Taxonomic reappraisal of the mangrove genus Avicennia (Acanthaceae) in India

A taxonomic reappraisal of the mangrove genus Avicennia in India was undertaken through extensive field surveys and critical examination of herbarium specimens. Three taxa, Avicennia alba , Avicennia marina subsp. marina , and Avicennia officinalis , are described in detail. A synonymic list was compiled using the World Checklist of Vascular Plants (WCVP) and assessed through analysis of protologues and original material, with accompanying nomenclatural notes. Accordingly, four lectotypes and one neotype were designated. Leaf forms were investigated using principal component analysis (PCA), as foliar characters have historically served as important criteria for delimiting taxa within the genus. PCA was conducted under four approaches: 1) among A. alba , A. marina , and A. officinalis ; 2) among four infraspecific taxa of A. marina ; 3) across populations from the three major coastal regions of India; and 4) between A. marina subsp. marina and A. marina var. acutissima . In all cases, the analysis indicated that leaf form alone could not reliably distinguish taxa. However, PERMANOVA using quantitative variables employed in PCA showed that, in first two cases, the differences among Avicennia species and among the infraspecific taxa of A. marina were statistically significant. In contrast, the differences among A. marina populations from the three major coastal regions of India, as well as between A. marina subsp. marina and A. marina var. acutissima , were weak. Phylogenetic analysis using ITS sequences from India and other Indo‐West Pacific Avicennia accessions showed broad concordance with established multilocus frameworks; however, several GenBank accessions displayed incongruent placements, suggesting probable misidentifications. Similarly, inconsistency in GBIF occurrence records further point to widespread identification errors. The findings also indicate that A. officinalis populations from India are morphologically distinct from conspecific populations in Australasia, highlighting taxonomic complexity within the genus. To facilitate identification, a taxonomic key to Avicennia taxa in India is provided.