Notes on Scotophaeus blackwalli

The Mouse Spider, Scotophaeus blackwalli, is a familiar inhabitant of homes and gardens, but there is a fly in the ointment. There is a second species of Scotophaeus in the UK, S. scutulatus. However, although widespread in Europe, this is very rare in the UK with only three British specimens recorded. The snag is that its close similarity to S. blackwalli means that other specimens may be overlooked. Thus, I feel morally obliged to check every Scotophaeus I see. Because Mouse Spiders are furry, it's difficult to get a good view of the epigyne without killing them, and as they are so common, that's a problem. Having been sent several Scotophaeus to I.D. today, I have been working on a better way of checking that works on live specimens.


Female Scotophaeus blackwalli

Scotophaeus blackwalli has 3 dorsal spines on femur III & IV (small juveniles may lack the diagnostic distal spine).
Scotophaeus scutulatus has 2 dorsal spines (proximal and median, no distal spine) on femur III & IV.

So telling them apart is "easy" - just look at the spines:


Male Scotophaeus blackwalli: P - proximal spine; M - median spine; D - distal spine (absent in S. scutulatus); S - scutellum (from the Latin for "shield"), an abdominal chitinous plate only present in males - is this for additional protection during mating?


I am indebted to Simeon Indzhov for his patient advice :-)

#LockdownSucksChallenge Round 4 - a couple of noobs

Pocadicnemis pumila

I've finished doing the I.D.s for round 4 (for me) of the #LockdownSucksChallenge. Most of the species are familiar from previous rounds (but a nationwide picture of abundance and phenology will be useful), but there are some changes. Ceratinella brevipes and Pocadicnemis pumila are new for me, and not frequently recorded in VC55 (possibly because of identification difficulty). In addition, my local Pardosa and Xysticus are now (mostly) mature, signalling the start of a mad scramble of the next couple of months.


Pardosa amentata

The full list from this round is:

Bathyphantes gracilis 2m 1f
Ceratinella brevipes 1m 3f
Dicymbium nigrum/brevisetosum agg 1m
Dismodicus bifrons 1f
Erigone dentipalpis 1m 2f
Erigonella hiemalis 5f
Oedothorax fuscus 1f
Pachygnatha degeeri 1m
Pardosa amentata Abundant
Pocadicnemis pumila 1f
Xysticus cristatus 2f

How to improve your microscopy

There's no doubt that microscope optics are important in forming a good image, and if you're going to record the output as a photo or a video, then the capture system and linking optics are important too.  However, I'm increasingly coming round to the view that the lighting is as important as the above.  It doesn't matter if you're using a fancy microscope and an expensive camera or a cheap microscope and holding your mobile phone to the eyepiece to take photos, if the lighting is working against you, then you're going to struggle. Like many people I've been using Ikea Jansjo LED lamps for microscopy. They're relatively cheap and they work OK, but it wasn't until I bought a Brunel Microscopes Dual Flexilite LED unit recently that my eyes were opened:



Using exactly the same optics, the quality of the images I can produce with my kit has improved 10-fold. Here's Dismodicus bifrons, a 2mm-long spider:



And here's the epigyne from this specimen, which is approximately 0.1mm:



I've never been able to produce images this good before. What has changed? Not the optics - only the lighting.