Phylogenetic relationships in Indian Daphne (Thymelaeaceae) based on nuclear ITS and cpDNAdata

Daphne (Thymelaeaceae) is a small group of shrubby plants mainly distributed in subtropical and temperate regions of the world with a few species also occurring in alpine habitats. Of ca. 95 species in the world, six species and one variety are reported from India. Phylogenetic relationships of the Indian Daphne were investigated based on nuclear (ITS) and plastid (rbcL and trnL-F) regions. A total of 21 sequences representing five taxa of the six species reported from India were newly generated for the present study. The phylogenies using ML and Bayesian analyses obtained from individual and combined datasets were congruent and strongly supported the monophyly of the genus Daphne. Combined analyses revealed two major well-supported clades. The systematic relationship of the narrow endemic species, D. thanguensis was also confirmed as sister to the morphologically similar D. tangutica. The study supports the independent species status of D. retusa and D. tangutica. Ancestral state reconstructions were done using two major features, viz. presence or absence of indumentum on calyx and colour of the calyx occurrence of species. A taxonomic key has also been provided for the Indian taxa. This is the first comprehensive molecular study on the Indian Daphne.

Automated summary

This study investigates the phylogenetic relationships of Indian Daphne species based on nuclear and plastid sequences. The results support the monophyly of the genus Daphne and reveal two major well-supported clades. The study also confirms the relationship between the narrow endemic species D. thanguensis and the morphologically similar D. tangutica, and supports the independent species status of D. retusa and D. tangutica.