How many species of bugs (arthropods) are identifiable from photos of living specimens?
With the increasing quality of digital photography, it is increasingly possible to identify taxa from one or more photographs.Even so, there is always a percentage of species that are cryptic or not identifiable in a photograph, when it is necessary to see details that are always hidden in the living animal without handling it /killing it to extract genitalia.
In the area where I live, in Europe: Iberian Peninsula: Spain.
In the case of diurnal butterflies (rhopalocera) it is possible to reach 100% as long as both sides of wings are clearly visible. (correct me if I am wrong)
In the case of many Araneidae web spiders it is possible to identify all species if with a good macro lens you can take good pictures of the epigynum of the female when it is in the web. (correct me if I am wrong)
Many bees of the large genus Lasioglossum hardly ever show the sculpture of the propodeum or the tergites, which are essential details in many cases, so I estimate that only about 5% of the species can be identified.
In many other groups I am sure that more than 50% of the taxa can be identified (Odonata, for example), while in others with very small species (diptera Chironomidae, hymenoptera Mymaridae) I think less that 5% can be identified.
Do you have data on the groups you work with/know, or what is your opinion on the matter?
Orthoptera are quite easy compared to other groups, Diptera varies, I see quite a lot of families being ided through photos, it matters more that you need some angles where you have to take fly in your hand (not even holding it, just using hand as a surface that you can rotate), pretty much every insect where something other than genitalia that are hidden inside the body is used for id, can be ided with photos only.
even in the diurnal butterflies have exceptions…like Leptidea sp. or actually also Pontia edusa/daplidice…For the correct identification you need genitalia…
In the United Kingdom there is a Spider and Harvestmen Recording Scheme, and each species has a “identification difficulty rating”, so i.e., species with “2” can be identified with a good photo. See the example for Argiope bruennichii, so we can assume species with levels “1” and “2” are identifiable with photo.
By “identifiable” do you mean identifiable to species?
@gcwarbler has been working on methods of identifying some moths without needing to dissect or examine them, I wrote a blog post and made a video about this a few years ago, in case it’s of any interest.
Well, I had some species ided that in this scheme are named as “only expert can id” (as UK resources always ahow up in searches, I like them), so having a knowledgeable person is really a must in this question, no good photo will serve the id purpose if nobody looks at it.
Soft-winged Flower Beetles are photographed very often in Spain, being so common, but they are identifiable at species level only in a few cases: Danacea, Enicopus, Dasytes etc. all require dissection.
“…when it is necessary to see details that are always hidden in the living animal without handling it /killing it to extract genitalia.”
Without handling it is a very different proposition from without killing it. With practice I guess you could photograph a male chironomid’s genitalia without killing it and you could probably squeeze out a beetle’s aedeagus without killing it. How functional it would be afterwards would probably vary widely.
The Victorian naturalists had a gadget called a compressorium. If you imagine one of those horror film rooms where the walls close in, but insect sized. I was thinking you could put the chironomid in, hold it still without squashing it and take the photos. Or you could anaesthetise it.
By the way, I haven’t had a spiritual conversion or a bang on the head. I’m not suggesting chironomids should be identified alive in this way, just pointing out that most photos needed for insect id could in theory be taken of a live specimen.
this would be wonderful, but I doubt it is humanly possible (perhaps with two people, one with the camera, another withe the chironomid abdomen)