116 



NORTH AMERICAN FAUNA 75 



Table 1. Reproductive characteristics of five adult (weight > 66 g) female 

 Heteromys desmarestianus from Heredia Province, Costa Rica.^ 



Date of 



capture Reproductive characteristics 



29 March 1986 



3 embryos x 12 mm (2L-1R), lactating 



30 March 1986 



pregnant female, mammae enlarged; released 



5 April 1986 



2 embryos x 22 mm (IL-IR) plus 1 resorbing embryo 



5 April 1986 



3 embryos x 23 mm (1L-2R) 



8 April 1986 



uterus enlarged, no embryos or placental scars 



'Eight females weighing between 45 and 66 g showed no sign of reproductive activity. All females 

 weighing more than 66 g were reproductively active. 



A tineid moth, Amydria selvae, phoretic on H. desmarestianus, was described 

 by Davis et al. (1986) from La Selva. Only females of A. selvae were found on 

 spiny pocket mice; no males were collected. All specimens were taken in July 1984. 

 Heteromys desmarestianus was trapped in both lowland and highland localities and 

 at La Selva in late August and September, but no additional moths were found 

 (Davis et al. 1986). We examined 47 H. desmarestianus captured from 280 to 

 1 ,520 m elevation in late March and April 1986 in Parque Nacional Braulio Carrillo 

 but found no tineids. Nor were any tineids found on 120 H. desmarestianus caught 

 near Monteverde, Puntarenas Province at elevations ranging from 1,380 to 1,860 m 

 in May 1986. Ticks found on H. desmarestianus included four adult female Ixodes 

 venezuelensis . This represents the first record of this tick on H. desmarestianus. 



Specimens examined (255)— Finca La Selva, 3 km S of Puerto Viejo [1 male, 

 2 females, KU; 9 males, 5 females, LACM; 101 males, 99 females, UMMZ]; 

 Puerto Viejo, Rio Sarapiqui [1 female, KU]; 1.7 mi S of Puerto Viejo [1 male, 

 LACM]; 3.2 mi S of Puerto Viejo [1 female, LACM]; 11 km S, 4.5 km W of 

 Puerto Viejo, 280, 325, 340, 365, and 369 m [2 males, 8 females, FMNH; 1 male, 

 UNA]; 1 km S, 11.5 km E of San Miguel, 680, 700, 710 m [6 males, 8 females, 

 FMNH; 1 male, 1 female, UNA]; 3.5 km S, 11.5 km E of San Miguel, 1,000 m 

 [3 males, 2 females, FMNH]; 9 km S, 11.5 km E of San Miguel, 1,520 m [1 male, 

 2 females, FMNH]. 



Family Muridae 



Nyctomys sumichrasti 

 Sumichrast's Vesper Rat, Raton 



Sumichrast's vesper rat is found from Mexico to eastern Panama (Fig. 92). 

 Three subspecies of Nyctomys sumichrasti occur in Costa Rica, N. s. costaricensis 

 along the Pacific slopes, N. s. nitellinus in the southeast, and A^. s. venustulus in 

 the northeast. It is found from sea level to 1,500 m. Ecology and morphological 

 variation in vesper rats in Nicaragua were reported by Genoways and Jones (1972). 



