Tiger beetles are awesome! So everywhere I go, I am on the lookout for these quick little beetles. Beaches are a prime place to find them, and my recent trip to Brazil yielded two species.
One was abundant everywhere we went. It was the tiniest tiger beetle I’ve ever seen, much smaller by a third than anything native to the east coast of the U.S. But it was similar to a few other beach species at home that have diminished markings and cream-colored wing covers that help it blend in with the sand.
The second species I saw was far less abundant. In fact, I only saw one after two weeks of time spent on the beach every day. One day I had an assignment to walk 4 kilometers of beach to check a spot for shorebird activity. Along the way a larger beetle caught my eye among the multitudes of the tiny species. I managed to get a quick photo as I walked. I never saw any others like it again. It reminded me of Cicindela marginata.
Even though tiger beetles are one of the best documented and described groups of insects, there aren’t many field guides for them and not much in the way of web resources for species in South America (although I did subsequently find a key to Brazilian tiger beetles).
So I sent my pictures to one of the world’s great tiger beetle gurus, David Pearson. He then consulted with other gurus, Ron Huber and Jürgen Wiesner.
From David:
The first one is almost certainly Cylindera (Plectographa) suturalis, but the second one looks like a Caribbean species that is presently known from only as far east as the greater Antilles islands (Cuba, Jamaica, etc.) Habroscelimorpha boops, or perhaps a closely related specie that is known from the coast of Venezuela, Habroscelimorpha auraria. If valid, this would be a considerable range extension.
Wow! That second beetle was something interesting.
Ron Huber helped confirm that it was the latter possibility, Habroscelimorpha auraria. It seems that the closest documented location for this species is on Margarita Island off the coast of Venezuela. My sighting near Sao Luis, Brazil puts it another 1,630 mile east of there.
Cassola and Pearson compiled a list of all neotropical tiger beetles in 2001. From this I made country distribution maps of the two tiger beetle species I saw, with blue showing where the species has been found.
We can see that Cylindera (Plectographa) suturalis is a very widespread species, occurring throughout the Caribbean Islands and mainland South America (we can also see that somebody needs to do a beetle survey in Suriname – the one gap in the map).
The taxonomy of this species and its subspecies is very confused, but, according to Ron, there is at least two subspecies: hebraea on the mainland and suturalis on the islands. The island versions vary in appearance quite a bit from island to island and there are numerous other proposed subspecies among the islands, but this complexity has yet to be sorted out by scientists.
In contrast, Habroscelimorpha auraria, appears to be neatly tucked into the northwest corner of South America. But my sighting suggests that the species may string all along the coastline of northern South America.
One way to help improve our knowledge of beetle distribution is to have more people looking for them. As Cassola and Pearson say in the intro to their Neotropical checklist, they hope to “encourage further field collecting in many poorly known Neotropical areas by voyagers, collectors, and non-specialist biologists.”
This non-specialist biologist is stoked that he was able to contribute to the cause!