Great compilation Dinesh ji.
... There is one interesting thing in the nomenclature.
Euphorbia neriifolia L. and Euphorbia nivulia Buch.-Ham. are surely distict two species.
But there is one Euphorbia neriifolia Roxb. [notice the change in authority] which is a SYNONYM of Euphorbia nivulia Buch.-Ham.
So, name "Malekalli", (ಮಾಲೆಕಳ್ಳಿ) you can assign for Euphorbia neriifolia L.
And ಗೂಟಕಳ್ಳಿ (gutakalli) OR ಗೂಟಗಳ್ಳಿ (gutagalli) for Euphorbia nivulia Buch.-Ham. (Synonym Euphorbia neriifolia Roxb )
I believe, the plant authorities are not mere suffix, but decides the Authenticity of the plant material.
Wishes,
Gurumurthi Hegde.