Subfamily Lophiomyinae
crested rat

Lophiomyinae is an Old World cricetid subfamily containing just one genus and one species, Lophiomys imhausi, or crested rats. (Musser and Carleton, 2005)

Crested rats are native to eastern Africa, including Sudan, Ethiopia, Somalia, Kenya, and Tanzania. (Carleton and Musser, 1984)

Crested rats inhabit mountain forests and woodlands, as well as rocky slopes and ravines. They are generally found at high elevations, up to 3,300 meters. (Carleton and Musser, 1984; Nowak, 1999)

The uniqueness of these animals has long been recognized, and most authors have classified crested rats as either a family or as a subfamily of Cricetidae--a view which has support from an analysis of dental characteristics (Musser and Carleton 2005). Lavocat (1973), breaking from this tradition, placed Lophiomyinae in the family Nesomyidae, believing Lophiomys to be derived from the extinct group Afrocricetodontidae. However, a phylogenetic analysis based on IRBP gene sequences suggested that Lophiomys is a murid (Jansa and Weksler 2004). The taxonomic position of Lophiomyinae will likely remain uncertain until more molecular analyses are performed. (Carleton and Musser, 1984; Jansa and Weksler, 2004; Lavocat, 1973; Musser and Carleton, 2005)

Crested rats are large rodents, ranging from 255 to 360 mm in head and body length. The tail adds another 140 to 215 mm, and these rodents weigh 590 to 920 grams. Females are generally larger than males. Crested rats are stockily built, with short snouts, broad heads, short legs, and wide feet. They have short ears. Their fur is long, thick, and fine-textured, except for a middorsal crest of coarse hairs that can be erected. Flanking the crest are prominant rows of scent glands. When it has its crest raised, a crested rat resembles a miniature porcupine. The coat is boldly patterned with black and white (or brown and white) stripes or patches. The underparts are gray to black, and the feet are black. The tail is short and bushy, and the soles of the feet are hairless. Crested rats have semi-opposable big toes, making them well-suited to their arboreal lifestyle.

The dental formula of crested rats is 1/1, 0/0, 0/0, 3/3 = 16. The incisors are smooth and orthodont, and the molars are rooted and cuspidate. Each zygomatic plate bears a prominant tubercle where the superficial masseter attaches. Crested rats have long incisive foramina, which extend back beyond the anterior margins of the molar rows. They also have a long, wide mesopterygoid fossa that extends between the third molars. There are small sphenopalatine vacuities, and a wide region of the squamosal separates the foramen ovale and masticatory foramen. The paroccipital processes are long and thick. The tympanic bullae are medium-sized, and there is an accessory tympanum. The malleus is of parallel construction, and a small orbicularis apophysis is present. (Carleton and Musser, 1984; Nowak, 1999)

Crested rats may live almost eight years in captivity, but their lifespan in the wild has not been reported. (Nowak, 1999)

Crested rats are arboreal; they climb with slow and deliberate movements. When climbing downward, they descend forefeet-first. They rest in hollow trees, fallen logs, burrows, or among boulders during the day, and come out to forage at night. Usually they are observed singly, but sometimes they are seen in pairs or in small groups consisting of a mother and her offspring. (Carleton and Musser, 1984; Kingdon, 1974)

Crested rats most likely perceive visual, auditory, tactile, and chemical signals, as do most rodents, but no information is available on the relative acuteness of these senses. These rodents are known to make peculiar hissing and growling noises. (Carleton and Musser, 1984)

Crested rats are herbivorous, eating leaves and tender young shoots. They will also eat insects and meat when kept in captivity. (Kingdon, 1974; Nowak, 1999)

These rodents have several unique adaptations for avoiding predation. Each crested rat possesses a row of erectile hairs lined by scent glands in a strip down the back. Each hair resembles a tiny sponge; when laid flat, it soaks up scent from the adjacent gland (Stoddart 1979). When the animal feels threatened, it raises the crest, diffusing its foul scent into the air, making itself look larger, and exposing large, aposematic white patches. In addition, some have suggested that the raised crest is meant to make the animal look like a porcupine, or that the glands or saliva of crested rats contain toxins. The latter has been backed up by reports of dogs foaming at the mouth and dying after attacking crested rats. Finally, the extra roofing of bone in the crested rat skull probably protects the brain and orbits from damage should a predator attack the head.

There have been no reports of a predator successfully attacking and eating a crested rat. (Carleton and Musser, 1984; Kingdon, 1974; Nowak, 1999; Stoddart, 1979)

Crested rats are primary consumers. They are parasitized by fleas, including Amphopsylla conversa. (Kingdon, 1974; Nowak, 1999)

If they truly are toxic, crested rats could pose a hazard to humans or domestic dogs who kill and eat them. Also, they harbor fleas that carry plague. (Kingdon, 1974)

There are no known positive effects of crested rats on humans.

Lophiomys is not currently considered threatened by the IUCN, but it may nevertheless be rare and more research is needed into its habits and distribution. (Amori and Gippoliti, 2003)