| dc.description.abstract | Hygrophila R.Br., a prominent genus within the tribe Ruellieae of the Acanthaceae
family, is known for its diverse aquatic and semi-aquatic species, predominantly
found in the Old-World tropics. Despite its ecological significance, the genus has
been under-explored, particularly within India, where no comprehensive taxonomic
studies have been conducted since the Flora of British India. This work addresses
the taxonomic ambiguities and evolutionary relationships within the Indian species
of Hygrophila through an integrative approach that combines morphological and
molecular analyses.
Consultation of major herbaria and literature survey recorded 15 species of
Hygrophila in India. Extensive fieldwork across India facilitated the collection and
identification of 12 Hygrophila species. The 3 species of Hygrophila (2 in Flora of
British India and 1 from Little Andaman) were documented only once from their
type localities and have not been reported since, making it impossible for us to
collect them. Detailed descriptions, phenological data, distribution maps, and
taxonomic keys for Indian Hygrophila species are provided. The research revealed a
high species diversity in Peninsular India, with approximately 40% endemism. The
study reported the extended distribution of Hygrophila phlomoides Nees from South
India. Notably, the study reinstated Hygrophila phlomoides Nees and clarified the
nomenclature and identity of several species.
Morphological studies were complemented by molecular analyses using nuclear
(ITS) and chloroplast (rbcL) genomes. This work represents the first molecular
phylogenetic analysis of Hygrophila in India, contributing significantly to the global
understanding of the genus. The phylogenetic data, supported by high bootstrap
values, highlighted the non-monophyly of Hygrophila, suggesting the inclusion of
the genus Brillantaisia P.Beauv. Based on this analysis, four species of Brillantaisia
are proposed to be transferred to Hygrophila. These findings necessitate further
global sampling to resolve taxonomic complexities within the genus. This comprehensive treatment of Hygrophila enhances the documentation of India's
plant diversity and paves the way for future research in phytochemistry,
pharmacology, and conservation. The study's outcomes, including submitting DNA
sequences to GenBank and developing an optimized DNA extraction protocol,
provide a foundation for subsequent systematic and evolutionary studies in
Acanthaceae | en_US |
