15-million-year-old insects stun scientists with their unusual traits

Miocene sediments in parts of New Zealand have always hinted at a lively past. Now, new finds in the Hindon Maar Complex suggest that ancient insects may have been more varied than once imagined. 

Among these specimens, researchers identified a new genus of whitefly, along with the first known psyllid wing fossil from this part of the world.

They studied puparia on old leaf fragments and noted fascinating features, including distinct body segments and specialized shapes around the insect’s feeding and breathing areas.

Ancient whitefly fossils

These discoveries broaden what is known about insect life in the region. Middle Miocene rocks, roughly 14.6 million years old, yielded delicate traces of creatures that once moved among ancient plants. 

“These represent the first fossil records of these sternorrhynchan families (Hemiptera) from New Zealand,” said Dr. J. Drohojowska from the Geology Department, University of Otago. 

Dr. Drohojowska and the team found the samples in sedimentary layers that had been created by volcanic explosions that shaped small maar lakes in Otago.

Naming the new whitefly

The new species is called Miotetraleurodes novaezelandiae. Its puparia, or final juvenile forms, were still attached to ancient leaves when excavated.

This insect measured about 1.5 millimeters in length, had a sturdy outer covering, and sported clear impressions of each body segment. 

Such definition of distinct segments is not as common in modern whiteflies, which usually show smoother boundaries.

The unique structure may help experts compare Miocene whiteflies with contemporary relatives and trace changes in the group’s morphology.

Studying psyllid history

The second discovery involves a psyllid wing. Researchers say it is about 3.6 millimeters long and has vein patterns that match members of the family Psyllidae.

In many modern psyllids, wings look fragile and glassy, often with unique breaks or curves near the edges. 

This fossil wing shares some structural details with species found in Europe today. The team could only classify it down to the family level because the rest of the insect was missing.

Still, it represents the first known psyllid from New Zealand’s fossil record, which is a remarkable addition to the nation’s entomological timeline.

Roots of New Zealand’s insect fauna

Before these discoveries, local fossils offered limited evidence about how the country’s insect families established themselves over time. In modern New Zealand, sternorrhynchans include small aphids, scale insects, whiteflies, and psyllids. 

Studies show some groups have only a handful of native species, whereas others, like certain scale insects, have branched into numerous forms. 

It is widely believed that a big part of New Zealand’s fauna drifted along with landmasses or arrived via oceanic or airborne dispersal. However, actual fossil snapshots help fill gaps and suggest that some insect lineages might have been on the islands for longer than was previously assumed.

Possible insect-plant relationships

Fossil leaves uncovered at the Hindon Maar Complex are packed with details about plant-insect interactions.

Many of the whitefly puparia were attached to their host leaves in a life position, leaving behind a record that reflects the insects’ feeding style. 

Plant hosts for these ancient whiteflies remain unidentified, but the presence of multiple puparia on single leaves points to group feeding in certain spots.

Such clues open new doors for comparing host choices in early Miocene insects with those of living species in the same family.

Whitefly species outside New Zealand

Researchers in other parts of the world have explored whitefly and psyllid fossils in places like the Eocene deposits on the Isle of Wight, as well as the Miocene layers in Europe.

Comparisons across continents could indicate whether these insects traveled widely or stuck to regional plant communities. 

In modern settings, whiteflies often cause economic troubles by weakening crop plants, while psyllids transmit diseases in orchards.

By analyzing ancient relatives, scientists may be able to see whether similar traits (like feeding preferences) were present millions of years ago.

Contributions from the research team

The fossils of Miotetraleurodes novaezelandiae are housed in the Geology Museum at the University of Otago.

The lead investigators used scanning electron microscopy and other techniques to examine the puparia and the single psyllid wing. 

Each fossil was kept safe in carbonaceous mudstone. This find boosts the number of insect groups described from the Hindon Maar Complex, which already included dragonflies, beetles, and more.

What happens next?

There is still much to learn from these rocks. Fossil-rich maar sediments hold fish, plant, and insect remains that reveal how New Zealand’s climate and habitats have changed.

Some experts think these small lakes, formed by explosive volcanic events, might hide still more families of insects. 

The interplay between ancient vegetation and invertebrates presents countless angles for new research. As more specimens emerge, they may transform ideas about which lineages survived regional climate shifts and how modern species took shape over time.

Implications for modern biodiversity

Modern-day New Zealand is known for having unique species that are adapted to island life, from flightless birds to specialized insects.

Each fossil find, especially one that shows direct plant-insect links, gives specialists another line of data to interpret present-day diversity.

The story of how animals reached and thrived in an isolated archipelago is central to island biogeography. Insects like whiteflies and psyllids, which depend on particular plant hosts, can supply insights about ecosystem resilience.

The study was published in Palaeobiodiversity and Palaeoenvironments.

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