Paucidentomys

Paucidentomys is a genus of rodents of a type commonly known as shrew-rats which was discovered in 2012 in a remote rainforest on the Indonesian island, Sulawesi. The genus is monotypic, consisting of the species Paucidentomys vermidax. The name, which is Latin and may be translated as "worm-eating few-toothed mouse", refers to the fact that they have only two teeth and may live exclusively on a diet of earthworms.[2][3]

Paucidentomys
On an Indonesian stamp
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Family: Muridae
Genus: Paucidentomys
Esselstyn, Achmadi & Rowe, 2012
Species:
P. vermidax
Binomial name
Paucidentomys vermidax
Esselstyn, Achmadi & Rowe, 2012
Specimen collections from Sulawesi, Indonesia

Description

Paucidentomys vermidax is larger than Melasmothrix naso, Sommeromys macrorhinos and Tateomys macrocercus, similar in size to Tateomys rhinogradoides, smaller than Rhynchomys soricoides and substantially smaller than species of Echiothrix. The face is more elongate than that of any other Sulawesi shrew-rat, but similar in this regard to Rhynchomys. It has a very long rostrum (relative to other Sulawesi shrew-rats), small eyes, large ears, a soft pelage and a long, thick, hairy and dorsoventrally bicoloured tail.[2]

Unique dentition

Paucidentomys vermidax is the only known rodent with no molars, which is an adaptation to its diet which may be exclusively earthworms (it appears to be a specialist vermivore based on the stomach contents of one individual). Moreover, rather than gnawing incisors, this animal has bicuspid upper incisors, which is also unique among the more than 2,200 species of rodents. The upper incisors are short with an anterior cusp and slightly inferior posterior cusp; these cusps are connected by a sharp, concave cutting edge at the lateral margin of the tooth. The pterygoid plate is absent. The dentary is long and delicate, lacking significant muscle attachment points. The lower incisors are unicuspid, procumbent, sharp and delicate.[2] Its dental formula is 1.0.0.01.0.0.0.

Distribution

Paucidentomys vermidax is known from Mount Gandangdewata and Mount Latimojong in Sulawesi, Indonesia.[1]

Etymology

The generic name combines the Latin paucus (few) with dentis (tooth) and the Greek mys (mouse) in reference to the lack of molars. The epithet is a hybrid of vermi (worm) and edax (devourer), in reference to the animal's diet.[2]

References
  1. Engelbrektsson, P. (2016). Paucidentomys vermidax. The IUCN Red List of Threatened Species. doi:10.2305/IUCN.UK.2016-2.RLTS.T46205590A46207038.en
  2. Esselstyn, J.A., Achmadi, A.S. Rowe, K.C. (2012). "Evolutionary novelty in a rat with no molars". Biology Letters. 8 (6): 990–993. doi:10.1098/rsbl.2012.0574. PMC 3497122. PMID 22915626.CS1 maint: multiple names: authors list (link)
  3. Gnaw way! New species of long-nosed rat discovered that cannot chew. mirror.co.uk. 22 August 2012
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