text: transandinomys bolivaris transandinomys bolivaris , also known as the long - whiskered rice rat , is a rodent in the genus transandinomys . 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 . taxonomy in 1901 , joel asaph allen described four new species of rice rat in the genus oryzomys : three from ecuador and the peruvian oryzomys perenensis . the three ecuadorian species – oryzomys bolivaris from porvenir , bolívar province ; oryzomys castaneus from san javier , province ; and oryzomys rivularis from río verde , pichincha province — were each based on a single specimen collected in 1899 or 1900 . he distinguished the three on the basis of coloration , size , and relative tail length . philip hershkovitz listed all three among the many synonyms of " oryzomys laticeps " ( currently more narrowly defined as hylaeamys laticeps ) in a 1960 paper . edward alphonso goldman described oryzomys bombycinus in 1912 from four specimens from panama . he compared it to oryzomys talamancae and placed it with the " oryzomys laticeps group " . three years later , he described oryzomys nitidus alleni from costa rica as a subspecies of oryzomys nitidus , without mentioning bombycinus . he revised oryzomys of north america in 1918 and recognized oryzomys bombycinus as the only member of its own group , with alleni as a subspecies distinguished by the proportions of the skull . he also mentioned that the group occurred in ecuador and indicated that o. bombycinus probably reached colombia . goldman considered the group to be similar to o. talamancae , but suggested that bombycinus and alleni might only be subspecies of o. nitidus . in 1939 , oliver pearson added a third subspecies , o. b. orinus , from eastern panama , and in 1966 the species was first recorded from colombia . ronald pine reviewed oryzomys bombycinus in 1971 , when 59 specimens of it were known , and first recorded the species from nicaragua and ecuador . he kept the three described subspecies — alleni from nicaragua to western panama , bombycinus from central panama , and orinus from eastern panama to ecuador . alfred gardner and james patton suggested in 1976 that allen 's o. rivularis may be the same species as o. bombycinus . they considered o. bolivaris as probably the same as o. nitidus and listed castaneus as a synonym of o. capito ( equivalent to modern hylaeamys megacephalus and closely related species plus transandinomys talamancae ) . in 1984 , and colleagues reported the first record of oryzomys bombycinus from honduras . guy musser and marina williams reviewed o. talamancae in 1985 and included o. castaneus as one of its synonyms , though without having examined the holotype . in the 1993 second edition of mammal species of the world , musser and michael carleton used the name oryzomys bolivaris for the species previously known as o. bombycinus , and in 1998 , musser and colleagues fully documented the allocation of the names bolivaris , castaneus , rivularis , bombycinus , alleni , and orinus to the same species , oryzomys bolivaris . they noted its similarity to o. talamancae , but did not attempt to determine phylogenetic relationships among the species they discussed . in their limited material , they found geographic variation within the species inconsequential and they recognized no subspecies . in 2006 , marcelo weksler published a phylogenetic analysis of oryzomyini ( " rice rats " ) , the tribe to which oryzomys is allocated , using morphological and dna sequence data . his results showed species of oryzomys dispersed across oryzomyini and suggested that most species in the genus should be allocated to new genera . later in the same year , he , together with alexandre percequillo and robert voss , named ten new genera for these species , including transandinomys , which has oryzomys talamancae ( now transandinomys talamancae ) as its type species . they also included oryzomys bolivaris in transandinomys , so that it is now named transandinomys bolivaris , although it had not been included in weksler 's phylogenetic study . the two species are morphologically similar , but they could identify only one synapomorphy ( shared - derived trait ) for them : very long superciliary vibrissae ( whiskers above the eyes ) . transandinomys is one of about 30 genera in oryzomyini , a diverse assemblage of american rodents of over a hundred species , and on higher taxonomic levels in the subfamily sigmodontinae of family cricetidae , along with hundreds of other species of mainly small rodents . various authors have used the common name " long - whiskered rice rat " for this species , but several other names have been proposed . in 1918 , goldman named o. bombycinus bombycinus the " long - haired rice rat " and o. b. alleni the " allen rice rat " . musser and carleton , writing in the 2005 third edition of mammal species of the world , used " long - whiskered oryzomys " , the 2009 iucn red list gave " bolivar rice rat " , and thomas lee and colleagues used " long - whiskered trans - andean rice rat " in 2010 . description transandinomys 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 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 ) . skull and teeth the skull is relatively long and has a long , narrow rostrum ( front region ) , broad interorbital region ( between the eyes ) and narrow braincase with almost vertically oriented walls at the sides and behind . it differs from that of t. talamancae in various proportions . although the subspecies previously recognized in " oryzomys bombycinus " have been separated by small differences in skull features , pine rejected these on the basis of his much larger samples . musser and colleagues agreed , but noted that colombian animals appeared to have larger skulls . the zygomatic plates are broad and the zygomatic arches ( cheekbones ) behind them are nearly parallel to each other . the margins of the interorbital region contain prominent beads , which extend to the braincase as temporal ridges ; these are usually less well - developed in t. talamancae . unlike in t. talamancae and h. alfaroi , the parietal bone is usually limited to the roof of the braincase and does not extend to the sides . the incisive foramina , which perforate the front part of the palate , do not extend between the molars . the palate ends beyond the third molars and is perforated by posterolateral palatal pits there . behind it , the roof of the mesopterygoid fossa is perforated by poorly developed sphenopalatine vacuities . the auditory bullae , which house the inner ear , are large . usually , the mastoid bone lacks openings ( fenestrae ) , which are present in t. talamancae . the pattern of the arteries in the head is primitive , as indicated by the condition of various foramina ( openings ) and grooves in the skull . the mandible ( lower jaw ) looks chunky and has a long condyloid process at its back ; that of t. talamancae is more slender . the capsular process , a projection at the back of the jaw which houses the root of the lower incisor , is poorly developed . the incisors are large and . their enamel is orange , but paler on the lowers . the orientation of the upper incisors is opisthodont , with the cutting edge oriented backwards . the molars are brachydont ( low - crowned ) and have two rows of main cusps separated by deep valleys and complemented by a network of crests and smaller cusps . the first upper molar is broader than in t. talamancae . as in this species , but unlike in many other rice rats , including h. alfaroi , the mesoflexus on the second upper molar , which separates the paracone ( one of the main cusps ) from the mesoloph ( an accessory crest ) , is not divided in two by an enamel bridge . the hypoflexid on the second lower molar , the main valley between the cusps , is very long , extending more than halfway across the tooth ; in this trait , it is similar to t. talamancae but unlike h. alfaroi . each of the upper molars has three roots ( two on the outer and one on the inner side ) and each of the lowers has two ( one at the front and another at the back ) . distribution , ecology , and behavior transandinomys bolivaris is an uncommon species . its known distribution extends from northeastern honduras , on the caribbean seaboard , through eastern nicaragua , costa rica , and panama , into coastal western colombia and northwestern and west - central ecuador . it has been found near sea level and the upper altitudinal records are at nearly 1 , 500 m ( 4 , 900 ft ) in panama and 1 , 800 m ( 5 , 900 ft ) in ecuador . this distribution coincides with that of the humid forest . it generally occurs in areas with mean temperatures above 16 ° c ( 60 . 8 ° f ) and annual rainfall of 4 , 000 to 6 , 000 mm ( 157 to 236 in ) , prefers mid - elevation forests ( 600 to 900 m or 1 , 970 to 2 , 950 ft ) , and often occurs near water . the actual range of this species may be expected to extend further north and west , perhaps into veracruz , southern mexico , and western venezuela , where it has not yet been recorded . omar linares mentioned a possible record from the lake maracaibo region of northwestern venezuela in 1998 . its range is similar to that of various other rainforest animals , including the hawk ( ) , the rice rats sigmodontomys alfari and s. aphrastus , the spiny rats and , and the opossum marmosa . t. talamancae and h. alfaroi are often found in the same localities as t. bolivaris , but also occur in other areas . little is known of its biology . the species mainly lives on the ground , but some young animals have been taken in vegetation , up to 1 . 5 m ( 4 . 9 ft ) above the ground . it is usually captured " under logs , around the roots of large trees , or among rocks along streams . " two females with four embryos each have been caught in panama in june , one with two in nicaragua in september , and one with four in costa rica in december . a very young specimen was trapped in costa rica in march . one pregnant female was herself still in juvenile fur . four species of mites have been found on t. bolivaris in panama ( gigantolaelaps gilmorei , g. , laelaps , and ) , two chiggers ( panamensis and pseudoschoengastia bulbifera ) , and two fleas ( polygenis roberti and polygenis ) . conservation status 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 .