Potamonautes lirrangensis ( Rathbun, 1904 )

Cumberlidge, Neil & Meyer, Kirstin S., 2011, The freshwater crabs of Lake Kivu (Crustacea: Decapoda: Brachyura: Potamonautidae), Journal of Natural History 45 (29 - 30), pp. 1835-1857 : 1845-1847

Potamonautes lirrangensis ( Rathbun, 1904)

( Figures 6–8 , Table 2)

Potamon (Potamonautes) lirrangensis Rathbun 1904 , pl. 14, fig. 8; Rathbun 1905: 169; 1921: 413–415, pl. 25,26, fig. 3, 8; Balss 1914: 404; 1929: 374–348; Chace 1942: 188– 189, fig. 1.

Potamon (Potamonautes) orbitospinus Cunnington 1907: 250–251 , pl. 16, fig. 1.

Potamonautes orbitospinus: Balss 1929: 439, 1936 : fig. 18.

Potamonautes lirrangensis: Balss 1936: 188–189 , fig. 24.

Potamon orbitospinus: Chace 1942: 218 .

Potamonautes (Lirrangopotamonautes) lirrangensis: Bott 1955: 268–270 , pl. 26, fig. 2a–d, 38, 39, 83.

Potamonautes lirrangensis: Reed and Cumberlidge 2006: 23–25 , pl. 5a–d, fig. 41–51, 153–154, 177; Ng et al. 2008: 171.

Material examined

Democratic Republic of Congo. Subadult male, Idjwi Island, Lake Kivu, February 1939, coll. A. Loveridge ( MCZ 11224) . Rwanda. Juvenile male (CW 30.0, CL 23.7, CH 11.2, 9.8) Lake Kivu at Gisenye , March 1936, coll. J. C. Bequaert ( MCZ 9177 ) . Malawi. Adult male (CW 46.5, CL 33.5, CH 12.8, FW 10.2) 7.2 km east-northeast of Monkey Bay , Lake Malawi, 23 May 1968, coll. D. H. Eades ( NMU TRW 1972.05 ) .

Type locality

Lirranga, at the junction of the Congo and Ubangi Rivers, Democratic Republic of Congo.

Diagnosis

Carapace medium height ( CH / FW 1.25); postfrontal crest distinct, complete; grooves on posterior part of carapace deep; exorbital tooth large, forward pointing spine; epibranchial tooth small spine; anterolateral margin behind epibranchial tooth curving strongly outward, then curving inward over posterolateral margin, lined by either granules or small teeth ( Figure 6A ); vertical sulcus on ischium of third maxilliped faint to absent; suborbital, subhepatic regions of carapace sidewall with granules; suborbital margin and horizontal sulcus of carapace sidewall both granulated ( Figure 6B ); first carpal tooth on carpus of cheliped large, sharp spine; second carpal tooth small spine, smaller than first tooth; ventral margins of merus of pereiopod 1 both heavily granulated; distal meral tooth sharp spine ( Figure 6A,C ).

Distribution

Lake Kivu, Democratic Republic of Congo and Rwanda, Lake Tanganyika in Tanzania, and Lake Malawi in Malawi ( Figure 8 ).

Conservation status

Potamonautes lirrangensis was assessed as Least Concern (LC) using the IUCN Red List criteria ( IUCN 2003; Cumberlidge et al. 2009, appendix) because it has a wide distribution, has been caught recently from a number of different localities, is well represented in museum collections, and has no known threats (Cumberlidge 2008c).

Remarks

A number of previous authors ( Cunnington 1907; Balss 1929, 1936) have reported on the presence of P. lirrangensis in Lake Kivu (as Potamon orbitospinus ), and Chace (1942) illustrated the carapace and GO1 of the specimen of P. lirrangensis from the lake (MCZ 11224). However, Bott (1955) was the first to consider Potamonautes lirrangensis to be the valid name for the species also described as Potamon orbitospinus Cunnington, 1907 , with P. lirrangensis being the senior synonym. Reed and Cumberlidge (2006) upheld this opinion and provided a redescription, photographs and illustrations of taxonomically important characters for P. lirrangensis , as well as a detailed distribution map for the species, but they did not include any localities from Lake Kivu. Another taxon, Potamonautes (Lirrangopotamonautes) lirrangensis adeleae Bott, 1968 , from the Democratic Republic of Congo near the Angolan border, was originally described as a subspecies of Potamonautes (Lirrangopotamonautes) lirrangensis , but was later recognized as the separate species P. adeleae Bott, 1968 , by Cumberlidge and Tavares (2006) and Ng et al. (2008). The type locality of P. lirrangensis is Lirranga on the Congo River in the Democratic Republic of Congo, and its range includes the Upper Congo River in Central Africa and a number of localities along the Rift Valley in Lakes Kivu, Tanganyika and Malawi ( Reed and Cumberlidge 2006).

Figures

Figure 6. Potamonautes lirrangensis (Rathbun, 1904). (A) Dorsal view; (B) frontal view; (C) sternal view. Adult male (NMU TRW 1972.05), CW 46.5 mm.

Figure 7. Potamonautes lirrangensis (Rathbun, 1904). (A) GO1, ventral view; (B) GO1, dorsal view; (C) GO2, ventral view. Adult male (NMU TRW 1972.05), length of the terminal article measured along the mid-line of the dorsal face from tip to dorsal membrane 3.7 mm.

Figure 8. Distribution of Potamonautes lirrangensis. Star, type locality; black circles, other localities. Scale bar 508 km.