Tylomyinae

Watson's climbing rat Tylomys watsoni, copyright D. H. Janzen.

Belongs within: Cricetidae.

The Tylomyinae, climbing rats and vesper rats, are a group of arboreal rodents found in Mexico and Central America.

Characters (from Animal Diversity Web): Medium to large-sized; 95 to 255 mm in length; tail 85 to 250 mm in length, tail usually slightly longer body; weight 29 to 280 grams. Fur short or long; cinnamon, buff, tawny, gray, russet, or brown above, white below. Ears nearly naked, short or long. Whiskers long and black. Eyes quite large, sometimes each surrounded by a dark ring. Tail either covered with long hairs and tufted at tip, or nearly naked. Hind feet modified for climbing. Two pairs of mammae present in the inguinal region. Molars brachydont, cuspidate, with major cusps lying opposite one another; cheek teeth bearing well-developed mesolophs and mesolophids; second upper molar with four roots; third lower molar relatively large with a crown pattern like that of the second lower molar. Interorbital region cuneate, with prominant supraorbital shelves continuing posteriorly as pronounced temporal ridges. Interparietal bone large, contacting the squamosal, to which the tegmen tympani are united. Zygomatic plates narrow, usually without a dorsal notch. Alisphenoid strut present; subsquamosal fenestra absent; postglenoid foramen quite small. Mesopterygoid fossa usually completely ossified; parapterygoid fossa shallow and slender. Sphenopalatine vacuities, if present, tiny slits. First rib attaching to only first thoracic vertebra. Humerus with entepicondylar foramen. Calcaneum with wide, proximally-positioned trochlear process. Stomach single-chambered; gall bladder absent. Caecum long and complex. Glans penis wide and short (though longer than baculum), with large, well-spaced spines.

<==Tylomyinae [Tylomyini]
    |--Ototylomys phyllotis RC06
    |--Otonyctomys hatti RC06, IT07
    |--Nyctomys sumichrasti RC06, G69
    |    |--N. s. sumichrasti G69
    |    |--N. s. colimensis G69
    |    `--N. s. pallidulus G69
    `--Tylomys RC06
         |--T. bullaris G69
         |--T. fulviventer IT07
         |--T. mirae IT07
         |--T. nudicaudus RC06
         |    |--T. n. nudicaudus G69
         |    |--T. n. gymnurus G69
         |    |--T. n. microdon G69
         |    |--T. n. tumbalensis G69
         |    `--T. n. villai Schaldach 1966 [=T. n. villae] G69
         |--T. panamensis IT07
         `--T. watsoni IT07

*Type species of generic name indicated

REFERENCES

[G69] Goodwin, G. G. 1969. Mammals from the State of Oaxaca, Mexico, in the American Museum of Natural History. Bulletin of the American Museum of Natural History 141 (1): 1–269, 40 pls.

[IT07] Isaac, N. J. B., S. T. Turvey, B. Collen, C. Waterman & J. E. M. Baillie. 2007. Mammals on the EDGE: conservation priorities based on threat and phylogeny. PloS One 2 (3): e296.

[RC06] Reeder, S. A., D. S. Carroll, C. W. Edwards, C. W. Kilpatrick & R. D. Bradley. 2006. Neotomine-peromyscine rodent systematics based on combined analyses of nuclear and mitochondrial DNA sequences. Molecular Phylogenetics and Evolution 40 (1): 251–258.