Flamboyant Firefly

New species from Brazilian Atlantic Forest

Amydetes marolae

Coleoptera: Lampyridae

Amydetes marolae is one of three fireflies recently discovered in South America.  It, like the entire subfamily Amydetinae, with 50 species in three genera, is known only from the Neotropical region and, curiously, so far only from male specimens.  Traps have failed to turn up even a single female, leading researchers to speculate that females are flightless and possibly larviform.  That is, females of this subfamily may, like certain other fireflies, remain larvae-like in appearance, never fully developing into a typical, fully morphologically formed adult female.  Males of the subfamily continuously glow and have closely set eyes, among other features.  Amydetes have flabellate antennae with 23, or more, segments.

Flabellate antenna are truly impressive.  Their asymmetry is striking and, in some species, their size seems disproportionate to the beetle possessing them.  Flabellate antennae have evolved many times, both among beetles and in other insect orders.  The word comes directly from the Latin flabellum, meaning “fan.”  Flabellate antennae involve several, to many, antennal segments being elongated to one side forming parallel lobes that, when lying against one another, are indeed suggestive of a folded paper fan. 

Molecules associated with bioluminescence, extracted from beetles in this genus, have been used to detect temperature and pH within cells, and may have other applications not yet conceived.  The subfamily is especially species-rich in the Brazilian Atlantic Forest, a biodiversity hotspot with a large proportion of species found nowhere else on earth.  When Portuguese colonists first arrived five hundred years ago, the Brazilian Atlantic Forest was one of the largest rain forests on earth.  Covering about half a million square miles, it was second in area only to the Amazon.  Today, deforestation has destroyed more than 85% of this unique ecosystem and we can only speculate about the species that have been lost.

The new species was collected in hilly areas of Rio de Janeiro, in southeastern Brazil, between 160 and 660 m.  Males fly during the first hours of complete darkness, from near the ground to about 4 m above, emitting blue-green light, and bending their abdomens downward in flight, perhaps as part of their female-searching behavior.

The common name firefly refers to an entire family of beetles, the Lampyridae, with more than two thousand species distributed in both temperate and tropical regions.  As the name glowworm suggests, larvae have bioluminescence and are predators on other insects and gastropods. Many, but not all, adults are bioluminescent, too, with the location of the light organ on the body differing among species, and sometimes between male and female of the same species.  Some adults are predators, too, while others feed on nectar or pollen.  Their life histories are diverse.  Adults are soft-bodied, most living only a few weeks at most, while the larval stage varies among species from several weeks to two years, possibly more.  Fireflies show up in the fossil record in the late Cretaceous, about 99 million years ago. 

It is thought that bioluminescence first appeared in larval fireflies as a defensive mechanism, a warning to predators that they taste absolutely awful.  Fireflies later evolved the use of lights, and specific flashing patterns, to attract mates.  There are even some species that synchronize their flashes so as to be seen, as a group, at great distances.  And, in a sinister turn, females of the genus Photuris evolved the ability to mimic, at will, the flash pattern of unrelated species of the genus Photinus. Using this false flag maneuver, she lures amorous male Photinus.  The unsuspecting males, thinking they have located a mate, draw near, only to be eaten.

Amydetes marolae, male: (A) ventral; (B) lateral; (C) dorsal.  Scale bar is 1 mm.  From Campello et al (2022), with permission of Dr. Lucas Campello.

Fireflies hold a special place in cultural mythology, and are one of only a dozen beetles known from classical antiquity.  They are mentioned in Dante’s Inferno, and Pliny the Elder suggested sowing millet and harvesting barley when glowworms appear.  Fireflies have been associated with superstitions in various cultures, at different times, from the foretelling of crop failure to predictions of death, good luck, and love. In Japan, special parks exist where people gather to observe fireflies on warm evenings. 

It appears that firefly populations are declining around the world, including eighteen species in the U.S. that are considered threatened.  Anecdotal observations suggest the phenomenon is widespread, but reliable data exists for very few species.  It is thought that degraded and destroyed habitats are a major driver, along with light pollution, pesticides, and climate change.  So, find a location in the country, far from the glare of city lights, recapture a little of your youthful sense of wonder, and enjoy one of the most amazing displays of nature.

Acknowledgment

I thank Dr. Lucas Campello of the Universidade Federal do Rio de Janeiro for permission to reproduce the photos of A. marolae.

Further Reading

Campello, L., Vaz, S., Mermudes, J. R., Ferreira, A.L.D., and L.F.L. Silveira (2022) Comparative morphology and key to Amydetinae genera, with description of three new firefly species (Coleoptera, Lampyridae).  ZooKeys 1114: 131-166.

Ineichen, S. (2016) Light into darkness:  The significance of glowworms and fireflies in Western culture.  Advances in Zoology and Botany 4: 54-58.