I’ve been collecting spiders for a bit and I really want to take good photographs of their epigyne/palps, but I’ve never figured out the proper placement. I know that both should be viewed/photographed under ethanol, but when I try to do this eg. place the palps in a petri dish with ethanol, they always float around and I cannot put them in the desired orientation. Does anyone know the standard procedure for taking these photographs?
fill the petri dish with silica beads. They absorb the alcohol, and become transparent. You can then use them as a base for manipulating the palps to the correct position/angle. The following observation was of a small spider caught in a pitfall trap, the photos are under a usb microscope and a petri with a layer of large silica beads that are just covered by alcohol. Use smaller beads to better position smaller parts. You can get the beads from those little dessicant packets that come in shipped goods to keep them dry…
Some people also use fine purified sand, like the kind you can buy in a pet store for your lizard terrarium.
For small money spiders, clear alcohol hand gel is an excellent temporary mounting medium allowing positioning of the spider (or other small insects) on a microscope slide.
ethanol is less dense than water, about 0.8x, so you shouldn’t have problems of the palps floating. if they do, just stack the silica in a sloping fashion, and place the palps at the point where they are just covered by the alcohol. The silica beads I mentioned, which I get from desiccant packets (which also come in medicine and vitamin bottles), comes in different sizes…
I haven’t had any problems with palps floating around, but dissected epigynes are another story. It’s quite a challenge sometimes to keep them positioned just right for photographing. I haven’t tried hand gel as I worried about it leaving a residue. Is the hand gel easy to clean off? Any other suggestions?
Thanks again for all your replies!
Thanks for responding to my concerns regarding the palps floating, this was my strange experience with the palps of a Myrmarachne specimen. I will try again using the silica beads in a sloping fashion, and post results here too for future reference.
Regarding the use of hand gel, I resonate with @zygy’s concern with the medium leaving a residue, as I would like to have these specimen stored permenantly.
I’m thinking one that is alcohol based should be fine. One of the other ingredients used is glycerine, which has been recommended to me (in diluted form) as the fluid to use in pitfall traps. The only ingredient of concern would be fragrances, so try and choose a fragrance free one!
The hand gel is very easy to clean off with no residue. Specimens can be cleaned either in water or 70% alcohol.
Personally I try to avoid removing palps if I can get the ID without removing them, but if I do I usually partially submerge them in sand to get a good look at them. Usually with a tray of sand, or silica beads it is possible to angle the spiders in such a way that the parts of the palps needed for identification can be seen. Though there are definitely times where removing the palp all together makes things much easier.
That was what I was told in another group, though I’m still quite inexperienced, is it not much more difficult to leave it in the perfect orientation (ventral, retro-lateral, dorsal) for photographs? There’s quite a lot of unidentified specimen here in Hong Kong and I would like to take good photos so I can ask for ID help.
That’s fair, better photos can definitely be achieved if the palp is disconnected, though I find that with some effort you can get the palp to remain mostly extended on the spider so you just need to angle it, but that doesn’t always work.