Dalbergia spp. of the family Fabaceae. There are numerous Dalbergia species that are given the common name of (among others) Madagascar rosewood. These include at least the following: D. baronii, D. greveana, D. madagascariensis, D. maritima, D. perrierim, and D. trichocarpa.
I do not have any knowledge of what differences there are among those species, nor which of them any of the following pics are.
Another common name for the same wood is "bois de rose", which just means "wood that is red" and at present, woods sold under that name have their own page on this site, but I believe that most, if not all, of the woods shown there are what is also meant in the USA by the term Madagascar rosewood (although "bois de rose" encompasses MANY more species). I also note that most of the woods on that page are purple, whereas the woods on this page show a more likely range of colors.