A NEW FRESHWATER CRAB FROM PRINCIPE 
P. principe has a row of distinct pointed teeth along its length, 
whereas this margin in P. anchietae, lacks teeth, and is either 
granular or smooth. Finally, the suborbital and pterygostomial regions 
of P. principe are smooth, whereas these regions are distinctly 
granular in P. anchietae. 
Bott (1953, 1955, 1964) described two subspecies of P. anchietae: 
P. (1.) a. biballensis Rathbun, 1905, and P. (I.) a. machedoi Bott, 
1964, both of which are found in Angola. However, comparison of 
the types of these taxa with P. principe indicates that both differ 
substantially from the new species described here. For example, the 
epibranchial tooth of P. (I.) a. biballensis is large and pointed 
whereas that of P. principe is small and granular, and the carapace of 
P. (1.) a. biballensis is flattened, whereas that P. principe is high (ch/ 
fw P. principe 1.45, P. (1.) a. biballensis 1.25). Similarly, the 
epibranchial tooth of P. (/.) a. machedoi is large and pointed whereas 
that of P. principe is small and granular, and the frontal margin of P. 
principe is narrower than that of P. (/.) a. machedoi (fw/cw P. 
principe 0.26, P. (I.) a. machedoi 0.33). 
Potamonautes principe was also compared here with a specimen 
of P. margaritarius from Sao Tomé (SMF 2668), and the two taxa 
can be distinguished by the following characters. The carapace of 
the latter species is distinctly flattened (ch/fw P. margaritarius 0.95, 
P. principe 1.45), the anterolateral margin of P. margaritarius 
behind the epibranchial tooth is clearly toothed (whereas this margin 
is completely smooth in P. principe), and the ischium of the third 
maxilliped of P. margaritarius is smooth and lacks a vertical suture 
(whereas this suture is deep in P. principe). 
ECOLOGICAL NOTES 

The island of Principe is ovoid in outline, with a total land area of 
about 139 sq km (Fig. 3). The highest point is Pico de Principe 
(945 m), which is a volcanic mountain whose lower slopes are 
vegetated by lowland rain forest that grades into cloud forest at 
higher elevations. The climate of Principe is tropical, hot, and 
humid, and there is a single rainy season from October to May. 
Rainfall levels are high, averaging around 1,000 mm per year in 
the north and 5,000 mm per year in the south, and monthly tem- 
peratures range between 25° and 31° C (Bredero et al., 1977). The 
two specimens were collected from the summit of the Pico do 
Principe at 945 meters above sea level on two separate occasions. 
The terrain at the summit of the Pico do Principe is volcanic and 
mountainous, and the vegetation cover is cloud forest with small 
stunted trees, and a high abundance of epiphytes and bryophytes. 
The thick cloud cover and regular rainfall keep the soil and leaf 
litter very damp. On both occasions when crabs were collected the 
weather was extremely damp and the mountain top engulfed in 
cloud cover. Both specimens were collected on land from under 
damp and decaying leaf litter. There was no river or body of water 
near the location where the specimens were found. The nearest 
stream was observed at lower altitudes (830 m), but there were 
numerous temporary small pools at the summit which form after 
heavy precipitation. It is likely that P. principe can breathe air, 
given its extremely terrestrial lifestyle. When crabs were disturbed 
by removing the leaf litter cover, they ran rapidly across the forest 
floor and took cover under leaf litter or any available crevasse. 
Specimens were collected close to holes near the Pico do Principe, 
but crabs were not actually observed moving in or out of these 
holes, and it ramains possible that the holes may not have been dug 
by the crabs. 
17 
ACKNOWLEDGMENTS. Gilles Joffroy and Tariq Stevart (Université libre 
de Bruxelles) assisted in the collection of specimens. Phil Crabb (NHM 
Photo. Unit) took the photographs reproduced in this paper. 

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