122 NORTH AMERICAN FAUNA 75 



Oryzomys fulvescens occupies a variety of habitats and a wide range of elevations 

 from near sea level to 3,400 m. They are frequently trapped in open grassy and 

 weedy habitats which suggests that they might be more abundant now in disturbed 

 habitats than they were in pristine forests. In Nicaragua, Jones and Engstrom (1986) 

 reported that pregnant females carried an average of four embryos, with a range 

 of three to six. 



Only three specimens of O. fulvescens are known from Heredia Province. A 

 single adult female was obtained by E. H. Taylor along the Rio Puerto Viejo on 

 6 August 1954 "under a log," and a male and female were trapped south of 

 Cariblanco in August 1967. We suspect that the few records from this region reflect 

 a lack of concerted effort in searching for pygmy rice rats in appropriate habitats, 

 and not that the species is rare. 



Specimen examined (1)— Puerto Viejo River [1 female, KU]. 



Additional records (2)— 1.5 mi S of Cariblanco [1 male, 1 female, MVZ]. 



Peromyscus nudipes 

 Cloud Forest Deer Mouse, Ratdn 



The systematic status of the white-footed mice and deer mice (genus Pero- 

 myscus) in Central America is in a state of flux (Fig. 96). Specimens of Peromyscus 

 collected 5 km SE of Turrialba, Cartago Province, were regarded by Hall and 

 Kelson (1959) and later by Hall (1981) as representing Peromyscus mexicanus sax- 

 atilis, whereas all other specimens from Costa Rica were regarded as representing 

 a high-elevation species, P. nudipes, which was restricted to Costa Rica and adja- 

 cent Panama. In a revision of the P. mexicanus group, Huckaby (1980) reduced 

 the name nudipes to a junior synonym of P. mexicanus. Thus, all Peromyscus^within 

 Costa Rica would represent the widespread species P. mexicanus, which, as Huck- 

 aby defined it, ranges from San Luis Potosi and Veracruz, Mexico, to western 

 Panama. He recognized no subspecies within P. mexicanus, although he did state 

 that there was considerable geographic variation. Huckaby 's concept of the species 

 P. mexicanus has not been supported universally by subsequent authors. The mor- 

 phology of the Y chromosome of nudipes differs from P. mexicanus in that nudipes 

 has a small metacentric Y, whereas in P. mexicanus the Y is a small acrocentric 

 (Rogers et al. 1984; Smith et al. 1986). In both studies, P. nudipes was regarded 

 as a distinct species. 



The mean litter size, as judged by counts of embryos and recent placental scars 

 of eight adult females, was 2.5 (Table 3). Mean testes length and width for 17 adult 

 males was 15.1x8.5 mm. 



Ticks collected from cloud forest deer mice include Ixodes venezuelensis 

 (6 nymphs). 



Specimens examined (46)— Barva, Sta. Lucia [2 males, 3 females, UNA]; 2 km 

 N, 0.5 km E of Sacramento, 2,600 m [6 males, 3 females, UNA]; 1 km S, 11.5 km 

 E of San Miguel, 710 m [3 males, 5 females, FMNH; 2 males, 1 female, UNA]; 

 3.5 km S, 11.5 km E of San Miguel, 750 and 1,000 m [7 males, 8 females, FMNH; 

 1 male, UNA]; 5 km E of Vara Blanca, 2,050 m [3 males, 2 females, FMNH]. 



Additional record (1)— 1.5 mi W of Cariblanco [1 female, MVZ]. 



