Tenebrionidae

Darkling beetles, comb clawed beetles, long jointed beetles, mealworms (larvae). About 15,000 species worldwide. Primarily detritus feeders, some feed on living plants, a few predaceous. Many species adapted to xeric habitats.

The best species name ever!

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Entomoderes satanicus

Entomoderes satanicus | Ruta Nacional 20 @ km 367, San Luis Province, Argentina

This past February while traveling to see research plots in Argentina, I had the pleasure of accompanying colleague and scarab expert Federico Ocampo to San Juan Province in west-central Argentina to see some of the endemic scarabs that live in the sand dunes that dot the region. Along the way we made a quick stop at a sandy spot along Ruta Nacional 20 in San Luis Province to see what was out and about. Several interesting insects were seen, but one of the most impressive was this marvelously armoured darkling beetle (family Tenebrionidae) belonging to the genus Entomoderes—also endemic with nine species ranging from southern Bolivia to central Argentina (Flores & Roig-Juñent 1997).

Entomoderes satanicus

Stout spines and a heavily sclerotized body surely provide effective anti-predation defense…

The stout, backwards-directed lateral spines on the pronotum are as evil as any I’ve ever seen, perhaps being the the reason behind the most awesome species epithet I have ever encountered—satanicus! Actually, there was some question about whether it represented this species or another in the genus with an almost equally awesome name—draco! I wasn’t able to access the more recent, paywall-protected revision by Flores & Roig-Juñent (1997); however, a relatively recent prior work (Peña 1990) seems to confirm its identity as the former by the presence of distinct raised costae on each elytron between the lateral keel and sutural margin confirm.

Entomoderes satanicus

…but not from tiny enemies (note parasitic mite on the venter behind the right procoxa).

Surely the sharp, stout spines and heavily sclerotized, ridged body provide effective protection from vertebrate predators and perhaps also help to minimize loss of water, since all of the species are found strictly in arid habitats (Peña 1990). I did not collect the specimen, but many such heavily sclerotized darkling beetles can be difficult to nearly impossible to pin by normal means (I have actually used a hammer to help in the case of one species I collected in South Africa. Seriously!), and I’m sure this one would have been no different. For all its armoured protection, however, there still remain chinks—note the tiny, bright red, parasitic mite on the ventor behind the right procoxa in the last photo.

REFERENCE:

Flores, G. E. & S. Roig-Juñent. 1997. Systematic revision of the Neotropical genus Entomoderes Solier (Coleoptera: Tenebrionidae). Insect Systematics & Evolution 28(2):141–162 [abstract].

Peña, L. E. 1990. El género Entomoderes Solier (Coleoptera: Tenebrionidae). Boletin del Museo Nacional de Historia Natural Textos sobre patrimonio natural de Chile 37:253–259 [ISSUU].

© Ted C. MacRae 2015

Black olives with legs

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While searching the open red-cedar woodland at Oklahoma’s Wichita Mountains National Wildlife Refuge back in September, I rather regularly encountered these darkling beetles (family Tenebrionidae) that I recognized as the species Eleodes tricostata. I really wanted to photograph the first several that I found, but I soon abandoned this idea because they just… wouldn’t… stop… crawling! Not that I’m impatient and couldn’t wait one out if I put my mind to it, but what I was really after was more photos of the beautifully black Cicindelidia obsoleta vulturina (Prairie Tiger Beetle) population that I had just found there. It would take most of the afternoon before I finally got the nice, closeup photos of the tiger beetle that I wanted, and as I started to leave the site I found yet another of these darkling beetles… just sitting there! The beetle didn’t move at all as I took first a few lateral profiles, then moved around to the front for the face shots that I so love, and finally back to the side for even more profiles. I was even able to remove the stick that the beetle had siddled up against to improve the composition of the profile shot and then place it behind the beetle as a backdrop in the frontal shot. Another lesson in why it pays not to waste too much time with uncooperative subjects when others are available.

I already knew about this species because I have encountered it several times before in my travels across the western states, but most memorably during my first visit to the Great Plains back in 1986 when I saw large numbers of this species and the related E. suturalis crossing the highway in front of us during the early evening hours in south-central Kansas. I’d never seen such en masse movement by large beetles, and although I’ve seen both of these species numerous times since I’ve not seen another such migration. Eleodes is the largest genus in the family in North America but occurs exclusively in the western states. Famous for their skunk-like head-stand when disturbed, Triplehorn et al. (2009) note the genus name is derived from Greek and means “olive-like.” This is certainly the case for most of the other members of the genus—mostly black and shiny, the larger species resemble “black olives with legs”; however, this species has not quite such aspect. Rather, its dull color, depressed fusiform shape and elytra with distinct, tuberculate costae (Triplehorn et al. 2009, Bernett 2008) make it immediately recognizable amongst the dozens of congeners that are likely to be found co-occurring with it in the different parts of its wide range.

Not quite a head stand, but he wants to do it.

Although the normal range of this species covers the Great Plains from Canada to Mexico, its eastern limit of distribution is still incompletely known. There are some historical records from western and central Iowa, but it was only recently that Maxwell & Young (1998) reported the species for the first time from east of the Mississippi River in Wisconsin. Seeing this report made me wonder if I might be able to find the species in Missouri also; however, those authors noted that the Wisconsin population was encountered exclusively in open habitats with exposed soil surfaces and sandy soil in close proximity to shrub and tree cover. No such habitat exists in western Missouri, and although tiny remnants of sand prairie  habitat remain in the southeastern lowlands of the state they lack significant shrub and tree cover and are instead vegetated primarily by grasses and forbs.

REFERENCES:

Bernett, A. 2008. The genus Eleodes Eschscholtz (Coleoptera: Tenebrionidae) of eastern Colorado. Journal of the Kansas Entomological Society 81(4):377-391.

Maxwell, J. A. & D. K. Young. 1998. A significant eastern range extension for Eleodes tricostatus (Say) (Coleoptera: Tenebrionidae). The Coleopterists Bulletin 52(1):90–92.

Triplehorn, C. A., D. B. Thomas, and E. G. Riley. 2009. The genus Eleodes Eschscholtz (Coleoptera: Tenebrionidae) in Texas. The Coleopterists Bulletin 63(4):413-437.

Copyright © Ted C. MacRae 2012

Post processing—then and now

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I recently happened upon one of my first attempts at post processing a photograph of a pinned insect specimen. The subject was Anomalipus elephas (large armoured darkling beetle), a tank of an insect (this example measuring 32 mm in length) belonging to the family Tenebrionidae. At the time, I was quite pleased with the results of my crude post processing efforts and proudly posted the “enhanced” photo in full-sized glory for all to behold. Since then, I’ve gained some experience with post processing of photos, and when I saw the processed photo this time I knew that there was considerable room for improvement. I thought it might be interesting to give the photo another PP whack and compare the two efforts from then and now.

Here is the original photo—keep in mind that the photo was taken with a small (though fairly decent) point-and-shoot camera (Panasonic DMC-FX3) a few months before I made the move to my current dSLR setup. I pinned the specimen to a styrofoam board, illuminated it with two 23w compact fluorescent light bulbs, and took the photo with the camera set on its “macro” setting. For the original post processed version (using Adobe Photoshop Elements version 6.0), I rotated and cropped the photo, then increased brightness and contrast (I don’t remember the values for each), used the clone tool to remove the pinhead (I’d just figured out how to do this), and increased sharpness using unsharp mask. This is all well and good (although I think the added contrast was a little excessive); however, I did make two big mistakes. The first was using the eraser tool to create a white background—a tedious process, especially around the perimeter of the subject to avoid “clipping” any of the subject’s body. The second was leaving the numerous small pieces of debris clinging to the subject. Debris on pinned (and even live) specimens is now a pet peeve of mine—I find it detracts greatly from the appearance of the photo, yet it is remarkably easy to remove in all but the most extreme of cases. At any rate, here is the result of that original attempt:

For the latest attempt, I rotated and cropped the original photo as before. Next, I created a white background, not with the “Eraser Tool” but rather by opening “Levels”, clicking on “Set White Point”, and touching the darkest part of the background. Voilá—a beautiful white background with no clipped subject edges! The subject still needed to be brightened up (two 23w fluorescent bulbs don’t put out that much light); however, instead of directly adjusting brightness I set “Lighten Shadows” to a value of +30% (a rather heavy handed setting) to also reduce shadows around the subject’s legs. Then I used the “Clone Stamp Tool” to clone out the pinhead, but this time I didn’t stop there—I continued using the tool to clone out all of the tiny little pieces of debris on the subject surface. Using the clone stamp tool effectively requires some practice, but eventually one learns to adjust the size and define the source set point to achieve almost perfect results. Lastly, I increased sharpness with “Unsharp Mask” (118%, 1.0 pixels, 8 levels). That’s it—took me all of about 3 or 4 minutes to post process the original photo to achieve the following result:

To compare the two post-processed images directly click here. Of course, my current camera setup is capable of much higher quality photographs than the point-and-shoot used for the subject of this post; however, the sequence of post processing  steps that I use is essentially the same (if less heavy handed). One final note—I am not a Photoshop expert, and perhaps some of the processes I have described can be done even more effectively or easily than in the manner I have described. I would welcome any comments or tips that you think might offer a better way to post process photos of pinned specimens.

Copyright © Ted C. MacRae 2012

Answers to ID Challenge #5 – Artrópodes em casca de árvore morta

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Dead tree in Campinas, Brazil

After checking into my hotel in Campinas, Brazil I couldn’t wait to start exploring the grounds to see what insect life I might be able to find.  Almost immediately, I encountered this dead tree in back of the hotel.  To a beetle collector, a dead tree is an irresistible draw – especially one that is still standing and with loosely hanging bark, as in this one.  I approached the tree, gave it a look up and down the trunk to see if any beetles or other insects might be found on the outer surface of the bark, and when none were seen began carefully peeling sections of the bark away from the trunk.  Out from beneath the first section darted a small, black lizard – it reminded me in general form of our North American fence lizards (genus Sceloporus), but honestly it darted so fast up the trunk that I didn’t get a good look at it (much less even the chance to attempt a photograph).  Peeling the bark further away from the wood revealed a goodly number of what I took to be beetle larvae, although they were unlike anything I’d ever seen before.  They were fairly good-sized – about 25mm in length, and although there are a number of beetle families whose larvae may be encountered under the bark of dead trees, there aren’t many with larvae of this size.

Coleopteran larva (Tenebrionidae?) under bark of dead tree.

Despite their odd appearance, their basic gestalt suggested to me that they might be something in the family Tenebrionidae (darkling beetles).  Sadly, the state of beetle larval taxonomy is far from complete, especially in the tropics, and given the extraordinary diversity of the order as a whole I knew it could be difficult to impossible to identify them.  This task was further complicated by the fact that I did not collect any voucher specimens.¹

¹ Insect collecting permits are required in Brazil and are exceedingly difficult to obtain.  Although enforcement is lax, a few unlucky foreigners have been caught and suffered tremendous inconvenience at the hands of notoriously unsympathetic authorities.  This being a business trip, I had no desire to tempt fate for the sake of a few larvae in a group I don’t even study.

Despite a millipede-like appearance, six legs and loose cluster of ocelli indicate its true identity.

After consulting all of the print and online resources at my disposal and failing to find a convincing match at even the family level, I began to second guess not only whether these were tenebrionids, but larvae or even beetles.  I’m not aware of any tenebrionids with larviform adult females, but such are common in the Lampyroidea.  That didn’t seem to fit, however, as the latter tend to be much more flattened and armored in appearance, and the round head is really unlike the elongate and narrow head so often seen in that group.  The actually began to wonder if it was even a beetle – most xylophagous beetle larvae are light-colored and rarely so heavily sclerotized, and the antennae are unlike the typical 3-segmented antennae seen with most xylophagous beetle larvae.  In fact, the antennae and the shape of the head actually reminded me of a millipede, but the obvious presence of six legs (and no more) made this untenable (even though 1st instar millipedes are hexapod, the large size of these individuals precludes them from being 1st instar anything).  Eventually, I could only conclude that they were coleopteran – possibly a larviform adult, but more likely larval.  As a last resort I sent photos to Antonio Santos-Silva, a coleopterist at the University of São Paulo.  Although he specializes in Cerambycidae, I reasoned this might be a fairly common species since I had found good numbers on a single tree in an urban area near São Paulo, and as such it might be something he would recognize.  Antonio quickly replied saying that he agreed it was the larva of a species of Tenebrionidae, with an appearance similar to the larvae of Goniodera ampliata (a member of the Lagriinae, formerly considered a separate family).  I’ve not been able to find photos of the larva of Goniadera or related genera, but these do bear a striking (if more glabrous) resemblance to these presumed tenebrionid larvae from Australia.  Until a more convincing opinion is forthcoming, Tenebrionidae seems to be the consensus.

Polyxenid millipedes and two types of Collembola (several Poduromorpha and one Entomobryomorpha)

Three tiny adult coleopterans (family?) surround a large larval coleopteran

Although nobody zeroed in on Tenebrionidae for this challenge (#5 in the ID Challenge series), I must say that I enjoyed the diversity of opinion about what it might represent.  Moreover, congratulations to those who ‘took nothing for granted’ and noted the presence of several other organisms in the photo – this is where the big points were to be earned, and several participants successfully ID’d what I take to be a number of poduromorph collembolans, a single entomobryomorph collembolan, a central cluster of polyxenid millipedes, and several indistinct but clearly coleopteran adults (see super crops above).  David Hubble got the most correct answers to earn 15 points and the win in this inaugural post of BitB Challenge Season #2, while Dave and Troy Bartlett earned 13 and 10 points, respectively, to complete the podium.  Seven other participants got in on the fun and earned some points – I hope you’ll join the fun next time, too!

Copyright © Ted C. MacRae 2011

The “best” Eleodes suturalis

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Eleodes suturalis - "sutured" clown beetle

Testing with my new diffuser setup¹ continues. I’ve kept this “sutured” clown beetle (Eleodes suturalis) alive since last July as a terrarium-mate with my Great Plains giant tiger beetles (Amblycheila cylindriformis). The first photos I took of it in the terrarium with the old diffusers (Sto-Fen + Puffers) can only be described as “ho-hum.” The next series (with the beetle cleaned up a bit) was taken in a white box with indirect flash and represented a nice improvement over the first shots. Here, the beetle is back in the terrarium on a piece of bark using direct flash and the new diffuser. I think it has the best of both worlds – nicely diffused lighting on a natural substrate (without the need for a white box). Yes, the focus is a bit off in the head area – the beetle was really not very cooperative during the shoot, and I was just interested in seeing how the lighting would look without spending too much time trying to capture the “perfect” shot.

¹ Photos of the diffuser and instructions on how to make it are coming, I promise! I’ve made a few improvements over the prototype by eliminating the tape to hold things together and am just working on the attachment to the MT-24EX flash bracket.

I really hope this diffuser works out for me in the field!

Photo Details: Canon 50D w/ 100mm macro lens (ISO 100, 1/250 sec, f/16), direct Canon MT-24EX flash w/ oversized concave diffuser. Typical post-processing (levels, minor cropping, unsharp mask).

Copyright © Ted C. MacRae 2010

…the “better” Eleodes suturalis

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As I mentioned in my previous post, I really wasn’t satisfied with the photographs I took of the clown beetle, Eleodes suturalis, that I brought back from Oklahoma. I had placed the beetle in a terrarium of native soil and taken the obligatory whole beetle and head close-up photographs, both showing all the characters needed to identify the species in adequate detail. They were good, scientific photos, but they weren’t very exciting. In fact – they were boring! Now, I know not every subject I photograph is going to be a wower (the giant desert centipede I recently featured probably setting that standard), but it is important to me that the photographs I post here at least be interesting. After taking those first E. suturalis photographs, then being underwhelmed as I brought them up one-by-one on the computer, I started thinking about whether certain insects are just ‘homely’, and no matter how you photograph them they will still be homely. Eleodes suturalis is by no means a homely beetle in real life, but that is due mostly to the impressiveness of its size – a quality not easy to project in photographs.  Beyond that, its somber coloration, lack of unusual morphological modifications, and “beady little eyes” (fide Adrian) don’t offer much else in the way of help.  Combine that with the unflattering salmon coloration of its native soil as a substrate and an exoskeleton just shiny enough to cause annoying specular highlights, and you’ve got a recipe for really boring beetle photographs!

That’s when it occurred to me to try photographing the beetle in a white box.  I’ve only just begun to experiment with this technique and have been impressed with its ability to make somber-colored subjects (e.g., Gromphadorina portentosa) attractive and truly beautiful subjects (e.g. Buprestis rufipes) simply stunning.  The sharp, clean environment of a white box demands a clean beetle, so I gave the beetle (who had done much digging since the previous photo shoot) a good soaking and scrubbing (to the beetle’s great disapproval!).  Yes, I know there is still some dirt on him, but I think a dental pick and wire brush would have been needed to remove every last bit, caked on as it was!  Despite that, I think I achieved the desired effect – specular highlights… gone!  Boring background… gone!  Clean and crisp and ready to impress! The photos also do a much better job of highlighting the 3-dimensionality of the beetle than the original photographs.  Of the many photos I took, my favorite is featured above, and below I present two more that closely approximate the vantage of the two photos I posted from the first shoot in a side-by-side comparison.

For those of you wondering how I managed to secure the beetle’s cooperation for these photos, I used a modification of the “lens cap” technique, covering the beetle with a large glass bowl instead.  The beetle crawled around under the bowl for a bit but eventually would end up settled down against the edge.  By carefully lifting the bowl I was able to avoid disturbing the beetle and fire a few shots before it would start wandering again.  I just repeated the process until I was satisfied I had a few good shots in the sequence.

Does this mean an end to my preference for in situ photographs?  Certainly not.  But some beetles just look better in white!

Photo Details:
White box: Canon 50D w/ 100mm macro lens (ISO 100, 1/250 sec, f/18-20), Canon MT-24EX flash, indirect. Typical post-processing (levels, minor cropping, unsharp mask).
Terrarium: same except f/18, direct flash w/ Sto-Fen diffusers.

Copyright © Ted C. MacRae 2010

The real Eleodes suturalis…

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I recently posted a photograph of a clown beetle (Eleodes hispilabris) (family Tenebrionidae) that I found last July in the Glass Mountains of northwestern Oklahoma.  I had encountered that individual while stumbling through the mixed-grass prairie in the middle of the night in search of the Great Plains giant tiger beetle (Amblycheila cylindriformis).  Although I eventually found the latter species, it took a few hours, during which time I was forced to examine numerous individuals of another clown beetle, Eleodes suturalis – perhaps the most conspicuously common clown beetle in the Great Plains.  I didn’t bother to take photographs of them, focused as I was on my tiger beetle search and owing to the fact that this was not the first time I’d encountered that species in abundance (the first time being many, many years ago as they crossed the highway en masse just a few miles north of the Glass Mountains in Barber Co. Kansas).  In fact, I was becoming rather annoyed with them due to their great similarity in size and coloration to the object of my desire¹, and only when I found the previously photographed individual doing the defensive “head stand” so characteristic of the group did I relent and break out the camera for a series of shots (not easy in the dark of night).

¹ Wrigley (2008) even suggested a mimetic association for Amblycheila cylindriformis and Eleodes suturalis due to their similarity in size, shape and coloration (black with a reddish-brown sutural stripe).

Of course, that individual turned out not to be E. suturalis, but the closely related species E. hispilabris, a fact that I did not realize until several days later as I was examining the photographs more closely. Fortunately, I happened to bring home with me a live individual of what truly represents E. suturalis, which I show in these photographs.  I’m not sure exactly why I brought a live one home with me – I’ve done more and more of this in recent years, mostly just to observe them and see what they do.²  I think in this case, I was intrigued by the possible mimetic association between this species and A. cylindriformis and wanted an individual for comparison with the several live A. cylindriformis individuals that I also brought back with me.

² The singular focus on collecting “specimens” that I had during my younger years seems to be giving way to a desire to know more about species as living entities and not just their external morphology.

Unlike E. hispilabris (my identification of which I only consider tentative), there can be little doubt that the individual in these photographs represents E. suturalis.  No other clown beetle in the Great Plains exhibits the sharply laterally carinate elytra and broadly explanate (spread outward flatly) pronotum (Bernett 2008).  The reddish-brown sutural stripe of the distinctly flattened elytra is also commonly seen in this species, although occasional individuals of a few other clown beetle species exhibit the stripe as well (including E. hispilabris, which likely was the reason I assumed it represented E. suturalis).  All of the characters mentioned above can be seen in the photographs shown here.  However, I nevertheless find the photos rather unsatisfying.  If you think you know why, feel free to comment, otherwise you can wait for the “better” photos…

Photo Details: Canon 50D w/ 100mm macro lens (ISO 100, 1/250 sec, f/18), Canon MT-24EX flash w/ Sto-Fen diffusers. Typical post-processing (levels, minor cropping, unsharp mask).

REFERENCES:

Bernett, A. 2008. The genus Eleodes Eschscholtz (Coleoptera: Tenebrionidae) of eastern Colorado. Journal of the Kansas Entomological Society 81(4):377–391.

Wrigley, R. A.  2008. Insect collecting in Mid-western USA, July 2007.  The Entomological Society of Manitoba Newsletter 35(2):5–9.

Copyright © Ted C. MacRae 2010

Clown beetle surprise

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As I slowly scanned my flashlight through the darkness across the mixed-grass prairie in the Glass Mountains of northwestern Oklahoma last July, there was one thing that I hoped not to see (prairie rattlesnake, unless from afar) and one thing that I hoped more than anything to see (Great Plains giant tiger beetle, Amblycheila cylindriformis). Fortunately, I encountered none of the former and found several of the latter.  It took awhile before I saw the first one, but in the meantime I saw all too abundantly the clown beetle, Eleodes suturalis.  A member of the family Tenebrionidae, this species is one of the most conspicuous components of the Great Plains beetle fauna.  Adults are commonly encountered walking about the grasslands or crossing roads, especially after summer rains.  I recall my first encounter with this species when I made my first insect collecting trip to the Great Plains in 1986, marveling as I literally watched hundreds of individuals crossing a remote highway in southwestern Kansas.  Now, they were just an annoyance – close enough in size and appearance to the object of my search that I had to pause and look at each one I encountered to verify its identity.¹

¹ In fact, a mimetic association has been suggested for Amblycheila cylindriformis and Eleodes suturalis due to their similarity in size, shape and coloration (black with a reddish-brown sutural stripe) (Wrigley 2008).  This may be true, as Eleodes suturalis is an abundant species capable of defending itself with noxious sprays that contain benzoquinone and other hydrocarbons, while Amblycheila cylindriformis is a much rarer species (as mimics tend to be) that lacks defensive compounds.

After finding a few of the Amblycheila, I encountered this particular individual clinging to a root sticking out of the side of a wash.  My closer look caused it to immediately assume its characteristic defensive headstand pose (from which the name ‘clown beetle’ comes), so I decided to take a few photographs (not an easy task at night).  The photos have been sitting on my hard drive since, but in examining them more closely, I realized that this particular beetle is not E. suturalis.  Rather, it is one of several similar appearing species that co-occur with E. suturalis in the Great Plains and sometimes resemble it due to their large size, sulcate elytra, and occasional presence of a similar reddish-brown sutural stripe.  From these species, E. suturalis is at once distinguished by its broadly explanate (flanged) pronotum and laterally carinate, distinctly flattened elytra.  This individual clearly exhibits more rounded elytra and as best as I can tell keys to E. hispilabris – distinguished from E. acuta and E. obscurus by possessing a normal first tarsal segment (not thickened apically) on the foreleg (Bennett 2008).  Presumably this and the other related species of Eleodes also possess chemical defenses similar to E. suturalis – an example of Müllerian mimicry where multiple species exhibit similar warning coloration or behavior (in this case headstanding) along with genuine anti-predation attributes.

Photo Details: Canon 50D (ISO 100, 1/250 sec, f/14), Canon 100mm macro lens, Canon MT-24EX flash (1/4 ratio) w/ Sto-Fen diffusers. Post-processing: levels, unsharp mask, slight cropping.

REFERENCES:

Bernett, A. 2008. The genus Eleodes Eschscholtz (Coleoptera: Tenebrionidae) of eastern Colorado. Journal of the Kansas Entomological Society 81(4):377–391.

Wrigley, R. A.  2008. Insect collecting in Mid-western USA, July 2007.  The Entomological Society of Manitoba Newsletter 35(2):5–9.

Copyright © Ted C. MacRae 2010