The Mithraneans are a sapient alien race native to a temperate planet with two suns. They're biologically-related to, but have a strong social enmity with the Atheleni.
Mithraneans are significantly taller than the Atheleni, but share their cousins' well-developed telepathic abilities. It has been mentioned that Atheleni females can be considered attractive by the Mithraneans, which suggests that both species are also physically similar.
Like the Atheleni, the Mithraneans have a tripedal mammalian body with a single rear-limb and a pair of short forelimbs which can be used for combat. Since they haven't got hands or any other form of manipulative organ, they haven't developed any kind of technology and have to live with what nature offers them.
- "Second Dawn", by Arthur C. Clarke (1951)