Phylogeny and Historical Biogeography of Veronica Subgenus Pentasepalae (Plantaginaceae): Evidence for Its Origin and Subsequent Dispersal

Abstract

Veronica subgenus Pentasepalae is the largest subgenus of Veronica in the Northern Hemisphere with approximately 80 species mainly from Southwest Asia. In order to reconstruct the phylogenetic relationships among the members of V. subgenus Pentasepalae and to test the “out of the Iranian plateau” hypothesis, we applied thorough taxonomic sampling, employing nuclear DNA (ITS) sequence data complimented with morphological studies and chromosome number counts. Several high or moderately supported clades are reconstructed, but the backbone of the phylogenetic tree is generally unresolved, and many Southwest Asian species are scattered along a large polytomy. It is proposed that rapid diversification of the Irano-Turanian species in allopatric glacial refugia and a relatively high rate of extinction during interglacial periods resulted in such phylogenetic topology. The highly variable Asian V. orientalis–V. multifida complex formed a highly polyphyletic assemblage, emphasizing the idea of cryptic speciation within this group. The phylogenetic results allow the re-assignment of two species into this subgenus. In addition, V. bombycina subsp. bolkardaghensis, V. macrostachya subsp. schizostegia and V. fuhsii var. linearis are raised to species rank and the new name V. parsana is proposed for the latter. Molecular dating and ancestral area reconstructions indicate a divergence age of about 9 million years ago and a place of origin on the Iranian Plateau. Migration to the Western Mediterranean region has likely taken place through a North African route during early quaternary glacial times. This study supports the assumption of the Irano-Turanian region as a source of taxa for neighboring regions, particularly in the alpine flora.

A new species of Veronica (Plantaginaceae) from Western Iran

“…Fisch. only by its dense, compact habit, thinner petals and some other subtle morphometric differences, but the molecular studies confirmed that it is a distinct species ( Doostmohammadi et al 2022 ). However, V. kurdistanica is a unique species within V. kurdica complex differing from all others by its glandular indumentum, apart from other subtler differences mentioned above.…”

“…6 ), by far the most species-rich subgenus in Iran, with many perennial, mountainous species. It has been demonstrated that this subgenus has probably originated in the Iranian plateau, with several relict and morphologically isolated species distributed at present along the Zagros and Alborz Mountains ( Doostmohammadi et al 2022 ).…”

“…12808 HKS) was generated using ITS1 and ITS4 primers ( White et al 1990 ). The new sequence was added to a sequence matrix, based on published sequences of Doostmohammadi et al (2022) . All sequences were aligned using MAFFT v. 6.0 ( Katoh and Toh 2010 ) and edited manually using PhyDE v. 0.9971 ( Müller et al 2010 ).…”

“…However, several new taxa were added afterwards ( Saeidi-Mehrvarz et al 2001 ; Saeidi-Mehrvarz and Assadi 2003 ; Saeidi-Mehrvarz 2005 , 2011 ) and the genus includes 61 species with 18 species endemic to the country according to the latest “Flora of Iran” ( Saeidi-Mehrvarz 2011 ). At least two species have since been added to the flora of Iran ( Doostmohammadi et al 2021 , 2022 ). Among these, most species occur in the Zagros and Alborz (also Elburz) Mountains of Iran, which are important centers of diversity of Veronica .…”

Advances in Plant Taxonomy and Systematics

“…Stereothrix (Fabaceae, Fabales, eudicots) [ 24 ] and Veronica subg. Pentasepalae (Plantaginaceae, Lamiales, eudicots) [ 25 ] from Eurasia were addressed. Whole plastome comparison revealed phylogenetic relationships in Crassula (Crassulaceae, Saxifragales, eudicots) [ 26 ] and in the family Magnoliaceae (Magnoliales, early branching angiosperms) [ 27 ].…”