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| Tamarix humboldtiana Akhani, Borsch & N. Samadi
in Akhani, Samadi, Noormohammadi & Borsch. 2019.
DOI: 10.3372/wi.49.49113
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Abstract
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.
KEYWORDS: Caryophyllales, endemic species, Flora of Iran, molecular diagnosis, phylogenetics, reticulate evolution, species concept, Tamaricaceae, Tamarix
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| Fig. 1. Tamarix humboldtiana. – A: habit and habitat along Minab river; plants grow on the river side and many of them are damaged by flooding; B: part of inflorescence with young flowers; C: part of inflorescence, showing whitish petals and reddish ovary and anthers.
– All photographs taken at the type locality on 21 Feb 2013 by H. Akhani.
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| Fig. 2. Details of leaf, inflorescence and flower parts of Tamarix humboldtiana. – A: part of leafy young branch showing vaginate leaves; B: raceme, note long pedicels; C: calyx outside (left), calyx inside (centre), ovary and stigma (right); D: petals; E: staminal disk, showing 5 peridiscal filaments attached to synlophic disk.
– Scale bars: A–E = 1 mm.
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Tamarix humboldtiana Akhani, Borsch & N. Samadi, sp. nov.
Morphological diagnosis — Based on molecular phylogenetic data, Tamarix humboldtiana is closely related to T. kotschyi and T. tetrandra. It differs from both species by its pentamerous flowers. It differs further from T. kotschyi by its clearly pedicellate (vs ± sessile) flowers. Anatomically, T. humboldtiana differs from T. kotschyi by the absence of ingrowing papillae that overarch the stomatal pores.
Molecular diagnosis — Rpl16 intron, positions in the sequence of the type specimen, upstream of the large 3′ exon: nucleotide character states “C” in pos. 135, “G” in pos. 195, “C” in pos. 323, “G” in pos. 896. TrnGtrnS spacer, positions in the sequence of the type specimen, downstream of the trnG exon: nucleotide character state “T” in pos. 550.
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Eponymy — The epithet “humboldtiana” commemorates the great German phytogeographer Alexander von Humboldt (1769–1859) whose 250th birthday is in the year of publication of this species. The name was also inspired by the Alexander von Humboldt Foundation having supported a research internship on diversity and phylogeny of the genus Tamarix.
Hossein Akhani, Nafiseh Samadi, Alireza Noormohammadi and Thomas Borsch. 2019. A New Species of Tamarix (Tamaricaceae) from Hormozgan Province, S Iran, supported by Morphology and Molecular Phylogenetics. Willdenowia. 49(1);127-139. DOI: 10.3372/wi.49.49113
