Small, odd and old: The mysteriousTarsius pumilusis the most basal Sulawesi tarsier

Abstract

In this study, we present the first genetic evidence of the phylogenetic position of Tarsius pumilus, the mountain tarsier of Sulawesi, Indonesia . This mysterious primate is the only Eastern tarsier species that occurs exclusively in cloud forests above 1800 m.a.s.l. It exhibits striking morphological peculiarities—most prominently its extremely reduced body size, which led to the common name of ‘pygmy tarsier’. However, our results indicate that T. pumilus is not an aberrant form of a lowland tarsier, but in fact, the most basal of all Sulawesi tarsiers. Applying a Bayesian multi-locus coalescent approach, we dated the divergence between the T. pumilus lineage and the ancestor of all other extant Sulawesi tarsiers to 9.88 Mya. This is as deep as the split between the two other tarsier genera Carlito (Philippine tarsiers) and Cephalopachus (Western tarsiers), and predates further tarsier diversification on Sulawesi by around 7 Myr. The date coincides with the deepening of the marine environment between eastern and western Sulawesi, which likely led to allopatric speciation between T. pumilus or its predecessor in the west and the ancestor of all other Sulawesi tarsiers in the east. As the split preceded the emergence of permanent mountains in western Sulawesi, it is unlikely that the shift to montane habitat has driven the formation of the T. pumilus lineage.

Habitat preferences and site fidelity of Tarsius supriatnai in agricultural area and secondary forest of Popayato-Paguat Landscape (Gorontalo, Indonesia)

“…The genus includes T. tarsier Erxleben 1777, T. fuscus Fischer 1804, T. sangirensis Meyer 1897, T. dentatus Miller and Hollister 1921, T. pumilus Miller and Hollister 1921, T. pelengensis Sody 1949, T. lariang Merker and Groves 2006, T. tumpara Shekelle et al 2008, T. wallacei Merker et al 2010, T. spectrumgurskyae Shekelle et al 2017, T. supriatnai Shekelle et al 2017, and T. niemitzi Shekelle et al 2019 (Niemitz et al 1991;Merker and Groves 2006;Shekelle et al 2008;Merker et al 2010;Groves 2012;Shekelle et al 2017Shekelle et al 2019. Based molecular data using autosomal phylogenetic and the SRY gene showed that the Tarsier came to Proto-Sulawesi during the initial Miocene tectonic uplift (Driller et al 2015), with T. pumilus being the basal Tarsier in Sulawesi (Hagemann et al 2022). The conservation status of the Tarsier, especially 12 species of Tarsier in Sulawesi, is categorized as data-deficient to critically endangered (Supriatna 2022).…”