guest photo

Featured Guest Photo: A Spectacular Case of Mimicry

/ Ted C. MacRae / 9 Comments

On occasion I receive photos from readers that are so remarkable I simply must share them (with the owner’s permission, of course). Recently I received a note from Len de Beer in Maputo, Mozambique, who was looking for help identifying a tiger beetle he had photographed on the beaches of the Maputo elephant reserve. My knowledge of Afrotropical tiger beetles is rudimentary, so I had to tap the expertise of fellow cicindelophile Dave Brzoska for the ID (many thanks, Dave), but in the ensuing correspondence Len sent me the following photograph that he took of another tiger beetle species while living in Madagascar:

The mimic: Peridexia hilaris

The mimic: Peridexia hilaris | Anzojorobe, Madagascar (photo © Len de Beer) 

A spectacular species to be sure, but the story behind its appearance is even more remarkable. This tiger beetle is one of two species in the Madagascan-endemic genus Peridexia, both of which exhibit color patterns that are a near-perfect match for that of the local pompilid wasp, Pogonius venustipennis (see photo below). According to Pearson & Vogler (2001), not only do these tiger beetles share the wasp’s bright yellow and black color pattern, but they also run in constant small circles (rather than the distinct, straight-line sprints that are more typical of tiger beetles) and fly readily when frightened, only to land again on the forest floor. These running and flying behaviors more closely resemble the foraging movements of the wasp than the movements of a typical tiger beetle, resulting in mimicry so effective that even tiger beetle collectors have been fooled and stung on the fingers when they attempted to collect their first Peridexia!

The model: Pogonius venustipennis

The model: Pogonius venustipennis (photo © Len de Beer)

Camouflage is the most widely observed predator avoidance mechanism in tiger beetles, with numerous species known whose color patterns closely resemble or otherwise allow them to blend in with the color and texture of the soils found in their preferred habitats. Nevertheless, mimicry is common enough (although anecdotal evidence still far outweighs true experimental evidence). Pearson & Volgler (2001) list examples of tiger beetles resembling mutillid wasps (commonly called “velvet ants”) from North and South America, as well as India, and also mention a South American tiger beetle species, Ctenostoma regium, that is the same size and shape as Paraponera clavata (or “bullet ant”), a large solitary species that is purported to pack the most painful of all insect stings (that this is true, I am inclined to agree). Tiger beetles can also serve as models—there is a katydid in Borneo whose immatures bear a remarkable resemblance to arboreal species of tiger beetles in the genus Tricondyla (Pearson & Vogler 2001, Plates 26 and 27). It has also been suggested that mimicry in tiger beetles might not be restricted to Batesian associations (unprotected mimic and harmful model) but may also include Müllerian associations (both model and mimic are distasteful or harmful).

My sincere thanks to Len de Beer for allowing me to post his photographs of this remarkable tiger beetle and the wasp it mimics.

REFERENCE:

Pearson, D. L. & A. P. Vogler.  2001. Tiger Beetles: The Evolution, Ecology, and Diversity of the Cicindelids.  Cornell University Press, Ithaca, New York, xiii + 333 pp.

Copyright © Ted C. MacRae 2013 (text)

Featured Guest Photo – Dromica kolbei

/ Ted C. MacRae / 9 Comments

Dromica kolbei? - Kruger National Park, South Africa. Copyright © Joe Warfel 2011.

Shortly after I returned from Brazil, this stunning photo was sent to me by Joe Warfel, who himself had just returned from a trip to South Africa.  Joe had seen the beetle at Punda Maria camp in the northern part of Kruger National Park, had deduced that it represented a species in the genus Dromica, and included the following notes about its behavior:

It did not fly, only ran, ran, ran, ran…. you get the picture.  But stopped briefly now and then to deposit eggs in the  soil.  My best guess from my limited tiger beetle references is Dromica sp.  Any help for identification you may give would be appreciated.

Although I have not collected this genus myself, I recognized it instantly as a member of such based on specimens and images I have seen.  Carabidae of the World contains fine images of a number of species in this genus, of which Dromica kolbei (W. Horn, 1897) seems to be a pretty good match.  However, more than 170 species are currently included in the genus, and while a modern revision is in progress (Schüle and Werner 2001; Schüle 2004, 2007), the bulk of the genus still remains to be treated.  As a result, this really should be considered as just a provisional ID.

Dromica is a strictly sub-Saharan African genus of tiger beetles whose included species are denizens of dry lands – savannahs, grasslands, open woodlands, and semideserts, and are generally absent in the moister, more heavily forested areas of western Africa.  Like a number of other tiger beetle genera, they have given up the power of flight to capitalize on their fast running capabilities.  This flightlessness and the strict association of adults with often short rainy seasons has led to both spatial and temporal isolation of numerous, localized populations of restricted geographical range.  This has no doubt contributed to the diversification of the genus across the mosaic of suitable habitats covering central, eastern, and southern Africa.  Schüle and Werner (2001) suggest that a good number of new species may still await discovery in the more remote or yet inaccessible areas of the countries of occurrence.  I had hoped to encounter these beetles (and also Manticora, or the giant African tiger beetles) during my visit to South Africa in 1999, but luck was not with me in this regard (although I did collect several fine specimens of the handsome Ophryodera rufomarginata (Boheman) and also a few species in the genera Cicindina and Lophyra).

My sincere thanks to Joe Warfel for allowing me to post his excellent photograph.  I featured photographs by Joe in an earlier post (A Tiger Beetle Aggregation), and his other photos can be seen at EighthEyePhotography (you must see this striking harvestman from Trinidad!).

REFERENCES:

Schüle, P. 2004. Revision of the genus Dromica. Part II.  The “elegantula-group” (Coleoptera: Cicindelidae). Folia Heyrovskana 12(1):1–60.

Schüle, P. 2007. Revision of the genus Dromica. Part IV.  Species closely related to Dromica albivittis (Coleoptera: Cicindelidae). African Invertebrates 48(2):233–244.

Schüle, P. and K. Werner. 2001. Revision of the genus Dromica Dejean, 1826. Part I: the stutzeri-group (Coleoptera: Cicindelidae). Entomologia Africana 6(2):21–45.

Copyright © Ted C. MacRae 2011 (text)