A Synoptic revision of Acanthaceae in Egypt, With a new record from Gebel Elba. Eman M. Shamso The Herbarium, Botany Dept, Faculty of Science, Cairo Univ., 12613 Giza, Egypt; e-mail: e.Shamso@yahoo.com . Shamso, E. M., 2010. A Synoptic revision of Acanthaceae in Egypt, With a new record from Gebel Elba. Taeckholmia 30: 127-144 A systematic revision of the native taxa of the family Acanthaceae in Egypt is carried out. The study revealed the presence of nine species belonging to seven genera, two tribes and one subfamily, mostly restricted to the southeastern corner of Egypt. Monechma Hochst. is a new record to the flora of Egypt represented by Monechma debile (Forssk.) Nees, while the presence of Justicia ladonoides Lam. is doubtful. For the investigated taxa, valid name, synonyms, types, general distribution, representative specimens and conservation status are given. Identification keys for the determination of all genera and species are also provided. Key words: Acanthaceae, conservation status, flora of Egypt, Monechma Hochst., new record. Introduction Acanthaceae is a large tropical family of advanced sympetalous dicotyledons. It comprises about 212 genera and 3175 species of herbs and shrubs; several are cultivated as ornamentals (Mabberley, 2008). The family has four centers of distribution: Indomalysia, Africa, Brazil and Central America northward into Mexico (Heywood, 1978). It shows a wide range of morphological variation and is readily distinguished by the usual presence of cystoliths in vegetative parts, the presence of floral bracts and bracteoles, the usually bilabiate corollas, the bivalvate elastically dehiscing explosive capsule and by the retinacula (hook-like funicle) projecting the seeds. Four general classifications of the family were made by Nees ab Ezenbeck (1847), Bentham (1876), Lindau (1895) and Bremekamp (1965). Other geographically based classifications were presented by Burkill & Clarke (1899-1900) and Balkwill & Norris (1988). The most important classification is that of Lindau (1895), who recognized four subfamilies of which the Acanthoideae comprised the genera with retinculate fruits; this character is lacking among the genera of the other three subfamilies viz. Nelsonioideae, Thunbergioideae and Mendoncioideae. Meanwhile Bremekamp (1965) categorized Nelsonioideae under Scrophulariaceae, raised Thunbergioideae and Mendoncioideae to familial level (viz. Thunbergiaceae and Mendonciaceae) and divided his restricted Acanthaceae into two groups (viz. Acanthoideae and Ruellioideae) on the basis of presence or absence of cystoliths, articulated stems, monothecate anthers and colpate pollen.