Stick and leaf insects are a clade that has evolved remarkable morphological adaptations for botanical camouflage and mimicry. Phasmatodea includes more than 3,000 known species distributed across most regions of the world, with dozens of species new to science described annually. Most phasmids resemble sticks, bark, and twigs. However, rarer instances of mimicry exist, like mosses, lichen, and leaves, allowing them to blend seamlessly into their arboreal habitat. Several new species are described annually.
An international research team, including the University of Göttingen, has discovered seven previously unknown species of leaf insects, also known as walking leaves. These insects are members of the stick and leaf insect group, and their distinctive appearance protects them from predators while presenting a challenge to researchers.
The researchers discovered “cryptic species” that cannot be differentiated by their exterior appearance. The findings are essential for the systematic research of leaf insects and the protection of their variety.
Taxonomy is difficult in the case of leaf insects since individuals of various species might be difficult to distinguish, and there can be huge variations within a species.
The Project Lead, Dr Sarah Bank-Aubin, Göttingen University’s Animal Evolution and Biodiversity Department, said, “Individuals of different species are often counted as belonging to the same species based on their appearance. We could only identify some new species by their genetic characteristics.”
The researchers could only identify some new species based on their genetic characteristics. Some Individual insects from India were previously assumed to be members of a species widespread in Southeast Asia. However, researchers have found that they represent an entirely new species of leaf insect. Other newly discovered species come from Vietnam, Borneo, Java, and the Philippines.
Bank-Aubin emphasizes, “The finding is important for species conservation: if all the individuals die out in India, it is not just a group within a species that is reduced, as was previously thought. A whole distinct species is being wiped out. This means that the Indian species is essential to protect.”
Dr Sven Bradler, who has been researching the evolution of stick and leaf insects at the University of Göttingen for more than 20 years, explains, “There are around 3,500 known species of stick and leaf insects, and there are currently just over 100 described species of leaf insect. Although they only make up a small fraction of this diverse family of insects, their spectacular and unexpected appearance makes them unique.”