The genus Tamarix (Tamaricaceae) is a lineage of shrubs and trees with leaves reduced to scales and numerous species adapted to moist and often saline soils in arid and semi-arid climates. Extensive morphological variation and hybridization complicate species delimitation and identification. Based on both morphological and DNA sequence characters, Tamarix humboldtiana Akhani, Borsch & N. Samadi is described as a new species from S Iran. Phylogenetic analysis of plastid rpl16 intron and trnG-trnS spacer sequences depicts a sister group relationship of its unique plastid haplotype to T. tetrandra, whereas nuclear ITS sequence data show close affinities to T. kotschyi. The new species differs from T. kotschyi by distinctly pedicellate, 5-merous flowers and vaginate-amplexicaul leaves. The stem and foliar anatomy and the epidermal micromorphology provide additional characters differentiating the new species from T. kotschyi. The gametic chromosome number of n = 12 reflects that of most of other species of the genus. Tamarix humboldtiana is a rare species living at freshwater riversides in S Iran and is according to current knowledge critically endangered.

Citation: Akhani H., Samadi N., Noormohammadi A. & Borsch Th. 2019: A new species of Tamarix (Tamaricaceae) from Hormozgan Province, S Iran, supported by morphology and molecular phylogenetics. – Willdenowia 49: 127–139. doi:  https://doi.org/10.3372/wi.49.49113

Version of record first published online on 17 April 2019 ahead of inclusion in April 2019 issue.