The current literature recognizes three subspecies of this small (7-10 mm), ubiquitous tiger beetle:
(Cicindela) Cylindera lemniscata lemniscata LeConte,
(Cicindela) Cylindera lemniscata rebaptistata Vaurie, and
(Cicindela) Cylindera lemniscata bajacalifornica Shook.
Cylindera lemniscata lemniscata LeConte |
Some publications characterize it as restricted to open grasslands of the Sonoran and Chihuahuan Deserts, but it is frequently encountered in large numbers at lights in urban environments indicating great ecological tolerance and vagility. There is even a small population just outside my front door at home.
Cylindera lemniscata lemniscata LeConte Greenish-blue coloration |
Morphologically, these greenish-blue phenotypes display no appreciable differences from typical Cyl. lemniscata lemniscata - except of course in coloration. Apparently, some Mexican populations of this subspecies are composed entirely of green individuals (R.L. Huber, pers. comm.).
These greenish-blue specimens, along with the typical metallic reddish-orange phenotype, were collected in early July at lights of a shopping center in the town of Willcox, Arizona. This unusual color divergence raises several questions. First being, how does the change in structural coloration effect thermoregulation and heat transfer - if at all?
A recent study of the polymorphic Cicindelidia hornii demonstrated that metallic green morphs attained the same body temperatures as those that were black - under controlled conditions (Schultz & Hadley 1987).
Chrysina gloriosa (LeConte) |
On the other hand, because of the absence of red light in darkness, red animals, as in typical Cyl. lemniscata lemniscata, are invisible. Red, being a single pigment, is much easier to produce than black pigment while still having the same cryptic effect. But consider, Cyl. lemniscata lemniscata is cathemeral - both nocturnal and diurnal. Interestingly, the nocturnal tiger beetle genus, Amblycheila, are primarily black but some species display a deep reddish dorsal coloration.
Amblycheila cylindriformis (Say) |
Brady, P., & Cummings, M. 2010. Differential Response to Circularly Polarized Light by the Jewel Scarab Beetle, Chrysina gloriosa. The American Naturalist. 175(5):614-620.
Schultz T.D., & Hadley N.F. 1987. Structural colors of tiger beetles and their role in heat transfer through the integument. Physiological Zoology. 60:737–745.
Cylindera lemniscata lemniscata and Amblycheila cylindriformis image courtesy of Alex Wild, Myrmecos.net.
Chrysina image courtesy of Sonoran Tree Service.
© Delbert La Rue 2012. All Rights Reserved
Very interesting Delbert. In all our collecting
ReplyDeleteof this species in Arizona and New Mexico I have
never seen these blue/green coloration. As you
get further east in New Mexico, however, as you
are aware you do get the C. lemniscata rebaptisata subsp. with the dark legs.
Happy holidays, "Modoc Charlie" Smith
Thanks, Charlie!
ReplyDeleteI have tried to suggest some thoughts as to why a greenish-blue morph but, of course, it's anyone's guess.
You should consider doing a "guest post" on here sometime. Maybe something on tiger beetles, or Acmaeodera, or Pleocoma?
... appreciate your comments and input.
Best wishes and Happy New Year,
Delbert