A new species of Stilbopogon from the Monvero dunes of California (Tiphiidae, Hymenoptera)

One new species in the brachycistidine tiphiid genus Stilbopogon, monveroensis is described from the Monvero Dunes in Fresno Co., California. A revised key to the species of Stilbopogon is included.


Introduction
Brachycistidine wasps are an obscure group of generally nocturnal aculeate parasitoids. Males are winged and very different appearing than females, in much the same pattern as in the Mutillidae. However, brachycistidines lack any kind of colorful pigmentation, ranging in color from yellowish brown to nearly black. For decades there was a separate taxonomy for males versus females and no sex associations were made until Kimsey (2006). One consequence of making the sex associations was that the genus Quemaya Pate, 1947 (based on males) was predated by Stilbopogon Mickel & Krombein, 1942 (based on females). Stilbopogon, under the old name of Quemaya, was first revised by Kimsey and Wasbauer (1996).
Very little is known about the biology of the Brachycistidinae. The winged males are generally collected in blacklight traps and the wingless females in pitfall traps. Members of this group were assumed to be parasitoids much like the rest of the family.
The first host record for any species of Brachycistidinae was found to be a tenebrionid larvae found being attacked by a female Stilbopogon in the daytime (Borowiec and Kimsey 2015).
Males in the genus Stilbopogon exhibit a number of unusual features, even among the brachycistidines. Stilbopogon is the smallest bodied group in the subfamily. The largest males belong to Stilbopogon confusa Kimsey & Wasbauer, which reach 6 mm in length. Males in the majority of species range in length from 3-4 mm. Females are much smaller. There are also a few species of Stilbopogon, including costaricaensis Kimsey & Bohart, and the new species described below, that have proportionally small eyes and even smaller ocelli. These species are also dark brown to black in coloration. These head and coloration modifications suggest that the new species and costaricaensis may actually be diurnal.

Materials and methods
The new species described below was collected in Malaise traps run on the Monvero Dunes in Fresno County, California, in June and July, 2015. This is odd sand dune system is located on top of a ridge in the interior central coastal range of California, between 600 and 670 m above sea level (Fig. 1). It is considered to be the remains of an Upper Cretaceous reef (Stewart 1946). The dunes are vegetated by a combination of inner coastal range and Mojave Desert plant species, including large Ephedra californica plants.
Remarks. Most species of Stilbopogon appear to be quite widespread in arid and desert regions of North and Central America. Stilbopogon monveroensis appears to be the exception to this. However, its restricted distribution may be more the result of limited collecting than actual endemism.