Abstract
Tribulus, a highly polymorphic genus, includes many intermediate forms. Taxonomy of these taxa, mostly found in the same population has been studied over a wide range and a number of problematical species is discussed to resolve which of these merit taxonomic recognition. Five new combinations are proposed and the reasons for dropping the status of a few specific epithets, including amanense Hosni, to the level of synonyms are discussed in detail. Of the taxa described, T. rajasthanensis Bhandari and Sharma (1977) is reported for the first time from the Arabian Peninsula.