Do You Have “An Inordinate Fondness”?

December 16, 2009October 10, 2011 / Ted C. MacRae / 23 Comments

Last week I mentioned that I had been thinking about starting a blog carnival devoted exclusively to beetles. Actually, I’ve been thinking about it for some time now, but following up on the idea apparently needed a catalyst. That catalyst came last week when Amber Coakley and Jason Hogle announced the debut of House of Herps—another specialty nature blog carnival, focusing on reptiles and amphibians. I supported the idea of a herp carnival when Amber first mentioned it, and she responded to that support by actually going out and doing it! Amber penned a guest post on Nature Blog Network called House of Herps: The Origin Story that described in fascinating detail the process that she and Jason went through in creating a new blog carnival.

Well, the story that Amber told and the details she provided were enough to convince me that I could do it, and the many comments I got on my post last week mentioning what I was thinking about convinced me that I should do it. The screenshot above is a first peek at the home site of nature blogging’s newest carnival, An Inordinate Fondness (AIF)—the monthly blog carnival devoted to beetles. The name honors J.B.S. Haldane’s perhaps apocryphal riposte when queried about what his studies of nature’s diversity had taught him about the Creator (a quote made even more famous by the breathtakingly beautiful An Inordinate Fondness for Beetles, written and illustrated by my friends and colleagues, Drs. Charles L. Bellamy and Arthur V. Evans). Some of you may recall that the alternate name, “Beetle Bacchanalia,” also received strong support (even edging out AIF in raw vote count). However, while both names imply unbridled passion, I eventually decided that AIF better described the nature of that passion and added historical context.

Even though the AIF website is up and running, the first issue is not scheduled to appear until mid-February. The reasons for this are primarily personal—I’m already slated to host House of Herps #2 on Jan 18 and Circus of the Spineless #47 on Feb 1 (does this make me a carnival hosting slut?). There are also still a few things I’d like to have in order before AIF debuts—primarily a badge. Seabrooke Leckie has offered some help in this regard, and I’ve got a few ideas of my own, but please don’t hesitate to let me know if you’ve got ideas as well. In addition, I’m hoping this will be the start of getting the word out so that by the time Feb 15 (first issue submission due date) rolls around there will be enough submissions on hand to make the inaugural edition a memorable one. Lastly, I’m hoping to recruit volunteers for hosting future editions—AIF will be a migrating carnival, dependent upon a community of science and natural history bloggers to keep it going.

My deepest thanks to Amber, Jason, Seabrooke, and Mike Bergin for their very helfpul and supportive comments.

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A bid for OpenLab

November 28, 2009October 10, 2011 / Ted C. MacRae / 14 Comments

I’m going to do something I’ve not yet done before—ask for your support. OpenLab is an annual compilation of the year’s best science-blog writing, as determined by a panel of judges, and the closing date for submissions for 2009 is December 1st—this coming Tuesday. I’ve vacilated about whether to throw my hat into this ring—the world of science blogs is a crowded place with many erudite writers, and although science is my profession, the science that I write about is purely avocational. Whether my particular brand of science writing can compete with that of the true academicians that seem to dominate the competition remains to be seen. Nevertheless, I am willing to put my ego on the line and give it a shot. If you have seen anything in the past year (since December 1, 2008) here at Beetles in the Bush that you consider exemplary, please consider submitting it. Feel free to search the sidebar archives (“Taxa,” “Tags” or “Life History”), browse the site Contents, or select from the following list of my own personal favorites (arranged chronologically):

So I don’t get accused of asking but not giving, I leave you with this photograph of a group of Kern’s flower scarabs (Euphoria kernii, family Scarabaeidae) congregated in the flower of large-root prickly pear cactus (Opuntia macrorhiza, family Cactaceae). Photographed this past June at Four Canyon Preserve in northwestern Oklahoma, this common, extremely variable species (ranging from all black to black and white to black and yellow to nearly all yellow) can be found throughout the southern Great Plains, where it congregates tightly in flowers of Opuntia , pricklypoppy (Argemone spp., family Papaveraceae), thistle (Cirsium spp., family Asteraceae), and yucca (Yucca spp., family Liliaceae).

Photo details: Canon 100mm f/2.4 macro lens on Canon 50D (manual mode), ISO-100, 1/250 sec, f/16, diffused MT-24EX flash.

A “Really” Big-headed Tiger Beetle

November 24, 2009October 10, 2011 / Ted C. MacRae / 4 Comments

Megacephala megacephala 3rd-instar larva. Photo © Artur M. Serrano.

In my recent summary of the latest issue of the journal Cicindela, I included a scan of the cover of that issue and its stunning image of the 3rd-instar larva of Megacephala megacephala¹ from Africa. This otherwordly-looking, four-eyed beast was photographed with jaws agape at the entrance to its burrow in Guinea Bissau by Dr. Artur M. Serrano (University of Lisbon, Portugal). I was grateful for his permission to post a scan of this spectacular image; however, he did even better and sent me high-resolution images of not only the larva (above) but the adult (below) as well. This species is one of 13 assigned to the genus—presently restricted to Africa (though not always, see discussion below), where they are usually found in savanna-type habitats and are active during the crepuscular and nocturnal periods (Werner 2000).

¹ An example of a tautonym, i.e. a scientific binomen in which the genus and species names are identical. Familiar tautonymic binomina include the gorilla (Gorilla gorilla), green iguana (Iguana iguana), and European toad (Bufo bufo). Tautonyms are expressly prohibited in plant nomenclature (see Article 23.4 of the International Code of Botanical Nomenclature) but are permitted and, in fact, quite common in zoological nomenclature; Wikipedia lists 51 mammals, 82 birds, 15 reptiles & amphibians, 54 fish, and 33 invertebrates (though not Megacephala megacephla!).

Megacephala megacephala adult. Photo © Artur M. Serrano.

For those of you who see a strong resemblance by this species to another tiger beetle I featured recently, Tetracha floridana (Florida Metallic Tiger Beetle), this is not merely a coincidence. Megacephala and Tetracha are quite closely related, and in fact the two genera, along with a handful of other closely related genera, are at the center of one of the longest-standing disputes in tiger beetle taxonomy (Huber 1994). The genus Megacephala was established by Latreille (1802) for the species pictured here (originally described as Cicindela megacephala Olivier). As additional taxa were found in Africa, Australia and the Western Hemisphere and assigned to Megacephala, several workers attempted to divide the genus into multiple genera (with New World taxa being assigned to Tetracha and a few other mostly South American genera); however, there was little agreement on how these genera should be defined and on what characters they should be based. The debate was effectively swept under the rug in the early 20th Century when Walter Horn, one of the most influential cicindelophiles of all time, accepted a monotypic Aniara based on the strange South American species A. sepulcralis but reunited the world’s remaining taxa within the single genus Megacephala in his world catalogue (Horn 1910). Horn’s use of Megacephala as a catch-all genus was followed by subsequent workers for almost a full century until Huber (1994) once again proposed restricting Megacephala to certain of the African species and resurrecting the genus Tetracha for the bulk of the New World fauna. He also urged additional analyses to resolve the status of the remaining generic names and their composition, which subsequently saw increasing use as subgenera of Megacephala² and later as genera.

² Thus, as type-species for the genus, the species featured here became known as Megacephala (Megacephala) megacephala (Werner 2000)—a triple tautonym that translates to the “Big-headed, Big-Headed, Big-Headed” tiger beetle! Perhaps it’s best that I’m not an African tiger beetle specialist; I probably would have been unable to resist the temptation to resurrect M. senegalensis and assign it as a subspecies of M. megacephala, just so I could refer to the nominate form as Megacephala (Megacephala) megacephala megacephala!

The reversal of Horn’s concepts now appears to be complete, with all seven former subgenera of Megacephala formally being accorded full generic status (Naviaux 2007). This classification is strongly supported by molecular analysis of nuclear 18S and mitochondrial 16S and cytochrome oxidase gene sequences (Zerm et al. 2007), with the resulting dendrogram indicating three monophyletic clades corresponding to the African/Palearctic (Megacephala and Grammognatha, respectively), Western Hemisphere (Aniara, Metriocheila, Phaeoxantha and Tetracha) and Australian (Australicapitona and Pseudotetracha) genera³. The African/Palearctic clade was found to occupy a basal position in the tree, while the Western Hemisphere and Australian clades were more derived. These data support the hypothesis that the early evolution of the megacephalines took place during the break-up of the ancient Gondwana megacontinent, which began about 167 million years ago (middle Jurassic period) and sequentially disconnected Africa from South America and Australia.

³ One striking deviation from the current classification, however, was the support for nesting the single Aniara species within Tetracha, a placement that renders Tetracha paraphyletic and, thus, requires either its division into multiple genera or the sinking of Aniara as a distinct genus. The support for this placement was quite strong and mirrored the results of a broader molecular phylogenetic study of tiger beetles based on full-length 18s RNA data (Galian et al. 2002). The authors concede that this puzzling placement is not corroborated by numerous morphological, ecological and ethological characters that distinguish Aniara from all known Tetracha species.

REFERENCES

Galián J., J. E. Hogan and A. P. Vogler. 2002. The origin of multiple sex chromosomes in tiger beetles. Molecular Biology and Evolution 19:1792–1796.

Horn, W. 1910. Coleoptera Adephaga, Fam. Carabidae, Subfam. Cicindelinae. In P. Wytsman (editor). Genera Insectorum. Fascicle 82a. Desmet-Vereneuil, Brussels, Belgium, pp. 105–208.

Huber, R. L. 1994. A new species of Tetracha from the west coast of Venezuela, with comments on genus-level nomenclature (Coleoptera: Cicindelidae). Cicindela 26(3/4):49–75.

Latreille, P. A. 1802. Histoire Naturelle, Générale et Particulière des Crustacés et des Insectes. Paris: F. Dufart 3 xii 13 + 467 pp.

Naviaux R. 2007. Tetracha (Coleoptera, Cicindelidae, Megacephalina): Revision du genre et descriptions de nouveaus taxons. Mémoires de la Société entomologique de France 7:1–197.

Werner, K. 2000. The Tiger Beetles of Africa (Coleoptera: Cicindelidae). Volume 1. Taita Publishers, Hradec Kralove, Czech Republic, 191 pp., 745 figures.

Zerm, M., J. Wiesner, J. Ledezma, D. Brzoska, U. Drechsel, A. C. Cicchino, J. P. Rodríguez, L. Martinsen, J. Adis and L. Bachmann. 2007. Molecular phylogeny of Megacephalina Horn 1910 tiger beetles (Coleoptera: Cicindelidae). Studies on Neotropical Fauna and Environment 42(3):211–219.

Moustached Tiger Beetle

November 16, 2009October 10, 2011 / Ted C. MacRae / 14 Comments

Dry sand scrubland on Lakes Wales Ridge in central Florida—home to Cicindela highlandensis and Ellipsoptera hirtilabris

In my previous post, I featured the rare Cicindela highlandensis (Highlands Tiger Beetle), restricted entirely to sand scrubland and pine woodland habitats along the Lake Wales Ridge in central Florida (Choate 2003). However, that would not be the only Florida endemic tiger beetle that I would encounter during my early August visit. Another of the several tiger beetle species that I’d hoped to see would also be found that day, although in much lower numbers. Ellipsoptera hirtilabris (Moustached Tiger Beetle) is so named¹ because of the dense covering of prostrate hairs on its labrum that distinguish it from the closely related E. gratiosa (Whitish Tiger Beetle). Both of these species exhibit striking white maculations that cover almost the entire elytral surface and dense white pubescence covering the head, thorax, underside and legs. They are the only species of the genus occurring in Florida, but their ranges do not overlap (Pearson et al. 2006)—E. gratiosa occurs in the coastal pine barrens of Virginia, the Carolinas, southern Georgia and the Florida panhandle, while E. hirtilabris is restricted to peninsular Florida in pine woodlands, sand hills and other habitats with open white sand. Although the latter is considered a Florida endemic, it has been found just outside of Florida in extreme southeastern Georgia on St. Simon’s Island (Choate 2003). In addition to the pubescence of the labrum and their allopatric distributions, the two species may further be distinguished by the slightly less expanded markings and more diffuse edges where they contact the central bronze area in E. hirtilabris and the slightly larger size of E. gratiosa. Like C. highlandensis and C. abdominalis, it seems likely that E. hirtilabris and E. gratiosa evolved from a common ancestor, diverging in isolation from each other during the pre-Pleistocene separation of peninsular Florida from the North American mainland.

¹ The species epithet is derived from the Latin words hirtum meaning “hairy” and labrum meaning “lip”.

Ellipsoptera_hirtilabris_IMG_1091_1200x800_enh

Ellipsoptera hirtilabris in the alert position

I found E. hirtilabris to be exceedingly difficult to see and photograph. Unlike C. highlandensis, which resemble bits of debris laying on the surface of the white sands where it lives, the largely white E. hirtilabris blend into the white sand itself and are almost impossible to see until they move. The small bronze-colored patches along the elytral suture augment their cryptic capabilities by resembling small bits of debris, which is especially evident in the photo below. Both Pearson et al. (2006) and Erwin and Pearson (2008) state that adults of this species freeze in position when approached, which may be the reason why I saw so few individuals. Once I did see them, they were extremely wary and difficult to photograph no matter how cautiously I approached. The photos shown here represent the only two individuals that I succeeded in photographing, and in neither case did I succeed in getting a frontal perspective to show the pubescent labrum (stifling heat and oppressive humidity during the photo session did not help matters, either).

Ellipsoptera_hirtilabris_IMG_1131_1200x800_enh

The white coloration with small brown markings helps adults blend in perfectly in their white sand habitats

Photo details:
Photo 1: Canon 100mm macro lens on Canon 50D (landscape mode) ISO-100, 1/250 sec, f/16, natural light.
Photos 2 & 3: Manual mode, f/25, MT-24EX flash w/ Sto-Fen diffusers @ 1/8 ratio.

REFERENCES:

Choate, P. M., Jr. 2003. A Field Guide and Identification Manual for Florida and Eastern U.S. Tiger Beetles. University Press of Florida, Gainesville, 224 pp.

Erwin, T. L. and 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.

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.

Highlands Tiger Beetle

November 12, 2009October 10, 2011 / Ted C. MacRae / 11 Comments

When my wife and I made plans to spend a week at her sister’s condominium in Florida this past summer, I began making a list of the tiger beetle species that I wanted to see. I would be happy to see anything, since I had never before tiger beetled in Florida, but early August was looking to be on the late side for many things. In addition, since this was a family vacation, I would only have a couple days at most to sneak off on my own and immerse myself in bug hunting. All this meant that I would have to be very judicious about where I went and what I looked for. I sought advice from a few other cicindelophiles on species and localities, and by the time we made the 16-hour drive from St. Louis to Seminole (near St. Petersburg) I had settled on two destinations—the Lake Wales Ridge of central Florida to look for Cicindela highlandensis (Highlands Tiger Beetle), and the so-called “Road to Nowhere” near Steinhatchee where as many as 10 species of tiger beetles can be seen when the season is right. Things started out well when, before even looking for any of these species, I stumbled upon Ellipsoptera marginata (Margined Tiger Beetle), its sibling species E. hamata lacerata (Gulf Beach Tiger Beetle), and some 3rd-instar larvae in their burrows that proved to be the Florida endemic Tetracha floridana (Florida Metallic Tiger Beetle) in the small coastal preserve just outside the back door of my sister-in-law’s condo.

Dry sand scrubland on Lakes Wales Ridge in central Florida

The big target of the trip, however, was not so straightforward. Cicindela highlandensis is one of Florida’s rarest endemic tiger beetles, being restricted entirely to remnant sand scrubland and pine woodland habitats along the Lake Wales Ridge of Polk and Highlands Counties in central Florida (Choate 2003). The Lake Wales Ridge represents former shorelines deposited when the rest of peninsular Florida was covered by seas. The quick draining sands have created desert-like open habitats dominated by oaks, pines, and other drought-tolerant species. Cicindela highlandensis is one of many plants and animals endemic to the Lake Wales Ridge, which has the highest concentration of endangered plants in the continental U.S. Unfortunately, the natural communities found on the Lake Wales Ridge have suffered severe reductions from their historical occurrence. An estimated 85% of the scrub and sandhills has been converted to citrus groves and urban developments, and the few remaining tracts face not only continued development pressure, but also the threat of degradation from reductions in the frequency and extent of the wildfires that are essential for their maintenance (Turner et al. 2006). NatureServe (2009) estimates that C. highlandensis populations have declined by as much as 90%, and only a few of the sites where it is known to occur are large enough to sustain viable populations. While the species has a global status of G1 (critically imperiled) due to its limited range, restricted habitat, and very small population size, and is a candidate for listing as an endangered species by the U.S. Fish & Wildlife Service (Pearson et al. 2006), it remains—bafflingly—unlisted even as threatened by the State of Florida. As a result, there is no formal conservation management plan for this species to ensure its survival. Fortunately, the largest populations of C. highlandensis occur on an assemblage of public and private lands that are under partial to full conservation ownership, and preservation/management activities are taking place at most of these.

Cicindela_highlandensis_IMG_1126_1200x800_enh

Cicindela highlandensis, Highlands Tiger Beetle, in alert position

I had debated whether to look for Cicindela highlandensis at all—not because I wasn’t anxious to see it, but because I lacked confidence that I would be able find it. A late season search for a rare species had all the hallmarks of a potential wild goose chase. Nevertheless, I like a good challenge, and I had succeeded in obtaining information about specific locations for the species (a matter of public record; however, I prefer to maintain some discretion in this venue). Although I began my search with tempered optimism, it didn’t take long for me to acheive my goal. Similar to my experience with Cylindera celeripes in Oklahoma, I had barely walked ten yards into a gorgeous sand scrub habitat at the first site I had planned to search before I saw an individual. The dark metallic blue coloration of the species would seem to make it easily seen in its white sand environs; however, in reality it is almost impossible to see until it moves. Some have suggested that its coloration functions to make the beetle resemble the many small pieces of debris that litter the sand surface—perhaps the bits of charred wood that are common in open, fire-mediated environments. Its dependence upon natural disturbance factors such as fire was made apparent to me by the distinct preference I noted for adults to congregate along trails kept open by human disturbance, and to a lesser degree in the larger, naturally open scrub areas. The adults made very short escape flights and were easy to follow but difficult to approach closely enough for photographs due to extreme wariness—their long legs giving some indication of their highly cursorial capabilities.

Cicindela highlandensis - note absence of setae on thorax and abdomen

Cicindela highlandensis is closely related to two other species of tiger beetles in Florida—C. abdominalis (Eastern Pinebarrens Tiger Beetle), widely distributed throughout the Atlantic and Gulf Coastal Plain, and C. scabrosa (Scabrous Tiger Beetle), confined to the Florida Peninsula and adjacent southeastern Georgia. Both of these species are absent from the Lake Wales Ridge and, thus, do not co-occur with C. highlandensis. It is likely that C. highlandensis evolved from isolated populations of the widespread C. abdominalis that diverged during pre-Pleistocene separation of the Lake Wales Ridge from the mainland (Choate 1984). Despite its resemblance to both C. abdominalis and C. scabrosa, C. highlandensis can be distinguished from both of those species by the complete absence of flattened, white setae on the sides of the prothorax and the abdomen and by the highly reduced or absent elytral maculations (note the very small apical markings on the individuals in these photographs). All three of these species belong to the subgenus Cicindelidia (American Tiger Beetles) and possess red adominal coloration that is prominent during flight.

Photo details:
Photo 1: Canon 17-85mm zoom lens on Canon 50D (landscape mode), ISO-100, 1/160 sec, f/13, natural light.
Photos 2–3: Canon 100mm macro lens on Canon 50D (manual mode), ISO-100, 1/250 sec, f/14 (photo 2) or f/20 (photo 3), MT-24EX flash w/ Sto-Fen diffusers.

REFERENCES:

Choate, P. M., Jr. 1984. A new species of Cicindela Linnaeus (Coleoptera: Cicindelidae) from Florida, and elevation of C. abdominalis scabrosa Shaupp to species level. Entomological News 95:73–82.

Choate, P. M., Jr. 2003. A Field Guide and Identification Manual for Florida and Eastern U.S. Tiger Beetles. University Press of Florida, Gainesville, 224 pp.

NatureServe. 2009. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available at: http://www.natureserve.org/explorer (accessed: November 12, 2009).

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.

Turner, W. R., D. S. Wilcove and H. M. Swain. 2006. State of the scrub: conservation progress, management responsibilities, and land acquisition priorities for imperiled species of Florida’s Lake Wales Ridge. Archbold Biological Station, Lake Placid, Florida, iii + 44 pp.

Beetle Research Roundup

November 5, 2009October 10, 2011 / Ted C. MacRae / 14 Comments

The latest issue of the journal Cicindela arrived in my mailbox today, and as usual some interesting papers are included. For those of you unfamiliar with it, Cicindela is “a quarterly journal devoted to the Cicindelidae,” publishing papers dealing with any aspect of the study of tiger beetles. Founded in 1968 by North American tiger beetle experts Ronald L. Huber, Robert C. Graves, and Harold L. Willis, it was dubbed in those early issues as “…an experiment—an inquiry into the merits (and shortcomings?) of extreme specialization…”. Richard Freitag succeeded Willis in 1975, and that trio has edited and produced this “experiment”—now in its 41st year—ever since! Issues are available for a very nominal $10 per year ($13 outside of the U.S.). My sincere thanks to Artur Serrano (University of Lisbon) for permitting me to post his stunning photograph of the third-instar larva of Megacephala megacephala, photographed in Guinea-Bessau, Africa and gracing the cover of this latest issue.

Tetracha virginica in Wisconsin
Despite the common occurrence of this species across the southern two-thirds of the eastern U.S., its northern and western limits of distribution are still poorly known. Grimek discusses records of this species in Wisconsin during the 45-year period between 1962 to 2007, noting that all of the captures were from sandy areas near rivers in, with the exception of a single specimen, the “Driftless Area” covering the southwestern quadrant of the state. (The Driftless Area, also called the Paleozoic Plateau, is an area that escaped glaciation during the last glacial period). The capture of a specimen very near the Mississippi River suggests the species may also be found in Minnesota, where its occurrence has not yet been documented.

Grimek, H. 2009. Distribution of Tetracha virginica (Linnaeus) in Wisconsin. Cicindela 41(3):57-61

Brasiella cuyabaensis in Bolivia
Brasiella is a large genus (47 species) of small to very small, mostly Neotropical tiger beetles, of which B. argentata is among the most common and widespread. While examining specimens of this species that he had collected in Bolivia, Italian coleopterist Fabio Cassola found a second species among the material. At first thought to potentially represent a new species, its identity was ultimately revealed after examination of the unique male type specimen of B. cuyabaensis from Brazil. This specimen is very similar to B. argentata except for its genitalia (longer and narrower than in B. argentata), and Cassola has confirmed this in his material as well. The previously unknown females were especially problematic; however, Cassola found their longer, more convex labrum (upper lip) to be a useful diagnostic character. Cassola collected B. cuyabaensis some 700 km west of the type locality and speculates that additional specimens of the species may exist in entomological collections, incorrectly placed under B. argentata.

Cassola, F. 2009. Studies of tiger beetles. CLXXV. Occurrence in Bolivia of Brasiella cuyabaensis (Mandl, 1970) (Coleoptera: Cicindelidae). Cicindela 41(3):63-67.

DNA degrades rapidly in pinned tiger beetles
DNA molecular analyses are increasingly being used to elucidate relationships among tiger beetles, both at the species level and at higher levels of classification. However, such research is often hampered by the limited availability of sufficient fresh material representing less common taxa. Pinned museum specimens offer a potential source of DNA for such uncommon taxa; however, successful extraction of useable DNA from pinned specimens has been limited. Kritsky and Duennes, using a standardized DNA extraction method, determined that DNA extracted from pinned tiger beetles rapidly degrades during the first 25 years after collection before stabilizing at ~10% of the original DNA. The authors found that frozen specimens yeilded more DNA than specimens killed in ethanol, perhaps due to degradation of DNA by water in the ethanol, and noted that choice of killing method and use of fumigants during storage can also contribute to loss of DNA. More research is needed to determine optimal conditions for protecting museum specimens while preserving their DNA for future research.

Kritsky, G. and M. Duennes. 2009. The rate of DNA degradation in pinned tiger beetles. Cicindela 41(3):69-73.

Mississippi tiger beetles scavenge dead fish
An established breeding population of Cicindela pamphila [= Habroscelimorpha pamphila] was observed during 2006–2008 in a Mississippi coastal salt marsh. This species was previously considered a rare straggler into Mississippi, occurring primarily along the Texas Gulf Coast south into Mexico. The Mississippi population was observed co-occurring with C. hamata [= Ellipsoptera hamata], C. severa [= Habroscelimorpha severa], and C. togata [= Eunota togata]. On one occasion, individuals of C. hamata and C. severa were observed feeding on a fresh mullet (Mugil sp.) carcass resulting from a raptor kill, adding these two tiger beetle species to the list for which scavenging on dead vertebrates has now been confirmed. Despite the co-occurrence of four species of tiger beetles within this area, the author noted no apparent resource partioning and speculates that carrion resulting from predation by birds, racoons, etc. may provide a valuable resource for scavenging tiger beetles that reduces competition for food.

Grammer, G. L. 2009. A breeding population record of Cicindela pamphila in Mississippi and observations on the scavenging behavior of C. severa and C. hamata. Cicindela 41(3):75-80.

Florida Metallic Tiger Beetle

October 27, 2009October 10, 2011 / Ted C. MacRae / 22 Comments

Tetracha floridana (Florida Metallic Tiger Beetle), dorsal view

In my previous post, I showed some photographs of the larva of an undetermined species of tiger beetle that I collected from its burrow in dry ground adjacent to a coastal salt marsh near St. Petersburg, Florida. I had assumed the larva belonged to the genus Cicindela or one of its former subgenera and was suprised to learn that this assumption was incorrect when the adult emerged 2 months later. Looking back at the photos, however, I realized that the photos and the information I gave regarding its location and habitat contained all of the necessary information to identify this larva. Five points to Mike Baker, who correctly deduced the genus (Tetracha), and in fact the larva represents Tetracha floridana (Florida metallic tiger beetle).

Hump of 5th abdominal segment, showing simple, thorn-like inner and outer hooks

The hump of the 5th abdominal segment bears simple, thornlike hooks.

The larva can be placed in the genus Tetracha by virtue of its simple, thorn-like hooks (in other eastern U.S. tiger beetle genera, the outer hooks are distinctly curved). Two other genera of Nearctic tiger beetles that do not occur in Florida also bear simple hooks—Omus (Night-stalking Tiger Beetles, occurring along the Pacific Coast) and Amblychelia (Giant Tiger Beetles, occurring in the central and southwestern U.S.); however, the former bears three rather than two pairs of hooks, and the latter has the inner and outer hooks distinctly separated from each other.

Tetracha floridana (Florida Metallic Tiger Beetle), lateral view.

Four species of Tetracha occur in the U.S., three of which occur in Florida—T. carolina (Pan-American Big-headed Tiger Beetle), T. floridana (Florida Metallic Tiger Beetle), and T. virginica (Virginia Big-headed Tiger Beetle). However, T. carolina is restricted in the state to the panhandle and interior of the peninsula along rivers and in disturbed sparsely vegetated areas (Choate 2006). Of the two remaining species, T. virginica is widespread throughout the southern two-thirds of the eastern U.S. and occurs in a variety of habitats (Pearson et al. 2006), while T. floridana is restricted to salt marsh and mud flat habitats along the Gulf coast of Florida from Dixie County south to the Keys (Choate 2006). While the widespread occurrence and generalist tendencies of T. virginica might suggest that it is the more likely choice, the locality and habitat match precisely with T. floridana.

The anterior lobes of the apical lunules are divergent.

Tetracha floridana is very similar to T. carolina and was long considered a subspecies of that more widely distributed species until Naviaux (2007) elevated it to species rank in his revision of this large genus. Tetracha floridana is distinguished from T. carolina by the divergent anterior lobes of the apical lunules (photo above) and the uniformly black to dark green elytra that lack any violet or coppery reflections in the anteriolateral regions (photo below) (Choate 2003).

The anteriolateral areas of the elytra lack violet or copper reflections.

I was happy as heck when I saw the first newly emerged adult in the rearing container, as this is a true Florida endemic. I have encountered the two other eastern U.S. species commonly under street lamps and at building lights here in Missouri—T. virginica throughout the state and T. carolina in the southeastern lowlands, where it appears to reach its northern limit of distribution. A fourth U.S. species in the genus, T. impressa (Upland Metallic Tiger Beetle) (T. “affinis” in earlier works), occurs in northern Mexico and the Lower Rio Grande Valley (LRGV) of south Texas (Erwin and Pearson 2008). Although I have not yet encountered it on any of my many trips to the LRGV (all of which pre-date my current cicindelophily), I understand it is regularly attracted to building and street lights in Brownsville (Pearson et al. 2006). I believe I will have to go down there again and verify this for myself someday.

Feasting on a corn rootworm larva.

The last photo in this series illustrates the unique feeding behavior of these beetles, which despite their terrifyingly toothy mandibles are strictly fluid feeders. The long, sharp mandibular teeth function primarily in prey subdual and in slicing and shredding their tissues, while the maxillae (second pair of feeding appendages behind the mandibles) and labium (fused third pair of appendages) comprise an “oral mill” that masticates the prey and and rolls it into a bolus. Two brush-like structures can be seen behind the mandibles in the photo above—these are part of the maxillary laciniae and apparently function in containing and shaping the bolus as it is being masticated. While this occurs, proteolytic enzymes are extruded from the midgut and mixed with the bolus to liquify its digestible components, which are then sucked into the beetles tiny mouth by the action of a pharyngeal pump. Like the larva, the adult beetle thus “chews” but does not swallow its prey—a manner of feeding that is not too unlike that of spiders and other arachnids (sans the venom).

Photo details:
All photos: Canon EOS 50D, manual mode, ISO-100, 1/250 sec, MT-24EX flash w/ diffuser caps.
Photo 1: Canon 100mm macro lens w/ 68mm extension tube, f/25, 1/2 power flash.
Photo 2: Canon MP-E 65mm 1–5X macro lens, f/16, 1/8 power flash.
Photos 3–5: Canon 100mm macro lens w/ 36mm extension, f/18–f/22, 1/4 power flash.
Photo 6: Canon 100mm macro lens w/ 68mm extension, f/20, 1/2 power flash.

REFERENCES:

Choate, P. M., Jr. 2003. A Field Guide and Identification Manual for Florida and Eastern U.S. Tiger Beetles. University Press of Florida, Gainesville, 224 pp.

Choate, P. M., Jr. 2006. Tiger Beetles of Florida, Cicindela spp., Megacephala spp. (Insecta: Coleoptera: Cicindelidae). University of Florida, IFAS Extension Service Circular EENY-005, 5 pp.

Naviaux R. 2007. Tetracha (Coleoptera, Cicindelidae, Megacephalina): Revision du genre et descriptions de nouveaus taxons. Mémoires de la Société entomologique de France 7:1-197.

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.

Anatomy of a Tiger Beetle Larva

October 22, 2009October 10, 2011 / Ted C. MacRae / 13 Comments

My first experience looking for tiger beetles in Florida had gone well. Despite its small size and urban surroundings, the narrow strip of coastal scrub and saltwater marsh along the intracoastal waterway behind my sister-in-law’s condominium boasted a robust population of what I took to be a single tiger beetle species. The specimens I collected and photographs I took would later reveal that two co-occurring and closely related species were present: Ellipsoptera marginata (Margined Tiger Beetle) and E. hamata lacerata (Gulf Beach Tiger Beetle). I had spent close to two hours under the August sun observing and photographing the beetles before I decided that I had given the preserve a thorough enough look.

As I was heading back, I noticed a little bit of high ground alongside a red mangrove thicket and went over to give it a look. As I approached I saw something I hadn’t yet seen that day – tiger beetle larval burrows. Larval burrows, especially larger ones such as these were, are unmistakeable – almost perfectly circular (slightly cut out on one edge) and smoothly beveled around the perimeter. There were a number of burrows clustered on the small bit of high, dry ground, and my first thought was that their inhabitants represented the same (what I thought was a single) species that I had encountered so commonly that day as adults. I then reasoned, however, that more likely they represented another species whose adults are active later in the season – perhaps one of the so-called “spring/fall” species whose larvae typically reach maturity during the heat of summer. The size of the burrows (~5mm dia) suggested they were inhabited by 3rd instar larvae (the final instar before pupation), in which case it may be possible to rear a few to adulthood – if I could get at them. I tried fishing (Pearson and Vogler 2001) a few holes with a grass blade but didn’t get any bites, so I decided to watch for awhile and see if any of the larvae, believing the danger of my approach had passed, would reappear at the tops of their burrows. Waiting for tiger beetle larvae to appear is a crap shoot – maybe they’re active, and maybe they’re not, and crouching in the stifling summer air of a coastal marsh in Florida is not an easy thing to do for very long. Fortunately my wait was short, as within a few minutes I saw one re-appear at the top its burrow. I slowly got out my knife and moved to place the tip on the soil about 1″ from the burrow at a 45° angle for an attempted tunnel block (Pearson and Vogler 2001), but it spooked and dropped back down into its burrow before I could get then knife in place. No matter, I knew it was in there now and that it would likely reappear if I could muster the patience. I positioned the knife and waited – crouched under the baking Florida sun, until when it did re-appear I plunged the knife into the soil with authority. It was a good jab – I had blocked its retreat without injuring it, and a quick flip of the knife popped out the soil plug and exposed the startled larva, flipping vigorously in a vain attempt to escape before settling down amidst its unfamiliar, exposed surroundings.

For those of you who have never seen a tiger beetle larva, they are among the most other-wordly creatures one can imagine. The large, heavily sclerotized head bears two long, sickle-shaped, upward-pointing mandibles and up to three pair of highly-acute eyes whose arrangement on each side conveys the image of a “face” with congenital birth defects. The top of the head is flattened to lie flush with the surrounding soil as the larva sits at the top of its burrow, and huge, powerful mandibular muscles fill the cranial cavity. The remainder of the body – long, narrow, and cylindrical – hangs from the head at a 90° angle down into the burrow and is unremarkably grub-like, save for a curious hump on the dorsal side of the 5th abdominal segment. Close examination of the hump reveals an intricate pattern of forward-facing hooks and spines that function in anchoring the larva against the side of its burrow to prevent struggling prey from dislodging it. The life of a tiger beetle larva is a life of waiting – unlike the adults who run down their prey, the larvae sit in their burrows and wait for prey to come to within lunge’s reach. While the eyes of most grub-like insects detect little more than light and dark, those of tiger beetle larvae are densely packed with photoreceptors that permit detailed focusing and depth perception for detecting whether potential prey has ventured close enough to their burrow (Pearson et al. 2006). When that happens, they strike with lightning speed, plunge their mandibles into their prey, and drag it down into the depths of their burrow where it is summarily dispatched with a few bites of their powerful mandibles. Larvae consume they prey in a manner similar to that of adults in that they chew but don’t swallow their prey. Rather, they secrete digestive secretions containing proteolytic enzymes that begin digesting the prey extra-orally as they chew. The resulting bolus is masticated and its liquid components sucked out until nothing but a dry wad of indigestable chitin remains, which is spat out of the burrow (Pearson and Vogler 2001).

Looking at this strange insect, it occurred to me that I had not yet attempted macrophotographs of a tiger beetle larva out of its burrow, and this would be a good opportunity to get more practice with my Canon MP-E 65 mm macro lens – a lens with incredible magnification capabilities, but one that is also a bit of a temperamental beast to use hand-held in the field. The subject was unusually cooperative, perhaps too stunned by its sudden predicament to know what to do, and as I took the photographs I focused in particular on characters of the head and dorsal hump (often useful in identifying tiger beetle larvae, at least to genus). Time was growing short once I finished taking photographs, so I placed the larva in a vial and returned the following day to extract a chunk of native soil to place in a rearing container, managing to collect two more larvae as well (unfortunately, one became instant “prey” for the other. Note to self: when placing multiple tiger beetle larvae in a container of soil, seal the artificial burrows into which you place each one!). I paid little further attention to the photographs, other than to transfer them onto my computer and add metadata upon my return to St. Louis. I didn’t know what species the larvae represented, but I assumed they were something in the genus Cicindela or one of its several former subgenera. However, had I studied the photos and considered the locality and habitat, I would have realized that my assumption was incorrect¹. That realization would come in surprise fashion two months later when the two adults emerged within a few days of each other…

¹ Ten points to whoever can use this information to arrive at an identification before my next post 🙂

Photo details:
All photos: Canon EOS 50D, manual mode, ISO-100, 1/250 sec, MT-24EX flash w/ diffuser caps.
Photo 1: Canon 100mm macro lens, f/22, 1/4 power flash (photo slightly cropped).
Photos 2-4: Canon MP-E 65mm 1-5X macro lens f/16, 1/8 power flash.

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.

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

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Beetles In The Bush

Experiences and reflections of a Missouri entomologist

Coleoptera

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A bid for OpenLab

A “Really” Big-headed Tiger Beetle

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Beetle Research Roundup

Florida Metallic Tiger Beetle

Anatomy of a Tiger Beetle Larva

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