We suck

Posted by Graeme Lyons , Saturday, 16 November 2019 08:17

Last weekend I was lucky enough to spend some time in the field with other arachnologists. The shadow in the above photo is Richard Gallon, with Ray Gabriel central and me on the right. We were looking for the enigmatic and extremely rare Thanatus formicinus. A big and impressive spider last seen in Sussex in 1969. There is about as much chance of finding Winnie the Pooh, also from the Ashdown Forest. Yet it did just turn unexpectedly up at Clumber in Nottinghamshire, where I assume it has remained undetected for decades.

We didn't find it. Possibly due to a thick layer of Scotch Mist.

However, we did have an awesome day and recorded something in the region of 45 species of spider. Armed with a trio of suction samplers, we looked like a cross between the Ghostbusters and Last of the Summer Wine. Richard had his petrol driven beast and Ray and I had an electric one a piece. First sample and Richard got a lifer for him and a new one for the year for me. A big female Agroeca brunnea. Only the second time I have seen it and the first female.

I didn't take many more photos on the day, except this Himacerus boops recorded at Duddleswell. It seems to be a genuinely scarce species in Sussex. I do a lot of sampling on heathland and this is the first Sussex record since 2011!


Now back to the spiders. I was able to tease out just what I wrote down from my sampler in the field and make a comparison between a single petrol suction sampler and an electric one. 

Species Status Petrol Electric
Agrocea brunnea 1
Agroeca proxima 1
Araneus diadematus 1
Bathyphantes gracilis 1 1
Centrmerita concinna 1
Centromerus dilutus 1 1
Ceratinella brevis 1
Ceratniella brevipes 1
Cercida prominens NS 1
Clubiona subtilis 1 1
Cnephalocotes obscurus 1
Ditcyna latens 1 1
Erigone atra 1
Erigone dentipalpis 1 1
Ero cambridgei 1
Ero frucata 1
Euophrys frontalis 1
Evarcha arcuata 1
Gonatium rubens 1 1
Gongylidiellum vivum 1
Hahnia montana 1
Hypselistes jacksoni NS 1
Hypsosinga pygmaea 1
Hypsosinga sanguinea NS 1 1
Mangora acalycpha 1 1
Mermessus trilobatus 1
Metellina mengei 1
Neon reticulatus 1
Pachygnatha degeeri 1 1
Palliduphantes eicaeus 1 1
Pelecopsis parallela 1
Pholcomma gibbum 1 1
Pisaura mirabilis 1 1
Pocadicnemis pumila 1
Simitidion simile 1 1
Sintula corniger NS 1 1
Tenuiphantes mengei 1
Tenuiphantes tenuis 1 1
Tenuiphantes zimmermanni 1
Thanatus striatus NS 1 1
Walckenaeria antica 1
Walckenaeria unicornis 1
Zora spinimana 1 1
TOTAL SPECIES 43 35 25
Percentage 100% 8.41% 58.1%
Unique n/a 18 8
Ubiquitous 17 17 17
Species with status 5 4 4
Proportion of sp. with status 11.6% 11.4% 16.0%

This has proved a really interesting exercise. It was fairly standardised, we did about as many samples as each other. Mine certainly took longer to collect and a shorter time to process but I think this is a fairly standardised comparison without getting really science about it. Clearly the petrol gets more but they do get slightly different things when using them together. In this case, it would seem the electric sampler slightly inflates the metric of 'proportion of species with conservation status' that is a valuable tool for assessing a site's quality through its invertebrate assemblage.

EDIT: Totally forgot to say that Sintula corniger is new to East Sussex!

It was such a great day, so good to spend time with other arachnologists, something I rarely do being almost entirely self-taught. A big thanks to Richard and Ray and thank to Richard for the cake and coffee. I have been driving by Duddleswell Tea Rooms for 12 years! I was a bit gutted I didn't take more photos, so on Tuesday I went back up to the forest and did two hours sucking with one electric battery at Old Lodge and got a few goodies. First up I took some photos of species from above.

Here is the tiny Centromerus dilutus which is super common. This is on full zoom. This spider has a maximum length of 1.5 mm when adult! I never take the time to take photos of linys, this was quite a fun exercise but the photos are all poor, the light was awful too.

An adult male Walckneaeria antica.

And also very common, Centromeritus conccinus.

Evarcha arcuata and Cercidia prominens, both adult males at Old Lodge in November. There do not appear to be any records for either in November. It just goes to show it's worth getting out there even on these cold November days.

I did get a few species we didn't find on Saturday. These were.

Ozyptila atomaria
Micrommata virescens
Crustulina guttata
Meioneta mollis (new to site and Nationally Rare)
Tapinopa longidens (first Sussex record since 1968!)
Hahnia helveola (new site record and a lifer)

The last two of these species being new for the year putting me on 336. only 19 behind Matt! Here is a young Micrommata virescens.

Not to be mistaken for a young Tibellus

To the naked eye, these and young Thanatus striatus all look quite similar but Micrommata have what I can only describe as 'feet'. Like in this shot. Showing that they are related to huntsman.


And finally the adult male Hahnia helveola, which happens to be the 48th new spider I have had this year and my 7500th species in all. Now I wrote this pretty quickly in just over an hour as I am now going to go to, you've guessed it, Ashdown Forest. It saves me driving to the north of England to look for linys, while still getting good records for Sussex.

So yes, we suck. But we are awesome at finding spiders. If Tapinopa longidens can turn up at after 51 years, we won't miss Thanatus formicarius. I am sure it's out there. One thing I learned from Richard was the habitat I was looking in is a bit off, a little too Molinia dominated so now I am concentrating on a heather dominated structure that I think I understand. Watch this space!

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