The ever-increasing diversity of Oklahoma beetles

My idea to return to Oklahoma’s Gloss Mountains this spring actually began taking shape during last year’s fall visit to the area, when I found a single Chrysobothris octocola adult on a dead mesquite (Prosopis glandulosa) branch. While common across the southwestern U.S. in association with this plant, its occurrence in the Gloss Mountains represented a northeastern range extension and new state record for Oklahoma! On that same trip I also collected an interesting beetle in the family Rhipiphoridae representing the species Toposcopus wrightii—also not previously recorded in the literature from Oklahoma. Combined with finding Acmaeodera macra here the previous year, it was becoming clear to me that area held good potential for other more typically southwestern species of wood boring beetles. Although I had by then visited the area several times, most of these visits were more focused on tiger beetles rather than wood boring beetles. If I could find such interesting species of wood boring beetles when I wasn’t focused on them, imagine what I might find if I timed a visit in late spring when such species should be at their peak of adult activity.

Chrysobothris quadrilineata | Gloss Mountains State Park, Major Co., Oklahoma

Chrysobothris quadrilineata | Gloss Mountains State Park, Major Co., Oklahoma (new state record).

Of course, success came quickly during this early June visit. I immediately found C. octocola common on the mesquite and would collect a nice series of voucher specimens before the day was over, and the second species I encountered, also on mesquite, was the longhorned beetle Plionoma suturalis—another new state record! I spent a bit of time working the mesquite, and when I had collected a sufficient series of both species, I turned my attention to the eastern red-cedars (Juniperus virginiana) in the area. Actually, I had had my eye on the red-cedars since last fall, when I noticed that nearly every tree had dead branches mixed in amongst the living branches. Closer examination revealed the workings of jewel beetle larvae in all of these dead branches, and a few larvae typical of the genus Chrysobothris were cut from one of the branches. A common species in the Great Plains associated with Juniperus is C. ignicollis, but these larvae looked rather big to represent that species, so I bundled up some dead branches and brought them back home for rearing but forgot to check on them before I left on this trip. At any rate, I walked up to one of the red-cedars, placed my beating sheet under a dead branch, gave the branch a whack with the handle of my net, and onto the sheet fell a rather robust Chrysobothris that I didn’t immediately recognize. I knew it wasn’t C. ignicollis, a much smaller species that I have collected on numerous occasions, so I thought maybe it could be C. texana, another western Juniperus-associate that I’ve collected less commonly. Still, the robust body and broad, distinct elytral and pronotal ridges had me second guessing that identification (especially after I found some individuals that looked more like what I remembered C. texana looking like). Over the next two days I beat hundreds (literally!) of dead juniper branches, finding many C. ignicollis but every now and then getting also one of these big, robust individuals.

Chrysobothris quadrilineata

Adults were beaten from dead branches on live Juniperus virginiana (new adult host).

After returning home, I checked my heavily annotated copy of Fisher (1942) and quickly determined the robust specimens as representing C. quadrilineata—a rather uncommon species and one that I’d never collected before. Described by LeConte in 1860 from New Mexico and recorded early in the 20th century from Arizona, Nevada and California, it has in more recent years been found to occupy a rather wide distribution across the western U.S., including Texas (Barr & Westcott 1976), Colorado, Oregon, South Dakota (Nelson et al. 1982), and Utah (Nelson 1987). Notice one state that is not in that list—Oklahoma! That’s right, another new state record! I later found photographs of this species on BugGuide taken in the very same area a year earlier (7 June 2012).

Chrysobothris quadrilineata

Adults also emerged from dead J. virginiana branches collected Sept. 2012 (first reported larval host).

When I returned home, I also checked the rearing cans and found several adults had emerged from the branches I collected last September. The only host associations that have been recorded for this species are adults collected on Juniperus californica (Linsley & Ross 1940) and J. pachyphloea [= J. deppeana] (Barr & Westcott 1976). Thus, J. virginiana not only represents a new host record for the species but is also the first known larval host. Considering how broadly distributed across the western U.S. this species is, it seems likely that it utilizes a number of Juniperus spp. throughout its range.

REFERENCES:

Barr, W. F. & R. L. Westcott. 1976. Taxonomic, biological and distributional notes of North American Chrysobothris, with description of a new species from California (Coleoptera: Buprestidae).  The Pan-Pacific Entomologist 52(2):138–153.

Fisher, W. S. 1942. A revision of North American species of buprestid beetles belonging to the tribe Chrysobothrini. U. S. Department of Agriculture, Miscellaneous Publication 470, 1–275.

Linsley, E. G. & E. S. Ross. 1940. Records of some Coleoptera from the San Jacinto Mountains, California.  The Pan-Pacific Entomologist 16(2):75–76.

Nelson, G. H. 1987. Additional notes on the biology and distribution of Buprestidae (Coleoptera) in North America, II.   The Coleopterists Bulletin 41(1):57–65.

Nelson, G. H., D. S. Verity & R. L. Westcott. 1982. Additional notes on the biology and distribution of Buprestidae (Coleoptera) of North America.  The Coleopterists Bulletin 35(2) [1981]:129–152.

Copyright © Ted C. MacRae 2013

Plionoma suturalis in Oklahoma—a new state record!

When I returned from my vacation/insect collecting trip to western Oklahoma two weeks ago, most people upon learning where I went responded with a funny look that said, “Why would you want to go to Oklahoma?” Even entomologists familiar with my inclination for beetles merely assumed I went there to collect tiger beetles and were surprised to learn that, for this trip, I was actually targeting jewel beetles (family Buprestidae) and longhorned beetles (family Cerambycidae). Jewel beetles and longhorned beetles, of course, are largely associated with dead wood, and western Oklahoma is smack dab in the middle of the Great Plains. However, this does not mean that there are no trees in the area, or that whatever trees do exist are merely western examples of pedestrian eastern species with a depauperate beetle fauna. In fact, I came to this area precisely because previous visits had seemed to indicate high potential for interesting species of woodboring beetles. On my September 2011 visit, passing through on my way back from Colorado, I found several individuals of the unusual fall-active Acmaeodera macra (representing a northern range extension), and during last year’s fall visit I found a single Chrysobothris octocola adult on a dead mesquite (Prosopis glandulosa) branch—a northeastern range extension and new state record for Oklahoma! Interesting records for other species of beetles over the past few years also supported the idea that western Oklahoma was understudied and held the promise of more interesting new records for anyone willing to spend time in the area.

Plionoma suturalis (male) | Gloss Mountains, Major Co., Oklahoma

Plionoma suturalis (male) on mesquite (Prosopis glandulosa) | Gloss Mountains, Major Co., Oklahoma

Nearly all of these interesting records have been found in the Gloss Mountains, a fascinating system of gypsum capped, red clay mesas in Major Co. I now regard the Gloss Mountains State Park as my “portal” to northwestern Oklahoma and can’t imagine traveling to or through the area without stopping and spending time knocking around this fascinating, brick-red landscape. Such was the case during this year’s trip, and while I had decided to spend at least the first field day in and around the State Park, the collecting was so good that I stayed for a second day and returned for a third later in the week. The beetle shown in these photos is part (and only part) of the reason why. Arriving in the morning of the first day in the field, I headed straight for the mesquite tree on which I had found the C. octocola adult last fall. It’s a common species in the southwestern U.S. that normally wouldn’t warrant any special attention, but since the Oklahoma record was based on a single specimen I wanted to see if I could find additional individuals to confirm that the species was actually established in the area and that last year’s record wasn’t just a one-off. I whacked a dead branch, and onto my beating sheet fell a C. octocola adult! I whacked another dead branch, and off fell another adult! As it was, I would find the species as abundantly here, in strict association with mesquite, as I have seen it at other locations further to the southwest. Soon after collecting the first few C. octocola adults, however, I whacked a live branch on the same mesquite tree, and off fell two large, colorful longhorned beetles that I recognized instantly as representing the species Plionoma suturalis.

Plionoma suturalis (female) | Gloss Mountains, Major Co., Oklahoma

Plionoma suturalis (female) on mesquite flowers | Gloss Mountains, Major Co., Oklahoma

Plionoma suturalis belongs to the great tribe Trachyderini. Beetles in this tribe are known for the bright colors, attraction to flowers, and diurnal (day-active) tendencies, and while we have a few species in the eastern U.S. they are far more diverse in the southwestern states. Plionoma suturalis and another U.S. species (P. rubens) are known to occur from Texas west to California and south into northern Mexico, but I immediately had the feeling that finding this species in Oklahoma was a significant record. The beetles were abundant on the mesquite trees that lined the parking lot and dotted to landscape below the main mesa, with many observed feeding on the flowers (the trees were in full bloom) and numerous mating pairs also observed. Considering its abundance at the site and possible significance of the record, I collected several dozen specimens to serve as vouchers (not to mention I had only collected a handful of specimens in all of my previous years of collecting). Checking my database later that evening (I never leave home without my computer!) confirmed my suspicions—Oklahoma was not only a new state record, but a significant northeastern range extension. In fact, the closest previous record was by Lingafelter & Horner (1993), who recorded eight specimens from Wichita Co., Texas—just over 200 miles to the south! Further, the Wichita Co. specimens were all collected in 1956, and subsequent collecting had yielded no additional specimens, leading the authors to consider the status of this species in north-central Texas as doubtful.

The female feeds on flowers of mesquite (Prosopis glandulosa)

Large number of individuals were seen feeding on mesquite flowers.

Plionoma suturalis is one of only a handful of North American longhorned beetle species in which the adults exhibit bimodal seasonal activity, with adults appearing during the spring months, disappearing during the summer, and reappearing in the fall (see  for a previous example from Missouri) (Linsley 1962). In the Lower Rio Grande Valley of south Texas (where the activity of many species of longhorned beetles and other insects is distinctly bimodal to coincide with moderate temperatures and increased precipitation during spring and fall), this species has been found on fresh-cut mesquite and huisache (Acacia farnesiana) in the fall months and on the blossoms of fabaceous trees during spring and early summer (Hovore et al. 1987).

REFERENCES:

Hovore, F. T., R. L. Penrose & R. W. Neck. 1987. The Cerambycidae or longhorned beetles of Southern Texas: a faunal survey. Proceedings of the California Academy of Science 44(13):283–334, 20 figs.

Lingafelter, S. W. & N. V. Horner. 1993. The Cerambycidae of north-central Texas. The Coleopterists Bulletin 47(2):159–191, 7 figs.

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.

Copyright © Ted C. MacRae 2013

Why are this beetle’s elytra outstretched?

Toposcopus wrightii on dead branch Juniperus virginiana | Major Co., Oklahoma

I’ve puzzled over the beetle in the above photo since I first saw it back in September on Day 2 of this year’s Annual Fall Tiger Beetle Trip. I encountered it on a dead branch of eastern red-cedar (Juniperus virginiana) on top of the main mesa at Gloss Mountain State Park in northwestern Oklahoma. At about 8 mm in length, it immediately struck me as possibly something in the family Ripiphoridae (wedge-shaped beetles). Still, the full-length elytra covering the abdomen made me doubt that identification, so I collected the specimen to get a better look at it when I returned home. Later that same day, while scanning the base of another mesa across the highway from the park at night, I came upon another individual that seemed to represent the same species—this time on a dead branch of fragrant sumac (Rhus aromatica). That individual is seen in the photo below, and two things are immediately apparent: 1) the beetle is a female in the act of oviposition, and 2) it is holding its elytra outstretched in a most curious way.

Another female oviposits on a dead branch of Rhus aromatica.

A quick browse through BugGuide’s ripiphorid images quickly showed a likely match with the genus Toposcopus, and consulting the original description of both the genus and its only included species—T. wrightii (LeConte 1868) showed agreement with the key diagnostic character (eyes divided into two lobes connected by a slender line of smooth, non-faceted corneous membrane). These two females differ from the male by their much less flabellate antennae (presumably the male uses these organs to detect female-emitted pheromones). LeConte described this species from New Mexico, and Rivnay (1929) also saw specimens from Texas and Arizona when he reviewed the North and Central American species of the family. Although the species is listed on Don Arnold’s Checklist of the Coleoptera of Oklahoma, the listing seems to be based only on the presence of specimens in the Oklahoma State University insect collection, while published records of its occurrence in the state are, as far as I can tell, still lacking. This species, thus, seems to be, along with Acmaeodera macra and Chrysobothris octocola (both family Buprestidae), an example of a typically southwestern U.S. species whose distribution extends northeast into the Red Hills Region of northwestern Oklahoma. Considering that Cylindera celeripes (Swift Tiger Beetle) and Amblycheila cylindriformis (Great Plains Giant Tiger Beetle) also have only recently been discovered in this area, it would seem that this part of the state is still undersampled and has the potential to yield additional interesting southwestern U.S. species.

Why is this female holding her elytra outstretched while ovipositing?

Regarding the outstretched elytra, I’ve not seen this type of behavior before with a beetle in the act of oviposition. While several groups of insects in other orders may hold their forewings outstretched as part of threat displays, I’ve not seen a beetle hold its elytra outstretched for any reason at all other than flight and don’t recall seeing such behavior mentioned in the literature either. Thus, I’m at a loss to explain why the beetle is doing this. If you have any ideas I would love to hear them.

One thing that I enjoy immensely about 19th Century taxonomic literature is the rich, often effusive prose that frequently accompanies the descriptive portions of the text. (I also lament that such colorful writings are nearly universally frowned upon my modern editors. Perhaps as taxonomy advances more fully into electronic-only publishing the concerns about space will dissipate and taxonomic authors will no longer be constrained to such sterile, uniform, precisely formatted writings.) The naming of this species provides an especially colorful example of the embellishments permitted to 19th Century authors:

I desire in the name of this beautiful and interesting addition to our fauna, to commemorate the ability of Gen. W. W. Wright, the Chief Engineer and Commander of the Survey in which the species in the present memoir were collected. His attention to the comfort and safety of the party while traveling through a hostile Indian country will not soon be forgotten by any of his companions; while the skill with which the more difficult portions of the route were examined, and the labors of his assistants directed to the most easy methods of surmounting the difficulties, will commend itself to every admirer of correct engineering.

John L. LeConte is widely regarded as the father of North American coleopterology. I don’t think there is anybody from the 19th Century, save perhaps Charles Darwin, that I would have more liked to meet.

REFERENCES: 

LeConte, J. L. 1868. New Coleoptera collected on the survey for the extension of the Union Pacific Railway, E. D. from Kansas to Fort Craig, New Mexico. Transactions of the American Entomological Society 2:49–59.

Rivnay, E. 1929. Revision of the Rhipiphoridae of North and Central America (Coleoptera). Memoirs of the American Entomological Society 6:1–67, 3 plates.

Copyright © Ted C. MacRae 2012

Just repanda… er, wait a minute…

Update 10/7/12, 10:41 a.m.—Thanks to Ben Coulter, who pointed out my rather silly misidentification of these beetles that actually represent Cicindelidia ocellata rectilatera (Reticulated Tiger Beetle). I have only my failure to even consider the possibility of a southwestern species to blame for the error, as the evidence was staring me right in the face (the lack of any trace of lateral connecting band and, most obviously, the reddish parts on the underside). No wonder the habitat didn’t seem quite right! I was not aware of the occurrence of this species east of Texas, so I’ll have to dig a little bit to see if this is an unusual record. Pearson et al. (2006) show the northeastern limit of distribution coming very close to but not actually reaching the southwestern corner of Arkansas, and the closest records given by Graves & Pearson (1973) are in western Louisiana and adjoining Texas. It would be immensely rewarding should this turn out to be a new state record (though there are many sources still to check to confirm this)—not to mention the irony of it in view of the post title (call it a double “er, wait a minute”!). At any rate, I should have been a lot more excited when I saw it than I was.

After a fun-filled day of photographing the Limestone Tiger Beetle in northern Texas, it was time to start working my way back to Missouri. I had one last goal that I wanted to accomplish before spending my last day in our state’s White River Hills, and that was to find and photograph the unbelievably gorgeous Cicindela formosa pigmentosignata. Dubbed the “Reddish-green Sand Tiger Beetle” by Erwin & Pearson (2008), this brilliant violaceous and nearly immaculate subspecies of the Big Sand Tiger Beetle is restricted to sandy areas of open pine forests in eastern Texas, southwestern Arkansas, and northwestern Louisiana (Pearson et al. 2006). I had a few specific localities that I’d gleaned from colleagues and the literature and targeted the two “best” (specificity of location, recent occurrence, and reasonably “on the way” back to Missouri) for Day 7 of the trip. The first site in Texas looked perfect—deep, dry sandy 2-tracks leading through open pine/oak forest, and I was actually surprised when I’d searched a mile or so of track and hadn’t yet seen one (the habitat just looked that good). Still, I spent quite a bit more time searching, thinking that numbers could be low and it might take such an effort. Sadly this was all in vain, and the time came to give up and try again at the second locality in Arkansas. The story was largely the same at this second locality also, and by late afternoon I had come to accept that this was one challenge that I was going to lose (for now at least).

Cicindela duodecimguttata Cicindelidia ocellata rectilatera | Nevada Co., Arkansas

As I searched one bit of potential habitat at the Arkansas location, I noted the presence of Cicindela repanda (Bronzed Tiger Beetle). This species is dreadfully common throughout much of the eastern U.S. in just about any near-water habitat, which told me I was probably too close to water to find the higher, drier-ground preferring Big Sand Tigers. I’ve seen millions of C. repanda through the years (this may not be an exaggeration), and since they show so little polytopism (geographically-based variation), at least in the parts of its distribution that I have visited, I hardly pay them mind anymore. As I was walking, however, something caused me to take a closer look—some of them didn’t seem quite “right.” Of course, you can’t just walk up to a tiger beetle and stoop down for a good look at it. Stalking is required, usually of several individuals before finding one that you can approach closely enough to see the necessary characters, and when I did this I realized most of the C.repanda” I was seeing were actually a different species—Cicindela duodecimguttata (12-spotted Tiger Beetle)!

Even tiger beetles get bored during sex—this female preening her antennae seems oblivious to the male engaging her.

I get the impression from literature sources that 12-spotted Tiger Beetles are quite common further east, especially in the northeastern U.S. and southeastern Canada. However, here in the central U.S. they are not commonly encountered. In fact, these are the first of the species that I have seen since I began photographing tiger beetles more than 3 years ago. In Missouri the few instances that I have seen them were along creeks and small rivers with banks composed of sand and a fair bit of dark clay. This makes sense, given their generally darker coloration compared to Bronzed Tiger Beetles, and it is this character that first stands out amongst the hoardes of C. repanda with which it usually co-occurs.  Once the darker coloration draws the eye, the markings of the elytra—reduced and broken into six spots (usually) on each one—confirm its identity. Despite the similarity of appearance to C. repanda, this species is actually more closely related to Cicindela oregona (Western Tiger Beetle), an exceedingly common species found from the Rocky Mountains to the Pacific Coast and north deep into Alaska. In fact, the two species are so closely that they have formed a hybrid zone where they come into contact along the front range of the Rockies—one could almost argue that they are only subspecifically distinct because of this. 

A male pauses briefly while hunting for prey (or mates).

That I found them in this particular habitat was a bit of a surprise to me. I mentioned that in Missouri I’ve seen them on darker creek and river banks, but the creek bank at this location was quite lightly colored and seemed to consist almost entirely of sand. There were a few C. repanda mixed in with this small population. In all, it was a welcome consolation prize that made up for not finding C. formosa pigmentosignata—sort of!

Habitat for Cicindela duodecimguttata Cicindelidia ocellata rectilatera along Mill Creek, Nevada Co., Arkansas.

REFERENCES:

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.

Added: Graves, R. L. & D. L. Pearson. 1973. The tiger beetles of Arkansas, Louisiana, and Mississippi (Coleoptera: Cicindelidae). Transactions of the American Entomological Society 99(2):157–203.

Added: Pensoft

Copyright © Ted C. MacRae 2012

Josef Knull was wrong!

A few weeks ago I received an email from Kyle Schnepp, an entomology student at Purdue University.  Kyle has taken on the rather ambitious project of developing an illustrated key to the Buprestidae of eastern North America, for which he has been spending the past year acquiring material for photographs.

During his examination of specimens in the Field Museum of Natural History, Kyle came across two examples of an extraordinarily rare species of Buprestidae, Agrilus audax Horn.  Although described more than 100 years ago from specimens collected in Texas (Horn 1891), few records have been published in the years since.  Chamberlin (1926) reported the species also from Arizona and Illinois but without further details, causing Fisher (1928), in his revision of the genus (woefully out-of-date now, but still the only comprehensive resource for identifying the North American species), to regard at least the Illinois record as probably erroneous (common for many of Chamberlin’s records).  The first undisputed report of this species from outside of Texas was by Josef Knull (1934), who reported the species emerging from living, wind-thrown branches of slippery elm (Ulmus rubra) collected in western Missouri.  More than half a century would pass before the species would turn up again – first in Oklahoma (Nelson and MacRae 1990) and twice again in Missouri through the efforts of Gayle Nelson and myself (MacRae 1991, MacRae and Nelson 2003). All but one of these specimens were beaten from bur oak (Quercus macrocarpa).

Agrilus audax Horn, 1891 – male (L) and female (R)

While the rarity of this species makes Kyle’s find significant enough, there is an even more significant – and interesting – aspect to his discovery.  Both of the specimens, one male and one female, were collected in Ohio, which is a rather extraordinary geographical range extension. Additionally, the specimens were collected by none other than Josef Knull.  To students of North American Buprestidae, the name Josef Knull is as familiar as Carl Linnaeus, Charles Darwin, or Thomas Say. A Professor of Entomology at The Ohio State University from 1934-1962, Knull published nearly 200 papers on the taxonomy, biology, and distribution of these and other families of beetles (Davidson and Bellamy 2002).  Although he lacked a Ph.D., he was an indefatigable collector and describer of beetles – to his fellow colleagues and students, he was known as “Professor” or “Doctor” as a show of respect.  He spent many of his summers traveling through the southwestern U.S. with his wife Dorothy Knull (herself an entomologist specializing in leafhoppers), and by the time he died in 1975 he had described 233 species and subspecies of beetles (as well as one species of Fulgoridae).  He was, and is, an icon among North American beetle collectors.

Curiously, Knull did not recognize these specimens for what they were, instead identifying them as the similar and much more widespread species, Agrilus vittaticollis.  Curious, because Knull collected these specimens in 1949 and 1953 – after first reporting the species in Missouri.  Agrilus audax belongs to a small group of species that look very similar to each other by way of their large size and striking coloration – black elytra and a red pronotum with a densely pubescent median channel.  Agrilus vittaticollis is the most common of these (though still not as commonly encountered as many other species in the genus), and the much less common A. benjamini also belongs to this group.  Kyle had sent me the above photo in an attempt to confirm their identity, but true confirmation would require examination of characters of the face and ventral surface.  Kyle quickly took additional photographs of these characters and sent them to me – they are shown below and leave no doubt as to the identity of these specimens.

Agrilus vittaticollis prosternum – note sides bent downward to sharp points.

Agrilus audax prosternum – sides normal, not bent downward to sharp points.


Agrilus audax frons is moderately depressed and uniformly pubescent (deeply depressed & pubescent only on lower half in A. benjamini).

Agrilus audax male sternite – the deep, smooth, elongate depression is diagnostic (A. benjamini males have only an obsolete depression).


Finding a new state record buprestid in Ohio – the land of Knull – based on specimens collected by Knull himself is nothing short of remarkable (almost like proving E. O. Wilson wrong¹). The occurrence of A. audax in Ohio also lends some credibility to Chamberlin’s record of the species in Illinois. Kyle is graciously allowing me to include these new records in a forthcoming publication; my thanks to him for this and also for allowing me to use his fine photographs in this post.  Kyle did also mention that these were the only misidentified specimens he saw in the Knull collection at the Field Museum of Natural History. For those interested in acquiring reprints of Knull’s papers, pdfs of the 50 papers he published in the Ohio Journal of Science may be found at this link.

¹ The title of this post is a play on the title of a recent post by Alex Wild at Myrmecos. No true disrespect is intended to Josef Knull, who’s legacy (with the possible exception of his frustratingly vague label data) is rightfully held in high regard by all who knew him or know of his work.

REFERENCES:

Chamberlin, W. J. 1926. The Buprestidae of North America, exclusive of Mexico, a catalogue including synonymy, bibliography, distribution, type locality and hosts of each species. W. J. Chamberlin, Corvallis.

Davidson, J. M., and C. L. Bellamy.  2002. The entomological contributions of Josef Nissley Knull (1891-1975).  Zootaxa 37:1-24.

Horn, G. H. 1891. The species of Agrilus of Boreal America. Transactions of the American Entomological Society 18:277-366.

Knull, J. N. 1934. Notes on Coleoptera, No. 4. Entomological News 45(10):207-212.

MacRae, T. C. 1991. The Buprestidae (Coleoptera) of Missouri. Insecta Mundi 5(2):101–126.

MacRae, T. C., and G. H. Nelson. 2003. Distributional and biological notes on Buprestidae (Coleoptera) in North and Central America and the West Indies, with validation of one species. The Coleopterists Bulletin 57(1):57–70.

Nelson, G. H., and T. C. MacRae. 1990. Additional notes on the biology and distribution of Buprestidae (Coleoptera) in North America, III. The Coleopterists Bulletin 44(3):349–354.

Copyright © Ted C. MacRae 2010

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North America’s largest robber fly

Female Microstylum morosum perched on fragrant sumac (Rhus aromatica) bush

Female Microstylum morosum perched on fragrant sumac (Rhus aromatica)

A few days ago, I featured Promachus hinei, one of the so-called “giant robber flies” and a common inhabitant of the glades and grasslands that dot Missouri’s largely forested landscape. That individual was seen at Long Bald Glade Natural Area in Caney Mountain Conservation Area, one of the many limestone glades that are a prominent feature of extreme southwestern Missouri’s White River Hills, as it snacked on a small carpenter bee (Ceratina sp.) and posed obligingly for a series of super close-up photographs. Promachus and its congeners are impressively large; however, I would see an even larger robber fly that day. I didn’t know what it was at the time, but I knew that never before had I seen such a magnificent fly, with its large, shimmering, emerald eyes, streamlined body almost devoid of setae (hairs), and ludicrously large size. These monsters were actually quite common at the glade, so I failed to appreciate the significance of what I was seeing as I chased one after another – more intent on securing photographs than specimens. This was not an easy task – they were extremely wary, rarely allowing me to approach within 12 feet no matter how cautiously and slowly I moved. Not one to back down from such a challenge (remember, I stalk tiger beetles), I persisted, traversing the rough, rock-strewn terrain amidst clumps of big bluestem (Andropogon gerardii), Indian grass (Sorghastrum nutans), and fragrant sumac (Rhus aromatica) until, at last, I got within striking distance of the impressive female shown in these photos. Taking flight before I felt assured of a good shot, I followed her repeated long, loping escape flights until I was able to get another few shots and she disappeared for good.

Same individual as in previous photo after flying to another perch.

Same individual as in previous photo after flying to another perch.

It didn’t take long after I returned home to figure out what I had seen, as there is really nothing that can be mistaken for Microstylum morosum, North America’s largest robber fly (Back 1909)¹. At 35–40 mm of length, this individual didn’t quite match the astounding 50-mm upper body length for the species (that’s 2 inches, folks!). Nonetheless, it was an impressive beast indeed! It is not surprising that North America’s largest robber fly should be a species of Microstylum, as it is this same genus that contains the world’s largest robber fly – the aptly named M. magnum from Madagascar, with a body length of 60 mm and an almost preposterous wingspan of up to 84 mm (that’s over 3 inches folks!). I don’t know if any flies exist that are larger than this, but certainly none can be more imposing.  While I’m happy with the photos that I did obtain, I must confess some disappointment that I wasn’t able to get more than these basic lateral profile shots.  Of the several photographs of this species that can be found on the web, this female, photographed by Greg Lavaty of Houston, Texas, is (in my humble opinion) certainly the most stunning.

¹ Puzzled by the use of the prefix “micro” in the genus name – hardly seeming appropriate for such an enormous fly – I asked Eric Fisher (retired, California Department of Food and Agriculture) about the name’s derivation, to which he replied, “The name refers to the quite small ‘stylus’ of the antenna apex; Macquart specifically mentions this character in his 1838 original description of the genus. (This is not a very helpful diagnostic character, as many asilids share this feature…).”

Even more significant than its size, however, was its very occurrence on this glade. Like Ospriocerus abdominalis, which I had seen just a few weeks earlier in the Loess Hills of extreme northwestern Missouri, M. morosum is a denizen of the Great Plains, and also like that species it has until now not been known from Missouri. That’s right – another new state record!  Unlike O. abdominalis, however, the Missouri occurrence of M. morosus represents a significant northeastern extension of its known range.  The species was long considered a Texas endemic until Beckemeyer and Charlton (2000) confirmed its occurrence in southeastern Arizona and documented significant range extensions into Oklahoma, Kansas, extreme southeastern Colorado, and extreme northeastern New Mexico.  Its eastern distributional limit was thought to occur along a north-south line from Douglas County, Kansas to Mayes County, Oklahoma to Brazoria County, Texas; however, Warriner (2004) documented its occurrence some 200 miles east of this line in the blackland prairies of southwestern Arkansas.  The occurrence of M. morosum in the White River Hills of Missouri represents yet another significant eastern extension of its known range – Long Bald Glade lies 185 miles NNE of the collection site in Arkansas and 155 miles ENE of the nearest known record in Mayes County, Oklahoma (Locust Grove), making it the easternmost known locality for this species.

As in Arkansas, where the collection site represents one of the highest quality blackland prairie remants in the state, Long Bald Glade represents a high quality remnant of the limestone glades that once occurrred much more extensively within Missouri’s White River Hills.  Like the blackland prairie of Arkansas, the limestone glades of the White River Hills have been dramatically reduced since EuroAmerican settlement due to land use conversion, and fire suppression and overgrazing of the remaining tracts have resulted in significant woody encroachment – chiefly by eastern red-cedar (Juniperus virginiana) – and loss of vegetational diversity. This has caused dramatic reductions in populations of the many Great Plains plant and animal species that are found here and nowhere else in the state.  Considering the overall distribution of M. morosum, it is unlikely that it occurs more extensively within Missouri than the White River Hills, emphasizing the importance of continued conservation and restoration activities in this unique part of Missouri.  However, since the White River Hills extend into northwestern Arkansas, M. morosum may occur in that part of Arkansas as well as the southwestern part of the state.

I thank Eric Fisher and Herschel Raney for confirming the identity of this species and its status as a new record for Missouri.

Photo details: Canon 100mm macro lens on Canon EOS 50D (manual mode), ISO-100, 1/250 sec, f/10-11, MT-24EX flash 1/2 power through diffuser caps.

REFERENCES:

Back, E. A. 1909. The robberflies of America, north of Mexico, belonging to the subfamilies Leptograstrinae and Dasypogoninae. Transactions of the American Entomological Society 35:137–400.

Beckemeyer, R. J. and R. E. Carlton.  2000.  Distribution of Microstylum morosum and M. galactoides (Diptera: Asilidae): significant extensions to previously reported ranges.  Entomological News 111(2):84–96.

Warriner, M. D.  2004.  First Arkansas record of the robber fly Microstylum morosum (Diptera: Asilidae).  The Southwestern Naturalist 49(1):83–84.

Copyright © Ted C. MacRae 2009

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Ospriocerus abdominalis

Photo details: Canon 100mm macro lens on Canon EOS 50D, ISO 100, 1/250 sec, f/14, MT-24EX flash 1/4 power w/ diffuser caps.

Photo details: Canon 100mm macro lens on Canon EOS 50D, ISO 100, 1/250 sec, f/14, MT-24EX flash 1/4 power w/ diffuser caps.

My dipteran digression continues with this photograph of the robber fly, Ospriocerus abdominalis (Diptera: Asilidae).  More than just a pretty picture, this represents yet another apparently new state record that I and my colleague Chris Brown discovered a few weeks ago during our 2-day survey of Missouri’s critically imperiled hilltop prairies in the extreme northwest corner of the state.  Like the previously discussed Cylindera celeripes (swift tiger beetle) and Beameria venosa (a prairie-obligate species of cicada), O. abdominalis has not previously been recorded further east than Nebraska, Kansas, Oklahoma and Texas. This large fly is a grassland denizen that ranges over western North America and into Mexico (Cannings 1998, as Ospriocerus aeacus). It is somewhat suggestive of a mydas fly, although its short antennae immediately identify it as a robber fly (mydas flies have elongate clubbed antennae).  It also reminds me of the magnificent western robber fly Wyliea mydas by its mimetic, wasp-like coloration – presumably modeled after spider wasps of the genus Pepsis and Hemipepsis (Hymenoptera: Pompilidae) – but is distinguished by its black body and wings with red dorsal coloration on the abdomen (W. mydas has the abdomen wholly black and the wings red).  While not quite as handsome as W. mydas, it is impressive nonetheless.

The dry hilltop prairie remnants in which O. abdominalis, B. venosa, and C. celeripes were found are associated with the Loess Hills, a unique landform along the western edge of Iowa that reaches its southern terminus in extreme northwest Missouri.  Due to their extreme rarity and vulnerability to woody encroachment and anthropogenic degradation, these remnant habitats are considered one of Missouri’s most critically imperiled natural communities. Only about 50 acres of original habitat remain, and of this only half is in public conservation ownership.  Many of the plants and animals found in these habitats represent hypsithermal relicts that migrated eastward during a dry and warm period after the last ice age and were then “left behind” in pockets of relictual habitat as a return to cooler, wetter conditions forced the main populations back to the west.  More than a dozen plants and two vertebrates occurring in these prairies are listed as species of conservation concern.  As is typically the case, the flora and vertebrate fauna of these remnant habitats have been fairly well characterized, while precious little attention has been given to the vastly more diverse invertebrate fauna.  As we begin to study the insects of these habitats more carefully, we are almost sure to find a great many species that are more typically found further to the west and that live nowhere else in Missouri.  Their continued presence in the state will be wholly dependent upon the critically imperiled habitats in which they live, making conservation and restoration of the remaining loess hilltop prairie remnants in Missouri all the more important.

My thanks to Eric Fisher and Herschel Raney for confirming the identity of O. abdominalis.

REFERENCES:

Cannings, R. A. 1998. Robber Flies (Insecta: Diptera: Asilidae), in Smith, I. M., and G. G. E. Scudder, eds. Assessment of species diversity in the Montane Cordillera Ecozone. Burlington: Ecological Monitoring and Assessment Network.

Copyright © Ted C. MacRae 2009

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North America’s smallest cicada

Photo details: Canon 100mm macro lens on Canon EOS 50D, ISO 100, 1/250 sec, f/18, MT-24EX flash 1/2 power w/ diffuser caps.

Photo details: Canon 100mm macro lens on Canon EOS 50D, ISO 100, 1/250 sec, f/18, MT-24EX flash 1/2 power w/ diffuser caps.

While searching the hilltop prairies for Cylindera celeripes (swift tiger beetle) at McCormack Loess Mounds Natural Area in northwestern Missouri, I ran across a species of cicada that I’d not yet encountered in the state – Beameria venosa.  Cicadas as a rule are quite large insects, but with a body measuring only 16 mm (well under an inch) in length, B. venosa is one of – if not the – smallest species of this group in all of North America.  Had it not been for its distinctly cicada-esque call I might have thought it was some sort of fulgoroid planthopper (albeit a rather large one).  But a cicada it is, and a beautiful one at that despite its small size.

Beameria venosa is a prairie obligate species occurring from Nebraska and Colorado south to Texas and New Mexico.  To my knowledge, it has not been formally recorded from Missouri, although it is certainly already known from the state (it is listed in the 2009 issue of Missouri Species and Communities of Conservation Concern Checklist as “vulnerable” due to the restricted occurrence in Missouri of the prairie habitats in which it lives).  Froeschner (1952) listed 14 species of cicadas from Missouri but did not include this species even among those of possible occurrence in the state.  In my younger days, I managed not only to find all 14 of those species, but also a fifteenth species – the magnificent Tibicen superbus – in the southwestern corner of the state (formally recorded from the state some years later by Sanborn and Phillips 2004).  The occurrence of B. venosa in Missouri now brings to 16 the number of cicada species known from Missouri.

Despite its small size, the calling song of B. venosa is quite audible.  In fact, it was only due to its call that I noticed and began looking for this individual.  This brings up an interesting point regarding conspicuous insect songs and their role in enhancing predation risk.  Many predators are known to orient to the calls of cicadas (Soper et al. 1976), which in turn exhibit a variety of predator avoidance behaviors such as high perching, hiding, fleeing, and perhaps even mass emergence in the periodical cicadas.  Beameria venosa appears to avoid predators by producing its continuous train of sound pulses at a very high frequency.  Although audible to humans, the high frequency call apparently is not audible to birds and lizards – their chief predators (Sanborn et al. 2009).  In the open, treeless prairies where B. venosa lives, high frequency calling appears to provide the selective advantage for predator avoidance that fleeing, hiding, and high perching cannot.

REFERENCES:

Froeschner, R. C.  1952. A synopsis of the Cicadidae of Missouri. Journal of the New York Entomological Society 60:1–14.

Sanborn, A. F., J. E. Heath and M. S. Heath.  2009.  Long-range sound distribution and the calling song of the cicada Beameria venosa (Uhler) (Hemiptera: Cicadidae).  The Southwestern Naturalist 54(1):24-30.

Sanborn, A. F. and P. K. Phillips.  2004.  Neotype and allotype description of Tibicen superbus (Hemiptera: Cicadomorpha: Cicadidae) with description of its biogeography and calling song.  Annals of the Entomological Society of America 97(4):647-652.

Soper, R. S., G. E. Shewell and D. Tyrrell. 1976. Colcondamyia auditrix nov. sp. (Diptera; Sarcophagidae), a parasite which is attracted by the mating song of its host, Okanagana rimosa (Homoptera: Cicadidae).  The Canadian Entomologist 108:61-68.

Copyright © Ted C. MacRae 2009

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