|Rhynchomys labo & R. mingan|
Rickart, Balete, Timm, Alviola, Esselstyn & Heaney, 2019
The murine genus Rhynchomys includes the large-bodied Philippine “shrew-rats,” highly specialized members of the vermivorous clade of Philippine murids. Four species are recognized, all of which are endemic to Luzon Island: R. soricoides from mountains within the Central Cordillera, R. isarogensis from Mt. Isarog on the Bicol Peninsula, R. banahao from Mt. Banahaw in south-central Luzon, and R. tapulao from Mt. Tapulao in the Zambales Mountains. Field surveys in 2006 and 2008 revealed two additional populations of Rhynchomys, one from Mt. Labo (1,544 m), a dormant stratovolcano at the base of the Bicol Peninsula, the other from Mt. Mingan (1,901 m), the highest peak in the central Sierra Madre of east-central Luzon. Assessment of external and craniodental features of available specimens from throughout Luzon support our description of the populations on Mt. Labo and Mt. Mingan as new species. All species of Rhynchomys are restricted to high-elevation, montane, and mossy forest habitats, separated by intervening lowlands. These discoveries highlight the importance of isolated highland areas in the historical diversification of Southeast Asian murines, and as current centers of endemism.
biogeography, Chrotomyini, conservation, distribution, ecology, morphology, oceanic islands, systematics
| Rhynchomys labo.|
Drawing by Velizar Simeonovski.
Rhynchomys labo, new species
Rhynchomys sp.: Balete, Heaney, Alviola, and Rickart, 2013a:71.
Rhynchomys isarogensis: Heaney, Balete, and Rickart, 2016:160.
Etymology.— The new species is named for Mt. Labo, where the specimens originated. The specific epithet is used as a noun in apposition. We propose “Labo shrew-rat” as the English common name.
Distribution.— Known only from forested areas on the north slope of Mt. Labo between 1,250 and 1,413 m elevation.
| Dorsal, ventral, and lateral views of cranium and lateral view of mandible of adult Rhynchomys. |
A) Rhynchomys labo (KU 165952, holotype). B) R. isarogensis (USNM 573575).
Drawing by Velizar Simeonovski.
Rhynchomys mingan, new species
Rhynchomys sp.: Balete, Alviola, M. R. M. Duya, M. V. Duya, Heaney, and Rickart 2011:80.
Rhynchomys sp.: Heaney, Balete, and Rickart, 2016:163.
Etymology.— The new species is named for the Mingan Mountains where the specimens originated. The specific epithet is used as a noun in apposition. We propose “Mingan shrew-rat” as the English common name.
Distribution.— Known only from localities in old-growth montane and mossy forest on the southwestern slope of Mt. Mingan between 1,476 and 1,785 m elevation.
Eric A. Rickart, Danilo S. Balete, Robert M. Timm, Phillip A. Alviola, Jacob A. Esselstyn and Lawrence R. Heaney. 2019. Two New Species of Shrew-rats (Rhynchomys: Muridae: Rodentia) from Luzon Island, Philippines. Journal of Mammalogy. gyz066. DOI: 10.1093/jmammal/gyz066
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