Reinstatement of Acalypha fallax Mull. Arg. and description of A. brittoi sp. nov. based on micromorphological and molecular characters

In 1865, Müller Argoviensis proposed Acalypha fallax based on specimens from Peninsula Indiae orientalis, which is now considered synonymous with A. lanceolata Willd. A recent study conducted in Tamil Nadu, India, from 2019 to 2022 thoroughly examined Acalypha species using multiple criteria: leaf epidermal characteristics, seed morphology, pollen features observed via scanning electron microscopy (SEM), and sequencing of the ITS, rbcL and matK spacer regions. This work identified distinctions between A. fallax and A. lanceolata, such as longer peduncles, obovate bracts in male flowers, and stems with two types of trichomes: strigose and hirsute. Moreover, the study proposed a new species, A. brittoi, which is described here as distinguishable from A. fallax by its larger leaf blades with 13–14‐toothed margins (compared to smaller blades with 8–9‐toothed margins in A. fallax), and by the ovate perianth of its male flowers (versus orbicular perianth in A. fallax). Unique patterns of leaf epidermal crystals and granules on seed surfaces further aided in distinguishing A. fallax from A. brittoi. Molecular analysis additionally confirmed genetic differences among these three species.