After running into John & Jane Balaban's
Pepsis post below:
...I was motivated to check my archives for any photos I might have taken of the same
Pepsis, so I might scour them for more diagnostic characters to work on an ID. Many of us participants at the 2013 AZ BugGuide gathering saw pepsines (and
many other taxa) visiting galls strangely laden with "nectar" (actually honeydew) on the
oak tree in front the station.
Fortunately, I was able to find some
Pepsis photos from those oak galls that...although not very good aesthetically...at least manage to show critical characters for obtaining an ID.
The individual I photographed was a male, as can be seen here from the more-or-less straight, relatively thickened antennae...
and the presence of dense, abdominal "hair brushes" on the distal sternites (see pink arrows on the
full-size image). Such "hair brushes" are only present on males of certain (not all) species of
Pepsis...in our (north of Mexico) area, those species include:
angustimarginata, azteca, cerberus, elegans, mildei, and
saphirus (I've used the "old names" here, see the
Pepsis info page for the current synonymies).
These "hair brushes" can provide useful characters for keying males of these species (in terms of various details involving their location, shape, positioning, relative length and curvature, etc.). In the individual here, it can be seen that there are virtually
no hair brushes on the 5th sternite (just short, inconspicuous hairs there); and
two, short, inwardly-arched, longitudinal brushes positioned laterally near each edge of the 4th abdominal sternite...with their longish-hairs curl inward towards the central axis of the abdomen. Other important characters for the ID here are the entirely black antennae; the predominantly orange wings, with narrow dark marginal bands (with
out hyaline tips!); and the pronounced ("pointed") mesopleural tubercle (white arrows).
From the above-mentioned characters, this keys unambiguously to
Pepsis "angustimarginata" in Hurd
(1)(1952). That name has been used for many decades in the literature focusing on nearctic species of
Pepsis...but it was recently synonymized under the name
Pepsis basifusca by Vardy
(2)(2005), whose work focuses more on the neo-tropical area, where the great majority of
Pepsis species occur. The epithet
"angustimarginata" presumably refers to the (rather uniformly) narrow dark marginal borders of the fore and hind wings, which extend from near the tip of the marginal cell, around the apex of the wing, and continue along the posterior edge to near the axillary excision. Similarly, the epithet
basifusca presumably refers to the typically darkened base of the wings.
You can read Viereck's original 1907 description of a female
P. angustimarginata here; Banks has brief comments on males
here.
