410.

Talamancan Rice Rat

Transandinomys talamancae

French: Oryzomys de Talamanca / German: Talamanca-Reisratte / Spanish: Rata arrocera de Talamanca

Other common names: Transandean Oryzomys

Taxonomy. Oryzomys talamancae J. A. Allen, 1891, Talamanca, Limon, Costa Rica.

Transandinomys talamancae is the type species of the genus. Substantial variation in diploid numbers (2n = 34, 36, 40, 54) and fundamental numbers (FN = 64, 66, 67) suggests a potential species complex, clouded by morphological similarity. Additional taxonomic work needs to be done to calrify this. Monotypic.

Distribution. S Costa Rica through Panama to N & W Colombia, E to N Venezuela, and S to W Ecuador and extreme NW Peru.

Descriptive notes. Head-body 120-151 mm, tail 105-152 mm, ear 18-24 mm, hindfoot 28-32 mm; weight 47-74 g. The Talamancan Rice Rat resembles the Longwhiskered Rice Rat (7. bolivaris) in general size but with tail longer and smaller hindfeet. Dorsum is orange to reddish brown; venter is whitish gray. Legs are long and narrow. Mystacial and superciliary vibrissae are long (more than 40 mm). Toes are thin, with long hairs extending over all claws, except on thumb. Soles offeet are scarcely covered with indistinct scales. Tail is thin and bicolored, often with tip slightly mottled; its length is equalto orslightly shorter than head-body length, naked in appearance but finely covered with small hairs.

Habitat. Evergreen, semideciduous, and deciduous tropical forests, including moist and dry associations and within primary or secondary growth from sea level to an elevation of 1385 m. The Talamancan Rice Rat adapts well to secondary vegetation and plantations, and it is tolerant of habitat disturbance.

Food and Feeding. Talamancan Rice Rats eat fruits, seeds, herbaceous vegetation, and insects.

Breeding. Breeding occurs year-round, with an apparent peak in October-November; juveniles and subadults were most common in wet season when population levels were highest; testes of adult males did not appear to vary significantly in size throughout the year. Average litter size is 3-9 young, and females produce an average of 6-1 litters/year. Several females were known to produce two litters in rapid succession, suggesting females undergo postpartum estrus. Combining rate oflitter production with averagelitter size, each female can produce an average of 23-7 young/year. Females become sexually mature at less than two months old; males 55-65 days old had large numbers of spermatozoa in epididymis. Maximum measured longevity in the field was c.9 months.

Activity patterns. Talamancan Rice Rats are nocturnal. They are terrestrial but are good climbers at low levels.

Movements, Home range and Social organization. Talamancan Rice Rats are most common in forested lowland, in areas of dense undergrowth, and around fallen logs. They seem to be alloresponsive because marked individuals were captured at a significantly faster rate than unmarked individuals. Densities in Panama peaked at 3-2 ind/ ha (rainy season; October). Juvenile mortality is high. Home ranges averaged 1-3 ha; male home ranges were larger than female home ranges. No seasonal differences in movements were found between sexes.

Status and Conservation. Classified as Least Concern on The IUCN Red List.

Bibliography. Allen (1891c¢), Anderson et al. (2008), Carleton (2015b), Emmons (1997), Fleming (1971), Garcia, Delgado-Jaramillo et al. (2012), Linares (1998), Musser & Williams (1985), Musser, Carleton et al. (1998), Pérez-Zapata et al. (1986), Weksler et al. (2006).