Two new tarsier species have been discovered in the forests of the northern peninsula of Sulawesi, Indonesia.

Tarsiers are small, nocturnal, predaceous primates of the 45-million-year-old family Tarsiidae.

They are intermediate in form between lemurs and monkeys, measuring up to 6 inches (15 cm) long and weighing 100 – 150 g.

They have elongated hind legs and feet, a thin tail and long fingers. Their fur is velvety or silky and buff, grayish brown, or dark brown on the back and grayish or buffy on the underside.

These primates have the largest eyes relative to body size of any mammal on Earth, each typically larger than their brain. Similar to owls, tarsiers can rotate their necks a full 180 degrees in either direction.

Their unique anatomy allows them to be vertical clingers and leapers — they can jump 40 times their body length in a single leap.

While tarsiers, the world’s most carnivorous primates, are generally insectivorous throughout their geographic range, some were observed feeding on small birds, rodents and lizards.

They occur only on the islands of southeast Asia, including Sumatra, Borneo, Sulawesi, and Philippines.

The two new species — named the Jatna’s tarsier (Tarsius supriatnai) and the Gursky’s spectral tarsier (Tarsius spectrumgurskyae) — were found in Sulawesi, one of Indonesia’s main islands.

They are described in a paper published in the journal Primate Conservation by Western Washington University primatologist Dr. Myron Shekelle and three colleagues.

“The Gursky’s spectral tarsier is named in honor of Dr. Sharon Gursky, who has dedicated most of her professional life to studying the behavioral ecology of this species. Most of her work on this species was published using a taxonomy that is now superseded, in which her population was classified as Tarsius spectrum,” the researchers wrote in the paper.

“The Jatna’s tarsier is named in honor of Dr. Jatna Supriatna, who has dedicated most of his professional life to the conservation of Indonesian biodiversity, and has sponsored much of the foreign collaborative work done on tarsiers.”

“They look almost identical, but their calls are very different,” Dr. Shekelle said.

With these two new species, the total number of primates in Indonesia rises to 80 and the number of recognized tarsier species from Sulawesi and nearby islands rises to 11.

“These two new species of tarsier from Sulawesi are the 80th and 81st primate species new to science described since the turn of the century,” said co-author Dr. Russ Mittermeier, Executive Vice Chair of Conservation International.

“This represents about 16% of all primate species known and is indicative of how little we know of our planet’s unique and wonderful biodiversity.”

“If we haven’t even gotten a handle on the diversity our closest living relatives, which by comparison are relatively well-studied, imagine how much we still have to learn about the rest of life on Earth.”

_____

Myron Shekelle et al. 2017. Two New Tarsier Species (Tarsiidae, Primates) and the Biogeography of Sulawesi, Indonesia. Primate Conservation 31