| Shrewlike rat | |
|---|---|
 | |
| Rhynchomys soricoides (lower animal) | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Rodentia |
| Family: | Muridae |
| Subfamily: | Murinae |
| Tribe: | Hydromyini |
| Genus: | Rhynchomys Thomas, 1895 |
| Type species | |
| Rhynchomys soricoides | |
| Species | |
Rhynchomys banahao | |
 | |
| Distribution of shrewlike rats onLuzon Island. Orange =R. soricoides, red =R. tapulao, blue =R. banahao, and green =R. isarogensis. | |
Theshrewlike rats,genusRhynchomys, also known as thetweezer-beaked rats are a group of unusualOld World rats found only on the island ofLuzon in thePhilippines. They look a great deal likeshrews and are an example ofconvergent evolution. Shrewlike rats evolved to bevermivores andinsectivores feeding onsoft-bodiedinvertebrates associated withleaf litter.
The snout androstrum are very long. Eyes are small. Head and body is 18.8–21.5 cm with a tail 10.5–14.6 cm.[1] Only twomolars are present on each side of the upper and lower jaws; these are small and peg-like.Incisors are described asneedle-like andmandibles as delicate.[1][2] Their characteristic method of locomotion has given rise to the epithet "hopping rats," describing their method of pouncing on an earthworm prey before it can slide back into its hole.[3]
Shrewlike rats are found at elevations of 1,100 to 2,460 meters.[1][2] They are restricted to moist, mossy highland regions with ample rainfall and large populations ofearthworms. Populations appear to be very isolated, restricted to "sky islands" of Luzon. Specimens have been collected fromMt. Bali-it andMt. Data of theCentral Cordillera (R. soricoides),Mt. Tapulao of theZambales Mountains (R. tapulao),[2]Mount Banahao (R. banahao),[2]Mount Isarog (R. isarogensis),Mt. Labo of theBicol Peninsula (R. labo)[4] andMt. Mingan of theSierra Madre (R. mingan).[4]
Rhynchomys is anold endemic of the Philippines.[5] The genus is distinct enough to give it its own group distinct from all other old endemics.[5] It was classified as part of theChrotomys division along withApomys,Archboldomys, andChrotomys.[6] Within this division,Rhynchomys is most closely related to the other Philippine shrew-rats in the generaArchboldomys andChrotomys.[7]
From 1895 until 1981,Rhynchomys was only known from a few specimens taken from near the type locality ofR. soricoides. In 1981, this was expanded by one species with the discovery and description ofR. isarogensis. In 2007, two species,R. banahao andR. tapulao, were described from Mt. Banahao and Mt. Tapulao, respectively.[2] In 2019, two additional species were described,R. labo andR. mingan fromMt. Labo andMt. Mingan, respectively.[8][4]
