# Another Type of Beetle Larva of Elateridae from Kachin Amber: A Hairy Click Beetle Larva

## TL;DR

A new type of 100-million-year-old click beetle larva with long body hairs was discovered in Kachin amber, suggesting it may have hunted in termite nests.

## Contribution

A fourth morphotype of fossil click beetle larva is described from Kachin amber, with potential predatory adaptations and possible developmental stages.

## Key findings

- The new larval morphotype has long, stiff setae that may have provided protection during predation.
- The larvae likely hunted in termite nests, increasing their chances of being preserved in amber.
- Twelve specimens represent two or three species, including a possible developmental series.

## Abstract

Beetle larvae have very different functions in ecosystems today. This is also true for the larvae of click beetles. Very few fossils of click beetle larvae have been found to date. In 100-million-year-old amber from Kachin, Myanmar, a very diverse fauna is preserved, but even there, only three different morphotypes of click beetle larvae are known. In this study, we present a fourth morphotype of fossil click beetle larvae, which has very long setae on its body. The morphology of its mouthparts points to the larvae being predators. Because the setae on the body are long and apparently rather stiff, they might have protected the larvae while hunting, for example, in termite nests, which is what some click beetle larvae do today. As termites live near or in wood, this makes it more likely that the click beetle larvae will become trapped in resin, which will later become amber. Here, we present twelve of these fossilised larvae of the new morphotype, which represent two or three possible species and seem to include a developmental series for one of these.

In the modern fauna, click beetle larvae are important ecosystem components, fulfilling different ecological functions. The fossil record of click beetle larvae is still scarce. Even in the very diverse fauna of the Kachin amber forest (Myanmar, Cretaceous, ca. 100 million years old), only three morphotypes of click beetle larvae have been reported so far. Here, we add a fourth morphotype, characterised by very long setae. The mouthparts indicate a predatory lifestyle. The long and quite stiff-appearing setae might have protected the larvae, for example, when hunting in termite nests, which is a strategy that some extant click beetle larvae apply. This would also imply a closer association with wood and thus a greater likelihood of preservation in amber. Here, we present twelve larvae of this new morphotype, representing two or three possible species, including an ontogenetic series for one of these.