Six museum specimens of this species are known, two of which have been misidentified as the pygmy tarsier before their correct identity came out.

It is the second-largest tarsier; only the Sangihe tarsier is larger; published body weights are 67 to 117 g.[2] The Lariang tarsier (T. lariang) is portrayed by its dark grey-buff pelage, thick black pencil-like tail, finely marked black paranasal stripes, along with the form of black eye rims that distinguish it from its neighbor to the east (Tarsius dianae).

They are missing brown tones on their thighs and have a small bald spot at the base of their ear.

Their range includes from Palu Bay to Makassar Strait to Lore-Lindu National Park.

[2] It mostly inhabits the northern part of Western Sulawesi while bordering its congener Tarsius dentatus along the Palu-Koro fault.

[2] The Lariang tarsiers are obligate faunivores with the main part of their diet consisting of insects.

They would be considered strictly insectivores if it were not for their occasional interest in eating lizards such as house geckos, snakes, birds, and even bats.

Scientists have found that if fed crickets for a long period of time they start to reject them and seek a different prey item.

[4] Multivariate analyses have shown the T. lariang is significantly distinct from other species of Sulawesi tarsiers.