Rhytidocaulon is a plant genus in the family Apocynaceae, first described in 1962.Bally, Peter René Oscar. 1962. Candollea 18: 335Tropicos, genus Rhytidocaulon It is native to northeastern Africa and the Arabian Peninsula.
Species Species accepted by the Plants of the World Online as of February 2023: Rhytidocaulon arachnoideum Rhytidocaulon baricum Rhytidocaulon ciliatum Rhytidocaulon elegantissimum Rhytidocaulon fulleri Rhytidocaulon macrolobum Rhytidocaulon mccoyi Rhytidocaulon molamatarense Rhytidocaulon paradoxum - Ethiopia Rhytidocaulon piliferum - Somalia Rhytidocaulon pseudosubscandens Rhytidocaulon richardianum - Somalia Rhytidocaulon sheilae Rhytidocaulon specksii Rhytidocaulon splendidum Rhytidocaulon subscandens - Somalia, Ethiopia Rhytidocaulon tortum - Arabia
Taxonomy Phylogenetic studies have shown the genus to be monophyletic, and most closely related to the genus Echidnopsis which inhabits the same region. Marginally more distantly related is a sister branch comprising the genus Pseudolithos and the widespread Caralluma stapeliads of North Africa.P. Bruyns, C. Klak, P. Hanacek: Evolution of the stapeliads (Apocynaceae-Asclepiadoideae) - repeated major radiation across Africa in an Old World group. Molecular Phylogenetics and Evolution. 2014. v. 77, no. 1, p. 251--263. ISSN 1055-7903.
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