That’s not that hard though, just need to find a couple of specimens, nearby or not, I had it with quite a few taxa, but now there’re more observers, so it doesn’t count now.
If my ID is correct (which I’m always a bit paranoid it’s not), then this Pouched Anole is one of only 30 observations on iNat: https://www.inaturalist.org/observations/131501728
This eighty-eight (in this case, more like eighty-nine) butterfly is also one of 47 obs… and to think I photographed it on a friend’s jorts!: https://www.inaturalist.org/observations/131501721
Finally, not nearly as rare (759 obs) but I was baffled that the least-observed species of bird I’ve seen is the fiery-billed aricari-- it is a common, easy-to-spot and charismatic bird across its range. I suppose it’s just down to how limited that range is.
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Thanks for letting us know about this tool @sbrobeson . I’m having some fun with it. Did you put it together?
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This tool is wonderful! According to it, my least observed taxa is this observation of a stonefly, tentatively identified to subfamily Peltoperlinae, which has only 35 records on iNat. Probably under-observed/identified rather than rare, though. If current ID is too specific to prove, family-level ID is 222 obs on iNat. I’m now interested in photographing these better, considering the rather few observations of Peltoperlidae identified to genus-level or lower.
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yes, definitely not the rarest in some absolute sense… but nevertheless “rarest-on-iNaturalist”, or rarely observed/recorded to put it another way.
it’s all bound to be artefactual in some sense, and it depends on one’s definition of rarity (range-restricted but highly abundant? widespread but in very low density? necessarily both range-restricted and low-density?), of course…
I didn’t make it, credit goes to Elias Pschernig (I believe) – I don’t know enough about API use to make such a thing myself. It is a very fun tool though! 
edit: to contribute mine to the topic – I’m one of the only 4 iNaturalist observers of a very scarce cottonwood endemic to the Sierra Madre Occidental, Populus guzmanantlensis. I stumbled across the population while collecting with colleagues from the IBUG at the University of Guadalajara – unbeknownst to us it was in a previously recorded population, but we were all very surprised to see it that day.
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I recently imported the 2400 species in the California Native Plant Society Rare Plant list into an iNat project https://www.inaturalist.org/journal/maxo/77720-cnps-rare-plants-on-inaturalist. There are still 700 species which have no observations yet!
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Thank you @sbrobeson for informing us about the tool, and thanks Elias Pschernig for creating it!
According to stats, I have four obs where global score is <=5:
a coral: https://www.inaturalist.org/observations?taxon_id=1025905
a shrimp: https://www.inaturalist.org/observations?taxon_id=1241553
a nudibranch: https://www.inaturalist.org/observations?taxon_id=418364
a worm: https://www.inaturalist.org/observations?taxon_id=1350925
Now, I am just a layman :) but I think / I suspect, only no. 2 (the shrimp) that is probably not so common. No. 1 (the coral) and no. 3 (the nudibranch) are really a surprise (to me at least) that they make to the list at all! No 4 (the worm) (this is where I ‘score’ the highest, 40% of all obs :)), according to the expert, is rarely captured, and probably is a new species. So am very happy with this.
But all and all, there are many unidentified species among things underwater (ie not yet studied); you can see that there are so many genus and even higher taxa on underwater obs!
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Wow, I loved browsing through the list created from Elias Pschernig’s tool. Thanks for sharing that, @sbrobeson! This is my list of species I’ve observed with the fewest observations on iNaturalist:
1 observed / 1 (only) by me:
- Spider / Jumping Spider - Pseudeuophrys iwatensis
- Spider / Grass Funnel Weaver - Agelena choi
- Insect / Butterfly - Neozephyrus taxila
- Insect / Moth- Hiroshiinoueana gangweonensis
- Insect / Beetle - Cryptocephalus tetrathyrus
- Insect / Beetle - Saperda subobliterata
- Insect / Fly - Acidiella pachypogon
- Snail / Dove Snail - Mitrella martensi
2 observed / 2 (both) by me:
- Insect / Fly - Drinomyia hokkaidensis
3 observed, 2 by me:
- Insect / Beetle - Acicnemis shibatai
7 observed, 5 by me:
- Spider / Jumping Spider - Attulus albolineatus
8 observed, 7 by me:
- Spider / Jumping Spider - Evarcha coreana
9 observed / 5 by me:
- Insect / Mayfly - Cinygmula grandifolia
11 observed, 6 by me:
- Spider / Jumping Spider - Talavera ikedai
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Exactly, the thread does say Rarest Finds on Inaturalist (sic)… It does not say rarest in the world. As we move on and more and more people observe there will likely continue to be first observations global and regional. Especially as more diverse people survey more diverse realms looking at more diverse species. Just for fun, spend a day not looking at your favourite species in your favourite spot and look for something different. If you normally look in field, look at the seashore or lakeshore or underwater…something different.
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that is a really neat tool!
Using it I found I have:
Only observation for Troglohyphantes cantabricus
One of two for Phausis inaccensa - and the only live one
One of three for Pseudotremia nyx
Two of the three for Photinus macdermotti
and some others similar 3/3 2/3 etc. Basically all cave species and fireflies. Gee wonder what I like…and I think fireflies people just assume one of few as it’s what iNat tends to suggest but there are a lot and Dr Faust (not on here) has been teaching me and helping me ID them :)
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I like carabid beetles so it was really cool to discover via that tool that I apparently have an iNat-first (and so far only) observation of Carenum marginatum.
Even GBIF only has eighteen records, and none with images!
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We need more people as well as nomolosx identifying the leafhoppers of Botswana and other African countries. I’m sure there are so many new species we might find here in Botswana. Leafhoppers can also be so beautiful but unlike moths seem to be underphotographed and underappreciated ! https://www.inaturalist.org/projects/cicadellidae-leafhoppers-of-africa
https://www.inaturalist.org/projects/leafhoppers-of-botswana-cicadellidae
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Great tool, thank you for sharing!
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Currently the leader in a few species:
I have the only 3 observations on iNat of a Delphacid planthopper, Chionomus herkos (tentatively identified, working on getting a specimen): https://www.inaturalist.org/observations?taxon_id=1227843
As well as seeing a few other obscure hoppers:
https://www.inaturalist.org/observations?taxon_id=1243842
https://www.inaturalist.org/observations?taxon_id=637813
-Apparently my backyard has an abundance of obscure hoppers (Although this is probably the case for a lot of people)
Also saw a cool “Bromeliad mosquito:” Wyeomyia vanduzeei: https://www.inaturalist.org/observations/144113826
Also not rare or anything but just randomly found an exotic turtle in a new area for my region: https://www.inaturalist.org/observations/154683829
-Which is an exotic species from Australia that actually doesn’t have that many observations in general either.
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I’m looking at mostly invertebrates in an area which has very few iNatters and according to that search tool I have observations of 51 species which have fewer than 10 observations, and of those, I am the only contributor for 8 of them. The trouble is that this is only able to help with named and identified observations. Many obs are only identified to Family or worse and some could well be undescribed species which are much more interesting but we don’t even realise it.
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I uploaded the first observation of Figuladra muirorum on inat a couple days ago
https://inaturalist.ala.org.au/observations/154561747
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I never thought this thread would reopen. Is there a way to list all our species for the rarest species checklist???
