Molecular phylogeny elucidates the taxonomy of Indian Dipcadi Medik. (Asparagaceae) and reveal a new species from the bank of Hiranyakeshi River, Maharashtra, India

Abstract

Abstract Dipcadi (Scilloideae: Asparagaceae) is a genus of bulbous monocots with about 40 species. Species delimitation within the genus has been troublesome hindering a comprehensive phylogenetics. The most recent phylogeny (of Ornithogaloideae) by Martínez-Azorín et al. (2011) includes six species of Dipcadi but none is from India. Here, we reconstructed the phylogeny of Ornithogaloideae by including 23 accessions of Indian Dipcadi species. The phylogenetic analyses were based on nucleotide sequences of three plastid regions (rbcL, matK and trnL-F spacer) and one nuclear region (ITS). Pseudogaltonia clavata exhibited sister relationship to Dipcadi. Our combined data phylogeny (covering 31 Dipcadi taxa) resolved Dipcadi into four clades, Clade I, II, III and Clade IV. Clade I, II and III included mainly Indian taxa whereas Clade IV mostly consisted of African species. Clade I included nine taxa including our newly described species D. mukaianum. The new species was phylogenetically placed along with D. erythraeum, D. saxorum and D. ursulae. Morphologically, the species resembled D. montanum and D. ursulae but differed in characters such as tepal cohesion (1/2), number of ovules per locule and foul-smelling flowers. Clade II and III included 11 and six taxa, respectively. D. erythraeum which has a native range from Egypt to western India was found to occupy Clade I and Clade IV. The accession sampled in the present study was placed in Clade I along with D. saxorum whereas the accession from Bahrain grouped with African species (D. gracillimum and D. longifolium) in Clade IV. Similarly, D. serotinum was found sister to the Indian Clade (Clade I, II and III) whereas D. serotinum var. fulvum was nested in the African Clade (Clade IV). Our studies suggest that additional molecular markers (plastid as well nuclear) should be tested for their taxonomy utility. A robust phylogeny can elucidate the biogeography of this small genus across three continents, Africa, Asia and Europe.