I’ve recently been setting out dry pitfall traps on campus, to see what invertebrates are active, and keep my pan-species list on the increase! So far, it’s been mostly Carabid (Ground Beetle) larvae, with a few adult Carabids and Staphylinids. A few days ago, I caught a really cool little Ground Beetle: Asaphidion curtum, which I decided must become species of the week! It has almost alien bulging eyes, and is strikingly sculptured with a strong metallic sheen.
The photo was taken using ipad-microscopy. It nearly came out well, but the cling film from my cling film petri dish invention reflected the light a little too much! A.curtum is diurnal, and an active, fast-running hunter. It hunts mostly by sight, feeding on springtails, protura, and other small soft-bodied invertebrates. Although it’s only 4.5mm long, this species is a fearsome predator!
Asaphidion is easily recognisable as a genus: 4-6mm long, with very large bulging eyes and elytral striae (lines on the wing cases) replaced by heavy sculpturing and deep pits. Identification of A.curtum itself is a little more difficult. It was only split as a species from A.flavipes in 1986. The main features are: length at most 4.5mm, legs nearly all pale (femero-tibial joint darkened slightly), antennae all pale or gradually slightly darkened (not abruptly darkened from segment 5 onwards) and finally, the pronotum has its sides sharply angled in the middle. Nice and easy!
A.curtum is best found by pitfall trapping or direct searching on heavy soils, in relatively open habitats. It can be found in open woodland in leaf litter. The individual that I caught was in a pitfall trap in light leaf litter amongst a few Lime trees in a parkland habitat.
This species is fairly widespread in the UK, becoming rarer further north, with very few records from Scotland. It seems, however, to be rather patchy in where it occurs, though this could be due to under-recording. Here is its distribution:
Hopefully more people will be on the look out for this great little beetle, and more dots can be added to the map! Identification is tricky however, so make sure to get the specimen checked. A half decent close-up photo can often be enough!