(185ENint) Entomobrya intermedia Brook, 1884

This species appears to be widespread and common, but has been widely confused with E. nivalis to the point that the distributions of both must be suspect.  Gisin (1960) considered this species a junior synonym of E. muscorum, while Steve Hopkin dismissed E. intermedia as probably a junior synonym of nivalis, and specimens of this species will key down to nivalis in Hopkin (2007), ensuring that the names will remain confounded by UK researchers for decades to come!

 

There are a couple of literature records for this species, but since 2007 there has been something of a surge of records of this species as enthusiasts have uploaded images to the Flickr image-sharing website, followed by confirmation of ID by Frans Janssens who has added many helpful comments about field ID to many springtail photos, such as here.  I have accepted Entomobrya intermedia records from this site as long as the photos show abdominal patterning adequately.  Happily this species frequents open surfaces and has its abdominal patterning as its most conspicuous feature, hence the surge in new records.

 

A check of all Entomobrya photos on the Flickr site in February 2009 found at least 10 good new records (clear photo plus location plus date), and it is very likely that more remain to be found.  This appears to be the second case, at least for springtails, where web photographs have not just confirmed a species but transformed its distribution map!  (The first case was a story related by Arne Fjellberg, who identified the first record of Orchesella flavescens in Norway from a web-image, then followed up by visiting the site and collecting specimens to confirm the ID).  Re-assuringly, good numbers of E. nivalis, E. nicoleti and E. multifasciata also featured, sometimes co-occurring but all showing clearly different colour patterns.

 

The distinctions between Entomobrya intermedia and E. nivalis are summarised in Figure 2 below (by Frans Janssens).   Although apparently clear to see, springtail bodies can shrink and distort somewhat during preservation, hiding one of the crucial distinctive points (the broken “U” – see figure 2).  The other obvious point is the continuous “W” across the top of abd. 4, which Steve Hopkin certainly saw in some specimens (it can be seen on his web site) but did not draw in his key.

 

Although outside the distribution range shown on this Dmap coordinate set, a set of photographs from Jersey (2 sites about 6km apart) show an Entomobrya whose abd 4-6 correspond well to E. intermedia, except for a mid-line stripe on the thorax that, coupled with 2 lateral stripes, makes it intermediate between E. intermedia and E. handschini.  The images are copyrighted but have a hyperlink here.  Until specimens can be collected and examined it is not clear whether this is merely a colour variant or in fact a new species (an island endemic – Frans Janssens suggested E. intermedia "jerseyensis", but this name has no taxonomic validity at present.)

Distribution map for Entomobrya intermedia (185 ENint), last updated 2012

 

 

Figure 1: Entomobrya intermedia adult and juvenile, from Lincoln 27 October 2008. Photo by Mick Talbot, distributed as Creative Commons

 

Figure 2: Sketches summarising the differences in abdomen 4 patterns between Entomobrya intermedia, E nivalis and E. muscorum. (The latter has not credibly been recorded from the UK, yet).

Figure 3: emphasising the discontinuous "U" distinctive of this species.

 
Facebook icon    Twitter icon    Instagram icon    LinkedIn icon © Roehampton University