A treasure trove of new species discovered in Fiji’s highlands has revealed biodiversity far beyond what biological science researchers expected, according to Flinders University Associate Professor Michael Schwarz.

Three successive years of federal New Colombo Plan funding has enabled Flinders University, in collaboration with University of South Australia, the South Australian Museum, and the University of the South Pacific, to explore terrestrial biodiversity in Fiji – and led to the unexpected discovery of many new species.

Before the study project began in 2016, there were only three known species of Fijian native bees. The most recent research excursion, completed in April 2018, indicates there are more than 20 species.

Surprisingly, most of these new species are limited to specific mountain regions, sometimes only a few kilometres away from each other – an intriguing evolutionary biology puzzle that researchers are now keen to explore further.

Cale Matthews, who studied bee diversity at Fiji’s highest mountain Mount Tomanvi in 2017 and 2018, says Fiji holds a trove of biodiversity secrets that are yet to be discovered. “Every time we go back, we uncover more species and we are continually surprised by the extent of Fiji’s bee diversity,” says Cale.

Studies in Fiji funded by the New Colombo Plan have also provided tantalising evidence of how natural landscapes and their modification by humans have influenced biodiversity in the tropics.

“When we look at species today, we need to be mindful that what we see is not only the product of ancient evolution, but also human influences that have changed ecosystems over the past few thousand years,” says Associate Professor Michael Schwarz.

New genetic analyses show that at least one native bee has benefitted enormously since the mysterious Lapita people first colonized Fiji about 3000 years ago. Their use of fire and agriculture increased open clearings in Fijian lowlands and this would have increased the habitat that native bees need for nesting.

“Recent research suggests that biodiversity patterns can’t be understood just in terms of ecology, but also how speciation is shaped by interactions with parasitic micro-organisms,” says Flinders University’s Olivia Davies, who works on the genetics of Australian native bees and helped lead two of the latest research field trips to Fiji.

Other achievements from the past two years’ work including the identification of a new species of wasp, Gasteruption tomanivi. The find occurred during last year’s New Colombo Plan research trip to Fiji, when Flinders students Ben Parslow, James Dorey, Olivia Davies and Associate Professor Michael Schwarz and South Australian Museum’s Mark Stevens travelled with 18 students to the island of Viti Levu to collect bees and wasps in the mountains.

Close-up images of the new wasp species Gasteruption tomaniv discovered in Fiji: A, lateral head. B, frontal head. C, dorsal head. D, lateral hind leg. E, lateral mesosoma. F, dorsal mesosoma.

Cale Mathews was one of the few students on this field trip who was able to climb Fiji’s highest mountain, Mount Tomanivi, and collected this completely unexpected specimen close to the mountain peak. “Field work in these remote highland regions is very physically demanding, so recognising a very small but unique species after all the climbing requires some special skills,” explains PhD student Ben Parslow.

“I knew as soon as I saw the specimen that it was a species of Gasteruption. I was extremely excited as I am currently researching the genus in Australia and the Fiji specimen was very different to the Australian fauna. This wasp is the first representative of the genus Gasteruption to be discovered in Fiji and is a distinctive new species.”

The new species is identified in the article First record of Gasteruption Latreille (Hymenoptera: Evanioidea: Gasteruptiidae) from Fiji with the description of a new species, by Ben A. Parslow, Mark I. Stevens and Michael P. Schwarz, published in the journal Zootaxa (DOI: 10.11646/zootaxa.4407.1.7)

Associate Professor Mark Stevens says the recent discoveries have identified the importance of continuing and expanding the scope of biodiversity research being conducted in Fiji.

“I have worked extensively in the Antarctic, but was amazed to see how much greater the biodiversity was in the Fijian highlands and the potential effect of glacial cycles in promoting this diversity,” says Associate Professor Stevens. “We are still trying to understand why species numbers are so high in tropical latitudes and a new model of island biogeography is clearly needed”.

The most recent work by Flinders students in Fiji, completed in late April, included research into butterflies and pollination networks, to gain a deeper understanding of how Fiji has evolved into a tropical biodiversity hotspot.

Nature photographer and Flinders PhD student James Dorey has begun documenting Fijian butterflies to produce the first authoritative field guide to this stunning group of insects, along with genetic analyses to study their evolutionary origins.