Long-whiskered rice rat
Transandinomys bolivaris, also known as the long-whiskered rice rat, is a rodent in the family Cricetidae. It is found in humid forest from northeastern Honduras to western Ecuador, up to 1,800 m (5,900 ft) above sea level. Since it was first described in 1901 from Ecuador, six scientific names have been introduced for it, but their common identity was not documented until 1998 and the species has long been known under the name Oryzomys bombycinus, described from Panama in 1912. The name Oryzomys bolivaris was used before it was moved to the new genus Transandinomys with Transandinomys talamancae (formerly Oryzomys talamancae ) in 2006.
It is a medium-sized rice rat distinguished by its very long vibrissae (whiskers)—those above the eyes are up to 50 mm (2 in) long. The fur, which is soft and dense, is usually dark brown above and light gray below; it is darker in juveniles. The feet are long and the tail is about as long as the head and body. The skull is narrow and has a broad interorbital region (between the eyes). The species generally lives on the ground. Although it is rare, its conservation status is thought to be secure.
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starts withTransandinomys bolivaris is a medium-sized rice rat with very long superciliary vibrissae (more than 50 mm (2.0 in) long and extending well beyond the ears when laid back against the head). According to Fiona Reid's Mammals of Southeastern Mexico & Central America, it is distinguishable from any similarly sized rice rats by the length of these whiskers; T. talamancae also has long superciliary vibrissae, but not as long as in T. bolivaris. In both species, the mystacial vibrissae (above the mouth) are also long and extend beyond the ears when laid back, but they are again much longer in T. bolivaris. The vibrissae are mostly dark, but translucent at the tips. Handleyomys alfaroi, a rice rat with which young T. bolivaris are often confused, is much smaller. In T. bolivaris, the cheeks may be light gray, buff, or reddish. The ears are dark brown to black and are sparsely haired.
The fur, which is soft, dense, and thick, is dark brown to gray on the upperparts, grading to black on the midback and yellowish brown on the sides. The underparts are sharply different in color. There, the hairs are dark gray at their bases and white at the tips, so that the fur appears grayish white. The fur is shorter and darker than in T. talamancae and softer and thicker than in H. alfaroi. Young animals have darker, finer, and softer fur. Pine separated the subspecies alleni and orinus on the basis of their darker fur, but Musser and colleagues could not confirm this pattern and found paler and darker specimens within the same geographical regions.
The tail appears naked and is shorter than or about as long as the head and body; it is longer in T. talamancae. Its coloration is variable; it is dark brown above and at the sides and light brown and often white to a greater or smaller extent below, and in some specimens the tail has the same color above and below. The scales on the tail are smaller than in T. talamancae.
The forearms are dark gray. The forefeet are unpigmented and ungual tufts of white hairs surround the equally unpigmented claws. The animal has long, narrow hindfeet, longer than in T. talamancae, with usually smooth soles (lacking squamae, which are present in T. talamancae ). The three middle digits are much longer than the outer two. Six pads are present on the sole. The upper surface and the sides of the hindfeet are white and appear naked, although short, white hairs are present; these hairs are longer in T. talamancae. Ungual tufts of long, white or gray hairs are present around the claws, which are short and lack pigment.
Head and body length is 100 to 140 mm (3.9 to 5.5 in), tail length 90 to 130 mm (3.5 to 5.1 in), hindfoot length 27 to 35 mm (1.1 to 1.4 in), ear length 16 to 21 mm (0.63 to 0.83 in), and body mass 39 to 75 g (1.4 to 2.6 oz). Females have four pairs of mammae, as usual in oryzomyines. Like most rice rats, T. bolivaris has twelve thoracic (chest) and seven lumbar vertebrae. A study in Costa Rica found that there are 58 chromosomes, including many that are large and have two arms, and the fundamental number of arms is 80 (2n = 58, FN = 80), a highly differentiated karyotype. The karyotype of T. talamancae is variable, but has fewer chromosomes (34 to 54) and major arms (60 to 67). H. alfaroi has more chromosomes (60 to 62) and major arms (100 to 104).
The 2009 IUCN Red List lists T. bolivaris as "Least Concern", as it is a widely distributed species with a presumably large population that is found in numerous protected areas. However, habitat destruction by deforestation may pose a threat.
