Comparative leaf anatomy between two sister species: Artocarpus odoratissimus (Lumok) and A. mutabilis (Pingan) in Sarawak

Abstract

The indigenous Iban of Sarawak recognize Artocarpus odoratissimus Blanco as two distinct species, lumok and pingan, leading to the recent recognition of the latter as A. mutabilis Becc. While the morphology of these two species is similar, they differ in fruit, stipule, and twig characters. This study aims to identify distinguishing leaf anatomical characters in these taxa and aid in species delimitation. Lumok and pingan samples from primary and secondary forests in central and Southern Sarawak were preserved, sectioned, and mounted. Samples were observed using light and scanning electron microscopy. Findings have shown that these species differ in the type of epidermal walls, the number of cells in the glandular trichomes, the length of non-glandular trichomes, the number of vascular bundles in the midrib and petiole, and the number of collenchyma layers, which distinguish these two species. These anatomical differences support the distinction between A. odoratissimus and A. mutabilis, providing a practical tool for future anatomical and ecological studies of Artocarpus.