Using X-ray microtomography, a 3D imaging technique that uses X-rays to visualize cross-sections of the objects’ internal structure, Lewis and his collaborators digitally removed the scales that covered the weevils’ cuticle. They found that the underlying cuticle differs significantly between species and therefore can be used for taxonomic and classification purposes. Using this technique in combination with traditional optical microscopy and DNA barcoding, they discovered, described and named 12 new species of weevils from Japan, Malaysia, Vietnam and Taiwan. These species measure between 1.5 and 3.0 mm in length and are relatively small weevils.

Two of these new species are present in Japan: Aphanerostethus magnus (Oo-daruma-kuchikakushi-zoumushi) And Aphanerostethus japonicus (Nippon-daruma-kuchikakushi-zoumushi). One of them, Aphanerostethus japonicusis also found in Yanbaru National Park, Okinawa. This is the first time that X-ray microtomography has been used to remove obscuring scales to examine underlying morphological differences for taxonomic purposes. The results of this study were published in the journal Zoo Keys.

The researchers showed that removing scales using X-ray microtomography reveals significant morphological differences between species, which cannot be easily observed by other methods. Therefore, this technique could gain popularity as a tool for identifying new insect species, especially those covered in scales or debris.

Lewis, head of the OIST insect collection and lead author of the paper, examined specimens from collections in Canada, Germany, Japan, Malaysia, Taiwan and the Netherlands. One of the main objectives was to investigate the use of X-ray microtomography as a tool for weevil taxonomy. The gender Aphanerosthethe has been little studied in the past, but many undescribed species have been discovered in museum collections around the world, including the two new species from Japan.

Several methods for finding new species

Researchers used traditional methods such as light microscopy and dissections to observe differences between species, including scales along the elytra (backs), leg spines, and the shape of the rostral canal (a channel that protects the tribune). They also used DNA barcodes to analyze their genes and create a phylogenetic tree of eight species. Some species were not as easy to separate based on morphology alone, but because genetic sequences differ between species, the phylogenetic tree was informative and provided additional evidence for the existence of new species.

Although the above methods are common practice in taxonomy, the researchers’ use of X-ray microtomography was new and was successfully used to examine the structure of not only the hidden cuticle, but also the hindwings . Aphanerosthethe weevils have lost the ability to fly due to the gradual reduction of their hindwings, but the degree of reduction has been shown to differ between species. Normally, specimens would be dissected to visualize the hindwings, but because X-ray microtomography allows non-destructive examination of internal anatomy, it is invaluable when working with rare or valuable specimens that cannot be dissected. or modified.

The presence of partially reduced wings in some species offers a fascinating insight into the ongoing process of evolutionary change: “Some species have almost completely lost their hindwings, while others still have non-functional half-wings with vein patterns remaining. The loss of hindwings is not only useful for taxonomy and systematics, but also shows how different species within the same group can be at different stages of loss of a historically very important organ that played a crucial role in insect evolution,” Lewis explained.

Investing in Japan’s natural heritage

Discovering new weevil species can be difficult for two main reasons. First, weevils are incredibly diverse, making complete cataloging time-consuming and tedious. Second, many weevil species are very host specific, may only inhabit very particular microhabitats, and may only be active for a short period as adults. For example, some species feed on a single tree species and may only occupy a certain part of a tree, such as the canopy. Additionally, some weevil species are strictly nocturnal and rarely seen during the day.

This extreme specialization and variation in natural history means that unless researchers investigate day and night, through the seasons, and focus on specific parts of many different plant species, they will inevitably overlook some species .

Dr. Dan Warren, a researcher at the Gulbali Institute of Applied Ecology and former head of the Environmental Sciences and Informatics Section, highlighted the importance of investing in specimen collections: “These collections specimens are crucial for discovering new species and documenting changes in biodiversity. derived from both human activities and natural cycles, they are essential tools for scientific research and conservation biology,” he said. “Without adequate support for them and the people who maintain them, we risk losing irreplaceable information about species and ecosystems, potentially before we even discover them.”

“These new weevil species are part of Japan’s natural heritage, and although they are still poorly understood ecologically, discovering and naming them is the first step toward understanding their biology,” Lewis added. Protected areas like Yanbaru National Park, home to the newly discovered species A. japonicusare essential to the protection of the island’s rich and endemic biodiversity.