Micromacromia zygoptera (Libellulidae) was hiding, perched on a leaf above a small sandy-bottomed stream, with decomposing leaves, a stream winding through the dark forest. Despite a few take-offs, it patiently allowed itself to be photographed, and fortunately so, as throughout our entire stay, we would only see this male and one female.
This is a genus that includes only four species, all of which are rare and very seldom observed; prior to our survey, the species had only 6 observations on iNaturalist, between 2012 and 2022.
However, it has a rather amusing English vernacular name (can one speak of a common name for such rarities?): Small Micmac.
The genus Micromacromia (Karsch, 1890) is very close to Neodythemis, and is principally distinguished by the fact that the discoidal field of the forewing begins with only 2 cells: except for Micromacromia zygoptera, which, like Neodythemis, has only one! And it is probably for this reason that Ris (1909) described it under the genus name Eothemis, now defunct.
M. zygoptera is in principle the only species in Ghana; another, M. camerunica, is very similar, but it has 2 rows of cells at the beginning of the discoidal field of the forewing.
The genera and species are very close, and the taxonomy has been rich in complex debates, settled by Dijkstra and Vick (2006): M. zygoptera was called Eothemis zygoptera (Ris, 1909) and Neodythemis scalarum (Pinhey, 1964).
Ris measures its abdomen at 21.5 mm, Pinhey at 22 mm without the anal appendages; it probably barely reaches 34 mm in total length.
We found it entirely within the environment described by Dijkstra (ADDO, 2020 – ADDO, 2020), namely a small rainforest stream.
Its distribution extends from Guinea to Gabon; however, its presence is not confirmed in Benin or Equatorial Guinea.
IUCN Red List.
The only female we encountered was unlucky. Likely on the very day of her emergence, she ended up in a spider’s web. Note the very characteristic dark quadrangular mark in the center of her thorax.
Note the broad expansion of S8 in the photo above left; this dilation is normally absent in Neodythemis females.
Its abdomen can be compared with the one shown in Dijkstra & Vick, 2006:
Etymology of Micromacromia zygoptera
Micromacromia; from Greek micro for small and macromia which is constructed from Greek –macro for large or broad and –omos for shoulder, to emphasize the massive thorax. This is a very surprising name for a Libellulidae, and I will let Fliedner attempt to explain it…
« Karsch’s description of this libellulid genus does not mention Macromia at all. Perhaps, as with Hagen’s genus Macrothemis, the tooth on the claws led to the name [claws down, near the middle, with a distinct tooth]. But it should be noted that the only species on which Karsch based this taxon shows some superficial similarity to the genus Macromia: it has long, narrow wings, a dark, shiny main color with yellow (greenish) markings, the thorax is dark metallic green (for Macromia, see Wildermuth & Martens 2019: 540-542). In any case, with a total length of about 30 mm, it is a rather small libellulid. »
It should be noted that the specimens described by Ferdinand Karsch in 1890 were captured between 1887 and 1888 (by Dr. Paul Preuss, a German botanist and explorer who worked extensively in Cameroon at that time). Their color, having been in collection for 2 or 3 years, probably had little resemblance to their live appearance. Furthermore, the male we observed was old, covered in a grey pulverulence, while the female, very young, was closer to the coloration of Macromia.
Zygoptera, from Greek zygo, meaning a yoke or a homogeneous pair, and ptera for wing. Damselflies are indeed called zygopterans because their forewings and hindwings are almost identical. Karsch writes: « Von allen mir bekannten Libellulinen zeigt diese die geringste Differenzierung der Vorderflügel und Hinterflügel [Of all the Libellulines known to me, this one shows the least differentiation between the forewings and hindwings] ».
Dijkstra & Vick, 2006 – Inflation by venation and the bankruptcy of traditional genera: the case of Neodythemis and Micromacromia, with keys to the continental African species and the description of two new Neodythemis species from the Albertine Rift (Odonata: Libellulidae). International Journal of Odonatology, 9, 51-70.
Fliedner Heinrich, 2021 – The scientific names of Ris’ odonate taxa – Journal of the International Dragonfly Fund.
Pinhey, 1964 – Some new Odonata from West Africa. Bulletin Institut français Afrique, 26, 1144-1153.
Ris, 1909 – Libellulinen vol. 1, fasc. 9-11 – P. 71.