It has not been confirmed onscreen whether the Remans are an offshoot of the Romulans/Vulcans or if they are completely separate species. While certain Reman features, e.g., their telepathic abilities, pointed ears and their forehead patterns, are in agreement with a genetic relation to the Romulans/Vulcans, production sources have typically referred to them as a "species".
https://memory-alpha.fandom.com/wiki/Reman?so=search
Reman blood was dark purple in color. (LD: "I Have No Bones Yet I Must Flee")
As a slave caste, Remans were not allowed to participate in Romulan society and were often subjected to harsh and dangerous working conditions in the dilithium mines of their homeworld, Remus. Their society was largely underground due to their extreme photosensitivity.
https://memory-alpha.fandom.com/wiki/Reman?so=search
Reman blood was dark purple in color. (LD: "I Have No Bones Yet I Must Flee")
As a slave caste, Remans were not allowed to participate in Romulan society and were often subjected to harsh and dangerous working conditions in the dilithium mines of their homeworld, Remus. Their society was largely underground due to their extreme photosensitivity.