Afrithelphusa leonensis ( Cumberlidge, 1987 )

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, Journal of Natural History 57 (13 - 16), pp. 924-946 : 939-941

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))).

Figures

Figure 1. Distribution map of West Africa showing the known localities of all Afrithelphusa Bott, 1969 species in Guinea and Sierra Leone. Afrithelphusa afzelii (Colosi, 1924) (black triangle, not shown to scale); A. leonensis (Cumberlidge, 1987) (black circles, not shown to scale); A. monodosa (Bott, 1959) (black squares, not shown to scale); A. gerhildae Bott, 1969 (black diamond, not shown to scale). For exact localities see text. Scale bar = 111 km.

Figure 2. Afrithelphusa afzelii (Colosi 1924), adult ♂, CW 25.0 mm, ZMB Crust. 34,607, from Moyamba District, Sierra Leone: a, whole animal, dorsal view. Afrithelphusa gerhildae Bott, 1969, adult ♂ CW 22.5 mm, SMF 2619a, Le Voile de la Mariée, Kindia, Guinea: b, whole animal, dorsal view. Afrithelphusa leonensis (Cumberlidge, 1987), adult ♂, CW 26.4 mm, ZMB Crust. 34,606, from Guma Lake, Sugar Loaf Mountain, Sierra Leone: c, whole animal, dorsal view. Afrithelphusa monodosa (Bott, 1969), adult ♂, CW 24.3 mm, NMU 24.IV.2005, Sarabaya, Guinea: d, whole animal, dorsal view. Photographs a, c by PAMN; b by Michael Türkay; d by N. Cumberlidge and M. Lorenz. Scale bar: a = 17.2 mm; b = 15.5 mm; c = 18.9 mm; d = 15.7 mm. CW = carapace width, ZMB = Museum für Naturkunde, Berlin, Germany, SMF = Senckenberg Museum, Frankfurt, Germany, NMU = Northern Michigan University,USA,PAMN = Pierre Armand Mvogo Ndongo.

Figure 4. Afrithelphusa afzelii (Colosi 1924), adult ♂ CW 25.0 mm, ZMB Crust. 34,607, from Moyamba District, Sierra Leone: a, carapace, frontal view; d, thoracic sternum, h, mandible frontal view. Afrithelphusa gerhildae Bott, 1969, adult ♂ CW 22.5 mm, SMF 2619a, Le Voile de la Mariée, Kindia, Guinea: e, thoracic sternum, i, mandible frontal view (Cumberlidge 1999, fig. 48A). Afrithelphusa leonensis (Cumberlidge, 1987), adult ♂, CW 26.4 mm, ZMB Crust. 34,606, from Guma Lake, Sugar Loaf Mountain, Sierra Leone: b, carapace, frontal view; f, thoracic sternum, j, mandible frontal view. Afrithelphusa monodosa (Bott, 1969), adult ♂, CW 24.3 mm, NMU 24.IV.2005, Sarabaya, Guinea: c, carapace,frontal view; g, thoracic sternum, k, mandible, frontal view. Photographs a, c by P. A. Mvogo Ndongo; d by Neil Cumberlidge and Margaret Lorenz; e by Michael Türkay. Scale bar: a = 8.9 mm; b = 9.6 mm; c = 11.6 mm; d–g = 8.0 mm; h–k = 3.1 mm. CW = carapace width, ZMB = Museum für Naturkunde, Berlin, Germany, NMU = Northern Michigan University, USA.

Figure 5. Afrithelphusa afzelii (Colosi 1924), adult ♂ CW 25.0 mm, ZMB 34607, from Moyamba District, Sierra Leone: a, right cheliped, frontal view;b, left cheliped, frontal view;i, right cheliped carpus superior view; m, right cheliped merus superior view. Afrithelphusa gerhildae Bott, 1969, adult ♂ CW 22.5 mm, SMF 2619a, Le Voile de la Mariée, Kindia, Guinea: c, right cheliped, frontal view (Cumberlidge 1999, fig. 50A); d, left cheliped, frontal view (Cumberlidge 1999, fig. 50A); j, right cheliped carpus superior view; n, right cheliped merus superior view. Afrithelphusa leonensis (Cumberlidge, 1987), adult ♂, CW 26.4 mm, ZMB Crust. 34,606, from Guma Lake, Sugar Loaf Mountain, Sierra Leone: e, right cheliped, frontal view; f, left cheliped, frontal view; k, right cheliped carpus superior view; o, right cheliped merus superior view. Afrithelphusa monodosa (Bott, 1969), adult ♂, CW 24.3 mm, NMU 24.IV.2005, Sarabaya, Guinea: g, right cheliped, frontal view; h, left cheliped, frontal view; l, right cheliped carpus superior view; p, right cheliped merus superior view. Photographs a, b, e, f, i, k, m, o by P. A. Mvogo Ndongo; g, h, l, p by Neil Cumberlidge and Margaret Lorenz; j, n by Michael Türkay. Scale bar: a–h = 11.2 mm; i–p = 5.6 mm. CW = carapace width, ZMB = Museum für Naturkunde, Berlin, Germany, SMF = Senckenberg Museum, Frankfurt, Germany, NMU = Northern Michigan University, USA.

Figure 6. Afrithelphusa afzelii (Colosi 1924), adult ♂ CW 29.5 mm, SMNH 168, Sierra Leone: a, G1 ventral view; b, G2 ventral view; c, G1 dorsal view; m, third maxilliped, frontal view. Afrithelphusa gerhildae Bott, 1969, adult ♂ CW 22.5 mm, SMF 2619a, Le Voile de la Mariée, Kindia, Guinea: d, G1 ventral view; e, G2 ventral view (Cumberlidge 1999, fig. 53AA); f, G1 dorsal view (Cumberlidge 1999, fig. 52B); n, third maxilliped, frontal view (Cumberlidge 1999, fig. 49A). Afrithelphusa leonensis (Cumberlidge, 1987), adult ♂, CW 26.4 mm, ZMB Crust. 34,606, from Guma Lake, Sugar Loaf Mountain, Sierra Leone: g, G1 ventral view; h, G2 ventral view; i, G1 dorsal view; o, third maxilliped, frontal view.Afrithelphusa monodosa (Bott, 1969), adult ♂, CW 24.3 mm, NMU 24.IV.2005, Sarabaya, Guinea: j, G1 ventral view; k, G2 ventral view; l, G1 dorsal view; p, third maxilliped,frontal view. Photographs a–c, g–i, m, o by P. A. Mvogo Ndongo; j–l, p by Neil Cumberlidge and Margaret Lorenz;d by Michael Türkay.Scale bar:a, c, d, f, g, i, j, l = 10.0 mm; b, e, h, k = 5.8 mm; m–p = 2.4 mm. CW = carapace width, SMNH = Swedish Museum of Natural History, Stockholm,Sweden,G1 = gonopod 1, G2 = gonopod 2, ZMB = Museum für Naturkunde,Berlin,Germany, SMF = Senckenberg Museum, Frankfurt, Germany, NMU = Northern Michigan University, USA.

Figure 7. Afrithelphusa afzelii (Colosi 1924), lectotype, adult ♂ CW 29.5 mm, SMNH 168, Sierra Leone: a, whole animal, dorsal view; c, whole animal, sternal view; e, carapace, frontal-dorsal view. Afrithelphusa leonensis (Cumberlidge, 1987), holotype, adult ♂, CW 26.4 mm, NHM 1955.10.7.42–43, Sugar Loaf Mountain, Sierra Leone: b, whole animal, dorsal view; d, whole animal, sternal view; f, carapace, frontal view. Photographs a, c, e by Neil Cumberlidge, b, d, f by Phillip Crabb (NHM). Scale bar: a, c = 19.7; b, d = 20.3 mm; e = 12.0 mm; f = 11.0 mm. CW = carapace width, SMNH = Swedish Museum of Natural History, Stockholm, Sweden, NHM = The Natural History Museum, London, UK.