Cicindela formosa pigmentosignata (the “reddish-green sand tiger beetle”)

In my last post, I discussed Cicindela scutellaris rugata, the so-called “wrinkled fetiger beetle” (Erwin & Pearson 2008)—one of several geographically restricted subspecies of a more widespread and geographically variable species. This was not the only goal of the day, however, as I was also hoping to see a second geographically restricted subspecies—Cicindela formosa pigmentosignata, the “reddish-green sand tiger beetle (Erwin & Pearson 2008). The parent species of these two species show remarkably similar patterns of distribution, habits, and diversification—both occur most commonly as nominotypical subspecies in the Great Plains but have also expanded eastward and diverged there and around the periphery of their range into a number of distinctive subspecies; both favor deep, dry sand habitats without standing water; and both exhibit a “spring/fall” life history where sexually immature adults emerge in fall, pass the winter in burrows, and emerge again in spring ready to mate and lay eggs. In fact, these two species are so inextricably linked to each other that throughout most of their range, where one is found usually so is the other, and where one is represented by a distinctive subspecies so is the other. The main exception to this is in the far southeastern U.S., where C. scutellaris has established as the subspecies C. s. unicolor in sandy forest openings but C. formosa has not.

Cicindela formosa pigmentosignata W. Horn, 1930—Van Zandt Co., Texas

Cicindela formosa currently contains five recognized subspecies (Pearson et al. 2006)—the nominate subspecies (big sand tiger beetle) found west of Missouri (and which I’ve photographed in Nebraska), C. f. generosa (eastern sand tiger beetle) found in Missouri (photographed here and here) and further east, C. f. gibsoni (Gibson’s sand tiger beetle) found in Colorado and Manitoba (the consubspecificity of these two widely disjunct populations currently being the subject of debate), C. f. rutilovirescens (Mescalero sand tiger beetle) found in New Mexico (and which I’ve seen and collected a single specimen, but before my days as a photographer), and this one: C. f. pigmentosignata from eastern Texas and neighboring areas of Arkansas and Louisiana. Rumpp (1986) proposed that the parent species, C. formosa, radiated in central North America, adapting to barren sand conditions, dispersing along sand hills and major river systems into other areas, and ultimately diverging into the currently recognized subspecies.

Adults commonly exhibit “shade seeking” behavior during the hotter parts of the day.

As with C. s. rugata, I found this subspecies in a couple of old, rural cemeteries in eastern Texas (Henderson and Van Zandt Counties)—the photos shown here are from the second locality and were taken during the afternoon in the heat of the day. Because of this the beetles were quite wary and difficult to approach, but they also exhibited much more photogenic behaviors related to thermoregulation such as stilting and shade seeking. As I stalked the beetles through the deep, dry sand trying to get photographs, I was reminded yet again of why I love this species of tiger beetle so much—their bulk; their bulging eyes; their long, looping escape flights that end with a comical bounce and tumble, only to end up on their feet and facing their pursuer. These beetles are loaded with personality and behavioral charisma, and this particular subspecies with its brilliant and almost completely immaculate reddish-purple elytra and vividly contrasting blue-green legs and sides was an especially treasured sight to behold (especially after failing in my first attempt to find it back in 2012).

“Stilting” is another thermoregulatory behavior designed to raise the body up off the hot sand.

I am reasonably satisfied with these photos, although I would have liked to have gotten at least one without some part of the beetle obscured by foliage. That said, I now prefer some foliage in my tiger beetle photos, as I think it adds a bit of perspective, and when it is in the context of thermoregulatory behavior so much the better. And so, having now gotten good field photographs of this subspecies I am motivated more than ever to return to the Mescalero Sand Dunes in New Mexico and find and photograph C. f. rutilovirescens to complete my photographic “collection” of subspecies of the sand tiger beetle. Of course, by then I will probably be sufficiently dissatisfied with my existing photos of the other subspecies (already so with those of C. f. gibsoni due to excessively cropped compositions) that I will want to do the same with each of them as well. Such is the curse—and the blessing—of the insect photographer!

REFERENCES:

Erwin, T. L. & D. L. Pearson. 2008. A Treatise on the Western Hemisphere Caraboidea (Coleoptera). Their classification, distributions, and ways of life. Volume II (Carabidae-Nebriiformes 2-Cicindelitae). Pensoft Series Faunistica 84. Pensoft Publishers, Sofia, 400 pp [Amazon description, book review].

Pearson, D. L., C. B. Knisley & C. J. Kazilek. 2006. A Field Guide to the Tiger Beetles of the United States and Canada. Oxford University Press, New York, 227 pp. [Oxford description].

Rumpp, N. L. 1986. Two new tiger beetles of the genus Cicindela from western United States (Cicindelidae: Coleoptera). Bulletin of the Southern California Academy of Sciences 85(3):139–151 [Biodiversity Heritage Library pdf].

© Ted C. MacRae 2016