Mountain, in the northern part of the Western Area Peninsula National Park. Afrithelphusa leonensis has also been collected from Sherbro Island, off the coast south of Freetown, Bonthe District, Southern Province of Sierra Leone. A third locality for this species was discovered in 2021 in rainforest near Guma Lake, 10 km from the type locality (Figure 1).
Conservation
Afrithelphusa leonensis is considered a critically endangered species threatened with extinction under the IUCN Red List guidelines (Cumberlidge and Daniels 2020c). The newly collected material from Sierra Leone, and the additional data on its ecology, habitat preferences, and threats, will allow a reassessment of this species, although further population and distribution studies are still needed to evaluate conservation options for the protection of this threatened species and its habitat (Mvogo Ndongo et al. 2022).
Remarks
Cumberlidge (1987) originally assigned A. leonensis to Globonautes in the Gecarcinucidae, Globonautinae, but then Cumberlidge (1996a, 1996b) moved this species into Afrithelphusa in the same family and subfamily. Cumberlidge and Daniels (2022) recently reassigned this genus and its species to the Deckeniidae, Deckeniinae. The original description of A. leonensis was based on one male (holotype) and two females (paratypes) collected from Sugar Loaf Mountain, Sierra Leone in 1955, and on other specimens from Sherbro Island, Sierra Leone (Cumberlidge 1987). The present updated diagnosis is based on the type material and the freshly collected material, and both are from nearby localities on Sugar Loaf Mountain in Sierra Leone. These new specimens are conspecific with the A. leonensis types based on their key diagnostic characters (eg of the carapace, mandibles, G1, G2, and ambulatory legs) that all correspond closely to the types, but the telson of the new material from Sugar Loaf Mountain is bell-shaped with indented sides (Figure 4 (f)), (vs cone-shaped with straight sides in the holotype (Figure 7 (d))), the anterior thoracic sternum is broadened (Figure 4 (f)) (vs narrow in the holotype (Figure 7 (d)), and the cheliped ischium is lined with small granules (vs lined with small pointed teeth in the holotype (Figure 7 (d))).
description: Published as part of Cumberlidge, Neil, Mvogo Ndongo, Pierre A., Clark, Paul F., Salieu, Sankoh & von Rintelen, Thomas, 2023, A revision of the West African freshwater crab genus Afrithelphusa Bott, 1969 (Brachyura: Deckeniidae: Deckeniinae) based on new morphological and genetic data, pp. 924-946 in Journal of Natural History 57 (13 - 16) on pages 939-941, DOI: 10.1080/00222933.2023.2216908, http://zenodo.org/record/8221731