Final answer:
The Tarsiini lineage includes 8 species, which are specialized primates found in Southeast Asia.
Step-by-step explanation:
The Tarsiini lineage, part of the family Tarsiidae, currently includes 8 species. They are unique primates that fall under the category of haplorrhine, a group that shares the inability to produce Vitamin C. All existing species of this lineage are found in Southeast Asia, with specific adaptations like large, stationary eyes, and the ability to rotate their heads 360 degrees. As the only primate carnivores, they primarily feed on insects and small animals, demonstrating a specialized ecological niche.