Pena Blanca Springs area, off Ruby Road, Pajarito Mountains, Santa Cruz County, Arizona, USA
July 27, 2013
This is the companion post to the micropezid found a few feet away and a few minutes apart below:
The keys in both
Cresson (1938) and Merritt & James
(1) are nearly equivalent, and go as follows for the individual here:
1b) Notopleuron with 1 bristle (subgenus
Micropeza)............2
2b) Thorax black without broad pale notopleural stripe.......8
8a) Thorax shining.............................................
nitidor Cresson
8b) Thorax dull, pollinose.............................................9
9a) Antennae pale, arista entirely white; femora with dark disto-median and apical flexor spots; postabdomen with a black circular spot.....
abnormis Cresson
9b) Antennae black to dark brown, arista black basally, apical portion variable; femora without spots; postabdomen without circular spot..........10
At first I wasn't sure whether to go with:
"8a) Thorax shining"....leading to
Micropeza nitidior;
or with...
"8b) Thorax dull, pollinose".....leading to
Micropeza abnormis.
On the one hand, the flash on the photo was overly bright, and the apparent shininess might not be a faithful rendering. On the other hand, the thorax...while slightly pollinose beyond the suture...doesn't seem especially so. There didn't seem to be a clear choice here.
But my hesitations were addressed, firstly, by the remark of Merritt & James
(1) that the species
M. abnormis "differs from others in the genus
Micropeza by having a black thorax and a white arista." Those two characters (in particular, the white arista) are quite apparent in the full-size images in this series...which would seem to tilt the ID to
M. abnormis.
Moreover, reading the descriptions of the two species in Cresson (1938),
M. abnormis is described as having: "Thorax more or less cinereous but never densely so, otherwise surfaces
more or less shining", making the "thorax shining" character in the key leading to
M. nitidor less compelling. And the
description of M. nitidor as having: "two (yellow) median orbital spots on the frons, or, entire anterior part of frons (yellow)" does not fit at all here.
Finally, Merritt's 1972 "Geographic Distribution of Micropezidae in the Western U.S." lists two records for
M. abnormis from Santa Cruz Co., AZ (from "Ruby", and "Sycamore Cyn, near Ruby"), whereas it lists no records of
M. nitidor from Santa Cruz Co., AZ.
Thus, the best choice here seems to be
M. abnormis.