Madagapotamon humberti Bott, 1965

Cumberlidge, N., Reed, S. K. & Boyko, C. B., 2004, Distribution patterns of the Malagasy freshwater crabs (Crustacea: Decapoda: Brachyura), Journal of Natural History 38, pp. 1133-1157 : 1148

Madagapotamon humberti Bott, 1965

(figure 2D) Madagapotamon humberti Bott, 1965: 344–346 , figure 7, pl. 4, figures 14–17; Vuillemin, 1970:

245–265; Ng and Takeda, 1994: 162–163, table 1; Cumberlidge and Sternberg, 2002: 65,

67–68, figures 2E, 3G, 4L, 5H, 6G, 7K, L, 8G, 10G, H, 11H, tables 1 –4.

Material examined. All coll. S. M. Goodman. Madagascar: one adult female (cw 41.4 mm), one subadult male (cw 26.9 mm), one juvenile female (cw 18.6 mm), forest near the Andrafiabe cave , Réserve Spéciale d’Ankarana ( FMNH 6706 ) ; one adult female, forest near the Andrafiabe cave , Réserve Spéciale d’Ankarana ( FMNH 6707 ) ; one subadult male (cw 34.5 mm), one subadult female (cw 32.4 mm), forest near the Andrafiabe cave , Réserve Spéciale d’Ankarana ( FMNH 6708 ) .

Type locality. Northern Madagascar, between ‘ Ankara and Analamera’ . The locality ‘ Ankara’ is almost certainly Ankarana (Vuillemin, 1970) .

Distribution. Northern Madagascar, Ankarana, Montagne des Français and Nosy Be. Madagapotamon humberti is found in the Ankarana massif (Antsiranana Province) about 100 km south-west of Antsiranana, to the north of Ambilobe (figures 2D, 5). Figure 2D includes localities for M. humberti from the literature (Cumberlidge and Sternberg, 2002). The Ankarana massif is an undeveloped region of limestone formations (karst) consisting of caves and underground rivers with numerous forested valleys forming the Réserve Spéciale d’Ankarana. Ankarana is aligned obliquely north-east/south-west and forms the western part of a limestone plateau lying to the south of the Parc National de la Montagne d’Ambre. This limestone plateau continues eastward as the Andrafiamena–Analamera escarpment, which ends close to the Baie du Loky. The Ankarana and Andrafiamena escarpments are separated by a low-lying region occupied by the main road between Ambilobe and Antsiranana (Vuillemin, 1970). Madagapotamon humberti is also found on the slopes of the Anosiravo mountains (Antsiranana Province) and Montagne des Français (Vuillemin, 1972) a few kilometres south of Antsiranana. Photographs of the specimens in Vuillemin (1972) are strikingly like Madagapotamon , rather than Malagasya . Cumberlidge and Sternberg (2002) also reported that M. humberti occurs on the nearby island of Nosy Be (Antsiranana Province).

Remarks. Madagapotamon is closest to Malagasya , which shares the heart-shaped carapace outline, distinct teeth on the anterolateral margins and slender elongated walking legs (Cumberlidge and Sternberg, 2002). The two genera can be easily distinguished by differences in the mandible ( Madagapotamon has a simple terminal segment, Malagasya has a bilobed terminal segment) and third maxilliped ( Madagapotamon lacks a flagellum on the exopod, Malagasya has a long flagellum). In life, Madagapotamon has a light brown carapace and extremely long, strikingly purple-coloured walking legs.

Conservation status. Madagapotamon humberti is restricted to a specialized habitat (limestone karst) and it is known from less than 20 specimens, some of which were collected recently and are reported herein. Its conservation status is extremely rare/ highly endangered ( table 1). This species is found in a protected area, the Réserve Spéciale d’Ankarana (Antsiranana Province) .