As if Gomphus weren’t a strange enough name, now we’ve got Onychogomphus. These are attractively marked medium-sized dragonflies with the most fearsome anal appendages – on the males, that is.
These are rather difficult to identify by description, especially to separate from O. uncatus. The vernacular names don’t help much: Small vs. Large Pincertail is no use in isolation and eye colour is apparently not consistent enough for Green/Blue-eyed Hooktail to be reliable. Detailed diagrams tend to be necessary and there are some very good ones here. It’s also worth checking out dragonflypix.com.
To make things even more fun, O. forcipatus has a couple of subspecies. In France, at least, there’s O. f. forcipatus and O. f. unguiculatus, the angle of the delightfully named subterminal knob (see Dijkstra/Lewington) on the male’s lower anal appendage being the main distinguishing feature. Unfortunately, in most photographs the downturned tips of the male’s fearsome upper appendages tend frequently to obscure the subterminal knob on the lower appendage. Geography attempts to come to the rescue, there being few areas where both subspecies coexist (see Grand/Boudot). A combination of physical features and location makes me reasonably confident about my classifications below.
We have encountered O. f. forcipatus in France at the Pinail Trail in a less-than-wonderful year, 2011 – many pools were all but dried up after a long, hot spring – and at the superb Tourbières de Vendoire. We also now have them in Croatia and Germany. Our sole encounter with O. f. unguiculatus was at Montesquieu des Albères in 2014.
- blue-green eyes, greener in the north
- often a yellow bar on th evertex between frons and occiput
- the yellow anterior ridge of the thorax divided by a black line along the mid-dorsal keel
- see diagrams referred to above for the antehumeral stripe shapes
- ♂ – fearsome hooked appendages (the pincers), the lower one with a subterminal knob
- normally 3-celled anal triangle
|O. f. forcipatus|
|O. f. unguiculatus|