COLLEMBOLA > ENTOMOBRYOMORPHA > TOMOCEROIDEA > Tomoceridae

The Tomoceridae family, sometimes referred to as the 'long-horn springtails', consists of just five species in two genera, Pogonognathellus and Tomocerus, neither of which include subfamilies, thereby making the taxonomic classification here very straightforward.

Whereas the previously described Entomobryidae are characterised by their enlarged fourth abdominal segment (abd4), with Tomoceridae it is the third segment (abd3) that's the longest. The location though can be confusing if you misinterpret where the thoracic segments end and the abdominal segments start. All Collembola have three thoracic segments, the pronotum (th1), mesonotum (th2) and metanotum (th3), each of which bears a pair of legs so, in simple terms, the abdominal segments (abd1 to abd6) start after the final pair of legs.

There are two Pogonognathellus species in Britain, the featured species and Pogonognathellus flavescens, which is scarce and rarely recorded. They were originally in the Tomocerus genus and some literature may still refer to the old classification.

Pogonognathellus longicornis on the other hand is both common and widespread. It is regularly seen in gardens and is one of the Collembola that has been found to climb tree trunks, sometimes forming an important member of the canopy community. It is also the largest British springtail, reaching 6mm in length (excluding the antennae) and interestingly, having changed its name from Tomocerus longicornis, also has the longest name as well as the longest body! Whilst its close relative Pogonognathellus flavescens is similar, the two species can be separated, plus Pogonognathellus flavescens is much rarer and, because it’s only likely to be encountered in upland areas, can safely be disregarded locally. The long antennae are diagnostic of Tomoceridae, and in Pogonognathellus they taper, whereas in Tomocerus they’re more cylindrical. Pogonognathellus has a unique habit of rolling the end of the antennae into a coil as can be seen in the photos below. However, due to their length they are easily damaged and grow back at different rates so it’s not always possible to distinguish between the two genera. It’s also important to note that whilst these species are normally covered in dark scales, they are easily shed giving pale-coloured specimens.

Once again, I have to note that the NatureSpot website's associated 'Tomoceridae identification guide' provides some really useful and helpful information.

Some of the photos featured here show partially pale-coloured individuals that have lost most of their dark scales. There's also one with a broken antenna, although the outstretched right-hand antenna is intact. It is clearly longer than the body, which is characteristic of the species as in Pogonognathellus flavescens it would be shorter. In the second photo, notice the difference in size between Pogonognathellus longicornis and Orchesella cincta.