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Dryopid - Postelichus

Dryopid - Postelichus
Huachuca Mountains, Cochise County, Arizona, USA
March 12, 2011
Size: 6.5 mm
Collected with leaf litter from the stream.

Moved from Riffle Beetles.

P. immsi(?)
The species I always collected in AZ.

P. immsi
The species I always collected in AZ.

Postelichus in AZ
I've collected P. immsi and P. confluentus, both in numbers, from the same streams several times in and around the Huachucas. I've heard there may be a Mexican species wandering around down there, too.

is there a good key to the genus?
I've got the specimen on hand to key out.

Brown (1972)
Still the best key to species for the North American dryopids:

Couplet 96 will separate Helichus (goto 99) from Postelichus (goto 97), although this key predates the name Postelichus. You'll need to look at the naughty bits for Postelichus. The males are fairly straightforward, but the females less so. In addition to the two species I mentioned, I've also seen some females from AZ that don't seem to match either. Are these a third species or just undocumented variation on the two? I don't know.

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