Minagrion is a genus of rare and beautiful damselflies almost completely confined to the south-east of Brazil. Five species are known, of which two have been found during our survey at REGUA. Typical for the genus is that they have a process at the venter of S1, something difficult to see in the field, but that can be seen in the hand.
Rare Minagrion mecistogastrum has a very long and thin abdomen. The immature males are beautifully patterned with yellow, black and light blue. With age the males become strongly pruinose, obscuring the colors. They then are mostly bluish. At REGUA a young male was found in lowland forest away from water, but adult males were found perched along the heavily vegetated margin of clear pond about 30 cm over the water’s surface.
A spectacular find was the very rare Minagrion ribeiroi, listed as critically endangered by the IUCN. Unlike its congener M. mecistogastrum it has more usual proportions. The observed males had not developed pruinosity and presumably they keep their beautiful colors as adults. Their abdomens are largely ivory-white, rare amongst odonates. Several males and females have been observed at the forest edge close to a heavily vegetated and clear pond. Typically they would perch on a twig just inside the forest, but exposed to the sun. From their perch they would sally and snatch small insects out of the air in the immediate surroundings, to return to the same sunny perch, a habit that makes them relatively easy to spot.
Both species have been observed in winter only, M. ribeiroi in July and September, M. mecistogastrum in September. Whether they really only occur in the cooler period of the year is subject of further study. For odonate enthusiasts these species are another fantastic attraction at REGUA, although one will need patience and luck to encounter them.