Synoptic overview of exotic Acacia, Senegalia and Vachellia (Caesalpinioideae, Mimosoid Clade, Fabaceae) in Egypt.
For the first time, an updated checklist of Acacia, Senegalia and Vachellia species in Egypt is provided, focusing on the exotic species. Taking into consideration the retypification of genus Acacia ratified at the Melbourne International Botanical Congress (IBC, 2011), a process of reclassification has taken place worldwide in recent years. The review of Acacia and its segregates in Egypt became necessary in light of the available information cited in classical works during the last century. In Egypt, various taxa formerly placed in Acacia s.l., have been transferred to Acacia s.s., Acaciella, Senegalia, Parasenegalia and Vachellia. The present study is a contribution towards clarifying the nomenclatural status of all recorded species of Acacia and its segregate genera. This study recorded 144 taxa (125 species and 19 infraspecific taxa). Only 14 taxa (four species and 10 infraspecific taxa) are indigenous to Egypt (included now under Senegalia and Vachellia). The other 130 taxa had been introduced to Egypt during the last century. Out of the 130 taxa, 79 taxa have been recorded in literature. The focus of this study is the remaining 51 exotic taxa that have been traced as living species in Egyptian gardens or as herbarium specimens in Egyptian herbaria. The studied exotic taxa are accommodated under Acacia s.s. (24 taxa), Senegalia (14 taxa) and Vachellia (13 taxa). Identification keys for the studied genera, generic groups and species have been provided using different taxonomic criteria. For each taxon, the validated name with the first citation followed by relevant Egyptian citations, typification, synonyms, distinctive features, origin, ecology (when available), utilisation and selected specimens are provided. The study revealed the presence of 22 newly recorded taxa in Egypt. Additionally, a list of excluded, unvalidated and unresolved names is given.