20 April 1994 PROC. BIOL. SOC. WASH. 107(1), 1994, pp. 122-131 LOUISEA, A NEW GENUS OF FRESHWATER CRAB (BRACHYURA: POTAMOIDEA: POTAMONAUTIDAE) FOR GLOBONA UTES MACROPUS EDEAENSIS BOTT, 1969 FROM CAMEROON Neil Cumberlidge Abstract.—Globonautes macropus edeaensis Bott, 1969 and G. balssi Bott, 1959 from Cameroon are removed from the Gecarcinucidae Rathbun, 1904 and reassigned to the Potamonautidae Bott, 1970. Globonautes m. edeaensis is recognized as a valid species, and is established as the type species of Louisea, a monotypic new genus. Louisea is defined by a combination of characters of the mandible, third maxilliped, cheliped, and gonopods 1 and 2. Louisea edeaensis is compared to, and distinguished from, other freshwater crabs oc­ curring in West Africa. Globonautes balssi is close to Louisea but is regarded here as incertae sedis. A key to the West African genera of the Potamonautidae is provided. The African family Potamonautidae Bott, (1987) examined the mandible of G. balssi 1970 currently includes four genera, Pota- and concluded that this taxon also belongs monautes MacLeay, 1838, Sudanonautes in the Potamonautidae. Bott, 1955, Liberonautes Bott, 1955, and The exact classification of G. m. edeaensis Potamonemus Cumberlidge & Clark, 1992. and G. balssi within the Potamonautidae is Potamonautes is widely distributed more difficult. The two species most closely throughout sub-Saharan Africa (Bott 1955). resemble members of Potamonemus, which Sudanonautes is found from Cote d'lvoire are also from the same part of Cameroon to Central Africa (Bott 1955; Monod 1977, (Cumberlidge & Clark 1992, Cumberlidge 1980; Cumberlidge 1989, 1993a), and Libe­ 1993b). Potamonemus is characterized by ronautes is found in West Africa west of a potamonautid-type mandibular palp (2- Ghana (Cumberlidge & Sachs 1989a, segmented, and ending in a single lobe) to­ 1989b). The fourth genus, Potamonemus, is gether with a third maxilliped which com­ known only from southwest Cameroon pletely lacks a flagellum on the exopod. Two (Cumberlidge & Clark 1992, Cumberlidge male specimens of G. m. edeaensis from 1993b). Cameroon, recently discovered in the Mu­ seum fur Naturkunde der Humboldt-Uni- The present work reappraises the taxon­ versitat, Berlin, Germany (ZMB), allow a omy of two poorly known species from complete re-assessment of this taxon. G. m. Cameroon, G. macropus edeaensis Bott, edeaensis has a potamonautid-type man­ 1969, and Globonautes balssi Bott, 1959. dibular palp, together with a third maxilli­ Both species are presently included in the ped which completely lacks a flagellum on Gecarcinucidae Rathbun, 1904 (Bott 1959, the exopod. However, differences in the form 1969, 1970) but there is some doubt as to ofgonopod 2 of G. m. edeaensis argue against the validity of these assignments. For ex­ its inclusion in Potamonemus, or in any of ample, the form of the mandible of G. m. the other three potamonautid freshwater edeaensis indicates that this species belongs crab genera known from Africa. The new in the Potamonautidae, while Cumberlidge VOLUME 107, NUMBER I 123 genus Louisea is therefore proposed to ac­ Four dimensions of the carapace, cara­ commodate G. in. edeaensis, which is des­ pace length, carapace width, carapace height, ignated the type species, and a key to the and front width—were recorded from each West African genera of the Potamonautidae specimen using digital calipers (Table 1). is provided. The relative proportions of the latter three Unfortunately, the position of G. balssi measurements (adjusted for body size, CL) cannot be properly assessed because the male of both species were calculated (Table 1). type specimen is in poor condition; there­ The left mandible and the left gonopod 1 fore this taxon is regarded here as incertae and gonopod 2 were illustrated following sedis. removal from the specimens in order to de­ The following abbreviations are used: CW scribe these structures from different angles = carapace width at widest point; CL = car­ and under magnification. Characters of the apace length, measured along median line; gonopods, carapace, and third maxillipeds CH = carapace height, maximum depth of of these specimens correspond closely with cephalothorax; FW = front width, width of those of the holotype. The carapace, man­ front measured along anterior margin; M = dible and other characters of the largest of male, F = female, ad = adult, juv = juvenile, these specimens were illustrated. The length ovig = ovigerous; SMF = Natur-Museum of the propodus of the right and left che- und Forschungs-Institut Senckenberg, lipeds of all specimens was measured along Frankfurt am Main, Germany; USNM = the ventral margin (Table 2). National Museum of Natural History, Smithsonian Institution, Washington, D.C.; Louisea, new genus Z1M = Zoological Institute and Museum, Hamburg, Germany; ZSBS = Zoologische Globonautes Bott, 1959:995, pi. 1, figs. 1- Sammlung des Bayerischen Staates, Miin- 6; 1969:359; 1970:23. chen, Germany. Type species. —Globonautes macropus edeaensis Bott, 1969:360; 1970:24, pi. 1, figs. 3-5, pi. 26, fig. 8. Methods Diagnosis. —Mandibular palp 2-segment- The holotype of L. edeaensis was loaned ed, terminal segment single (Fig. 3d, e). from the ZSBS; two other specimens dis­ Third maxilliped lacking flagellum on cx- covered in the ZMB were subsequently opod (Fig. lc). Terminal segment of gono­ loaned. The male holotype of L. edeaenis is pod 1 directed outward, broad at base, nar­ in poor condition, and the entire left man­ rowing sharply, final 2h almost S-shaped, dible and the palp of the right mandible are tube-like, end blunt, rounded; completely missing. Fortunately the other specimens of lacking longitudinal groove; subterminal L. edeaensis are in good condition, and were segment of gonopod 1 very wide at base collected in Cameroon less than 90 km from (Fig. lg, h). Terminal segment of gonopod the type locality. The male holotype of G. 2 flagellum-like, almost as long as subter­ macropus (Rathbun, 1898) was examined minal segment (Fig. li). Dactylus of right in the USNM. cheliped of adult male slim, propodus with large 3-peakcd proximal tooth (Fig. le). The male holotype and the second female Propodus very long, as long as carapace paratype of G. balssi were examined in the width. Anterior dorsal margin of merus of SMF where they were on temporary loan. chelipeds with 1 large jagged tooth close to The male holotype of G. balssi is a juvenile, distal end, rows of small pointed teeth along and both second gonopods are missing. The rest of margin (Fig. la). Carapace distinctly female paratype of G. balssi was examined convex, half carapace length (mean CH/CL in the ZIM. 124 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON = 0.46), carapace, anterolateral margin, curving outward (away from medial lower margin of orbit, postfrontal crest, line); no intermediate tooth on the smooth (Fig. la, b). Exo-orbital, epibran- anterolateral margin between the chial teeth small, low, distinct intermediate exo-orbital tooth and the epibran­ tooth present, vertical flank suture meeting chial tooth Potamonautes anterolateral margin at epibranchial tooth (Fig. lb). Small species, mature at CW = Louisea edeaensis (Bott, 1969) 22.0 mm. Figs. 1-3, Tables 1, 2 Distribution. -Edea (3°48'N, 10°12'E) and Globonaules macropus edeaensis Bott, 1969: Yabassi (4°32'N, 9°58'E) are 90 km apart, 360; Bott, 1970:24, pi. 1, figs. 3-5, pi. 26, in the rain forest zone of the Littoral Prov­ fig. 8; Cumberlidge, 1987:table 1. ince of southwest Cameroon. Edea lies on the Sanaga River, while Yabassi lies on the Material examined. — Holotype of G. m. Wouri River. edeaensis, adult male, CW 22.52 mm, from Remarks. — This new genus of the Pota- Edea, Cameroon, Jan 1910, ZSBS 1118/1. monautidae is established to accommodate Two males, CWs 18.1, 13.7 mm, from Ya­ Louisea edeaensis previously considered as bassi, Cameroon, coll. Riggenbach, ZMB a subspecies of Globonaules macropus in the 21575. Holotype of G. balssi, juvenile male, family Gecarcinucidae. CW 12.5 mm, ZIM K-3506; 2 female para- types, CW 22.0 mm, 13.5 mm, largest fe­ male ovigerous, ZIM K-3506. All G. balssi Key to the Genera of the West African from Eosung, Bakossi highlands, Johann- Potamonautidae Albrecht-Hohe, 1060 m, Cameroon, coll. 1. Terminal segment gonopod 2 very Carl Rathke, 10 Sep 1909. short, stump-like, V,0 length of sub- Type locality. —Edea, Cameroon. terminal segment 2 Description of holotype. —Carapace (Fig. - Terminal segment gonopod 2 very la, b): Cephalothorax ovoid, widest in an­ long, flagellum-like, equal in length terior third (CW/CL = 1.27), relatively high, to subterminal segment 3 with maximum depth in anterior region 2. Third maxilliped with long flagel- (CH/CL = 0.51). Anterior margin of front lum on exopod Sudanonautes straight, curving under, front relatively nar­ - Third maxilliped lacking flagellum row, about 'A carapace width (FW/CW = on exopod Polamonemus 0.35). Surface of carapace smooth with no 3. Third maxilliped with long flagel­ deep sutures. Postfrontal crest smooth, lum on exopod; terminal segment postorbital portions present, mid-groove gonopod 1 curved, tapering to broad, shallow, epigastric crests poorly de­ pointed tip 4 fined, ending before meeting anterolateral margins. Exo-orbital tooth small, low, epi­ - Third maxilliped lacking flagellum branchial tooth present but almost unde­ on exopod; terminal segment gon­ tectable. Intermediate tooth on anterolat­ opod 1 weakly S-shaped, tube-like, eral margin between exo-orbital and with rounded end Louisea epibranchial teeth. Anterolateral margin of 4. Terminal segment of gonopod 1 carapace smooth. Posterolateral margin curving inward (toward medial line); curving inward, continuous with anterolat­ intermediate tooth on the antero­ eral margin. Posterior margin about 2h as lateral margin between the exo-or­ wide as carapace width. bital tooth and the epibranchial tooth Liberonautes Each flank with 2 sutures, 1 longitudinal, - Terminal segment of gonopod 1 1 vertical, dividing flank into 3 parts (Fig.