And this is what sets this new “species apart from other known Japanese species.” 

A new study reveals yet another surprising new species of weevil discovered in Japan’s pristine subtropical forests on Ishigaki Island and Yanbaru National Park in Okinawa. Scientists are “sure that taxonomists, conservation biologists, and local naturalists in Okinawa will be interested in knowing that yet another remarkable species has been discovered in the Ryukyu Islands.” 

A previously unknown species of weevil has been uncovered in the unspoiled subtropical forests of Ishigaki Island and Yanbaru National Park in Okinawa, Japan.

The Ryukyu Islands, renowned for their extraordinary biodiversity, form a chain of subtropical islands located between mainland Japan and Taiwan. These islands boast a distinctive and captivating insect fauna, thanks to their relatively isolated evolutionary history.

Since 2015, researchers from the Okinawan Institute of Science and Technology (OIST) have been using net traps to monitor insect populations on Okinawa Island. They have collected a diverse array of insects, including beetles, flies, wasps, and bees, which are preserved in ethanol, dried, and stored in the OIST insect collection.

Using meticulous microscope analysis and dissection techniques, OIST entomologist Jake H. Lewis, the Collection Manager in the OIST Environmental Science and Informatics Section, successfully identified and classified the newly discovered beetle species as Acicnemis ryukyuana.

“When I arrived at OIST in 2022, I dove headfirst into the OIST weevil collection. As I closely examined them, this species immediately caught my eye. It clearly belonged to the genus Acicnemis, but was unlike anything else described from East Asia,” adds Lewis. “Its elongated scales and unique coloration set this species apart from other known Japanese species.” 

Validating the finding of a new species within the genus Acicnemis necessitates comprehensive scrutiny of the available literature and museum collections, considering that this particular genus already comprises more than 180 known species.

Since the “type specimens,” the original specimens used for species description, are housed in European and Japanese museums, Lewis had to collaborate with various institutions, including the Kyushu University Museum (Japan), the Natural History Museum in London (UK), and the Senckenberg German Entomological Institute (Germany), to validate the status of Acicnemis ryukyuana as a distinct species.

Based on current knowledge, Acicnemis ryukyuana is endemic to the Ryukyu Islands. The entomologist bestowed the name “ryukyuana” [from Ryukyu] and “リュウキュウカレキゾウムシ” [pronunciation: Ryuku-kareki-zoumushi, translation: “Ryukyu dead-tree weevil”] in Japanese to emphasize its exclusive presence within the Ryukyu biodiversity.

Weevils represent one of the most diverse animal groups on Earth and typically subsist on plants. Certain weevil species exhibit high specialization and possess a limited range of preferred host plants. The host plant(s) for this newly discovered species remain unidentified, prompting Lewis to plan further field studies to investigate this aspect.

Acicnemis ryukyuana stands out with its noticeable yellow bands adorning its shoulders and a distinctive arrangement of grey, black, and yellow scales adorning its resilient forewings. Upon closer examination under a microscope, additional distinguishing characteristics become apparent, such as the elongated scales (resembling hairs) on its back and the unique shape of its leg’s final segment.

According to Lewis, “Based on the unique set of features observed in this new species, A. ryukyuana appears to be closely related to some other species in southeast Asia, however DNA analyses will be required to confirm this.”

Lewis expresses his fascination with Okinawa, stating, I was drawn to Okinawa as there are numerous undescribed weevil species in the region, unlike in Canada, my home country, where weevils have been much more thoroughly studied. Living in Okinawa and having Yanbaru National Park as a backyard is very exciting as it is home to many undescribed, endemic species.”

He further exclaims, “The Ryukyu Islands offer an irresistible playground for taxonomists, rich in species which you only find here.”

Despite the extensive deployment of insect traps across various regions of Okinawa Island, including densely populated and disturbed areas, A. ryukyuana was exclusively captured within a pristine and specially protected section of Yanbaru National Park. Additionally, specimens of this new species were collected from well-preserved subtropical forests on Ishigaki Island and identified by Lewis in the collection at the Kyushu University Museum. “Based on these collection locations, it appears that this weevil species displays a heightened sensitivity to human disturbances compared to other Acicnemis species commonly found in the Ryukyu Islands.”

Lewis suggests, “This newly discovered beetle might be considered a vulnerable, endemic element of the Ryukyu fauna, similar to the flight-less bird Okinawa rail, the Yanbaru long-armed scarab beetle and the Okinawa spiny rat.”

He adds, “I am sure that taxonomists, conservation biologists, and local naturalists in Okinawa will be interested in knowing that yet another remarkable species has been discovered in the Ryukyu Islands.”

Source: 10.1649/0010-065X-77.2.185

Image Credit: Getty