Tuesday, October 13, 2015

A new shrew rat: Hyorhinomys stuempkei

A shrew rat is not a true rat but a rodent that resembles a shrew. Species of this group are known only from Asia and today's new species was found on a remote, mountainous island in Indonesia.

The newcomer has a large, flat, pink nose and forward-facing nostrils for which it was named the Hog-nosed rat. With extremely large ears, long hind legs that may be used for hopping, and long white incisors, the Hog-nosed rat is so different from any other species that researchers described it as a new genus.

As mentioned above the new genus is named for its hog-like nose, by combining the Greek words “hyo” (hog), “rhino” (nose), and “mys” (mouse). The species is named in honor of Gerolf Steiner, who used the pseudonym Harald St├╝mpke, to publish a small book (Bau und Leben der Rhinogradentia) in English known as The Snouters. The Snouters describes a fictional island radiation of mammals with extraordinary nasal and aural adaptations and seemingly anticipates the discovery of the new species, with its large pink nose.

For the experts: We document a new genus and species of shrew rat from the north peninsula of Sulawesi Island, Indonesia. The new taxon is known only from the type locality at 1,600 m elevation on Mt. Dako, in the district of Tolitoli. It is distinguished from all other Indonesian murines by its large, flat, pink nose with forward-facing nares. Relative to other Sulawesi murines, the species has extremely large ears (~ 21% of head and body length), very long urogenital hairs, prominent and medially bowing hamular processes on the pterygoid bones, extremely long and procumbent lower incisors, and unusually long articular surfaces on the mandibular condyles. Morphologically, the new taxon is most similar to a group of endemic Sulawesi rats known commonly as “shrew rats.” These are long faced, carnivorous murines, and include the genera Echiothrix, Melasmothrix, Paucidentomys, Sommeromys, and Tateomys. Our Bayesian and likelihood analyses of DNA sequences concatenated from 5 unlinked loci infer the new shrew rat as sister to a clade consisting of Melasmothrix, Paucidentomys, and Echiothrix, suggesting that Sulawesi shrew rats represent a clade. The Sulawesi water rat, Waiomys mamasae, was sister to the shrew rats in our analyses. Discovery of this new genus and species brings known shrew rat diversity on Sulawesi to 6 genera and 8 species. The extent of morphological diversity among these animals is remarkable considering the small number of species currently known.

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