Springtails hitching rides on social insects

Fossil amber reveals springtails longstanding dispersal by social insects. (2019) BMC Evol Biol 19, 213 https://doi.org/10.1186/s12862-019-1529-6

Springtails (Collembola) are reported since the Lower Devonian and are thought to have originally been subterranean. The order Symphypleona is known since the early Cretaceous with genera distributed on every continent. This implies an ability to disperse over oceans, however symphypleonan Collembola have never been reported in marine water contrary to other springtail orders. Despite being highly widespread, modern springtails are rarely reported in any kind of biotic association. Interestingly, the fossil record has provided occasional occurrences of Symphypleona attached by the antennae onto the bodies of larger arthropods. Here we document the case of a ~ 16 Ma old fossil association: a winged termite and ant displaying not some, but 25 springtails attached or in close proximity to the body. By comparing the general constraints applying to the other wingless soil-dwelling arthropods known to disperse through phoresy, we suggest biases in the collection and observation of phoretic Symphypleona related to their reflexive detachment and infer that this behaviour continues today. The specific case of tree resin entrapment represents the (so far) only condition uncovering the phoretic dispersal mechanism of springtails - one of the oldest terrestrial arthropod lineages living today.

Isotoma viridis

In spite of all the rain and good numbers of springtails over the last few weeks (dominated by Dicyrtomina saundersi), Isotomids have been largely missing. However, the recent haul of leaf litter had good number of Isotoma viridis, a species I have not seen since last winter.

Return of some old friends

The springtails like the rain. I quite like the rain too, but maybe not this much. With the change in the season the springtails have changed. Some time ago I adopted Orchesella cincta as my index species for recording effort, on the basis that it is the commonest species in lowland Britain. Thus, when you don't see one specimen for six months, you begin to doubt. But now the season has changed they're back, and they're everywhere, and along with them are some old friends I haven't seen for a few months, Emtomobrya albocincta and E. multifasciata.

Springs Can Only Get Better

Monobella grassei.

I've got to admit not putting too much effort into springtail recording recently. Partly this is a hangover from the summer and partly it's because I've been busy with other things, but I do regularly record springtails when I'm out and recently it's become clear that what I think of as the "winter species" are here. Foremost among these is one of my favourites, Monobella grassei, which i've found several times recently.

I can't wait for the leaf litter season to kick off.

Recent Unusual UK Collembola Records

An update of the UK list which features two particularly notable additions. The first of these is Entomobrya intermedia, an extremely common species but not one which was not recognised by Steve Hopkin. Since we know know that it stands up under DNA, it has been formally added to the list. The other is the globally invasive Desoria trispinata, a species I have not yet recorded but seems to be spreading rapidly and needs to be on our radar.


Shaw, P., & Trewhella, S. (2019) Recent Unusual UK Collembola Records – Entomobryomorpha and Poduromorpha. British Journal of Entomology and Natural History, 32 (3) 217-230. https://pure.roehampton.ac.uk/portal/files/1192939/BJENH_Shaw19.pdf
Abstract: We report substantial updates to our understanding of the distribution of nine species of UK Collembola (orders Entomobryomorpha and Poduromorpha). We note four species omitted from the main UK key (one very common) and we note the rediscovery of five species in the UK after >50 years. Three of these were previously only collected in the UK by Richard Bagnall in the 1930s.
 

Progress on the VC55 Springtail Atlas

I have to admit that my springtail work has been on the back burner over the last month for a number of reasons. Summer is a good time to have a break and recharge the batteries, although the difference between the drought summer of 2018 and the wet August of 2019 is dramatic. What I have done recently is to take a look at the VC55 springtail records and do some data visualization using the R platform. Firstly, I mapped all previous VC55 springtail records (n = 560) to the end of 2018 (black squares) (all data copyright Leicestershire and Rutland Environmental Records Centre), then overlaid the records added in 2019 (blue triangles):


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This is encouraging because although there are a few other people sporadically recording springtails in VC55, I have specifically targeted most of my efforts this year at extending the geographical coverage into new areas. This is particularly important because so much biological recording defaults to the regular honeypots. It is easy to see this by merging the dataset into a heatmap of observations:


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I can make this a little more informative by breaking down the records into families and overlaying this on the heatmap:


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The problem with this is that the data set (~600 records) just isn't large enough to say very much about the whole County, or to put it another way, the density of records is too low for good geographical coverage. In addition, there's another problem. I'm not aware of any systematic springtail recording which includes negative results, i.e. the absence of species as well as the presence. We know (anecdotally and from the heatmap) that recording effort is not equally distributed, but the limited dataset means that we simply don't have accurate geographical coverage. Resource limitations mean that there will probably never be widespread systematic recording of springtails, so my approach to this problem has been to adopt a benchmark species to infer recording effort. Orchesella cincta is said to be the most widely distributed species in lowland Britain, so I have adopted this to infer geographical coverage:


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Thankfully (for my theory), the O. cincta data fits the heatmap pretty well, so validating this proxy for our atlas. What comes next is clearly getting off my backside and getting back out in the field :-)


Acknowledgements:

• All data Copyright Leicestershire and Rutland Environmental Records Centre.
• Data visualization performed using the R platform, v. 3.6.1 (R Core Team (2014) R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. http://www.R-project.org).
• J. Cann for assistance with data visualization.

Springtails in July

Pogonognathellus longicornis

Although July is pretty much the low point in the springtail calendar, the contrast between this year and last year is stark. While we've had the hottest ever day, we've also had plenty of rain and moderate temperatures. Out and about I've been finding springtails pretty much everywhere, recording the following species at the number of sites shown:

Entomobrya nivalis: 7
Deuterosminthurus pallipes: 4
Entomobrya nicoleti: 4
Orchesella cincta: 2
Entomobrya multifasciata: 1
Isotoma viridis: 1
Pogonognathellus longicornis: 1
Tomocerus minor: 1

Springtails about, but nothing of great interest. However, this has to count as a good July for springtails.

13.07.19 - Charnwood Lodge

Although Charnwood Lodge is the most heavily recorded site in VC55, I've only made one serious trip for springtails there previously, so it was past time to go back. There was a lot of the routine stuff I'm seeing everywhere at present - Deuterosminthurus pallipes, Pogonognathellus longicornis, Tomocerus minor. Notably, I also found a lot of juvenile Orchesella cincta, and some spanking new adults, a species I've not been seeing for the past few months now making a return:



The highlight of Charnwood Lodge is the acid heath, and grubbing around in the Sphagnum produced a number of Isotoma viridis, which although not unexpected, I think is a new species record for this site:

30.06.19 - Owston

In spite of temperatures over 30C the previous day, springtails were around in the damp bits of Owston. Dicyrtomina ornata reappears in its usual spot but Entomobrya nivalis remains by far the most prevalent species I'm seeing at the present time.