Hoplomys gymnurus
armored rat

Hoplomys gymnurus is a Neotropical rodent found in Central and South America. It ranges from southern Honduras to northwestern Ecuador and is never found east of the Andes Mountains. (Grzimek, 2003)

Throughout its geographic range, Hoplomys gymnurus is found in primary forests, disturbed forests, deserted farmlands, palm swamps, and lowland tropical evergreen forests. However, H. gymnurus is considered a habitat specialist because it is usualy found near wet habitats, such as wet lowland rainforests and stream sides. In fact it lives in the wettest forest habitat in the world, the pluvial rainforests of western Columbia. It prefers stream sides with steep slopes, rocky banks, plenty of fallen logs and a tall canopy. Hoplomys gymnurus limits competition with a closely related, sympatric species, Proechimys semispinosus, by being a habitat specialist living in wet microhabitats. (Eisenberg and Redford, 1999; Emmons, 1997; Grzimek, 2003; Reid, 1997; Tomblin and Adler, 1998)

Hoplomys gymnurus experiences two distinct seasons throughout its geographic range, a four month dry season from the middle or end of December to April and an eight month rainy season from May to December. The average rainfall is around 2,600 mm and 90% of the average precipitation falls during the rainy season. (Tomblin and Adler, 1998)

Hoplomys gymnurus has a long, narrow head with naked, erect ears. The hair on the dorsal part of the body is cinnamon-brown to dark brown. The anterior part of the body is covered with backward pointing spines. The spines are white at the base and black at the tip. The spines can be as long as 3 cm and as thick as 2 mm in diameter. The underside of the body and the inner parts of the legs and feet are white and there is usually a dark collar across the throat. The tail is naked and bicolored (dark on top and light colored below), but the tail is frequently lost in this species. Hoplomys is sometimes considered a subgenus of Proechimys, but H. gymnurus is much spinier than Proechimys. (Emmons, 1997; Grzimek, 2003)

Males are on average 38% larger than females. (Adler, Tomblin, and Lambert, 1998; Grzimek, 2003)

Little is known about the lifespan of Hoplomys gymnurus. Recaptures of wild individuals have occurred more than two years apart, but one researcher observed that H. gymnurus does not live more than 72 hours in captivity. (Adler, Tomblin, and Lambert, 1998; Buchanan and Howell, 1965)

Hoplomys gymnurus is nocturnal and terrestrial. It builds simple horizontal burrows in the sides of streams or uses abandoned burrows from other animals. The burrow consists of a 1.5 to 2 meter long tunnel with an enlarged chamber at the end for nesting. The nest chamber is kept dry and is covered with vegetative matter. There is also a separate chamber for defecating. Members of this species spend most of the day in their burrows and come out at night to find food. They build elaborate pathways in the vegetation on the forest floor which they travel through. Individual H. gymnurus is reclusive and runs to its burrow when disturbed. It has a rabbit-like gait when running and can jump 22 cm in the air from a standing position. (Buchanan and Howell, 1965; Reid, 1997)

Home Range

The home range of Hoplomys gymnurus is usually small and centered around its burrow. Its home range size also depends on the amount of microhabitat available. Haplomys gymnurus cannot tolerate dry areas and will not wander far from a stream or other wet environment. (Grzimek, 2003; Reid, 1997)

Hoplomys gymnurus can emit a loud “whee-unk” sound with considerable force when confronted by another animal. The function of this vocalization is not known. (Buchanan and Howell, 1965; Eisenberg and Redford, 1999)

Hoplomys gymnurus is primarily a frugivore, but it also includes some insects in its diet. Most insects consumed are of the orders Coleoptera and Orthoptera, and soft seeds, bananas, wild figs, avocadoes, mangoes, and other fruits make up the majority of its diet. Fruit is most abundant at the end of the dry season and the beginning of the wet season. Haplomys gymnurus caches some foods in its burrow. (Eisenberg and Redford, 1999; Mendez, 1993; Reid, 1997; Tomblin and Adler, 1998)

Some key predators of Hoplomys gymnurus are ocelots, jaguarundis, bushmasters, and other snakes. (Grzimek, 2003)

The spines of H. gymnurus are a great defense mechanism against predators. In addition to the spines H. gymnurus can drop its tail to confuse or escape a predator. (Grzimek, 2003)

Hoplomys gymnurus is an important disperser of seeds of the palm Attalea butyraceae. It is also a reservoir for equine encephalitis and cutaneous leishmaniasis and is an intermediate host of Echinococcus oligarthrus. Equine encephalitis and cutaneous leishmaniansis are vectored by mosquitoes and sand flies, respectively. (Mendez, 1993; Wright and Duber, 2001)

Haplomys gymnurus also affects the ecosystem by changing habitats with its burrows and pathways. These actions can create microhabitats for smaller organisms. They also affect animals that they may steal burrows from. One excavation of a burrow that H. gymnurus was inhabiting revealed an extra cavity that was full of the eggs of an iguanid lizard. (Buchanan and Howell, 1965)

Hoplomys gymnurus is involved in the transmission of some human and animal diseases. Equine encephalitis has a mortality rate as high as 20% in humans and 80% in horses. Cutaneous leishmaniansis causes sores to develop on the skin of the infected person. Some of the sores can be very large and painful. Echinococcus oligarthrus is an extremely rare cause of human echinococcosis, but can be very dangerous to humans. Echinococcosis in humans causes cysts to form on internal organs like the liver and lungs. (CDC, 2000; CDC, 2002; Derlet, 2002; Mendez, 1993)

Some native people of Panama eat Hoplomys gymnurus. (Mendez, 1993)

Hoplomys gymnurus is uncommon, but not rare throughout its geographic range. Conservation may become important because it is a habitat specialist. (NatureServe, 2003)