December Species of the Month: Black-lined Flatwing (Heteragrion calendulum)
Heteragrion calendulum (Male). Unfortunately, the high humidity destroyed our cameras and these are the best photos we could get. Photo by Juliana Sandoval-H.
Our DSA December Species of the Month is Heteragrion calendulum (Black-lined Flatwing) in the family Heteragrionidae. Its length is approximately 33 mm, and its range is from the south of Costa Rica to Colombia. Follow DSA webmaster Juliana Sandoval’s adventures as she encounters this rare species.
An Unintentional Find
Many of these blog posts look at the efforts of finding, photographing or collecting a species. My story is no exception. It’s a story of the fortunate event that led to the finding of an unusual species. It is a species that Indiana banker Edward Bruce (“E.B.”) Williamson, a prominent entomologist and devoted naturalist, was looking for more than one hundred years ago. Williamson had a passion for dragonflies and damselflies which took him on expeditions from the Amazon jungles to Caribbean islands. He described many species and compiled one of the world’s most important Odonate collections.
I was born in Colombia, a megadiverse country, where I have been fortunate to study biology. Because of this, I have been involved in different projects that allowed me to live for long seasons in amazing jungles in the Amazon, the Choco biogeographical region (considered the most diverse area in the world), and other Andean and inter-Andean locations in Colombia.
One of these places is a small town, Santa Cecilia (Risaralda), located at the foothills of the western Cordillera Occidental in Colombia, facing the vast Chocoan jungle. Santa Cecilia has a short but harsh story. Originally, native tribes were the only ones that inhabited this land; then, a couple of hundred years ago, afro communities reached the territory escaping from slavery, more recently, in the 1980s, the first highway brought in “development”, and with it, lumber trucks. By the year 2005, the horrors of war made this little town of less than 400 an unwelcome place. Today, thanks to a great improvement in the political situation, the population has increased to almost 9,000 inhabitants. Despite its difficult history, Santa Cecilia is a lovely multicultural place, surrounded by the crystalline rivers and a dense jungle that houses thousands of known and unknown species.
The streams around Santa Cecilia. Photo by Cornelio A. Bota Sierra.
The most pristine jungle areas require a steep, hilly hike. This story takes place in “Quebrada Ranas de Cristal” (Crystal Frogs Stream), so named for its abundance of Glass Frogs in the amphibian family Centrolenidae. To reach this place requires a muddy hike from Santa Cecilia to the first hydration station, which passes the beautiful Mumburutó stream at 500 meters (1,650 ft). We tried not to disturb the Sunbittern (Eurypyga helias) which nested over the ravine, then resumed the hike to our destination at 650 meters (2,100 ft). We visited the stream frequently, and while it was a difficult hike, it offered the reward of seeing lots of birds, mammals, snakes, and bullet ants. Of course, there were also amazing odonates, like the Giant Helicopter Damselflies (Megaloprepus caerolatus), Shadowdamsels (Palaemnema spp.), Clubtails (Gomphidae), Flatwings (Heteragrion spp.), Marta’s Flatwings (Philogenia martae), Coppery coras (Miocora aurea), many Dancers (Argia spp.), Skimmers (Orthemis spp.), Tropical Woodskimmers (Uracis imbuta), Rubyspots (Hetaerina spp.), and some Dragonlets (Erythrodiplax spp.) among others.
The “Quebrada Ranas de Cristal” is at the heart of the mountains. Photo by Cornelio A. Bota Sierra.
But odonates are exigent creatures that love to fly on sunny days. If you take into account that rainfall here is around 6,500 millimeters (254 inches) per year, sunshine is unusual. Often there is a sunny sky in the morning, then dense clouds move in before midday. Occasionally, sunshine appears through a gap in the clouds. When it did, we had to be ready. Dragons and damsels go crazy when the sun shines, even for just a few minutes.
The morning of February 16, 2017, was no different, dense clouds started settling over our heads. After looking for a while, Cornelio A. Bota Sierra and I decided it was time to start our long hike back. Then, the sun decided to shine one more time. In my memory, I have the vivid image of two small but very bright red damsels coming down to the stream among the vegetation. Cornelio was leading the way, and as always, he had his net ready. Before I could say something, he had already trapped both damsels.
I did not recognize this species! I asked Cornelio what species they were, and to my surprise, Cornelio was as clueless as I was. When we took them out of the net, I could see it was the most beautiful damsel I have ever seen in my life. It had a glittery bright gold frons and a bright red abdomen. Cornelio, an expert taxonomist, was still clueless.
The clouds over the mountains that we needed to hike to get to the stream. Photo used with the permission of Cornelio A. Bota Sierra.
We went back, very excited about this mysterious damsel. But the excitement grew when we finally figured out its identity and the story behind this species. One hundred years before, on February 17, 1917, Williamson was on an expedition in the Magdalena region in Colombia, where he found the first and only male known (and type specimen) of this species. He named it Heteragrion calendulum, based on “the brilliant metallic areas on the vertex”. Between the lines of his scientific text, you can read that his excitement about finding this specimen was no less than ours. That, and the mysticism behind the 100 years gap—almost to the exact date—gave us the feeling of closeness with Williamson.
In Williamson’s text, he describes his unsuccessful efforts to find another specimen. We were fortunate to find the female, previously unknown. Since his encounter, no one had reported seeing this species again.
Heteragrion calendulum (Female). Photo by Juliana Sandoval-H.
Luck, a little sunshine, and being at the right place at the right time allowed us to rediscover this long-lost species. In the end, we completed Williamson’s effort to find more specimens of this species in Colombia. Cornelio and I fear for its future, however. The type locality–where the species was first encountered — is long gone. We hope that the vast Chocoan jungle lasts as a refuge for this and many other species that have lost their original habitat.
Juliana Sandoval-H, the DSA webmaster, has spent most of her academic life exploring Tropical jungles, mainly in search of Odonates and birds. She is one of the four authors of the field guide “Dragonflies of the Colombian Cordillera Occidental, a look from Tatama”. You can reach her at julisando@gmail.com.
