The Pen-tailed Treeshrew, Ptilocercus lowii Gray, 1848, is a small arboreal mammal from Southeast Asia. It is the only extant species of Ptilocercidae and includes two subspecies: P. l. lowii from Borneo and offshore islands, and P. l. continentis from the Malay Peninsula, Sumatra, and smaller islands, including the Batu and Mentawai Islands. Intraspecific taxonomic boundaries in Ptilocercus have yet to be rigorously evaluated using modern morphological methods, so we investigated the morphometric variation between these subspecies using quantitative cranial and postcranial data obtained from museum specimens. Multivariate analyses revealed limited overlap between P. l. lowii and P. l. continentis in cranioskeletal morphospace, indicating some divergence of these two lineages. Future studies should incorporate additional morphological and molecular data to further test whether these lineages represent two distinct species. Recognition of two Ptilocercus species would have conservation implications for both populations, which should be reevaluated across their separate ranges in light of region-specific threats. Additional biological surveys, particularly from undersampled island populations, will be critical in reassessing the distribution and conservation priorities for P. lowii.
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This research was supported by the Yale College Dean’s Research Fellowship in the Sciences, the Saybrook College Richter Grant, the Alan S. Tetelman 1958 Fellowship for International Research in the Sciences, and the Yale Summer Environmental Fellowship to MMJ. Funding was also provided by National Science Foundation grants DEB-0542532 and DEB-0542725 and an Alaska EPSCoR grant to EJS and LEO, as well as SBR-9616194 to EJS. We thank the following curators, collection managers, and museums for access to the collections in their care: R. Portela-Miguez, L. Tomsett, and P.D. Jenkins (NHMUK); E. Westwig, I. Rahman, and M. Carnall (OUMNH); C. Smeenk (RMNH); L.R. Heaney, A. Ferguson, and J.D. Phelps (FMNH); M. Omura (MCZ); M. Hawkins, D. Lunde, and I. Rochon (USNM); and K. Zyskowski (YPM). We thank I. Rahman for CT scanning OUMNH ZC-08974. D. Boyer CT scanned FMNH 57450 (downloaded from MorphoSource M29789), which was collected by W. Hosmer in 1963. We thank the editor Darin Croft, Gabe Yapuncich, and one anonymous reviewer for valuable comments that greatly improved the manuscript. EJS and LEO are grateful to John Wible for his feedback on our first manuscript on treeshrew skulls eight years ago and for his continued support and encouragement of our ongoing exploration of morphological diversity in mammals.
This research was supported by the Yale College Dean’s Research Fellowship in the Sciences, the Saybrook College Richter Grant, the Alan S. Tetelman 1958 Fellowship for International Research in the Sciences, and the Yale Summer Environmental Fellowship to MMJ. Funding was also provided by National Science Foundation grants DEB-0542532 and DEB-0542725 and an Alaska EPSCoR grant to EJS and LEO, as well as SBR-9616194 to EJS.
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Appendix 1 Specimens Examined
Appendix 1 Specimens Examined
Specimens from the following institutions were included in this study: Field Museum of Natural History (FMNH), Chicago, IL; Museum of Comparative Zoology at Harvard University (MCZ), Cambridge, MA; The Natural History Museum (NHMUK), London, UK; Oxford University Museum of Natural History (OUMNH), Oxford, UK; Nationaal Natuurhistorisch Museum (RMNH), Leiden, Netherlands; United States National Museum of Natural History (USNM), Washington, DC; and Yale Peabody Museum of Natural History (YPM), New Haven, CT. Specimens used in the innominate analysis are indicated with an asterisk.
Ptilocercus lowii lowii (n = 8).—Borneo: no locality (OUMNH ZC-08974); Sabah: Sapagaya Forest Reserve (FMNH 76855*); mainland opposite Labuan (NHMUK 188.8.131.52); Sarawak, no locality (YPM MAM 10179*, NHMUK 19184.108.40.206*); Balingian (NHMUK 55.662); Bintulu (FMNH 57450); Kuching (MCZ 35380).
Ptilocercus lowii continentis (n = 35).—Malay Peninsula: Bukit Cherakah Forest Reserve (USNM 488065); Bukit Lagong Forest Reserve (NHMUK 61.1154, 61.1155, 19220.127.116.11*; USNM 481104, 481105, 488062); Gunung Benom (NHMUK 67.1479*); Johore (USNM 112611, 612250); Kepong (USNM 291272); Kuala Langat Forest Reserve (USNM 481108, 488057, 488059, 488060, 488061, 488064, 488071, 488072); Kuala Lumpur (type locality; NHMUK 10.4.17.1—holotype); Singapore (MCZ 51736*); Subang Forest Reserve (USNM 481103, 488053, 488054, 488055, 488066, 488067, 488068, 488069, 488070); Sungei Buloh Forest Reserve (USNM 481102, 488052, 488063, 488073); Sumatra: Deli: Tandjong Morawa (RMNH a*).
Ptilocercus lowii continentis (n = 3).—Batu Islands, Pini (= Pinie) (USNM 121855); Mentawai Islands, Siberut: Daman River (NHMUK 78.2939); Paitan River (NHMUK 78.2938).
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Juman, M.M., Olson, L.E. & Sargis, E.J. Skeletal Variation and Taxonomic Boundaries in the Pen-tailed Treeshrew (Scandentia: Ptilocercidae; Ptilocercus lowii Gray, 1848). J Mammal Evol 28, 1193–1203 (2021). https://doi.org/10.1007/s10914-021-09556-7