What's going on with Enoplognatha (mordax?)?

Posted by Graeme Lyons , Tuesday 29 June 2021 10:29

In 2018, I found immatures of what looked like Enoplognatha mordax, in the Brede Valley. Soon after this, they were independently found on the Pevensey Levels (both sites not that far from each other in East Sussex either side of Hastings - just where you would expect a colonisation event from the continent to come from). This is quite different behaviour to Enoplognatha mordax, which is low to the ground on the upper limits of saltmarshes. A very restricted spider. I could not find an adult and that was that for the year. In 2019, it started turning up all over the place as immatures and not just in wet grassland. By this point, I started believing it was something different and Peter Harvey said we should get hold of an adult, preferably a male, as it might be something different. It's a complex genus, so this could be something totally different from Europe or further afield or something genetically distinct. I only found my first adult, a female, in 2020 (below). 

But get this, it was nothing to do with levels/grazing marsh. It was from an arable margin on the Norfolk Estate on the top of the Downs. I sent it to Peter Harvey but what we really need was a male. The other recorder collected a male in 2019 from Pevensey but let it go, believing it to be mordax after photographing it. This shows the importance of keeping specimens, especially with such a bizarre occurrence like this as it's took me another two years to get a male. So finally, in 2021 I have started finding lots of adults. I had two males on a farm in East Sussex yesterday along the Cuckmere, with one running across a farm track in front of me (photo at the top of the page). 

In June alone, I have recorded four males from three sites, all on lush arable margins on the Downs in both East and West Sussex. I also found a number of adult females along the stream restoration at Knepp about ten days ago, again swept from rank vegetation along ditches and streams. It's clearly well distributed in both counties. Enoplognatha mordax is usually found in litter, deep in rush tussocks, by suction or by lifting matts of algae on saltmarshes etc. I would never expect to find it where you find this thing and I don't think I have ever found it sweeping. My money is on a new species, but what species? Here is the habitat of yesterday's males. Not especially specialised. It seems to prefer this stuff than the original sites of grazing marsh/levels. But that's where I have been recording a lot this year, so there could be an observer bias here.

Not the best video, but here is the male moving north across a farm track. This spider is clearly able to disperse well. Quite different to mordax. When I surveyed East Head and Rye Harbour, move a few metres from the saltmarsh edge and that's the end of mordax records. Why would a spider behave exactly the same for over a 100 years, then suddenly behave really differently, but only in one specific part of the country? It must be a colonisation event, surely? 

Here is an actual Enoplognatha mordax from Rye in 2013. Certainly looks pretty similar but this new thing appears a little more robust according to Peter Harvey and I would agree with that.

I am sending more of my specimens to Peter Harvey who is going to pass them on to Peter Merrett. Peter believes there are subtle but significant differences in the male's palps (I struggled with this to be fair but did notice one area on the palps that did look a little different - I am going to see if what I collected yesterday matches up with this now) and that it could be either a new species to the UK (my belief) or a speciation in action. I predict it is going to turn up in neighbouring counties before the end of the year. Whatever it is, it's going to be a very common spider soon. Keep an eye out if you live in Kent, Surrey or Hampshire as this is spreading fast. Do any global spider recorders recognise this or its behaviour as a different species? Any help greatly appreciated. If you could pass this blog on to any spider specialists you know, especially in Europe or America, that would be greatly appreciated. I am wondering if there has been a similar occurrence in northern France an this thing has just hopped the Channel? Does anyone have a contact for a north France spider specialist?

It's not just the spiders that benefit from spider year-listing!

Posted by Graeme Lyons 09:12

Yesterday started off very frustrating but ended up being pretty awesome. I started work late as the Sun was meant to appear about midday. On the Cuckmere I did find an area with Divided Sedge, Marsh/Golden Dock (I've never seen either in Sussex and will go back to confirm which species) and a Spotted Redshank flew overhead calling in the sea fog. But by midday, the forecast said about 4.00 pm. Without sun, the farm vegetation I was working on was going to remain sodden. So I went recording to Seaford Head. My target was linys on the saltmarsh and Lasaeola prona at its only known Sussex site.

The little saltmarsh at Seaford was hard work. It started raining as I got there and the sea fog was frustratingly stubborn. But then I saw a beetle flying over head, it looked like a longhorn in flight so I netted it. I looked in the bottom of the net and was about to dismiss it as Rhagonycha fulva when I realised it was a Wharf-borer (Nacerdes melanura). I have only seen one of these before at Rye Harbour. That's the 1st species I had new to the reserve.
I tried the suction sampler on the black litter that builds up at the base of Yellow Horned-poppies and got a spider new to the site and new for the year for me, Argenna patula! A nationally scarce saltmarsh species. It made up for the lack of linys. I did find Sitticus inexpectus immatures though but I already have that this this year, from Rye Harbour. 

I walked along the cliff top and kicked up a surprise, Palpita vitrealis. It flew off into some bushes but I got a good look at it although couldn't get a photo. That's three new to the reserve! I tried some suction sampling along here and got this nationally scarce tortoise beetle. Cassida prasina is amazingly new to the reserve network! Also around here was Formica cunicularia, again new to the site. It's amazing how you can work a site really hard for years and still find things, in numbers, that are new. There are lots of reasons for this.

  1. Many inverts occur at low densities, so luck is a huge factor. Especially for the things you only ever find one of.
  2. Sites are changing all the time, through succession or better/worse management. This can have a big impact in a short pace of time.
  3. Climate is changing things too, from migrant moths to colonising insects from the continent. Plus we have an ever increasing proportion of non-natives. A wet year like this with a lot of growth is going to be very different to a summer drought year like last year.
  4. I've changed. We all have. I am definitely better at finding things than I was five years ago and probably will be again in another five years time. I'm also faster and more efficient but I think this has plateaued.
So, the idea you can do one invert survey over one year (even with lots of visits) and expect to find everything is bobbins. That's why I created the Species on Reserves list in the first place for the Sussex Wildlife Trust reserves. Long-term effort is a great way to accumulate all these records together, so I am very glad that Glenn is keeping it going!  I also like to accumulate survey data from repeat surveys I am carrying out as a way of edging closer (but never ever getting there) to a site's true fauna. Anyway, I'm currently five up for the reserve.

Then I got to Hope Gap and in one suction sample I got two new to the site, including another new to the reserve network. One was the myrmecophile ladybird Platynaspis luteorubra (a Na species that is spreading) and the other was a new shieldbug. The Sand-runner Sciocoris cursitans. This really is a small shieldbug (5 mm) but until now, the only site I have seen it in Sussex is the Crumbles. Another nationally scarce species but you would be lucky to find this without suction.

And then after about ten fruitless suction samples, I found FOUR Lasaeola prona in one sample! Here's a sub-adult male.

I also added new for the year Ozpytila claveata (known from the site). Which leaves me on 290 for the year! I am going for the 400 this year by the way, but that's another story. So, in a three hour period wandering around I added all these new to the site:

Nacerdes melanura
Drassodes lapidosus
Meioneta simplicitarsis (Nationally Scarce)
Argenna patula (Nationally Scarce)
Drassyllus pusillus
Palpita vitrealis
Cassida prasina (Nationally Scarce and new to network)
Sciocoris cursitans (Nationally Scarce and new to network)
Teniuphantes flavipes
Formica cunicularia

So ten species! Four with status and two never recorded on a Sussex Wildlife Trust reserve before.  I had forgot how much I enjoy that spreadsheet. Pleased to have made a contribution with a few hours to kill. The sun came out about 3.00 pm so I dashed back to the farm I was working on and got Andrena hattorfiana and Atylotus rusticus before the thunder started. It was very strange to see cloud come in from the north at the same time as a sea fog slid in rapidly up the valley from the south. 

By working like mad through the heatwave, I've bought myself a tiny amount of free time at the end of June. So that's why I have been hitting the SWT reserves when I could. Also new to the reserve network this week is the smart woodlouse Armadillidium pulchellum from Graffham Common, appears to be a county first.

And the Dark Giant Horsefly (Tabanus sudeticus) from Black Hole, Burton Pond!

So, if you think spider year-listing is just about ticking things off a list you couldn't be further from the truth. As well as getting better at spiders, it has a direct benefit to spider recording that in turn, spills out into a wide range of other taxa! So what are you waiting for!? I still want to try year-listing Heteroptera one year but I am yet to find anyone to play with :(

This is just taking the Pistius now!

Posted by Graeme Lyons , Friday 11 June 2021 07:27

I have rarely had such a good day out in the field as I did last Sunday at Blean. By 08:59, I was looking at a very immature Pistius truncatus (have a look here for more info). A Critically Rare arboreal crab spider, something of a mega in the spider world. Not seen in the UK for 20 years and only ever known from the East Blean Woods complex (and old records in the New Forest). This was therefore a new location for the spider on the KWT managed land. It was also at the very far west of this area, about as far from East Blean Woods as it could possibly be. I picked this up on the second out of 24 plots I am surveying this year, so I expected I might see some more. I did not. I do still have three rounds of visits to go though. It's a gorgeous little spider, appearing to  have no hind legs to the naked eye. They're a translucent yellow, next to the greeny/brown body. Very similar in build and shape to Thomisus onustus. Here is my first view of it in the tray.

The spider list is epic. With Walckenaeria mitrata found in a conifer plantation last month, the total number of spiders with conservation status stands at 20 already! That's 20 out of the 127 spiders I have recorded so far. New this month was Salticus zebraneus and a stonking adult male Philodromus longipalpis. This really is clearly bigger than the other Philodromus in that group.

But it's not just the spiders. Across the board, rare species are turning up in droves. In fact, so far 46 of the 378 species recorded have some form of conservation status. I had four new beetles that day. First up being a real surprise for me that took a little while to digest. Lagria atripes was listed as Regionally Extinct in the 2014 review but it was widespread at Blean. I recorded 10 animals across six of the 24 compartments. It seems it has been turning up in a few places in Kent though, so is not that much of a surprise.

Then I had a "WTF?!" moment. I love that there are so many beetles in the UK that you can keep encountering ones that you have never even seen a photo of before. This is the Nationally Rare melandryid, Hypulus quercinus. Phwoar!!!

And quite a surprise was the recent addition to our longhorn fauna, Agapanthia cardui. Swept from a cleared area in the wood. I expect this will be all over the south east in a few years.

The fourth beetle was one that I am surprised it has took me this long to find, Pityophagus ferrugineus (not photographed). Additionally to all these lifers, there were loads of nice beetles I have only ever encountered once or twice before. First up the myrmecophile, Clytra quadripunctata. Found so far on three out of 24 plots. A stonking Nationally Scarce species. Not a surprise with all the Formica rufa there. Oh and I had a new ant, Guest Ant!

Two Anthribus fasciatus (Na) from one plot. Only the 2nd and 3rd examples of this I have ever seen. The last being Knepp in 2015.

Four Tritoma bipustulata (Na) on brackets on a recently fallen, rotten oak limb. I have only ever seen this at Levin Down in West Sussex.

Trogulus tricarinatus. Not sure why this isn't nationally scarce. This rather large and bizarre looking harvestman was found by suction sampling vegetated leaf litter (which is especially rich at Blean - the best leaf litter I have ever sampled).

A stonking Didea fasciata was a new hoverfly for me.

Always nice to see Lapidary Snail too. 

And a long overdue lifer. Although try as I might I cannot find this in any of the 24 plots. I walked passed a sunny bank of Cow-wheat and thought to myself, "if this isn't there, it can't be here at all". I found it in 30 seconds. The Cow-wheat Shieldbug Adomerus biguttatus. It must like plants growing on sunny rides and not under the canopy, not surprising really.

And of course, Heath Fritillary is the commonest butterfly there at the moment. What a beauty.

All this is baseline monitoring/research is driven by the application of the bison to the site. But it's important recording in its own right, with this area of Blean receiving relatively little invertebrate monitoring compared to East Blean Woods and the RSPB reserve. Monitoring like this is vital for nature reserves and rewilding projects alike, as it shows not only what is working but what isn't. So the management of sites can be adjusted accordingly. It's part of a whole package across a wide range of taxa that KWT are carrying out this year.

Definitely one of the best days I have ever had in the field and also, possibly the best survey I have ever done, for the sheer number of rare species and lifers. What makes it so good? Well, along with sites like the Surrey Heaths, it's the landscape scale effect I am sure. It's big enough to cope with small scale extinctions that can easily recolonise from other areas of the wood. Small, isolated sites can't cope with this. Continuity of management is always vital for good sites and it's also in the south east too, to be fair. I can't wait until July!

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