COLLEMBOLA > SYMPHYPLEONA > Dicyrtomidae > Dicyrtominae

The SYMPHYPLEONA order is made up of six families, Arrhopalitidae, Bourletiellidae, Dicyrtomidae, Katiannidae, Sminthuridae and Sminthurididae, which together include around 40 globular-bodied species in 18 or so genera.

Ignoring one extremely rare species that has been separated into its own subfamily, Dicyrtomidae includes four species in two genera, Dicyrtomina and Dicyrtoma. Whilst all four species are regarded as common, my limited encounters when this page was first published only covered Dicyrtomina ornata and the superficially similar Dicyrtomina saundersi, but I'm now pleased to be able to feature all these species.

When the original 'key' to the 'Collembola of Britain and Ireland' was published back in 2007, the author, Dr Steve Hopkin (now deceased), noted that the two species mentioned above were virtually identical apart from the shape of dark pigmentation at the posterior end of the abdomen - described in the following account for Dicyrtomina saundersi. He also questioned whether they were actually separate species, but it has now been confirmed that they are. Since then, there have been further observations including the fact that in Dicyrtomina ornata the antennae are all the same colour along their length, whereas in Dicyrtomina saundersi there is a distinct colour change at the joint of sections 2 and 3. Additionally, in Dicyrtomina ornata the dorsal colour of the 6th abdominal segment is dark, but in Dicyrtomina saundersi it is pale. However, and notwithstanding these differences, it is thought that the two species grade into each other, which can be confusing with some specimens if the abdominal markings aren’t clear. Both species are around 3mm long.

As a point of interest, over the past 150 years or so there has been a noticeable increase in the recorded numbers of Dicyrtomina saundersi at the expense of Dicyrtomina ornata. And, although not listed above, there's a further form known as Dicyrtomina violacea that is now being recorded. Some authorities are treating it as a separate species as it is on the European List, whilst others argue that it is just a colour variation of Dicyrtomina ornata.

Whilst the specific characters of the species are shown on the UoR taxonomy page, one of the most practical identification guides for Dicyrtomidae I've found is on the NatureSpot website.