Abstract
Precise characterization and delimitation of species are fundamental prerequisites for
biodiversity assessment, conservation planning, and the sustainable management of biological
resources. Bulbophyllum is a large and highly diverse genus of the family Orchidaceae.
Investigations in the Northeast Indian region have revealed an abundance of various
Bulbophyllum species. However, the taxonomy and phylogeny of these North-eastern species
still remain unresolved. This study is the first comprehensive phylogenetic assessment of 20
species of Bulbophyllum from Northeast India, revealing new insights into their relationships.
The complete nuclear ITS region (nrITS) (ITS1, 5.8S, ITS2) and the non-coding psbA-trnH
intergenic spacer of plastid DNA, together with morphometric characters, were used to resolve
the phylogeny of Bulbophyllum species of Northeast India. The nrITS dataset showed better
resolving ability compared to the plastid DNA marker. Phylogenetic trees generated from the
combined analysis of morphological and molecular datasets provided the most robust
phylogenetic framework, particularly at the sectional level. The results support the inclusion of
B. reptans in section Reptantia rather than in Racemosae. The three species, B. odoratissimum,
B. trichocephalum, and B. cauliflorum, were found to share a closer relationship, suggesting
that they belong to the same section. The section Desmosanthes requires further investigation
to redefine its boundaries. Furthermore, a taxonomic key for the 20 species has been developed
to facilitate accurate identification based on reliable diagnostic traits. The findings contribute
to a better understanding of species diversity and evolutionary relationships within the genus,
providing an essential foundation for future biodiversity assessments, conservation
prioritization, and management strategies for orchid diversity in Northeast India.