Rarest bugs in BugGuide

my vote goes to

Apystomyia elinguis. It has only been collected ~3 times, in the 1920s, the 1940s, and in 2005. Shaun Winterton & his colleagues set up dozens of malaise traps in the type locality and Apystomyia showed up in only one of them on one day. It is found in the hills around Los Angeles, which is a habitat with an uncertain future. No one has any idea about its habits or larvae other than it has been collected on flowers in the past.

It is very interesting phylogenetically; it is the only member of the family Apystomyiidae, and soon-to-be published research shows that it is probably the relictual sister group to Cyclorrhapha, in other words most 'higher' flies. Here is an ESA presentation about it (under 'recorded presentations). (you have to be a member of ESA :< oops) Here is a report about it from the Fly Tree of Life project- search for Apystomyia in the article.

… Keith Bayless, 27 February, 2009 - 4:17pm

Endemicity + habitat loss => rarity?

It seems like the rarest things will be endemic to inaccessible and/or very small habitats. For instance, I happen to know that the only known species endemic to the district of columbia is a subterranean amphipod. I'm sure there are species whose range is restricted to a single island or mountaintop, in fact I saw a talk in November about the island marble butterfly (Euchloe ausonides insulanus ) which is extremely rare in absolute numbers, but within the handfull of small islands near Vancouver where it still exists, it isn't particularly hard to find.

On a related note, I was just given several hundred old lepidoptera specimens (oldest so far was collected in 1898) many of which were collected at high altitude in California. They are all in paper triangles and need to be relaxed and spread, which is going to take me many months. I'm optimistic that I'll find some fairly rare species, so as I process them I'll try to post anything that isn't already in the guide.

… Mark Fox, 27 February, 2009 - 11:49am

Also, rarely encountered is different from rare.

Obvious, I know, but there are plenty of things that are perfectly abundant, but are almost never collected. Pelican ear/nose mites, anyone?

… Mark Fox, 27 February, 2009 - 11:52am

An important distinction

Rarity is usually based on representation in collections. Many, many species are known only from one or two specimens. Obviously they can't be that rare in nature or they would never be able to find each other in order to reproduce. Generally, rare means we don't know what they are doing or where they do it or when they do it.

A good example is the scarab genus Gronocarus, with two species endemic to sandhill areas of the Florida-Alabama coast and known by fewer than a dozen specimens until a few years ago, most of those found dead. Turns out they are diurnal and fly only during the rain in the middle of the winter. They are not particularly hard to find if you are in the right place at the right time. This probably is true of most apparently "rare" species.

… Michael C. Thomas, 28 February, 2009 - 1:01pm

Maybe

this is up there

… Graham Montgomery, 26 February, 2009 - 9:09pm

That eucnemid along with abou

That eucnemid along with at least a half dozen other species in the family are in my opinion one of the rarest species here in the Nearctic region. Other rare eucnemid beetles are:

Euryptychus arizonicus (Van Dyke)
Prautianus americana (Horn)
Vitellius texana Knull
Xylophilus crassicornis Muona
Hylis californicus (Van Dyke)
Nematodes collaris Bonvouloir - presumed extinct, but thriving in Ohio and Missouri
Hemiopsida robusta (Van Dyke)

Many are based on single specimens collected, not nescessary habitat loss. The thing is the natural histories of these beetles are unknown, which attributes in part to its rarity.

… Robert Otto, 28 February, 2009 - 9:41am

Maybe rare....

I found a small group of these springtails in one location. I have sent two preserved specimens to Dr. Snider and haven't heard anything yet.

… Scott Justis, 27 February, 2009 - 6:04pm