The species is known from two disjunct populations, which are being looked at taxonomically (Timm pers. comm.).
Panamanian Dry Forests Habitat
This taxon is found in the Panamanian dry forests, but not necessarily limited to this ecoregion. The Panamanian dry forests ecoregion occupies approximately 2000 square miles of coastal and near-coastal areas on the Pacific versant of Panama, around portions of the Gulf of Panama. Plant endemism is intermediate, and vertebrate species richness is quite high in the Panamanian dry forests.This key ecoregion is highly threatened from its extensive ongoing exploitation. Beyond the endemism and species richness, the ecoregion is further significant, since it offers a biological corridor from the moist forests to the coastal mangroves.
Plant endemism is intermediate in value within the Panamanian dry forests, likely elevated due to the (a) isolation of this ecoregion from the surrounding and intervening moist forest habitat; (b) arid conditions which likely enhanced speciation and hence species richness; and (c) absence of prehistoric glaciation, which has extinguished many species in more extreme latitudes.
Many of the plants are well adapted to herbivory defense through such morphologies as spiny exteriors and other features. Forest canopies are typically less than twenty meters, with a few of the highest species exceeding that benchmark. Caesalpinia coriaria is a dominant tree in the Azuero Peninsula portion of the dry forests, while Lozania pittieri is a dominant tree in the forests near Panama City. The vegetative palette is well adapted to the dry season, where water is a precious commodity.
Faunal species richness is high in the Panamanian dry forests, as in much of Mesoamerica, with a total of 519 recorded vertebrates alone within the Panamanian dry forests. Special status reptiles in the Panamanian dry forests include the American Crocodile (Crocodylus acutus), the Lower Risk/Near Threatened Brown Wood Turtle (Rhinoclemmys annulata), the Lower Risk/Near Threatened Common Caiman (Caiman crocodilus), the Lower Risk/Near Threatened Common Slider (Trachemys scripta), and the Critically Endangered Leatherback Turtle (Dermochelys coriacea). There are two special status amphibian in the ecoregion: the Critically endangered plantation Glass Frog (Hyalinobatrachium colymbiphyllum) and the Vulnerable Camron mushroom-tongued salamander (Bolitoglossa lignicolor).
Threatened mammals found in the Panamanian dry forests include the: Endangered Central American Spider Monkey (Ateles geoffroyi), the Vulnerable Giant Anteater (Myrmecophaga tridactyla), the Near Threatened Handley’s Tailless Bat (Anoura cultrata), the Vulnerable Lemurine Night Monkey (Aotus lemurinus), the Near Threatened Margay (Leopardus wiedii), the Near Threatened Yellow Isthmus Rat (Isthmomys flavidus), the Near Threatened White-lipped Peccary (Tayassu pecari), and the Near Threatened Spectral Bat (Vampyrum spectrum). There are two special status bird species occurring in the ecoregion: the Endangered Great Green Macaw (Ara ambiguus) and the Near Threatened Olive-sided Flycatcher (Contopus cooperi).
- C.Michael Hogan & World Wildlife Fund. 2013. "Panamanian dry forests".. Encyclopedia of Earth, National Council for Science and the Environment, Washington DC ed.Peter Saundry
- Jesse R. Lasky & Timothy H. Keitt. 2009. Abundance of Panamanian dry forest birds along gradients of forest cover at multiple scales. Journal of Tropical Ecology. Vol 26 pp 67-78
Habitat and Ecology
IUCN Red List Assessment
Red List Category
Red List Criteria
Yellow isthmus rat
The yellow isthmus rat (Isthmomys flavidus) is a species of rodent in the family Cricetidae. It is found only in Panama. It was discovered by W. W. Brown, Jr. on the southern slope of Volcan de Chiriqui (8° 49' N, 82° 32' W). He found it common in the upland forest from 1000 to 1500m, but no specimens were taken above or below these elevations (Bangs 1902; Goldman 1920; Goodwin 1946). Museum records specify two isolated populations in western Panama, one at Cerro Colorado where R. Pine et al. collected in 1980 (8° 31' 60N, 81° 49' 0W) and at Cerro Hoya on the Azuero Peninsula by C. Handley in 1962 (7° 23' N, 80° 38' W). The presence of I. flavidus or a closely allied form in Costa Rica is probable (Goodwin 1946), however, no specimens have been reported. There are no currently known fossil records of Isthmomys (McKenna and Bell 1997).
- Musser, G. G. and M. D. Carleton. 2005. Superfamily Muroidea. pp. 894–1531 in Mammal Species of the World a Taxonomic and Geographic Reference. D. E. Wilson and D. M. Reeder eds. Johns Hopkins University Press, Baltimore.
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