Thursday, October 19, 2017

Red-faced Dragonlet

Just north of the town of Sardinal, Costa Rica, on 5 July 2017, our tour bus came upon a grassy cattle pasture. A few trees shaded a pond. Our guide, Dennis Paulson, exclaimed that this looked like prime dragonfly habitat. Erika and I looked at each other with dismay as Dennis announced that we would definitely require two and a half hours at this location. Fortunately, the only nearby building was a small restaurant across the street.

Dennis was mistaken. He really needed all day in the pasture, but took every minute of his two and a half hours. A number of dragonfly species flew about the area. Most were Red-faced Dragonlets, found from Texas to Argentina, and north into the Lesser Antilles. Their variability makes these dragonflies fascinating. In the United States, Mexico, and northern Central America to northwestern Costa Rica, adult male abdomens are blue. Further south in Costa Rica and western Ecuador, the abdomens are red. East of the Andes and on the Caribbean side of Costa Rica, they are blue-tailed. As you can see in these photos, both morphs of Red-faced Dragolets are found in the Sardinal area.

Dennis later wrote me that “It would be interesting to know if a male that stays red is different genetically from one that becomes blue, but because there are at least some intermediates, it doesn’t seem like a simple genetic difference. It’s definitely an interesting situation. In fact it was very near there in 2010 that I first noticed this variation in one spot.”

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