Blesmol

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Blesmols
Fossil range: Early Miocene - Recent

Scientific classification

Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Rodentia
Suborder:	Hystricomorpha
Family:	Bathyergidae Waterhouse, 1841

Genera

Georychus
Fukomys
Cryptomys
Heliophobius
Bathyergus
Heterocephalus

The blesmols, also known as mole rats, or African mole-rats, are burrowing rodents of the family Bathyergidae. They represent a distinct evolution of a subterranean life among rodents much like the pocket gophers of North America, the tuco-tucos in South America, or the fossorial muroids.

1 Distribution
2 Anatomy
3 Behavior
4 Classification
5 References

[edit] Distribution

Modern blesmols are found strictly in sub-Saharan Africa. Fossil forms are also restricted almost exclusively to Africa, although a few specimens have been found in Israel. Nowak (1999) also reports that †Gypsorhynchus has been found in fossil deposits of Mongolia.

[edit] Anatomy

The skull morphology of blesmols sets them apart from all other rodents. As with all members of their suborder, their jaws are hystricognathous, but, unlike their relatives, they have a highly reduced infraorbital foramen. The medial masseter muscle shows only minimal passage through the infraorbital foramen leading most authorities to consider them protrogomorphous. They are therefore the only protrogomorphous hystricognaths.

Blesmols dig using their powerful incisors and, to a lesser extent, the foreclaws. Some species have been reported to be able to extend their burrows by an inch (2.5 cm) into the walls of concrete enclosures. Their unique skull shape is associated with delivering sheer power to the lateral masseter muscle which is responsible for the powerful bite of the anterior portion of the mouth.

The incisors of blesmols are projected forward and protrude from the mouth even when the mouth is closed. This condition allows the animals to burrow with their teeth without getting dirt in their mouths.

Blesmols, like many other fossorial mammals, have greatly reduced eyes and ear pinnae, a relatively short tail, and velvety fur.

[edit] Behavior

Blesmols live in elaborate burrow systems and different species exhibit varying degrees of sociality. Most species are solitary, but two species, the Damaraland Blesmol (Fukomys damarensis) and the Naked Mole Rat (Heterocephalus glaber) are considered to be the only two eusocial mammals. These species are characterized by having a single reproductively active male and female in a colony where the remaining animals are sterile.

These animals prefer loose, sandy soils and are often associated with arid habitats. They feed predominantly on underground roots and tubers, which they store in their burrows. Blesmols rarely come to the surface.

[edit] Classification

Although there is some controversy, the closest living relatives of the blesmols appear to be other African hystricognaths in the families Thryonomyidae (cane rats) and Petromuridae (dassie rats). Together these three living families along with their fossil relatives represent the infraorder Phiomorpha.

At present 22 species of blesmols from 6 genera are accepted, but this number is likely to increase. Like other fossorial rodents such as pocket gophers, tuco-tucos, and blind mole rats, blesmols appear to speciate rapidly. They become geographically isolated easily leading to various chromosomal forms and genetically distinct races. Some studies have suggested that the genus Bathyergus represents the basal-most lineage but most researchers accept that Heterocephalus holds that position.

Family Bathyergidae
- Subfamily Bathyerginae
  - Georychus - Cape Blesmol
    - Georychus capensis - Cape Blesmol
  - Fukomys
    - Fukomys amatus - Zambian Blesmol
    - Fukomys anselli - Ansell's Blesmol
    - Fukomys bocagei - Bocage's Blesmol
    - Fukomys damarensis - Damaraland Blesmol
    - Fukomys darlingi - Mashona Blesmol
    - Fukomys foxi - Nigerian Blesmol
    - Fukomys kafuensis - Kafue Blesmol
    - Fukomys mechowi - Mechow's Blesmol
    - Fukomys micklemi - Kataba Blesmol
    - Fukomys ochraceocinereus - Ochre Blesmol
    - Fukomys whytei - Malawian Blesmol
    - Fukomys zechi - Ghana Blesmol
  - Cryptomys
    - Cryptomys anomalus - Unnamed
    - Cryptomys holosericeus - Unnamed
    - Cryptomys hottentotus - Hottentot Mole Rat
    - Cryptomys natalensis - Natal Mole Rat
    - Cryptomys nimrodi - Matabeleland Mole Rat
  - Heliophobius - Silvery Blesmol
    - Heliophobius argenteocinereus - Silvery Blesmol
  - Bathyergus - Dune blesmols
    - Bathyergus janetta - Namaqua Dune Mole Rat
    - Bathyergus suillus - Cape Dune Mole Rat
- Subfamily Heterocephalinae - Naked Mole Rat
  - Heterocephalus - Naked Mole Rat
    - Heterocephalus glaber - Naked Mole Rat

[edit] References

Ingram, C. M., H. Burda, and R. L. Honeycutt. 2004. Molecular phylogenetics and taxonomy of the African mole-rats, genus Cryptomys and the new genus Coetomys Gray, 1864. Molecular Phylogenetics and Evolution, 31:997-1014.
Kingdon, J. 1997. The Kingdon Field Guide to African Mammals. Academic Press Limited, London.
McKenna, M.C. and S. K. Bell. 1997. Classification of Mammals above the Species Level. Columbia University Press, New York.
Nowak, R. M. 1999. Walker's Mammals of the World, Vol. 2. Johns Hopkins University Press, London.