Introducing Phytosciara greylockensis

You know I’ve been way too busy when I let weeks go by without celebrating the publication of a new species description in a BugTracks post. Julia and I spent much of July exploring Michigan and Ontario (including visiting the Canadian National Collection of Insects and attending the combined annual meeting of the Lepidopterists’ Society and Societas Europaea Lepidopterologica), and ever since I’ve been catching up on fieldwork and report-writing, trying to reclaim the parts of our yard that we don’t want to revert to forest, and wrapping up a series of papers on leaf-mining flies I’ve been working on with Owen Lonsdale. Oh, and I spent an intense and thoroughly enjoyable week teaching my Tracks & Sign of Insects… course at the Eagle Hill Institute in Maine. I’ve had to take a break from the leafminer book, but I’m looking forward to getting back on track with that in the coming weeks.

The last book installment I sent out covered all of the monocots except the order Poales (grasses, sedges, rushes, and cattails), and as it happens the July issue of Proceedings of the Entomological Society of Washington included two papers of mine that supplement this chapter. One of them answers the riddle of the agave leaf mines shown in the second half of this post. The other* describes the species of dark-winged fungus gnat (Sciaridae) I showed here. I always like to tell the tale of a species’ first discovery, so here goes…

Back at the 2016 Berkshire BioBlitz on Mt. Greylock, as Julia and I set out on the Rounds Rock trail loop, we passed some bluebead lily (Liliaceae: Clintonia borealis), and I suggested she keep an eye out for leaf mines on this plant.

Although it was not known to host any leafminers, three years earlier our friend Jesse had spotted some little squiggles on the leaves while we were standing in a parking lot, and ever since I’ve been hoping to encounter some with larvae inside.

Less than a minute had passed when Julia said, “You mean like these?”

Sure enough, she had spotted some mines, but as you can see, they were not like the ones I’d seen before. Rather than being narrow, yellowish lines that meandered freely across the leaf veins, these were transparent, elongate mines that tended to be bounded by the veins. But having already established that nothing was known to mine leaves of this plant, I knew these were worth investigating too, so we spent several minutes filling a big peanut butter jar with leaves containing larvae.

I could see that the larvae were long, narrow, and legless with distinct, brown head capsules, and I thought of Zygoneura calthella, the dark-winged fungus gnat we’d found mining leaves of marsh marigold. Unlike that species, these larvae soon exited their mines and began to window-feed on the lower surfaces of the leaves.

In about a week, they began to gather up bits of leaf and other debris to construct cocoons, which they attached to the undersides of the leaves despite having the option of burrowing into soil.

A few days later, pupae popped out of the cocoons, and out of these popped the adult sciarids.

That last photo shows the single male among the seventeen adults that emerged—but one was enough! I sent the specimens to Kai Heller and Björn Rulik, the same Germans that had helped me with the marsh marigold miners, and their morphological and DNA analysis confirmed that it was a new species—a member of the genus Phytosciara, which has three European species and (until now) none in North America.

I decided to name it Phytosciara greylockensis after the type locality, and not after the host plant, because based on the single collection I didn’t know whether it was specific to Clintonia or a generalist like the two European species whose larvae are known. I have been checking every patch of Clintonia I’ve encountered since 2016, without any further sign of P. greylockensis—until last month, when I found some empty mines near Jason Dombroskie’s cabin in Ontario. So maybe it’s a Clintonia specialist with a northern distribution, and we happened to catch it at its southern range limit on the highest peak in Massachusetts? If anyone else bumps into this species, I’d love to hear about it!

* Eiseman, Charles S., Kai Heller, and Björn Rulik. 2018. A new dark-winged fungus gnat (Diptera: Sciaridae) mining leaves of Clintonia borealis (Aiton) Raf. (Liliaceae). Proceedings of the Entomological Society of Washington 120(3):500-507.