This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Researchers have used genome-wide DNA data to identify a new insect species on the Ogasawara Islands, a remote Japanese archipelago roughly 900 to 1,000 kilometers (560 to 620 miles) south of Tokyo. The findings suggest that evolution among island insects is more intricate than appearances imply.
The study is published in ZooKeys. The Ogasawara Islands are a UNESCO World Natural Heritage site, celebrated for their endemic land snails and plants. Their insects, of which some 440 endemic species are known, have received far less evolutionary attention.
Jun Souma, of Hirosaki University's Shirakami Research Center for Environmental Sciences, and Naoyuki Nakahama, of the Graduate School of Agriculture at Osaka Metropolitan University, examined Omoplax, a genus of lace bugs found nowhere else and thought to have diversified rapidly across the islands. Analyzing 52 specimens with a genetic method known as MIG-seq, the team found that an insect previously regarded as a single species, Omoplax desecta, in fact comprised two species. Populations on the Chichijima and Hahajima island groups were genetically distinct, and subtle differences in male genitalia confirmed the split.
The Hahajima population is now described as Omoplax sandoru, named for its host plant's local name. Souma was first drawn to Omoplax desecta by its unusual diet. "The reason I took a particular interest in Omoplax desecta is that it feeds on both the native plant Rhaphiolepis indica var. tashiroi and the introduced plant Calophyllum inophyllum in the Chichijima island group," he said.
"This is quite unusual for lace bugs, which typically exhibit high host specificity. I was also intrigued by the fact that it is distributed across multiple island groups, which is different from other Omoplax species." The Hahajima population posed its own puzzle. "I had wondered why it fed exclusively on Rhaphiolepis indica var. tashiroi and why there were no individuals with a dark brown to black pronotum, which are sometimes seen in the Chichijima island group," Souma explained.
"After conducting population genetic and phylogenetic analyses, I began to suspect that this population might be a distinct species. Upon closely observing their morphological characteristics, I was certain of this." The evolutionary tree also overturned expectations. "The most surprising finding of my research was that species feeding on the same plant and appearing very similar are not necessarily sister groups," said Souma.
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