Male Osmia cornifrons, O. lignaria, O. taurus
We have been seeing more and more Osmia taurus in the Washington D.C. area and as that species is now known for PA, WV, VA, DC, NC it should be something everyone is looking out for. The males are a bit trickier than females. Below are the means I have come up with for separating the males including the somewhat similar O. lignaria. The characters for females are also included.
O cornifrons, O. lignaria, O. taurus - Combination of characters
O. cornifrons - Clypeus hair color white with a few black hairs on the sides - Scutum, scutellum, T1 and T2 hairs off-white to tan, with scattered black hairs intermixed on the scutum and scutellum
O. lignaria - Clypeus hair color entirely white - Scutum, scutellum, T1 and T2 hairs bright white, may or may not have black hairs intermixed
(note that this species' integument is bright blue while the others are usually a gold/green/blue that is obvious in comparison, but can be confused if you only have a single specimen)
O. taurus - Clypeus hair color white with scattered dark hairs on the far sides - Scutum, scutellum, T1 and T2 hairs clearly orange to burn sienna, no black hairs intermixed
O. cornifrons vs O. taurus - Head, clypeus, hairless region
O. cornifrons - Hairs present on the clypeus immediately above the very large horns - these horns located on the far sides of the clypeus
O. taurus - Hairs present on the clypeus farther away from the very large horns, the distance without hairs above the horns about the same distance as from the top of the horns to the rim of the clypeus
John Ascher and I would be very interested in any new records for this species
Sam Droege Sam_Droege@...
w 301-497-5840 h 301-390-7759 fax 301-497-5624
USGS Patuxent Wildlife Research Center
BARC-EAST, BLDG 308, RM 124 10300 Balt. Ave., Beltsville, MD 20705
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