Category Archives: Citizen science

Minagrion, a fabulous genus of damselflies at REGUA

<em>Minagrion mecistogastrum</em> male (© Tom Kompier)
Minagrion mecistogastrum male (© Tom Kompier)
<em>Minagrion mecistogastrum</em> immature male (© Tom Kompier)
Minagrion mecistogastrum immature male (© Tom Kompier)
<em>Minagrion ribeiroi</em> male (© Tom Kompier)
Minagrion ribeiroi male (© Tom Kompier)

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.

September-October survey of Odonata at REGUA turns up 115 species

Between September 22 and October 6 we did another survey of dragonflies and damselflies at REGUA and its immediate surroundings. 18 new species were added to the list for the Guapiaçu catchment, taking the total for this year to over 150 species, a testimony to the fantastic diversity of the ecosystem. Just in the wetlands next door to the lodge, already more than 60 different species can be found. Below we introduce just a few of the findings.

With the advent of spring the Gomphidae returned to the scene. A spectacular find was a dragonfly that may be the first recorded male of Praeviogomphus proprius. It will be studied further at the department of entomology of the Museu Nacional in Rio de Janeiro, thanks to the support of Prof. Alcimar do Lago Carvalho for the project. Praeviogomphus previously was only known from one female and from a few larvae. Other spectacular new gomphids were two species of Phyllocycla. Aphylla molossus, a large gomphid was also found regularly again.

<em>Praeviogomphus proprius</em> (© Tom Kompier)
Praeviogomphus proprius (© Tom Kompier)
<em>Phyllocycla cf. pallida</em> (© Tom Kompier)
Phyllocycla cf. pallida (© Tom Kompier)
<em>Phyllocycla gladiata</em> (© Tom Kompier)
Phyllocycla gladiata (© Tom Kompier)
<em>Aphylla molossus</em> (© Tom Kompier)
Aphylla molossus (© Tom Kompier)

Another great find was a species of Castoraeschna that may be new to science. This lovely dragonfly was found patrolling the bogs at Salinas, in the mountains above the lodge. Nearby an intriguing female Leptagrion was found that also still needs to be identified.

Tiny and elusive Peristicta jalmosi, only recently described, was found inhabiting a stream close to the old wetland, where males were hanging from the tips of leaves of trees in shady parts low over the water. These damsels are so small that they become next to invisible the moment they start flying. The fact that they perch in dark shady places obviously does not help either, so possibly it has been overlooked in the past.

Castoraeschna n. sp. possibly new to science (© Tom Kompier)
<em>Peristicta jalmosi</em> (© Tom Kompier)
Peristicta jalmosi (© Tom Kompier)

The trails turned up two new species of Heteragrion. This fantastic genus of beautiful and big damselflies keeps on turning up new species that are often as localized and rare as they are spectacular. The specific identity of these two species still needs to be confirmed and it is well possible they are as yet undescribed. So far this year this fabulous genus has turned up seven different species, the commonest of which is H. aurantiacum, which can easily be seen at streams around the lodge. Another more regular, if uncommon and difficult to find, species is H. consors.

<em>Heteragrion</em> sp. (© Tom Kompier)
Heteragrion sp. (© Tom Kompier)
<em>Heteragrion consors</em> (© Tom Kompier)
Heteragrion consors (© Tom Kompier)

Clearly amongst the many attractions of REGUA is also a fantastic Odonata fauna.