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Greetings Experts,

I could use some assistance in the identification of a difficult Diptera larvae taxon. Pictures are below (low res). Hi res at https://www.dropb...pJj9a?dl=0

The specimens in question were collected from a freshwater stream in Montgomery County, Maryland, U.S.A. (Piedmont/Coastal Plain), Riparian and marginal aquatic organisms were also found in the sample. Specimens are approximately 3mm in body length.

I've narrowed the field down to Cyclorrhaphous, but I'm having trouble characterizing the spiracles. On the posterior, there appears to be two spined lobes with a longitudinal crease (anal opening). Two darkened areas that may be spiracles lie dorsolaterally above that feature. A sclerotized feature resembling a "T" shape starts on the dorsum of the thorax.

Any thoughts? I'm shooting for genus, but a family name would be a great help. Thanks in advance.

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Original Poster here: I should mention that close ups (with a compound microscope) of the head and posterior can be found at the dropbox link: https://www.dropb...pJj9a?dl=0

https://www.dropbox.com/s/tw8ueqotyodjjln/IMG_0012a.JPG?dl=0


https://www.dropbox.com/s/3lm26airjdt21k3/IMG_0011a.JPG?dl=0

Thanks,

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Cecidomyiidae for sure, this T-shaped platelet is typical for this family.I cannot tell you more about the genus. Sometimes I encounter these larvae too in freshwater samples when sweeping with a pondnet, but these larvae are not aquatic.

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Thanks atylotus, I appreciate the help.

The T-shaped platelet should be present on the ventral side of the thorax, but it would appear to be on the dorsal side (convex) to me. What little detail I can make of the head appears to have parts directed away from the platelet.

I'm not sure what to make of that, but maybe this is just an oddball larva in regards to body shape.

Thanks again!

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I'm not an expert on this family, but you may check some characters with Smith (1989), freely available on the website of the Royal ent. Soc. (Vol 10, part 14):http://www.royens...-handbooks
2 Pdf's
By the way: you also photographed 2 nice larvae of Tabanids on IMG_10 (and a mayfly). But you probably knew this already.