Haleakala volcano
Haleakalā volcano in Hawaii, where the new beetle species were discovered.Joe Parks/Flickr

More than 70 new species of beetle have been discovered on one of Hawaii's volcanoes. Researchers announced 74 new round-waisted beetles had been identified on Haleakala volcano, Maui Island, in the latest edition of ZooKeys.

James Liebherr from Cornell University, said the discovery shows how Haleakalā is a centre for biodiversity, with the beetles evolving far faster into new species than normal because of their isolation. The group – Mecyclothorax – came from just one single colonising species, with speciation (splitting into a new species) taking place regularly since it arrived on Maui.

"All evidence points to Hawaiian Mecyclothorax having radiated after colonisation of Maui Nui, necessitating speciation that resulted in 239 species in 1.9 million years or less," they wrote. "The large number of new species is based on substantial new collections made from all quarters of the mountain. The dense geographic sampling allows fine-scale discrimination of species boundaries, elucidating the geographic disjunctions that are associated with speciation within this hyperdiverse radiation."

Mecyclothorax
Mecyclothorax medeirosi, a species that lives in Hawaiian rainforest.Prof. James K. Liebherr

As well as being extremely diverse, researchers also found the numbers of Mecyclothorax to be abundant, making their evasion from discovery all the more surprising. They were all found within the limits of Haleakalā's surface area.

Researchers say this may be due to the restricted distribution of many of the species, along with a prior lack of comprehensive field sampling. Liebherr found many areas of the mountain where more than 20 species of Mecyclothorax lived very close together.

He also found different forest areas that had been cut off from one another by the volcanic lava flows and other geographical features meant different areas supported different sets of species. "Haleakalā volcano is a large pie with different sets of beetle species living in the different slices," he said. "Actually, the different pie slices are just like the original Hawaiian land divisions called ahu pua'a, showing that the Hawaiian people had a keen sense for how their island home was organised."

Liebherr said Mecyclothorax will provide a valuable insight into monitoring biodiversity on Haleakalā, such as potential extinction: "Beetles represent a substantial and important source of information concerning the ecological condition of their island home," the study concludes.