Bizarre, beautiful extremes

February 15, 2009October 10, 2011 / Ted C. MacRae / 8 Comments

No niche, it seems goes unfilled. Specialization is likely to be pushed to bizarre, beautiful extremes.–E. O. Wilson, The Diversity of Life

Wilson didn’t mention treehoppers specifically when he made the above quote, referring to the exuberance of extreme behavioral and morphological adaptations seen in the biota of the tropics, but he could have just as easily led off with them. Treehoppers (order Hemiptera, family Membracidae) are well-known for their variety of oddly grotesque shapes resulting from a curiously inflated pronotum – presumably having evolved to resemble thorns and buds on their host plants, or the ants that vigorously defend numerous treehopper species in exchange for their sweet honeydew, or perhaps to aid in the dispersal of volatile sex pheromones (an attractive hypothesis but lacking experimental support). Despite inordinate attention in relation to their low economic importance, it remains that the pronotal modifications of many treehoppers are so bizarre that they continue to defy any logical explanation.

I must admit that, despite my passion for beetles, treehoppers were my first love. (Well, actually anything that I could bring home from my solo wanderings in the urban woodlands and vacant lots near my childhood home and keep alive in a terrarium was my first true love, but from an academic standpoint, treehoppers were the first group to arouse my taxonomic interest as I began my transformation from child collector to serious student.) I had just begun graduate school in the Enns Entomology Museum under the late hemipterist Tom Yonke to conduct leafhopper host preference and life history studies, and although far more Cornell drawers in the museum contained Cicadellidae, it was the treehopper drawers that I found myself rifling through each afternoon after completing the day’s thesis duties. Despite their lesser number, the treehopper drawers had recently benefited from the attentions of a previous student, Dennis Kopp, whose efforts during his time at the museum concentrated on collecting treehoppers from throughout Missouri and culminated in the four-part publication, The Treehoppers of Missouri (1973-1974). I was enamored by these little beasts – specifically by their exaggerated pronotum – and started collecting them whenever I could on my forays around the state surveying for leafhoppers. They were closely enough related to leafhoppers to make them relevant to my work, only cooler – like leafhoppers on steroids! With The Treehoppers of Missouri as my bible and my desk located a half dozen footsteps from the largest treehopper collection within a several hundred mile radius, I delved into their taxonomy and, for a time, considered a career as a professional membracid taxonomist.

Fast forward nearly 30 years, and my involvement as a taxonomist is neither professional nor deals with membracids. Beetles have taken over as my focal taxon, and I conduct these studies strictly as an avocation. Still, I continue to collect treehoppers as I encounter them, and although such efforts have been largely opportunistic, I’ve managed to assemble a fairly diverse little collection of these insects as a result of my broad travels. Much of this has occurred in the New World tropics, and it is this region that is the center of diversity for the family Membracidae (fossil evidence suggests that subfamily diversification and subsequent New World radiation began during Tertiary isolation about 65 million years ago after South America separated from Africa, since only the primitive subfamily Centrotinae occurs in both the Old and the New Worlds – all other subfamilies are restricted the New World (Wood 1993)). Every now and then, as I accumulate enough material to fill a Schmidt box, I sit down and study what I’ve collected, comparing it to my meager literature to attempt identifications. For material I collect in eastern North America, this works fairly well, as there have been a number of publications covering different parts of this area. Outside of this area, however, my only hope is to entice one of the few existing membracid specialists into agreeing to look at what I’ve accumulated and ask for their help in providing names, in exchange for which they will be granted retention privileges to benefit their research.

Most recently, I was able to convince Illinois Natural History Survey entomologist Chris Dietrich to take a look at the material I had accumulated during the past ten years or so, which included many specimens from Mexico and a smattering from other world areas, including South Africa. Chris did his doctoral work at North Carolina State University under “Mr. Membracid” himself, Lewis Deitz, and has since been conducting evolutionary and phylogenetic studies on Membracidae and the related Cicadomorpha. I recently received this material back from Chris (photo above), the majority of which he had been able to identify to species – only a few specimens in the more problematic genera were left with a generic ID.

Campylocentrus sp. (Mexico: Oaxaca)

Hyphinoe obliqua (Mexico: Oaxaca)

Poppea setosa (Mexico: Puebla)

Umbonia reclinata (Mexico: Oaxaca)

Umbonia crassicornis male (Mexico: Puebla)

Umbonia crassicornis female (Mexico: Puebla)

The selection of photos here show a sampling of some of the more interesting forms contained within this batch of newly identified material – all of which hail from southern Mexico. Campylocentrus sp. is an example of the primitive subfamily Centrotinae, distinguished among most membracid subfamilies by the exposed scutellum (not covered by the expanded pronotum). Hyphinoe obliqua is an example of the largely Neotropical subfamily Darninae, while Poppea setosa represents one of the more bizarre ant-mimicking species of the subfamily Smiliinae. Umbonia is a diverse genus in the subfamily Membracinae, occurring from the southern U.S. south into South America. Umbonia crassicornis is one of the most commonly encountered species in this genus, with the photos here showing the high degree of sexual dimorphism it exhibits. As membracids go, these species are quite large (10 mm in length from frons to wing apex for Campylocentrus sp. and P. setosa, a slightly larger 11-13 mm for the others); however, the many smaller species in this family are no less extraordinarily ornamented. I’ve also included a photo (below) of one of the drawers from the main collection after incorporating the newly identified material – this drawer represents about half of my treehopper collection, with the largely Nearctic tribe Smiliini and the primitive family Aetalionidae contained in another drawer. In all, the material contained one new subfamily, six new tribes, 13 new genera¹, and 30 new species for my collection. For those with an appetite for brutally technical text, a checklist of the species identified, arranged in my best attempt at their current higher classification, is appended below (any treehopper specialist who happens upon this should feel free to set the record straight on any errors). For each species, the country of origin (and state for U.S. specimens) is indicated along with the number of specimens, and higher taxa new to my collection are indicated with an asterisk(*). Don’t worry, I didn’t type this up just to post it here – it’s a cut/paste job from my newly updated collection inventory for Membracoidea. Happy reading!

¹Wildly off topic, and perhaps of interest only to me, but two of the genera represented in the material are homonyms of plant genera: Oxyrhachis is also a Madagascan genus of Poaceae, and Campylocentrus is a Neotropical genus of Orchidaceae. Scientific names of plants and animals are governed by separate ruling bodies (ICBN and ICZN, respectively), neither of which specifically prohibit (but do recommend against) creating inter-code homonyms. The number of such homonyms is surprisingly high – almost 9,000 generic names have been used in both zoology and botany (13% of the total in botany) (source). Fortunately, there is only one known case of plant/animal homonymy fr BOTH genus- and species-level names – Pieris napi japonica for a subspecies of the gray-veined white butterfly (Pieridae) and Pieris japonica for the popular ornamental plant Japanese andromeda (Ericaceae).

REFERENCES:

Kopp, D. D. and T. R. Yonke. 1973-1974. The treehoppers of Missouri: Parts 1-4. Journal of the Kansas Entomological Society 46(1):42-64; 46(3):375-421; 46(3):375-421; 47(1):80-130.

Wood, T. K. 1999. Diversity in the New World Membracidae. Annual Review of Entomology 38:409-435.
.

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Superfamily MEMBRACOIDEA
Family MEMBRACIDAE
Subfamily CENTROTINAE

*Tribe BOOCERINI
*Campylocentrus curvidens (Fairmaire) [Mexico] – 4
Campylocentrus sp. [Mexico] – 1

*Tribe GARGARINI
*Umfilianus declivus Distant [South Africa] – 3

*Tribe OXYRHACHINI
*Oxyrhachis latipes (Buckton) [South Africa] – 1

Tribe PLATYCENTRINI
Platycentrus acuticornis Stål [Mexico] – 11
Platycentrus obtusicornis Stål [Mexico] – 3
Platycentrus brevicornis Van Duzee [USA: California] – 7
Tylocentrus reticulatus Van Duzee [Mexico] – 4

*Tribe TERENTIINI
*Stalobelus sp. [South Africa] – 1

*Subfamily HETERONOTINAE

*Tribe HETERONOTINI
*Dysyncritus sp. [Argentina] – 1

Subfamily MEMBRACINAE

Tribe ACONOPHORINI
Aconophora sp. female [Mexico] – 1
*Guayaquila xiphias (Fabricius) [Argentina] – 7

Tribe HOPLOPHORIONINI
Platycotis vittata (Fabricius) [USA: Arizona, California] – 3
Umbonia crassicornis (Amyot & Serville) [Mexico] – 73
Umbonia reclinata (Germar) [Mexico] – 8

Tribe MEMBRACINI
Enchenopa binotata complex [Mexico] – 1
Enchenopa sp. [Argentina] – 6

Subfamily DARNINAE

Tribe DARNINI
Stictopelta nova Goding [Mexico] – 9
Stictopelta marmorata Goding [USA: Texas] – 1
Stictopelta pulchella Ball [Mexico] – 11
Stictopelta varians Fowler [Mexico] – 3
Stictopelta sp. [USA: Arizona, California] – 5
Stictopelta sp. [Mexico] – 5
Stictopelta spp. [Argentina] – 6
*Sundarion apicalis (Germar) [Argentina] – 2

*Tribe HYPHINOINI
*Hyphenoe obliqua (Walker) [Mexico] – 1

Subfamily SMILIINAE

Tribe AMASTRINI
Vanduzeea triguttata (Burmeister) [USA: Arizona] – 2

Tribe CERESINI
Ceresa nigripectus Remes-Lenicov [Argentina] – 3
Ceresa piramidatis Remes-Lenicov [Argentina] – 4
Ceresa ustulata Fairmaire [Argentina] – 1
Ceresa sp. female [Argentina] – 1
Poppea setosa Fowler [Mexico] – 11
Tortistilus sp. [USA: California] – 1

Tribe POLYGLYPTINI
*Bilimekia styliformis Fowler [Mexico] – 3
Polyglypta costata Burmeister [Mexico] – 18

Tribe SMILIINI
Cyrtolobus acutus Van Duzee [USA: New Mexico] – 1
Cyrtolobus fuscipennis Van Duzee [USA: North Carolina] – 1
Cyrtolobus pallidifrontis Emmons [USA: North Carolina] – 1
Cyrtolobus vanduzei Goding [USA: California] – 4
Cyrtolobus sp. [USA: Arizona] – 2
*Evashmeadea carinata Stål [USA: Arizona] – 4
*Grandolobus grandis (Van Duzee) [USA: Arizona] – 1
Ophiderma sp. [Mexico] – 1
Palonica portola Ball [USA: California] – 4
Telamona decora Ball [USA: Missouri] – 4
Telamona sp. [USA: Texas] – 1
*Telamonanthe rileyi Goding [USA: Texas] – 2
*Telonaca alta Funkhouser [USA: Texas] – 1
Xantholobus sp. [Mexico] – 1

Subfamily STEGASPINAE

Tribe MICROCENTRINI
Microcentrus perditus (Amyot & Serville) [USA: Texas] – 1
Microcentrus proximus (Fowler) [Mexico] – 1

Family AETALIONIDAE
Subfamily AETALIONINAE

Aetalion nervosopunctatum nervosopunctatum Signoret [Mexico] – 9
Aetalion nervosopunctatum minor Fowler [USA: Arizona] – 2
Aetalion reticulatum (Linnaeus) [Argentina, Uruguay] – 26

How to fail a test with dignity

February 12, 2009April 14, 2009 / Ted C. MacRae / 16 Comments

It’s been a long time since I’ve had to take an exam, but I wish I would have thought of some of these answers when I was stumped:

This student shows promise as future director of The Institute for Creation Research:

This one’s for Bug Girl:

I think this one takes the cake for thinking outside the box:

Elegant in its simplicity:

“Oh dear!” is right:

Technically, this is correct:

I’ll bet some of you professor-types could share a few that top these!

I thank my friend, colleague, and Ozark Trail hiking buddy Rich for sending these to me.

“Armoured tank beetle”

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

Photo details: Panasonic DMC-FX3 (macro setting w/ auto exposure, aperature, and focus), illumination by two 23w compact fluorescent light bulbs. Post processing details: Adobe PhotoShop Elements 6.0 to crop, adjust brightness and contrast, remove pinhead, erase background, and sharpen.

In my last post, I briefly mentioned a beast of a beetle that we had given the nickname “armoured tank beetle.” Using (Picker et al. 2002), I determined this beetle to represent the species, Anomalipus elephas (family Tenebrionidae) – whose actual common name of “large armoured darkling beetle” was amazingly close to our made-up common name (not to mention the appropriateness of its specific epithet) – and linked to an online photograph of the species. As it turns out, the genus Anomalipus is quite large, with 51 species distributed throughout eastern and southern Africa – 34 of which have been recorded from South Africa proper (Iwan 2002). I’ve learned better than to ascribe species names to specimens in diverse groups of which I am not an expert based on a photograph of a common species, so for now this specimen will have to be called Anomalipus sp. Endrödy-Younga and Tschinkel (1993) report that all species in this genus are heavily built with strong legs, with most species being restricted within their geographical range to dense bush-covered patches of woody savanna.

After I wrote that post, I got to looking at the larger of my two specimens and thought, “Gee, I bet I could get a nice shot of that thing.” After all, it measures an impressive 32 mm in length (that’s 1¼ inches, folks!). Here is the result, and I have to admit I’m quite pleased given my equipment limitations (I only wish I’d thought to brush him off a little bit). This really has to be the most beautiful “big, black, ugly beetle” I’ve ever seen. I recall when I was pinning these two specimens that the exoskeleton was so hard I literally had to use my scissors to hammer the pin to get it going into the specimens. I like “armoured tank beetle” better.

In unrelated news, there are a couple of Carnivals everyone should be aware of – I’m doing my part to get the word out:

Circle of the Spineless – Ed Baker over at Invertebrate Diaries is set to host the next issue on March 2, 2009. There’s your deadline!

Linneaus Legacy – The January issue, hosted at Greg Laden’s Blog, was a good one. Seeds Aside is hosting the February edition and is hoping to post it later this week if he gets enough submissions! Go to this post for details on where to submit your post (or those from other blogs you enjoy). EDIT: Too late – edition #16 is now posted.

REFERENCES:

Endrödy-Younga, S. and W. Tschinkel. 1993. Estimation of population size and dispersal in Anomalipus mastodon Fåhraeus, 1870 (Coleoptera: Tenebrionidae: Platynotini). Annals of the Transvaal Museum 36(4):21-30.

Iwan, D. 2002. Catalogue of the World Platynotini (Coleoptera: Tenebrionidae). Genus 13(2):219-323.

Picker, M., C. Griffiths and A. Weaving. 2002. Field Guide to Insects of South Africa. Struik Publishers, Cape Town, 444 pp.

Tempting tok-tokkies

February 7, 2009October 10, 2011 / Ted C. MacRae / 14 Comments

In the 19th and early 20th centuries, some of the America’s greatest entomologists were coleopterists. Army surgeons John L. LeConte and his protégé George W. Horn, California’s Henry C. Fall, Col. Thomas L. Casey (much maligned for his mihi itch¹ affliction, although in recent years regaining due respect for his insight on generic relationships), and “the Professor” Josef N. Knull, just to name a few. What did these fine men have in common? They studied beetles – not just tiger beetles or jewel beetles, but the entire order! The world was much smaller then, and new information was generated at a much more leisurely pace. Today such an approach is impossible. With 300,000 described species in the order (conservatively) and growing, today’s students of Coleoptera must narrow their focus in one way or another – either by concentrating on one family or ecological guild, or by restricting their studies to a small geographic region. I’ve tried, more or less successfully, to follow suite – jewel beetles are my primary focus, and I restrict my work with the ecologically similar longhorned beetles only to North American species. Well, and I’m also working on tiger beetles, but only in Missouri… although I have begun taking fall tiger beetle trips to neighboring states. Hmm, on second thought, I guess I haven’t been that successful at focusing (sigh! – and a likely explanation for my perpetual backlog of specimens unprocessed and papers unwritten).

¹In taxonomy, a term usually cast towards those who have a combination of disregard for quality over quantity when describing new taxa and a demonstrably high ego (Evenhuis 2008).

Whatever focus I do manage, it all goes out the window when I have the chance to collect in another country – especially someplace as exotic as Africa. This is not a huge problem, as I can at least stay pretty much focused on just beetles. Moths and butterflies are pretty, but it just takes too much effort to keep each specimen in good shape. Bees and wasps also capture my interest, but I never know for sure whether I’ll get stung, and the extra precautions required to avoid such possibility are enough to make me pass on them. Orthopterans don’t generally excite me unless they’re big and gaudy – in which case just one or two for the collection is fine. And flies? Well, they’re flies! About the only non-coleopterans that regularly distract me are treehoppers – running into a mess of them, with their bizarre, fantastical shapes will always stop me in my tracks. Fortunately, they’re not so abundant that they are constantly grabbing my attention.

Beetles, though – that’s a different story. While I can resist the temptation to collect many of the groups outside of my sphere of interest, there are others that are consistently too tempting for me to pass up. One of these is the Tenebrionidae, or darkling beetles. With some 20,000 described species worldwide, it is among the most speciose of beetle families (larger than my beloved Buprestidae), and this diversity combines with difficult taxonomy to make them truly challenging for even the most serious students of the family. For hacks like me, they’re impossible. Moreover, they’re not even especialy pretty – usually just black. Why do I collect them? Mostly because of their (in many cases) large size, comically awkward shuffling gait, and often exaggerated surface sculpturing. Especialy diverse in more xeric habitats, I’ve collected quite a few in my frequent trips through the southwestern U.S. and even managed to get many of them identified by tenebrionid icon Charles A. Triplehorn. Southern Africa is a true center of diversity for this group, with some 3,500 species recorded from the area – nearly 20% of the global diversity! A number of particularly large species that go by the common name “tok-tokkies” make their homes in the dry Namib desert and surrounding bushveld. Along with dungers and chafers and tyrant ground beetles, tok-tokkies would prove to be one more distraction in my nevertheless successful quest for African jewel beetles.

Psammodes hirtipes

“Tok-tokkie” refers not to a particular genus or tribe of tenebrionids, but rather a number of flightless species that have developed a unique “tapping” method of communication between males and females. The name “tok-tokkie” is onomatopoeic, referring to the sound these beetles make when they tap their abdomen on the ground. In the same way that fireflies have species-specific patterns of flashes, different species of tok-tokkies tap with differing frequencies. The beetle makes the noise by raising its abdomen and then bringing it down on the surface of the ground several times in quick succession. Males initiate the tapping and await a response from a receptive female. Signals are exchanged back and forth until, eventually, the two locate each other and mate. Females lay eggs in shallow excavations in the dry, sandy soil, and the larvae that hatch feed within the soil on the roots of small plants. The dry Namib Desert has some of the most astounding species of tok-tokkies. Some – called “fog tok-tokkies” – have developed specially modified grooves to trap moisture from fog banks rolling onto the Atlantic coast. Others drink by doing a “head-stand” to allow condensed dew to trickle down to their mouths. Heat avoidance is another challenge in the Namib. Some species extrude dots of white wax from small pores on their elytra in response to increasing sunlight intensity, eventually appearing white-spotted or striped. The wax reflects the sun’s rays and helps keep the beetle cool. Other species beats the heat by running – in fact, the fastest running beetle in the world is one of the Namib tok-tokkies (and not, as I would have suspected, a tiger beetle). Unlike its mostly clumsy brethren around the rest of the world, this beetle blasts across the scorching sand at lighting speeds. A related species boasts the longest relative leg length of any beetle in the world.

Psammodes virago

I knew none of this in 1999 when I was in South Africa’s Northern (now Limpopo) Province, and while the tok-tokkies we encountered in the bushveld habitat below the Waterberg Range were not quite as marvelous as those of the nearby Namib Desert, they were still irresistible to this indefatigable beetle collector. Not knowing their names, we came up with our own names for them based on their appearance. Psammodes hirtipes was “wrinkle butt” due to the numerous prominent tubercles at the sides and rear of its otherwise smooth elytra. Psammodes virago, was “helmet beetle” because of its smoothly domed “army helmet” shape. Our designation of “armoured tank beetle” for Anomalipus elephas (photo credit) was amazingly close to its actual common name of “large armoured darkling beetle” (Picker et al. (2002), as was “white legs” for Dichtha incantatoris (photo credit), which Picker et al. (2002) call the “white-legged tok-tokkie”. In all, I collected some dozen species of tenebrionids during my stay at Geelhoutbos farm. Most of the smaller ones are still unidentified, but hopefully someday they will prove useful to some tenebrionid specialist.

The online magazine Travel Africa offers an informative article about the Namib tok-tokkies and this humerous video from National Geographic:

Vodpod videos no longer available.

more about “Namib beetles – Travel Africa Magazine“, posted with vodpod

REFERENCES:

Evenhuis, N. L. 2008. The “Mihi itch”—a brief history. Zootaxa, 1890:59-68.

Picker, M., C. Griffiths and A. Weaving. 2002. Field Guide to Insects of South Africa. Struik Publishers, Cape Town, 444 pp.

What’s bugging you?

February 4, 2009October 10, 2011 / Ted C. MacRae / 5 Comments

It’s not often that I use this forum to write about other blogs. There are so many to choose from – good ones – that it’s hard to know where to start. Besides, I’d rather use the limited time I have to write doing so about bugs. Given this, it might seem remarkable that I’m going to write about a blog that – as of now – has only three postings. The writer of this new blog, however, is no ordinary writer, and I expect his blog will prove to be no ordinary blog.

Dr. Arthur V. Evans hardly needs introduction in the world of entomology. His prowess as a collector of insects – especially Scarabaeidae – is legendary, but it is his talent for writing that has earned him his true renown. While his list of research papers is impressive enough, his books are what set him apart from the rest of us. Blending depth of knowledge with humor and a passion for his subject, Dr. Evans’ books have been equally embraced by professional entomologists and the general public alike. His field guides (Field Guide to Beetles of California, Field Guide to Insects of North America, and Introduction to California Beetles) have helped to introduce the fabulous world of insects to nature lovers across the country, and the breathtakingly beautiful An Inordinate Fondness for Beetles (coauthored with my friend and colleague, Dr. Charles L. Bellamy) has become a staple on coffee tables around the world. His latest book, What’s Bugging You?, is a charming collection of essays that have appeared over the years as a column in the Richmond Times-Dispatch. It is also the name of his new blog, and this excerpt from its very first post suggests it will live up to the reputation of its author:

As I bent down to inspect the corpse a panicked wave of blow flies buzzed up past my face. Their tiny wings churned the air to propel their brassy green bodies out of harm’s way. But within minutes they were back. For scavengers like blow flies, life is short and the aroma of decaying flesh promising food, mates, and egg laying sites is just too much to ignore.

Dr. Evans is an artist, and words are his palette.

If you like insects, you will love What’s Bugging You? Check it out, bookmark it, and be prepared to enjoy what results when love of insects meets truly gifted writing.

Tragidion confusion

February 2, 2009October 10, 2011 / Ted C. MacRae / 3 Comments

Back in October, I discussed a recent review of the cerambycid genus Tragidion, authored by Ian Swift and Ann Ray and published in the online journal Zootaxa. These gorgeous beetles mimic the so-called “tarantula hawks” (a group of large, predatory wasps in the family Pompilidae) and have been difficult to identify due to poorly-defined species limits, wide range of geographic variation, unusually high sexual dimorphism, and apparent potential for hybridization in areas of geographic overlap. Swift and Ray (2008) recognized seven North American and four Mexican species, including two newly described species and another raised from synonymy. It was an excellent work that provided much needed clarity based on examination of types and included detailed descriptions and dorsal habitus photographs of all species and separate keys to males and females to facilitate their identification. Unfortunately, my summary caused some confusion regarding species that occur in the deserts of southern Arizona, southern New Mexico and western Texas. In this post, I’ll clarify that confusion and provide details for distinguishing these species.

Formerly, it was thought that two species of Tragidion inhabited this region, with populations exhibiting smooth elytra and breeding in dead stalks of Agave and Yucca (Agavaceae) representing T. armatum and those exhibiting ribbed elytra and breeding in dead branches of a variety of woody plants representing T. annulatum. This concept dates back to the landmark monograph of the Cerambycidae of North America by Linsley (1962). Swift and Ray (2008) noted that Linsley’s concept of T. annulatum was based on an erroneously labeled type specimen, and that true T. annulatum referred to populations in California and Baja California (for which other names – now suppressed – were being used). This left the AZ/NM/TX populations attributed to T. annulatum without a name. The previously suppressed name T. densiventre was found to refer to populations inhabiting lowland habitats and breeding in Prosopis and Acacia (Fabaceae), but those occurring in montane habitats and breeding in Quercus (Fagaceae) represented an as yet undescribed species, for which the name T. deceptum was given. I included Swift and Ray’s figure of T. deceptum in my post – but mistakenly included the male of T. densiventre alongside the female of T. deceptum!

This error may never had been noticed, had it not been for the discriminating eyes of BugGuide contributor, Margarethe Brummermann. Margarethe is currently collecting photographs for a field guide to Arizona beetles and had photographed a male and female of a “ribbed” species in Montosa Canyon. Using the illustration of T. “deceptum” in my post, Margarethe concluded her specimens represented T. deceptum and asked me to confirm her ID. When I told her the specimens represented T. densiventre, her confusion was understandable (given that her male appeared identical to the T. “deceptum” male in my post). Further query on her part prompted me to do a little digging, and I discovered my error. The figure in my post has since been corrected – both that figure and a figure from Swift and Ray (2008) showing the male and female of T. densiventre are included below, along with additional information to allow their identification.

Tragidion densiventre Casey, 1912

Tragidion densiventre was formerly synonymized under T. auripenne (a rare species known from the four corners region of northern Arizona, southern Utah, southwestern Colorado, and northwestern New Mexico). Males of T. densiventre can be distinguished by their longer antennae, tawny-tan elytra and distinctly red-brown head, legs, and scape, while females have shorter antennae and the elytra red-orange. Both males and females of this species are distinguished from T. deceptum by their five elytral costae that curve inward toward the suture and extend to near the elytral apices, as well as their relatively narrower basal black band. Females of this species may be further distinguished from T. deceptum by their all black (or nearly so) antennae. Tragidion densiventre is found predominantly in xeric lowland desert habitats in Arizona, New Mexico, and west Texas (as well as northern Mexico). Larvae have been recorded developing in dead Prosopis glandulosa and Acacia greggii, and adults have been observed aggregating on sap oozing from stems of Baccharis sarothroides (Asteraceae) and flowers of larval host plants. Although the biology of this species has not been described in detail, it is likely that the observations of Cope (1984) for T. auripenne refer to this species. This is the classic T. “annulatum” commonly observed in the desert southwest.

Tragidion deceptum Swift & Ray, 2008

Tragidion deceptum superficially resembles T. densiventre due to its ribbed elytra; however, it is actually more closely related to the Mexican species T. carinatum. Like T. densiventre, the males exhibit longer antennae and tawny-tan elytra, while females have shorter antennae and orange-red elytra. However, the head, legs and scape of males are black, as in females of the species, rather than red-brown as in males of T. densiventre. Females exhibit distinctly annulated antennae, in contrast to the all black antennae of T. densiventre. Both males and females are distinguished from T. densiventre by the elytral costae – only four rather than five, not incurved towards the suture and extending only to the apical one-third of the elytra. In addition, the basal black band is very broad – exceeding the scutellum by 2 × its length. This species is similarly distributed across the desert southwest as T. densiventre but occurs in more montane habitats, where it breeds in recently dead branches of several species of Quercus. Like T. densiventre, adults are often found feeding and aggregating on Baccharis sarothroides, and in a few lower canyons bordering desert habitats in the Huachuca Mountains of southeastern Arizona this species and T. densiventre have been collected feeding alongside each other on the same Baccharis plants. Tragidion deceptum is one of several species in the genus (along with T. coquus in eastern North America) that have been collected using fermenting molasses traps (more on this in a future post).

REFERENCES:

Cope, J. 1986. Notes on the ecology of western Cerambycidae. The Coleopterists Bulletin, 38:27–36.

Linsley, E. G. 1962. The Cerambycidae of North America. Part III. Taxonomy and classification of the subfamily Cerambycinae, tribes Opsimini through Megaderini. University of California Publicatons in Entomology, 20:1-188, 56 figs.

Swift, I. and A. M. Ray. 2008. A review of the genus Tragidion Audinet-Serville, 1834 (Coleoptera: Cerambycidae: Cerambycinae: Trachyderini). Zootaxa, 1892:1-25.

Done with dung, meat please!

January 30, 2009October 10, 2011 / Ted C. MacRae / 11 Comments

“No feces for this species.” “Carnivorous dung beetle shuns dung and decapitates millipede.” “Little dung beetle is big chopper.” “Dung beetle mistakes millipede for dung.” These were some of the clever headlines that I had to compete with in coming up with my own opener for a remarkable beetle that titillated the science blogosphere last week. At the risk of being redundant, I’d like to revisit that beetle and offer a few (hopefully novel) thoughts of my own. I can say that I have a unique and special treat for those willing to read further.

First the background. Deltochilum valgum is a so-called “dung beetle” in the family Scarabaeidae that lives in the lowland rain forests of Peru. As suggested by its common name, it belongs to a group of beetles that are well known for their dung feeding habits. Over 5,000 species of dung beetles are known throughout the world, all of which carve out balls of dung and bury them as provisions for larval development – or so it was thought. As reported by Trond Larsen of Princeton University and colleagues in Biology Letters, D. valgum has apparently abandoned its ancestral dung ball-rolling behavior in favor of a predatory lifestyle. Its prey – millipedes! Moreover, the species exhibits several distinct morphological traits that appear to have evolved as a direct result of their predatory behavior. Adult beetles were repeatedly observed killing and eating millipedes, and their disdain for dung was rather conclusively demonstrated by an exhaustive, year-long trapping program in which pit-traps were baited with a variety of bait types known to attract dung beetles (e.g., various kinds of dung, carrion, fungus and fruit) – and millipedes. In all, over 100,000 dung beetles representing 132 species were trapped (what a nice collection!), 35 of which were found to scavenge on dead millipedes, but only five of these dared tackle live millipedes. Of these, only D. valgum ignored all other foods – it only came to traps baited with live millipedes.

Larsen et al. determined that adults of D. valgum are opportunistic hunters and were much more likely to attack injured millipedes than healthy ones, even those weighing 14 times as much as the beetle. Ball rolling behavior was never observed by D. valgum. Most dung beetles have wide, shovel-shaped heads used to scoop and mold dung balls, but D. valgum has a much narrower head with sharp “teeth” on its clypeus (Fig. 1A vs. 1B). The teeth apparently aid in killing the millipede by piercing the ventral surface behind the head and prying upwards (decapitating it), and the narrow, elongate head facilitates insertion into the millipede body for feeding. Further, the hind tibia are elongate and curved, which are used to “grip” millipedes by holding them up against the dorsally reflexed pygidium (Fig. 1C vs. 1D). This allows the beetle to drag its coiled up victim with one hind leg while walking forward on the other five (Fig. 1E). Once killed, the beetles proceeded to break their prey into pieces and consume their meaty innards, leaving the disarticulated millipede exoskeletons licked clean (Fig. 1F). One of these “attack” episodes was filmed (using infrared lighting so as not to affect their nocturnal behavior) and can be seen in this BBC News video.

Figure 1. (a) Dorsal view of D. valgum head. Sharp clypeal teeth and angled clypeus act as a lever to disarticulate millipede. Narrow, elongate head permits feeding inside millipede; (b) dorsal view of Deltochilum peruanum head, lacking characters described in (a), head used to mould dung balls; (c) lateral view of D. valgum pygidium and hind tibia. Dorsally reflexed pygidial lip is used to support millipede during transport. Elongate, strongly curved hind tibia is used to grip millipede. (d ) Lateral view of D. peruanum pygidium and hind tibia, lacking characters described in (c), hind tibia used for rolling dung balls. (e, f ). Predation strategy by D. valgum. (e) Dragging live, coiled millipede with one hind leg, walking forwards; ( f ) feeding on killed millipede with head inside
segments; disarticulated empty millipede pieces nearby.
Credit: Larsen et al. (2009).

Much has been made about this remarkable shift from coprophagy to predation, which Larsen et al. speculate was driven by competition for limited resources with the many other dung beetle species that occur in the Peruvian rainforests. In fact, adult dung beetles are known to feed on a variety of resources besides dung, as exemplified by the range of baits used in their survey. Thus, my first thought after reading the coverage was actually a question: “Has this species abandoned dung provisioning completely as a reproductive strategy?” Everything I had read focused exclusively (quite understandably) on the bizarre feeding habits of the adults, but there was no mention of what the species’ larval provisioning strategies were. Wanting more information about this, I contacted Trond Larsen, who graciously sent me a PDF of the paper. Unfortunately (though not a criticism of the paper), no further insight about this was found in the paper either. Indeed, in all of the observations recorded by Larsen et al., millipedes killed by D. valgum were consumed entirely by the adults, and no mention was made of how or whether millipedes were utilized for larval provisioning. I wondered if D. valgum had truly abandoned dung provisioning for larval development (a remarkable adaptive switch), or if in fact the species might still utilize the strategy for reproduction (perhaps having specialized on a dung type not included in their survey), while also exploiting millipede predation as adults for a nutritional advantage. I asked Trond about this, to which he replied with this juicy tidbit (I told you I had a special treat!):

Yes, I would very much like to know what the reproductive/nesting behavior of D. valgum is. My best guess is that they also use millipedes as a larval food source, but as you say, we haven’t observed that behavior yet. I have observed other generalist dung beetle species rolling balls out of dead millipedes, presumably to bury for the larvae, so I certainly think it would be an adequate food source. Many dung beetle species use carrion for their larvae.

I am quite confident that D. valgum does not use any kind of dung. I have sampled these dung beetle communities very thoroughly, with many dung types and other bait types, and also with passive flight intercept traps that catch all beetles. Every dung beetle species that feeds on dung is at least sometimes attracted to human dung (this is not the case in African savannahs though, but is in neotropical forests – that is a whole different story). There are still a small handful of species we catch in flight intercept traps that we don’t know what they eat, although some of these mysteries have recently been solved – many of them live in leaf-cutter ant nests for example.

While predation of millipedes by a dung beetle is itself a fascinating observation, demonstrating the abandonment of dung provisioning in favor of captured prey for larval development would be a truly remarkable example of an ecological transition to exploit a dramatically atypical niche. I hope Trond (or anybody for that matter) actually succeeds in observing millipede/prey utilization for larval provisioning by this species.

Many thanks to Trond Larsen for his delightful correspondence.

SOURCE:
Larsen, T. H., A. Lopera, A. Forsyth and F. Génier. 2009. From coprophagy to predation: a dung beetle that kills millipedes. Biology Letters DOI: 10.1098/rsbl.2008.0654.

Christmas in January

January 27, 2009October 10, 2011 / Ted C. MacRae / 8 Comments

One of the ironies about collecting insects is that the winter months can be just as busy as the summer months, sometimes more so. Despite the lack of insect activity during these short, cold days, I actually find myself at times a little overwhelmed with the amount of “work” I’ve set myself up to do. There are specimens to mount, label, curate, and incorporate into the main collection. Data from the just concluded field season need to be assembled and summarized so that reports and manuscripts can be written. Applications for collecting permits need to be submitted, which can only be done once plans for the upcoming season have been formulated. The fact that entomology is also my profession only exacerbates the situation. Not that I’m complaining! I love the fact (and sometimes still have a hard time believing) that I actually get paid to play with bugs, which affords me the opportunity to study them as I wish in my free time.

In addition to these winter tasks for my own collection, I’ve also for a number of years now taken on the task of identifying material for other collectors. While this may seem very nice of me, I can’t honestly claim that my motives are completely altruistic. Doing this has given me the chance to develop relationships with a great many entomologists, specializing in taxa both within and outside my sphere of interest. Often, material sent to me contains specimens that represent new distributional or host plant records, providing fodder for my own research. Less frequently but more exciting, such material will contain species that I haven’t yet encountered on my own. In most cases, the sender will be gracious enough to let me keep an example or two for my collection. Such is the case with this gorgeous buprestid beetle, Hiperantha interrogationis, which was included in a recent shipment to me as a “gift” from long time friend and expert cerambycid specialist Dan Heffern. This Neotropical representative of the tribe Stigmoderini (which also contains the Australasian genera Calodema and Metaxymorpha, featured in this recent post) not only represents a new species for my collection, but a new genus as well (reminding me of the old adage, “some of the best collecting is in other people’s collections” – or something like that). Measuring right at 25mm in length, this spectacularly beautiful specimen is a welcome addition to my collection!

Hiperantha interrogationis is the only member of this otherwise South American genus to occur as far north as Central America and Mexico (Bellamy 2008). This particular specimen was collected in Jalisco, and as such represents the subspecies cruentata, occupying the northernmost portion (Colima, Durango, Jalisco, and Nayarit) of the distributional range of the species (Bellamy & Westcott 2000). Hiperantha interrogationis cruentata is distinguished from nominotypical populations by having all of the dorsal color pattern in red (nominate H. interrogationis exhibit some yellow markings) and the median longitudinal vittae of the elytra widely interrupted, thereby resulting in the formation of a distinctly transverse postmedian band. The apical transverse band of the elytra is also usually much wider in this subspecies than in the nominate form.

In a familiar refrain, not much is known about H. interrogationis other than distributional records. Adults have most often been encountered on flowers of tropical trees, but larval hosts are completely unknown. Manley (1985) published observations on the feeding behavior of adults on flowers of “Niguito”, Muntingia calabura (Elaeocarpaceae) near Guayaquil, Ecuador. The adults were observed to be rather strong, high fliers that hovered over flowers in the tops of the trees before alighting, often on the terminal flower of a high branch. Adults were observed consuming the petals of the flowers but were never observed feeding on the foliage. After consuming all the petals of a flower, a process that required around 20-30 minutes, the adults moved off to adjacent foliage to groom themselves or rest. No adults were observed on flowers of any other plant species in this area, but Bellamy & Westcott (2000) later recorded both subspecies on flowers of Acacia angustissima (Fabaceae) and the nominate subspecies on flowers of Chilopsis linearis (Bignoniaceae).

My sincere thanks to Dan Heffern for giving me his single specimen of this gorgeous species.

REFERENCES:

Bellamy, C. L. 2008. World catalogue and bibliography of the jewel beetles (Coleoptera: Buprestoidea), Volume 2: Chrysochroinae: Sphenopterini through Buprestinae: Stigmoderini. Pensoft Series Faunistica 77: 632-1260.

Bellamy, C. L. and R. L. Westcott. 2000. The genus Hiperantha: subgenera, type species, unavailable names and the Mexican fauna (Coleoptera: Buprestidae). Folia Heyrovskyana 8(1):25-34.

Manley, G. V. 1985. Notes on the biology of Hyperantha interrogationis Klug (Coleoptera: Buprestidae). The Coleopterists Bulletin 39(1):16-17.

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Done with dung, meat please!

Christmas in January

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