Animal Diversity Web

Di­ver­sity

Ty­lomy­i­nae, ves­per rats and climb­ing rats, is an ar­bo­real New World cricetid sub­fam­ily with ten species in four gen­era: Nyc­to­mys, Otonyc­to­mys, Ototy­lomys, and Ty­lomys). The four gen­era are di­vided be­tween two tribes. (Musser and Car­leton, 2005; Nowak, 1999)

Ge­o­graphic Range

Ty­lomyines are dis­trib­uted through­out Cen­tral Amer­ica, from south­ern Mex­ico to Panama. (Nowak, 1999)

• Biogeographic Regions
• neotropical
  • native

Habi­tat

Ty­lomyines live in trop­i­cal ever­green and semi­de­cid­u­ous forests, es­pe­cially those in rocky areas, at el­e­va­tions from sea level to 2,000 me­ters. (Hunt, et al., 2004; Lawlor, 1982; Nowak, 1999)

• Habitat Regions
• tropical
• terrestrial

• Terrestrial Biomes
• forest
• rainforest

Phys­i­cal De­scrip­tion

Ty­lomyines are medium to large-sized muroid ro­dents, rang­ing from 95 to 255 mm in length, with tails mea­sur­ing 85 to 250 mm. Their tails are usu­ally a bit longer than their bod­ies. They weigh 29 to 280 grams and, in some species, males are slightly heav­ier than fe­males. Other species ex­hibit no de­tectable sex­ual di­mor­phism. The fur is ei­ther short or long, and is cin­na­mon, buff, tawny, gray, rus­set, or brown above and white below. The tail is ei­ther cov­ered with long hairs and tufted at the tip, or it is nearly naked. The ears are nearly naked, and can be ei­ther short or long. There are long black whiskers, and some species have a dark ring around each eye. The eyes are quite large and the hind feet are mod­i­fied for climb­ing. Ty­lomyines have two pairs of mam­mae in the in­guinal re­gion.

Ty­lomyines have brachy­dont, cus­p­i­date mo­lars, with the major cusps lying op­po­site one an­other. The cheek teeth bear well-de­vel­oped mesolophs and mesolophids. The sec­ond upper molar has four roots, and the third lower molar is rel­a­tively large and has a crown pat­tern like that of the sec­ond lower molar.

Ty­lomyines have a cuneate in­teror­bital re­gion, with promi­nant supra­or­bital shelves that con­tinue pos­te­ri­orly as pro­nounced tem­po­ral ridges. The in­ter­pari­etal bone is large and con­tacts the squamosal, to which the tegmen tym­pani are united. The zy­go­matic plates are nar­row and there is usu­ally no dor­sal notch. There is an al­isphe­noid strut, but no sub­squamosal fen­es­tra, and the post­g­le­noid fora­men is quite small. The mesoptery­goid fossa is usu­ally com­pletely os­si­fied, and the para­ptery­goid fossa is shal­low and slen­der. If there are sphenopala­tine vacuities, they are pre­sent as tiny slits.

The first rib of ty­lomyines at­taches to only the first tho­racic ver­te­bra. There is an en­tepi­condy­lar fora­men in the humerus. The cal­ca­neum has a wide, prox­i­mally-po­si­tioned trochlear process.

The ty­lomyine stom­ach is sin­gle-cham­bered, and there is no gall blad­der. The cae­cum is long and com­plex. The glans penis is wide and short (though it is longer than the bac­u­lum), and it has large, well-spaced spines. (Nowak, 1999)

• Other Physical Features
• endothermic
• homoiothermic
• bilateral symmetry

• Sexual Dimorphism
• sexes alike
• male larger

Re­pro­duc­tion

The mat­ing sys­tem of ty­lomyines has not been stud­ied in the wild. Cap­tive Nyc­to­mys sumichrasti form monog­a­mous pairs and share some of the re­spon­si­bil­i­ties of rear­ing young. In­di­vid­u­als of this species emit reg­u­lar, high-pitched chirps to lo­cate mates, and males have been seen court­ing fe­males by chirp­ing at them for a few min­utes be­fore cop­u­la­tion. (Hunt, et al., 2004)

• Mating System
• monogamous

Ty­lomyines re­pro­duce year round. Fe­males are polyestrus, pro­duc­ing sev­eral lit­ters per year, and ex­pe­ri­ence a post­par­tum es­trus. In some species, im­plan­ta­tion may be de­layed if a fe­male be­comes preg­nant while nurs­ing a lit­ter. Ges­ta­tion pe­ri­ods, if im­plan­ta­tion is not de­layed, last 30 to 69 days. Lit­ter sizes av­er­age two to three, with a range of one to four. Young are rel­a­tively pre­co­cial. They are born par­tially furred and with par­tially erupted in­cisors. Their ears open in one or two days and their eyes open at 6 to 18 days. The young cling to their moth­ers' nip­ples until they are three or four weeks old and leave the nest shortly af­ter­wards. Ty­lomyines reach sex­ual ma­tu­rity at one to three months of age, with fe­males ma­tur­ing more rapidly than males. (Hunt, et al., 2004; Lawlor, 1982; Nowak, 1999)

• Key Reproductive Features
• iteroparous
• year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• fertilization
  • internal
• viviparous
• delayed implantation
• post-partum estrous

Fe­male ty­lomyines con­struct nests where they rear their rel­a­tively pre­co­cial off­spring. Young cling to their moth­ers' nip­ples for the first few weeks of life but may be left be­hind in their nests when their moth­ers go out to for­age. If their nests are dis­turbed, moth­ers drag their off­spring with them to safer lo­ca­tions. Fe­males also rush at at­tack­ers and try to bite. Nyc­to­mys sumichrasti males help build nests and re­main near their mates and off­spring for about a week after par­tu­ri­tion. (Hunt, et al., 2004; Lawlor, 1982)

• Parental Investment
• precocial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • male
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • male
    • female
• pre-independence
  • provisioning
    • female
  • protecting
    • female

Lifes­pan/Longevity

Cap­tive ty­lomyines have been recorded liv­ing up to five years and five months. Lifes­pan in the wild is prob­a­bly much shorter. (Nowak, 1999)

Be­hav­ior

Ty­lomyines are al­most ex­clu­sively ar­bo­real, and their hind feet are mod­i­fied for climb­ing. They build nests out of plant fibers and twigs on tree branches or on the ground among rocks. They are noc­tur­nal. These ro­dents are soli­tary or live in small fam­ily groups, and strangers placed to­gether in an en­clo­sure will fight vi­ciously. (Hunt, et al., 2004; Nowak, 1999)

• Key Behaviors
• arboreal
• scansorial
• nocturnal
• motile
• solitary
• territorial
• social

Com­mu­ni­ca­tion and Per­cep­tion

Ty­lomyines have large eyes and prob­a­bly have good vi­sion. They can be seen twitch­ing their ears and vib­ris­sae back and forth when in­ves­ti­gat­ing new ob­jects. They make a va­ri­ety of trills, squeaks, chirps, and grunts to com­mu­ni­cate with one an­other dur­ing courtship, cop­u­la­tion, ag­gres­sive en­coun­ters, and while rais­ing young. Young ty­lomyines are often very vocal, and they chirp when their nest is dis­turbed or when play­ing with lit­ter­mates. (Nowak, 1999)

• Communication Channels
• acoustic

• Perception Channels
• visual
• tactile
• acoustic
• chemical

Food Habits

These ro­dents are pri­mar­ily her­biv­o­rous; they con­sume seeds, fruits, and leaves. Oc­ca­sion­ally they eat moths. (Hunt, et al., 2004; Nowak, 1999)

• Primary Diet
• carnivore
  • insectivore
• herbivore
  • folivore
  • frugivore
  • granivore
• omnivore

Pre­da­tion

Ty­lomyines are preyed upon by owls and snakes. They bite vi­ciously, es­pe­cially if dis­turbed with young. (Hunt, et al., 2004; Lawlor, 1982)

• Known Predators

  • owls Strigiformes
  • snakes Serpentes

Ecosys­tem Roles

Ty­lomyines are, for the most part, pri­mary con­sumers, and they are food for sec­ondary con­sumers such as snakes and owls. In ad­di­tion, ty­lomyines are par­a­sitized by lae­lapid and trom­bi­culid mites, ar­gasid ticks, cer­ato­phyl­lid fleas, and fe­male sand­flies. Ty­lomyines are sus­cep­ti­ble to in­fes­ta­tions of Try­panosoma cruzi.

Sym­patric ty­lomyine species are po­ten­tial com­peti­tors with each other, but they may avoid com­pe­ti­tion by for­ag­ing at dif­fer­ent lev­els in the for­est. (Hunt, et al., 2004; Lawlor, 1982)

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

There are no known pos­i­tive ef­fects of ty­lomyines on hu­mans.

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

Ty­lomyines are re­sevoirs for cu­ta­neous leish­ma­ni­a­sis (Leish­ma­nia mex­i­cana). Also, they some­times enter build­ings and make their nests in un­wel­come places. (Hunt, et al., 2004; Lawlor, 1982)

• Negative Impacts
• injures humans
  • carries human disease
• household pest

Con­ser­va­tion Sta­tus

There are cur­rently four ty­lomyine species on the IUCN's Red List of Threat­ened Species. Two of those species are crit­i­cally en­dan­gered (Chi­a­pan climb­ing rats, Ty­lomys bullaris, and Tum­bala climb­ing rats, Ty­lomys tum­balen­sis), one is vul­ner­a­ble (Pana­man­ian climb­ing rats, Ty­lomys pana­men­sis), and one is lower risk (ful­vous-bel­lied climb­ing rats, Ty­lomys ful­viven­ter). (IUCN, 2004)

• IUCN Red List [Link]

  Not Evaluated

Con­trib­u­tors

Tanya Dewey (ed­i­tor), An­i­mal Di­ver­sity Web.

Al­li­son Poor (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor.

Ref­er­ences

Car­leton, M. 1980. Phy­lo­ge­netic re­la­tion­ships in neotomine-per­omyscine ro­dents (Muroidea) and a reap­praisal of the di­chotomy within New World Criceti­nae. Mis­cel­la­neous Pub­li­ca­tions of the Mu­seum of Zo­ol­ogy of the Uni­ver­sity of Michi­gan, 157: 1-146.

Cha­line, J., P. Mein, F. Pet­ter. 1977. Les grandes lignes d'une clas­si­fi­ca­tion évo­lu­tive des Muroidea. Mam­malia, 41: 245-252.

Eller­man, J. 1941. The Fam­i­lies and Gen­era of Liv­ing Ro­dents, vol. II. Lon­don: British Mu­seum (Nat­ural His­tory).

Hooper, E. 1960. The glans penis in Neotoma (Ro­den­tia) and al­lied gen­era. Oc­ca­sional Pa­pers of the Mu­seum of Zo­ol­ogy, Uni­ver­sity of Michi­gan, 618: 1-21.

Hooper, E., G. Musser. 1964. The glans penis in neotrop­i­cal cricetines (Fam­ily Muri­dae) with com­ments on the clas­si­fi­ca­tion of muroid ro­dents. Mis­cel­la­neous Pub­li­ca­tions of the Mu­seum of Zo­ol­ogy of the Uni­veristy of Michi­gan, 123: 1-57.

Hunt, J., J. Mor­ris, T. Best. 2004. Nyc­to­mys sumichrasti. Mam­malian Species, 754: 1-6.

IUCN, 2004. "2004 IUCN Red List of Threat­ened Species" (On-line). Ac­cessed July 05, 2005 at www.​redlist.​org.

Lawlor, T. 1982. Ototy­lomys phyl­lo­tis. Mam­malian Species, 181: 1-3.

Miller, G., J. Gi­d­ley. 1918. Syn­op­sis of su­per­generic groups of ro­dents. Jour­nal of the Wash­ing­ton Acad­emy of Sci­ence, 8: 431-448.

Musser, G., M. Car­leton. 1993. Fam­ily Muri­dae. Pp. 501-753 in D Wil­son, D Reeder, eds. Mam­mal Species of the World. Wash­ing­ton, D. C.: The Smith­son­ian In­sti­tu­tion Press.

Musser, G., M. Car­leton. 2005. Su­per­fam­ily Muroidea. D Wil­son, D Reeder, eds. Mam­mal Species of the World. Bal­ti­more and Lon­don: The Johns Hop­kins Uni­ver­sity Press.

Nowak, R. 1999. Walker's Mam­mals of the World, vol. 2. Bal­ti­more and Lon­don: The Johns Hop­kins Uni­ver­sity Press.

Reig, O. 1980. A new fos­sil genus of South Amer­i­can cricetid ro­dents al­lied to Wiedomys, with an as­sess­ment of the Sig­mod­on­ti­nae. Jour­nal of Zo­ol­ogy, 192: 257-281.

Reig, O. 1984. Dis­tribuçao geográfica e his­to­ria evo­lu­tiva dos roe­dores muroideos su­lamer­i­canos (Criceti­dae: Sig­mod­on­ti­nae). Re­vista Brasilera Genética, 7: 333-365.

Simp­son, G. 1945. The prin­ci­ples of clas­si­fi­ca­tion and a clas­si­fi­ca­tion of mam­mals. Bul­letin of the Amer­i­can Mu­seum of Nat­ural His­tory, 85: 1-350.

Step­pan, S., R. Ad­kins, J. An­der­son. 2004. Phy­logeny and di­ver­gence-date es­ti­mates of rapid ra­di­a­tions in muroid ro­dents based on mul­ti­ple nu­clear genes. Sys­tem­atic Bi­ol­ogy, 53(4): 533-553.

Tull­berg, T. 1899. Uber das sys­tem der nageth­iere: eine phy­lo­genetis­che studie. Nova Acta Re­giae So­ci­etatis Sci­en­tiarum Up­salien­sis, 3: 1-514.

Vorontsov, N. 1959. The sys­tem of ham­ster (Criceti­nae) in the sphere of the world fauna and their phy­lo­ge­netic re­la­tions. Bi­uleten’ Moskovskogo Ob­schestva Ispy­tate­ley Prirody Otdel Bi­o­logich­eskii, 64: 134.