The Myleans were a spacefaring species who occupied a region of space near Talax. They had well-developed sweat glands, and no taste buds, as well as a fused spinal column. They were intolerant of bright light because of their dilated pupils. Myleans and Talaxians occasionally interbred.
Neelix's great-grandfather was Mylean. His Mylean genes became hyper-stimulated due to a Srivani medical experiment in 2374. (VOY: "Scientific Method")
The fusing of Neelix' spinal gland meant that he expected to be able to walk in a few days. What that says about Mylean physiology is unknown.