ID Guide 7: Eoreuma-Diatraea-Donacaula

From our recent Timberlake bioblitz, it was clear that we were (collectively) confusing at least three different Crambid genera which have elongate triangular cream-colored wings. We labeled images of apparently the same individuals or similar moths as Eoreuma, Diatraea, and Donacaula. I was getting quite confused so I went back to sources including MPG, BOLD, and BG (not assuming everything there was properly IDed) and here’s what I think I’ve figured out:

Eoreuma: FW outer margin fairly square and rather straight. Veins are pale, flanked by fine dark speckling. The “discal dot” is at the end of the FW cell. Five species have been recorded in Texas but by far the most common one is E. densellus which occurs in Central, South, and East Texas.

Diatraea: FW outer margin fairly square and rather straight. Veins are darker than ground color, flanked by pale strips inbetween. I’m not seeing any small dark speckling along the veins. Discal dot is at end of FW cell same as Eoreuma. The two most common species in Texas appear to be D. evanescens and D. lisetta both of which are primarily found in deep E Texas.
(D. lisetta has rows of brown spots across FW.)

Donacaula: FW is much more pointed with an angular acute tip. In most species/examples, there is a dark brown streak through the length of the FW. Discal dot is actually beyond the FW cell. Eight spp. recorded in Texas; most widespread is D. mellinellus.

Based on this review, I think I’m seeing primarily Eoreuma densellus among our Timberlake “catch”.

Xubida (added 11/27/21): Certain species of the genus Xubida need to be added to this discussion. They appear to have the dark veins flanked by pale margins like Diatraea. At least some of them also have a discal dot. The set of 8 or so species listed on MPG are all so similar that I hold out little hope of distinguishing species from photos. Knudson & Bordelon (2018) didn't list any species of Xubida in Texas but iNat has several apparent records of one or two species:

由使用者 gcwarbler gcwarbler2019年10月10日 03:07 所貼文


I believe I have a moth similar as well. One at the moth sheets and a daytime observation. Had not had a chance to look them over well yet. Hopefully will post tomorrow.

發佈由 mikef451 超過 4 年 前

Of course, we also had plenty of Agriphila vulgivagellus which is more elongate and tubular, with long dark palpi; pretty easy to pick out.

發佈由 gcwarbler 超過 4 年 前

Thanks Chuck! As always! :-)

發佈由 annikaml 超過 4 年 前


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