Last summer, while looking for North America’s most beautiful longhorned beetle in the dolomite glades of southwest Missouri’s White River Hills, I also came across good numbers of a tiger beetle species that I had previously considered rather uncommon in the state – Cicindela rufiventris (eastern red-bellied tiger beetle).  While I have seen this species at numerous localities throughout the Ozark Highlands, I had not seen them in such numbers as were present along a rocky 2-track leading through one of the glades and into the adjacent dry upland forest.  I had intended to post about them much sooner than now, but they took a backseat to the photos I obtained of the stunning Plinthocoelium suaveolens and the fantastic diversity of Floridian tiger beetles that I encountered in the following weeks.  I had, in fact, completely forgotten that I had these photos until Steve Willson, author of Blue Jay Barrens, presented two posts with some excellent behavioral observations of this species in Ohio (see his posts Eastern Red-Bellied Tiger Beetle and Tiger Beetle Behavior).

In Missouri, I have found this species exclusively in the Ozark Highlands region, primarily along rocky clay exposures along roadsides and on trails and 2-tracks through open pine forests on sandstone substrates.  As I mentioned, however, I never saw large numbers of individuals – just a few here and there.  On this rocky, dolomite 2-track though, the species was quite abundant, to the point that I was able to pick and choose the more “cooperative” subjects for photography instead of stalking interminably behind a precious skittish few.  In my second trip to the region two weeks later, I would find the species again abundant along trails winding through the region’s finest and most extensive dolomite glade systems at Hercules Glades Wilderness.  In previous years I haven’t spent much time in the extreme southern Ozarks during July and August, since by then most woodboring beetle activity has largely ceased – this probably explains why I’ve not seen this summer active species more abundantly before now.

Cicindela rufiventris is quite closely related to C. ubiquita¹, both of which are included in the subgenus Cicindela (Cicindelidia), dubbed the “American Tiger Beetles” by Pearson et al. (2006).  It is immediately recognizable, however, by its red-orange abdomen – hints of which can be seen in these photos and which is fully exposed during flight.  It also lacks the distinct sutural row of green punctures on the elytra exhibited by the latter, and the upper body coloration tends to be a little more variable in Missouri, ranging from dull dark brown or black to dark blue.  According to Pearson et al. (2006), populations in southern Missouri represent the northern fringe of an intergrade between the nominate subspecies to the east and subspecies cumatilis ranging from southwestern Louisiana into eastern Texas.  The distinction between these two subspecies is a matter of degree, with the latter exhibiting reduced maculations and a blue rather than brown or black upper body.  The influence of cumatilis can be clearly seen in the individual shown in the first three photographs, while the individual in the photo below is much more “nominate” in appearance. For taxonomic purposes, individuals from these populations are probably best classified as “Cicindela (Cicindelidia) rufiventris rufiventris x rufiventris cumatilis intergrades.” Such nomenclature implies that these individuals represent hybrids between two geographically distinct populations, since subspecies in the strictest sense represent genetically divergent populations made allopatric or near-allopatric as a result of isolating geographical barriers. However, tiger beetle taxonomy is replete with “subspecies” that more likely represent extremes of clinal variation, of which cumatilis appears to be one example. The opposite expression of this cline can be found in a few isolated populations near Boston, in which the elytral maculation is at its most developed – these populations have been designated as subspecies hentzi.

¹ Referred to by most authors as Cicindela punctulata.

Photo Details: Canon 50D w/ 100mm macro lens, ISO 100, 1/250 sec, f/25 (photos 1-2), f/29 (photo 3), f/18 (photo 4),  Canon MT-24EX flash (1/4 ratio) w/ Sto-Fen diffusers. Typical post-processing (contrast and unsharp mask).

REFERENCES:

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

Copyright © Ted C. MacRae 2010

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