Zombies in the Tunnel

I took myself into a tunnel today in search of overwintering mosquitos and spiders that are fond of the dark. No joy with the mozzies, but I did find plenty of interest when it came to the spiders.

That tunnel is about four and a half feet diameter

This tunnel goes under the road and the water spills out onto the crofts below as a small burn which then runs into the sea. Earlier this year it would have been impossible to enter the tunnel due to the force of water racing through it, but now the stream of water is only a few inches deep and less than a foot wide. Easy access. Headtorch on, in I went...

It didn't take me long to find my first spider, a female Metellina merianae guarding her egg sac

Looking around I saw a few more Metellina merianae on the roof of the tunnel, plus a few unguarded egg sacs. I also blundered face first through a large web which I presume belonged to a Metellina, clumsy great lummox that I am. 

Metellina egg sac on the roughcast between concrete pipe sections

But then it all went a bit kind of grizzly and gruesome. No, I didn't slip and fall into the water (you'll be disappointed to hear), I made a series of pretty yucky discoveries, in an exciting kind of way.

Metellina - does my bum look big in this?

This spider has been colonised, immobilised and then killed by a fungal pathogen, which really is as gruesome as it sounds. It would have been immobile but very much alive when the fungus erupted through the tissue, bursting outwards from within. I don't know how quickly such victims die once the fungus erupts from them, but I hope it's quickly. The fungus then extends upwards to produce the spikes you can see in the image above. It is from these that the spores are released to colonise any spider sitting below or downwind of the infected individual. Considering I was in a tunnel with a decent amount of breeze flowing through it, I expected the fungus to have infected several more spiders deeper within. I wasn't wrong.

This is another Metellina

There could be anything beneath that mass of fungal fruitbodies

This may actually be a second species of spider-killing fungus, again on Metellina

I didn't collect any of these zombie spiders, but I may end up going back to do just that. It seems there are several fungal pathogens that do this to spiders and I'd like to know which one(s) are in that tunnel. The commonest one is Gibellula leiopus, which has recently changed name and is currently known as Torrubiella arachnophila var leiopus. But that is supposed to infect small spiders, not big things like a Metellina. More online digging brought up Engyodontium rectidentatum as occuring on Meta spiders, which are in the same family as Metellina. There are several other species of Engyodontium that occur on spiders, notably E.aranearum which infects Pholcus phalangioides and seems to be fairly widely reported in Britain. So yeah, I need to go back and pop some fungi under the compound microscope and check the spores. I have no problem collecting fungi from dead wood, but collecting from dead spiders seems just a bit kind of gross. But I think I need to do it anyway. I just so happen to know an extremely competent mycologist named Bruce Ing, he lives up near Ullapool. I may send him some images, see if he'd be interested in checking a few specimens. At least I know the ID would be correct if he does it! 

So there you go, next time you find yourself in a 4ft diameter storm drain running beneath a road keep an eye open for zombie spiders. And regular zombies too, I guess. 

Spot the zombies on the roof yet?

Predestined to Damnation

It was yet another glorious though bitterly cold day out there today. I took myself down to the shore in search of a particular species of spider, one which I'd tried and failed to find a few weeks back. The tide was out and I headed down the beach to where a jumble of fair sized boulders lay part embedded in the gritty sand. They all had seaweed hanging from them, for these rocks are completely submerged at high tide. Not the most obvious spot to go searching for spiders, I hear you say. Well yeah, ordinarily you'd be right, but there's one species that dwells in precisely this type of habitat and I was determined to find it this time around.

The upper image seems to show a bit of silk web, I've never seen that before with this species

Bingo! This is Halorates reprobus, a liny which is exclusively found on the shore, typically in the zone inundated with seawater at high tide. It's a niche that is also exploited by various mites, springtails, beetles and a centipede, all of which are air-breathing animals. During high tide, small air pockets form where the underside of these rocks meet the coarse, gritty sediment. Clearly these suffice for the air-breathing inverts that live here. I collected four individuals from beneath one rock with the expectation of securing both sexes. Back indoors I was a tad surprised to discover that they were all adult females. Where were the males??

It's a very distinctively-shaped epigyne

The Spider Recording Scheme page suggests that both sexes are adult throughout the year, so it's a mystery to me why there were no males amongst the specimens I collected. Maybe they keep seperate outside of the mating season? It makes no difference, the epigynes are enough to clinch a definitive ID, it's just a bit weird is all. 

I don't know what this spider did to deserve being called a reprobate, but it makes me smile anyway. In my mind's eye I imagine them kicking in doors, smashing up bars, dancing drunkenly through the streets of a night, running away from the police and pissing through letterboxes. Reminds me of my misspent youth in London, I think I'd get along with this type of spider very well. According to Calvinism, a reprobate is "a sinner who is not of the elect and is predestined to damnation". I'm not convinced that concept applies to non-humans (or actually, that it applies at all!) but again, completely seems my kind of person/spider.

The Spider Recording Scheme's page for Halorates reprobus is here and there are a couple of other pages about it here and here. If you have access to some shoreline/saltmarsh, maybe have a look for your own reprobate, best of luck! 

Not a Groundhopper

Sub-zero temperatures (day and night) and work have both conspired to keep my fly and spider challenge severely reined in for most of the past ten days. However, I've now completed all my indoor jobs and can't progress with the remainder of my outdoor jobs until it warms up a bit. So, as of two days ago, I'm back on flexi-furlough and able to spend time out in the wilds once more. 

The first week of February was remarkably unremarkable, insofar as progressing the totals for my Big Year. Whilst re-arranging an outbuilding and putting up a load of shelving, I disturbed a Protophormia terraenovae from it's slumber, the first calliphorid I've recorded this year. A large Amaurobius similis in the same shed summed up the spider interest. Even my bathroom Pholcus seems to have disappeared of late. Lean times indeed!

Yesterday I managed to team up with Neil, one of the naturalists I know here on Skye. We headed off to Lyndale Point and Woods, I was determined to find something of interest. It was bitterly cold in the east wind, Neil seemed notably bemused as I stood there screwing my net onto its handle. Needless to say, there was absolutely nothing at all flying (apart from birds, obviously) and the net was essentially a complete waste of time. Sweeping heather and grasses produced bits of twigs and seeds, not even a single springtail to be found. We then tried kicking through some wrack on the beach but that too was completely fruitless, though I did glance up to see I was being filmed. I expect he'll share the video with his friends, doubtless explaining how I'm allowed out on day release as long as I'm accompanied by a responsible adult...

We clambered up a cliff and a piece of rock came away in my hand, revealing a huddle of suddenly exposed legs. I took a few pics before potting my find. How many arachnids can you see here?

The correct answer is three

This is a rather large and very dark female Metellina merianae. Tucked up just beneath her abdomen is a Tetrix denticulata and sitting on her head is a soil mite. I think it's fair to say they were all dormant until I unceremoniously shoved them into a single pot and walked several more miles with them in my pocket. I've yet to check the SRS distribution maps, but I very much doubt there are spider records from this particular patch of coastline, it's not precisely on the beaten track. So that's good news, another couple of my 5MR monads with invert records (I also added some woodlice and molluscs plus a few rove beetles I've still to check) and another small part of this fabulous isle explored. 

We ended up having a quick wander through the woods back near the road, loads of deep leaf litter, mature Beech trees with sap runs and rot holes, masses of dead timber standing and laying, shedloads of Birch Polypores and an all-round good feel to it. I definitely need to come back here with my sieve and tray. That's when I spied a couple of Holly bushes. A short while later and...

Phytomyza ilicis. Officially safe to count again.

There are two species of European agromyzid flies that create mines in Holly, Phytomyza ilicis which occurs in Britain, and Phytomyza jucunda which doesn't (yet) occur here. There are differences in the form of the mines/pupae between these two species and obviously the adults differ too. There have been a handful of atypical British mines which closely resemble those of P.jucunda, but rearing the adults from these mines has always resulted in P.ilicis.

Last year, a couple of European workers discovered that Phytomyza ilicis actually comprises two species, differentiated by slight differences in the male genitalia. This instantly threw all previous European records into uncertainty and the British National Agromyzidae Recorder felt compelled to quarantine all holly-mining records until adult specimens were checked for evidence of the 'new' species. Fast forward a tad, our agromyzid recorder has critically re-examined the European material from which the new species was described and found the European workers to be at fault. There is no 'new' species, and everyone can breathe a sigh of relief. Phew, Phytomyza ilicis is officially out of quarantine and countable once more. And on my yearlist.

Also Phytomyza ilicis

I did briefly have a Trichocera in my net, ragged from an overhang of moss, but I was too slow grabbing a tube and it flew off before I could secure it, something Neil found rather amusing. Ho hum.

Back indoors I had a close look at the two spiders I'd potted up. I suspected the large one was a Metellina and a quick look at the distinctive epigyne confirmed it as Metellina merianae

The second species I recognised straight away, thanks to the full body-length white mohican and long tapering spinnerets. This was Tetrix denticulata, one I see here in Uig from time to time. It looks a lot like a wolf spider, but the aforementioned mohican and spinnerets distinguish it. 

Tetrix denticulata - a particularly smart spider

You may be wondering what I'm doing with all of the spiders I collect. Do I just chuck them in the bin once I've identified them? Do I put them in a sandwich and have a late night snack? Do I hide them under the bedcovers in the guestrooms? Well, I'm vegetarian so it won't be the second option. I do bin immature specimens that are essentially unidentifiable, though some are identifiable as immatures and I keep those. They are popped into tubes of alcohol, along with their data label which states the species, the locality name, a grid reference, the date and my name on one side. The reverse of the label details the habitat and method, eg sieved from grass tussock or brushed from mossy tree trunk etc. Like this

Ready to go into the storage cabinet that I've wall-mounted in my room

Next stage is to enter my finds onto iRecord. Which is where I received a bit of a shock. Tetrix denticulata is a spider I know by sight and can even remember its name. One of the few. 

Except that's not it's name! I typed Tetrix into iRecord. It did not offer me a denticulata. Oh. What??

Tetrix is a genus of groundhoppers, small cousins to the grasshoppers and something that I used to bump into regularly when I was living in England (though the Common Groundhopper Tetrix undulata is here on Skye). By my reckoning my spider would have the vernacular name of Toothed Groundhopper, clearly not correct! My spider is actually Textrix denticulata, something I'd read and spoken on many occasions without noticing the extra 'x' in Textrix. What a flippin' div! I've said it before, my memory for scientific names is terrible and my pronunciation of them is probably a topic best left ignored. I think I'll probably remember the extra 'x' next time I see this spider. I now need to go and change it on my spreadsheet. 

My 2021 tallies are 19 species of fly and 12 species of spider (plus 2 harvestmen). Not sure what The Ghost is on for his diptera or hopper tallies so far. Hopefully both are still in low single figures......

January Summary

You'll hopefully notice that the title of this post is January Summary and not January Summery. It's hovering a tad below the freezing mark at the moment but feeling distinctly cooler than that, according to the weather station situated just a few hundred metres away. The sun may be shining most days, but summery it ain't.

I've now completed the first month of my Big Year tackling spiders and flies, how has it been for me so far? Well I've certainly found spiders every time I've visited Uig Wood. And I've also found a few adult flies whilst sieving leaf-litter in search of those spiders, which was something I wasn't really expecting. I haven't undertaken any dedicated leaf-litter searches for hoverfly larvae yet, though I did stumble across this rather fine looking Dasysyrphus albostriatus larva on a fencepost. 

I've been back to see if it's still there; it isn't. Presumably it needed to be somewhere less exposed and moved. Either that or it's been predated by a Robin or Great Tit. 

My time spent sieving tussocks and leaf-litter in Uig Wood has been good fun, but it has also been rather limiting insofar as diversity of species encountered. I'm definitely not overlooking any spiders, I've collected quite a few that are smaller than the springtails that also occur in the sieved material. So why am I only finding the same few species time and again? 

I have a theory. Firstly, geographically speaking, I'm hardly located at the epicentre of British spider diversity. In fact, scrolling through the SRS Species Maps Skye, and the far north in general, seems particularly poorly represented for many species (though the species in that particular link certainly bucks the trend). Secondly I think the habitat itself is a bit limiting, or maybe my methods of sampling it are. Yeah, probably the latter.

Despite shaking quite a bit of moss/leaf-litter/grass tussocks through the sieve, my Uig Wood spider list for January is as follows: Tenuiphantes zimmermanni, Lepthyphantes minutus and Cryphoeca silvicola. That's it! By ragging mosses growing over fallen wood through the sieve I added Metellina merianae and Metellina mengei. I've also encountered good numbers of the harvestman Nemastoma bimaculatum in the leaflitter, All told that accounts for a mere six species. I was hoping for nearer twenty, and certainly for more liny variety. However, I am finding lots of subadult linys which I'm assuming to be a different species that matures later in the year. Give it another month or so and they'll be identifiable too. 

So far I've only been sampling the upper section of Uig Wood which is largely Wych Elm and Sycamore canopy over bracken with grass tussocks beneath it. 

This is the general area where I sieve tussocks and leaf-litter for spiders

Jackpot - two decent piles of leaf litter to sieve!

There are three main areas of Uig Wood. The images above show the uppermost section (eastern edge) of Uig Wood which is where I spend most of my time when on site in the winter months. It is sandwiched between sheep pastures upslope and a deadly drop into the river downslope. It's a smallish area, maybe 20 acres or so, but I do generally have it entirely to myself. 

The lowest section (located at the western edge) is heavily used by locals shortcutting from the shop to the village or walking their dogs. I don't particularly enjoy hanging around there in the leafless months - it leaves me just a bit too exposed to public gaze for comfort. I'm constantly on alert for an awkward confrontation. "Hey you! What are you doing there, hiding in the bushes??" or, even worse, "daddy, there's a strange man in the woods..." Plenty of crofting families here would view entomologists, or naturalists in general actually, with deep suspicion. It's just not understood. A bit bizarre really, seeing as they work on the land. I've been here over four years now and I'm pally with a good few folks in the area, but there are plenty more that I only know to nod to - and they don't always nod back (I suspect a couple of my comments regards the 'hordes of religious nutters around these parts' may have travelled further than I anticipated...) There's an undeniable sense of always being viewed as an incomer and hence not to be trusted. I can get away with wearing binoculars at the shore, that seems accepted, but I shall keep my sieving of leaves to myself until the tree cover develops enough to provide me with a screen to work behind. 

The central area of Uig Wood has some fantastic habitat but at the moment is pretty much inaccessible due to the river being in a state of spate, something which will probably last for some weeks yet. I've climbed up both sides of the gorge before, but I've never attempted to climb down into it. I don't think it would end well, not while the soil is as sodden as it is now. But once the river level drops, I'll be able to cross and explore the lower, more interesting part of the site located up inside the ravine itself. Last year I could cross the river by using a log jam as a bridge, a tad risky but entirely possible, but that was washed away earlier this winter. The alternative is to jump across from stone to stone, except they are all well underwater at the moment so I shall just have to wait a while. This inner area comprises proper Atlantic Rainforest habitat dripping with bryophytes and heaving with rare lichens. It has a diverse understorey and is an altogether more sheltered, humid part of Uig Wood, with a nice herb layer as opposed to the grass-under-bracken habitat to be found on the upper slopes that I've restricted myself to so far. I'm very much anticipating my spider and fly tallies to boom once I start exploring this part of the wood! I'm also planning to do some night visits into Uig Wood with a headtorch, explore the tree trunks and fenceposts for nocturnal species. But I shall probably leave that for when it starts to warm up a little, I think. 

Check out the cemetery wall

The wall around the old cemetery is about five feet tall and most of the stones along the top are loose. By carefully lifting these top stones, it's very easy to find a multitude of small creatures living hidden within. Typically I find lots of Balea perversa and other small snails, springtails, bristletails, a few millipedes and quite a few spiders. This is a great site for Tetrix denticulata and I expect there may well be some jumping spiders in there too. Certainly there are lots of Amaurobius present. My one exploration of the wall so far this year provided me with a female Centromerita bicolor and the harvestman Megabunus diadema. 

  

Centromerita bicolor - my only spider lifer of January

Megabunus diadema

Aside from Uig Wood, most of my remaining spider records have come from here at the hotel. I have a few nailed-on species available, ranging from Pholcus phalangioides in my bathroom to Tegenaria domestica in the boiler room 

Pholcus phalangioides (upper) and Tegenaria domestica (lower) - both regulars in the hotel

 

Leaf-litter sieving in Uig Wood has rewarded me with a fine selection of sphaerocerids (Lesser Dungflies), every one of which was a lifer for me - a nice wee bonus! They were Pteremis fenestralis (of the brachypterous 'northern form'), Lotophila atra, Spelobia rufilabris, Ischiolepta denticulata and Leptocera fontinalis. Away from Uig Wood, I found the sphaerocerid Thoracocheata zosterae in decomposing wrack at the top of Earlish beach, this being yet another lifer. Sphaeroceridae is a family of small to positively minute sized flies, but I seem to be doing well by them so far and they certainly add interest to the sieving process. Happily they seem to walk, hop or flutter rather than fly away when they hit the tray, so securing them is an easy process.

The brachypterous Pteremis fenestralis -  it'll never gonna get airborne on those wings!

There are a few other groups of flies that I'm finding at the moment. By far the commonest are the Trichocera, also known as Winter Gnats. These are frequently encountered in moorland areas and also inside the laundry shed in the hotel grounds, where they are attracted to the lights. Oddly, I don't pick them up in Uig Wood, maybe because I always have my head in a sieve?

So far this year I have encountered Trichocera regelationis (common on moorlands) which has a clouded cross-vein in the wing and quite lengthy cerci in the male, Trichocera saltator is the common species to lights here at the hotel and I've also had a couple of Trichocera major, far larger than both of the previous mentioned species and with very long cerci/ovipositor in males and females respectively.

A male Trichocera major - the least common species of winter gnat that I find here in Uig

 Also attracted to the lit laundry shed are multitudes of the fungus gnat Mycetophila ornata 

Mycetophila ornata - I've had this species previously confirmed by diptera god Peter Chandler

At this time of year I usually find good numbers of the Window Gnats Sylvicola, but they've been rather scarce of late. By far and away the commonest one I find here is Sylvicola cinctus, and indeed that is the one I encountered in January. Fingers crossed I add another species or two from this family during February.

A female Sylvicola cinctus resting beneath a security light

To sum up the flies, I've encountered six species of Sphaeroceridae, all of which were lifers for me, plus a hoverfly, a window gnat, three species of winter gnats and a fungus gnat - all of which I've mentioned above. I've also found the cranefly Tipula rufina, the gall midge Semudobia skuhravae in a birch catkin, Lonchoptera lutea, Heteromyza commixta and the larval mines of Chromatomyia primulae in Primrose leaf blades. That totals seventeen species of fly from ten families (five Nematocera and five Brachycera). To sum up the arachnids, I've seen ten species of spiders from seven different families (plus two harvestman from two families). I think that's alright, it's a fair start and a nice spread of families for the first month of the year. I was hoping for more, but what can I say - I'm never satisfied!

For February I intend to do some nocturnal torchlit spider searches, pay more attention to the flies attracted to the laundry shed, and continue my surveying of the monads in my 5MR Zone, which if nothing else will add more dots to the Trichocera regelationis map! I also intend to find some kelp flies among the wrackline and the littoral spider Halorates reprobus whilst I'm on the beach. 

January totals are 12 species of arachnid comprising 10 spiders and 2 harvestmen (1 lifer) and 17 species of diptera (7 lifers). By close of February I'd like both totals to have doubled. We shall see...