Using the tool that @sbrobeson shared, it seems like I am currently the sole observer of two insects in iNat:
- Abroscelis psammodroma (A Carabid Beetle)
- Megacampsomeris asiatica (A Scoliid Wasp)
My rarest has got to be Euglesa compressa, a freshwater microbivalve which is a wide-spread but overlooked species: http://www.inaturalist.org/observations/206713288
It currently only has 4 other observations on iNaturalist.
Another species I saw would be Cryptocheilus attenuatum, a spider wasp with 23 observations. I was just outside my front door one summer morning and saw a small black blur land on the wall for less than a second before flying away. Luckily, I had my phone out and was able to take a single (blurry) photo.
It sat at “Needs ID” for nearly 2 years before somehow being identified to species: http://www.inaturalist.org/observations/130281159
I still can’t believe I just accidentally stumbled upon one of these, especially just right outside my own home. There are 2 other observations nearby but at least they’re actually in an expected habitat, taken by someone who was actively looking for insects, haha
Using https://elias.pschernig.com/wildflower/leastobserved.html?user=“insert yours here”
I count 44 taxa where I’m the only observer. Some are tentative/unconfirmed, while others are probably more common than the data suggests, but not identified to species in every case. Only 1 is not an arthropod … this Lobelia: https://www.inaturalist.org/taxa/880920-Lobelia-hartwegii
Using that tool tht everyone else is using, it looks like I’m the sole observer of a fair few species. My favourites are the vertabrates, as it seems to be a little more difficult to be a sole observer of a larger animal than an insect or plant :)
Lerista viduata, an extremely rare lizard that is only found on a series of hills around Ravensthorpe, WA
Lerista uniduo, another member of the genus that burrows in sand in the arid regions
And Delma concinna, a cryptic arboreal legless lizard that has 4 observations on iNat, all mine somehow
These are all most excellent lizards!
My current least observed species is Eubranchipus serratus (Ethologist Fairy Shrimp). When my observation was identified to species level, it was only the second record of the species in iNat. There were a number of misidentified records, however, that the taxon specialists revisited, so there are now 27 records at species level. I’m guessing there are more that aren’t identified yet as well.
Second-least-observed species is Cambarus fetzneri, the Allegheny Mountain Mudbug (59 observations).Unfortunately we were unable to actually find a crayfish, but we did find several mud chimneys indicating their presence. So whether it should “count” toward a species list is debatable, but at least it’s a valid observation!
I’m surprised, because it isn’t at all rare, but somehow, the only photo on the “browse photos” page for the larval stage of Pelaus Swallowtail is my observation.
But yesterday I came across another observation which I believe is also the larvae of this species. I commented to the observer and am awaiting a response.
I have neglected to post to this thread because it felt like bragging but I guess it’s just as much celebrating how iNaturalist can significantly contribute to the scientific community.
Here are some Florida seashells (the size of a grain of rice)
I don’t know that these are really that rare, but merely very hard to find and very few who try to find them. Anyway, these are presently the only ones posted to iNaturalist.
Many of them would be very pretty if they weren’t so small. I’ve added a picture to every other one
https://www.inaturalist.org/taxa/254793-Mitromica-foveata
https://www.inaturalist.org/taxa/292225-Retilaskeya-bicolor
https://www.inaturalist.org/taxa/254668-Cyclostremiscus-suppressus
https://www.inaturalist.org/taxa/1511096-Trabecula-laxa
https://www.inaturalist.org/taxa/292279-Vitreolina-bermudezi
https://www.inaturalist.org/taxa/254672-Solariorbis-infracarinatus
the other shellers who collect micros like me have similar numbers for first-time posts to iNat.
Bravo on your picture details!
I dont think i really have any rare ones myself maybe i would consider this observation of a Southern Hill Myna rare, as this observation is far out of it’s range. But i think the most rarest observation in Inaturalist itself is likely this observation of Mycena sp. growing out of a living frog. We’ve studied frogs for a long time now, but this is the first record of this occuring, and its from an Inaturalist observation, and the observation is made from my country and my state 
[@sriharsha444 heads up I moved your topic to this existing thread]
The rarest species of which I have research grade observations is Mycale toporoki, a type of sponge that looks a lot like a very interesting cheese.
The rarest species I’ve got, of which I don’t have any research-grade observations yet, is Rhiscosomides meineri, of which I am the only person with observations! An entomologist pointed me towards the species in this observation, and since then I’ve been trying to find more of them. I’m hoping millipede folks will eventually find them and confirm or correct them!
This observation of a tiny fern, Elaphoglossum stipitatum, along the stairs down to the caldeira of Piton de la Fournaise, 4 years ago, used to be the only observation of this species on iNat. Many thanks to germinalrouhan who identified it.
It is an endemic species of La Réunion, as reported by POWO.
I am surprised to see that POWO published my photos:
https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:17105620-1
A 2nd observation just arrived on iNat, yesterday (!). When I have time, I will post several other observations of this species I made in january 2024 (wet season). It was one of my travel objectives (my 6th travel to La Réunion) to see it again. I was surprised that it was easy to find several specimens, along these stairs. I took photos of them all. I never saw it elsewhere.
Many people go there, everyday, so I am surprised that my observation was the 1st one. Maybe because it’s tiny and because there are several other indigenous/endemic species to observe at the same location.
I found a distinctively patterned, small bee fly today that I was able to match with specimen photos on GBIF. I haven’t gone through other iNat or bugguide.net observations to see if they can be identified as this species, so it’s the only known living photographs of this species for now.
https://www.inaturalist.org/observations/210459795
This may or may not be a rare observation and reminds us that fortune favours the prepared mind!
While doing the usual evening toothbrushing garden lap to look for interesting things, I saw this fly and thought ‘ooh, I’ve not seen that before’, and took a quick picture, and thought nothing more of it.
It belongs to the genus Afrocneros, and it may either be A. mundus or A. mundissimus, which each have 8 or 0 iNaturalist observations respectively. Had I known the important ID characteristics for flies, I might’ve caught it and taken the necessary pictures to ID it.
My rarest find is Bryocamptus minutus which is currently the only confirmed observation of that species on iNat.
A few other rare finds are Protoparmeliopsis achariana and Lagynodes pallidus.
I am not at all impressed by my top 5, which is excellent, since I mostly observe in very common places with a mediocre smartphone. I would not expect to find many interesting unique finds. These <100 observation taxons are mostly from under-observed regions.
- The whole genus of Berry Aphids only has 30 observations worldwide atm. At the time of uploading, it was the only Dutch Berry Aphid observation.
- An Indonesian flower with only 37 observations.
- An Indonesian spider with 69 observations.
- An Italian snail with 74 observations.
- And yet again, an Indonesian observation, a flower with 76 observations.
Looking forward to rare finds that excite me this spring!
I recently went to remote parts of Honduras looking for insects so you’d think it would be one of those. Now not all of my observations have been identified to the species level but I doubt it will top my true rarest find. https://www.inaturalist.org/observations/168234733
A small beetle attracted to the light trap in my back alley. 9 total observations on iNat. Goes to show that there’s plenty of understudied wildlife in your neighborhood no matter where you live
I don’t know if I’ve added to this thread before but I’ll give mine.
Being a person who’s only advanced area of knowledge is birds, I’m always so grateful for the IDers of iNat because without them I would never know what I’m looking at.
This fall I saw a stray mule/hinny (I’ve had some people tell me it looks more like a hinny) wandering down the road near Duffield in Alberta, which give me the honour of being the first person in Canada to have a wild Mule observation.
Last summer I saw what I believe is (not research grade yet) is a Tenthredo erythromera near Bragg Creek, which was the 8th observation at the time and the 1st for Alberta.
Also last summer I saw a Shore Rove Beetle in Bragg Creek which was the first on iNaturalist for Alberta.
Probably my favourite though is my observations of Oberea schaumii, which was a first on iNat for western Canada. The cool thing about this one is that I uploaded my image to Wikimedia so it is the image that appears on it’s wikipedia page.
If a taxon counts as rare from having only 1 or 2 records in total worldwide, then eat your hearts out!
https://www.inaturalist.org/observations/66339259
https://www.inaturalist.org/observations/11270940
https://www.inaturalist.org/observations/204968737
A treat for my fellow southern Africans!