This member of the Euphorbiaceae family was given this name by Werner Rauh and Martine Bardot-Vaucoulon in 1999. It is found in the Antsiranana Province; central Madagascar, growing in a well drained soil with some water and some to lots of sun sun. The flowers are - look at the photo...
The genera name; Euphorbia dates back to the first century BC, where King Juba II of Mauritania used it in a reference to his doctor, Euphorbos, and that name was kept as a generic name by Carl von Linnaeus. The species name after Jean-Noël Labat, a French botanist. Recently a "Type 2" has been offered in trade. The leaves are wider, flat and almost red. The flowers has significantly smaller petals. The photos below are from this subspecies/variation or - what I guess - other species. And yes, in 2016, Sébastien Houyelle, raised it to its own species: Euphorbia nadiae. A typical Type 2 by Woot. Now Euphorbia nadiae, Sébastien Houyelle, 2016. The leaves of Type 2 by Woot.

