Open spaces: A new species of fly from the Yukon

There’s a little genus of small, rare flies that live in bird nests. They’re called Neossos, and a few years ago one of my former undergraduate students, Gregor Gilbert, pulled together what was known about the taxonomy and ecology of Neossos in North America and published a nice paper on the group. The three described North American species of Neossos are known from a few locations in northeastern USA and Quebec, and scattered records from British Columbia south to California. Because Neossos specimens are almost entirely restricted to bird nests (at least, it looks that way), they are rare in museum collections. In total, we managed to find a little more than 100 specimens of Neossos in museums in the course of that project, mostly from previous student projects on bird nest arthropods here in the lab.

Given all the above, it was a surprise when we were sorting through flies we collected in 2011 on wet subarctic tundra along the Dempster Highway up above treeline in the Yukon and found something that looked a lot like Neossos. Anna Solecki, a M.Sc. student in the lab and a specialist on arctic flies, decided to take a closer look and started comparing material of the other described species of North American Neossos in the museum collection here (This is one of many advantages of having accessible natural history collections). After a lot of microscope work we confirmed that our Yukon specimen was a new species, distinct from the three other North American Neossos.


Modified by CombineZP

Neossos tombstonensis. The tundra specimen. (photo by T. Wheeler)

We only collected one specimen that first year. It was a male, which in flies tend to have more definite species-level traits (female flies are often harder to identify to species). So, when we planned a return trip to the Yukon we were hoping to collect more specimens up on the tundra. In the meantime, we put the single fly away to see if we could add more data to the taxonomic description with additional specimens.

wet rep 3 dempster

“Wet Replicate 3”, Tombstone Mountains, Yukon. Collecting site of specimen 1. (photo by T. Wheeler)

We didn’t find any more specimens of the new species of Neossos in similar wet tundra habitats, but we did collect a second specimen in a very different habitat a few hundred kilometers south: a dry meadow south of Whitehorse.

Robinson roadhouse.jpg

Robinson Roadhouse, Yukon. Our new species of Neossos was collected near here. (photo by T. Wheeler)

It’s nice to have lots of specimens when we describe new species. It gives us a better sense of things like variation in traits, geographic distribution, ecology, etc. But taxonomy doesn’t always work that way and many new species are known from only one or a few specimens. It’s a start, and it lets us put a name on a new species, so future researchers have a reference point for identifying new material. Based on our two specimens, we wrote a description of the new species, which we named Neossos tombstonensis, after the Tombstone Mountains and Tombstone Territorial Park, where the first specimen was collected, and we published the paper in the recently launched Biodiversity Data Journal (which I highly recommend for taxonomic and other biodiversity data!)

Even with the taxonomy sorted out, there are still some lingering mysteries about Neossos tombstonensis. The other species of Neossos have been collected almost exclusively from bird nests, and each species seems to specialize in a different type of nest and host: Neossos marylandicus lives with cavity-nesting passerine birds; Neossos californicus in the nests of raptors; and Neossos atlanticus (a new species we described in 2007) is known only from the simple nests of cliff-dwelling seabirds. So, based on the known ecology of the other species, we can predict that Neossos tombstonensis lives in bird nests too. But we have no idea what kind of birds or nests. The wide distribution of Neossos tombstonensis (wet tundra at subarctic treeline and dry meadows in boreal forest clearings) doesn’t help narrow down the search. There are several species of flies that live in bird nests, and play a wide range of ecological roles there. Neossos is almost certainly a scavenger in the nest material. Clearly, we still have a lot of unanswered questions about these little flies. Somewhere, where the worlds of entomology and ornithology intersect, there are some more answers. But that’s a future paper.


Solecki, A.M. & T.A. Wheeler. 2015. A new species of Neossos Malloch (Diptera: Heleomyzidae) from the Yukon Territory, Canada, and a revised key to the Nearctic species. Biodiversity Data Journal 3: e6351. doi: 10.3897/BDJ.3.e6351

About terry wheeler

professor, museum director, entomologist, ecologist, naturalist
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