LA SELVA-BRAULIO CARRILLO MAMMALS 



115 



Family Heteromyidae 



Heteromys desmarestianus 

 Desmarest's Spiny Pocket Mouse, Raton Semiespinosa 



Desmarest's spiny pocket mouse is found from extreme southern Mexico to 

 Colombia (Fig. 91). Five subspecies of Heteromys desmarestianus currently are 

 recognized from Costa Rica; the race at La Selva being H. d. subaffinis. It is found 

 from sea level to high elevation cloud forest and may be extremely abundant local- 

 ly (Fleming 1983b). 



Heteromys desmarestianus is the most abundant forest floor rodent at La Selva 

 and is found in a wide array of forested habitats (Fleming 1974a,b, 1977a,b). 

 However, it is uncommon or absent in the successional plots at La Selva. All females 

 weighing more than 66 g were pregnant in April 1986 (Table 1). Mean testes length 

 and width for eight adult males was 19.8x13.1 mm. Spiny mice were found 

 carrying seeds of the following plants in their cheek pouches: Euterpe macrospadix, 

 Geonoma sp., Iriartea gigantea (Palmae), and Meliosma sp. (Sabiaceae). Bush- 

 masters {Lachesis muta) are abundant at La Selva and often are found coiled near 

 Welfia palms, the preferred food of spiny mice (Fleming and Brown 1975). It is 

 likely that spiny mice constitute one of the principal food items of bushmasters. 



We found one species of sucking louse, Fahrenholzia ferrisi (Hoplopleuridae), 

 to be abundant on H. desmarestianus. In April 1986, we found all life cycle stages 

 including eggs, first, second, and third instars, and adults, primarily on the dorsal 

 surface of hosts. 



Fig. 91. Desmarest's spiny pocket mouse, Heteromys desmarestianus. Photo by B. L. 

 Clauson. 



