Hitchin’ A Ride

May 10, 2010October 10, 2011 / Ted C. MacRae / 17 Comments

One of the more common species of longhorned beetles (family Cerambycidae) in Missouri, and throughout the eastern U.S., is Stenosphenus notatus. Despite its commonness, however, it is a species that is easily overlooked because of its very early seasonality, emerging during the first warm days of spring (late March here in Missouri) and disappearing by the time the bulk of longhorned beetle species become active during late spring and early summer. I found this individual on a recently fallen mockernut hickory (Carya alba) during the 2nd week of April, as Rich and I hiked the lower portion of the Wappapello Section of the Ozark Trail in southern Missouri (along with several other wood boring beetles species such as Dicerca lurida, Megacyllene caryae, and the woodboring beetle predator Enoclerus ichneumoneus). Longhorned beetles display a variety of host fidelities, ranging from highly polyphagous to strictly monophagous – this species falls near though not quite at the latter end of the spectrum, being associated almost exclusively with the genus Carya (hickories and pecan). I have reared adults from dead branches and trunk sections of not only C. alba, but also C. aquatica (water hickory), C. laciniosa (shellbark hickory), and C. ovata (shagbark hickory) (MacRae 1994, MacRae and Rice 2007). Linsley (1963) also records Celtis (hackberry) as a host, but I have not seen the species myself in association with plants of that genus, nor have I seen other literature references to such – I suspect this may, in fact, be an incidental adult association rather than indicative of a true larval host (an all too common problem in interpreting literature on woodboring beetle host plants).

The very early spring occurrence of this insect can be traced to a peculiarity of its life cycle shared by few other cerambycid species in the eastern U.S. – overwintering in the adult stage. Most eastern U.S. longhorned beetles overwinter within the host wood as either partially or completely grown larvae. Warming temperatures in the spring trigger resumption of growth in the former and a transformation to the pupal stage in the latter, which emerge as adults a few weeks later during mid-late spring. In contrast, S. notatus – which requires two seasons to complete its development – pupates in the latter part of the second season and transforms into the adult before the onset of winter. When warm temperatures return in spring, the adults are ready to emerge and search out fresh hickory wood that has died within the past few months on which to lay their eggs and begin the cycle anew.

As I photographed this individual, I noticed an object attached to its left mesothoracic (middle) leg. Zooming in on the object showed it to be a pseudoscorpion – a type of arachnid (relative of spiders, mites, and true scorpions) in the order Pseudoscorpiones. I have not the resources nor the expertise to attempt a more specific ID, but its attachment to the beetle almost surely represents an example of phoresy – defined as a phenomenon in which “one animal seeks out and attaches to the outer surface of another animal for a limited time during which the attached animal (termed the phoretic) ceases feeding and ontogenesis, such attachment presumably resulting in dispersal from areas unsuitable for further development, either of the individual or its progeny” (Farish and Axtell 1971). Pseudoscorpions have been reported attached to insects from several orders, primarily Diptera but also beetles and including longhorned beetles (Perry et al. 1974, Haack and Wilkinson 1987). Many species of pseudoscorpions develop beneath the bark of dead trees and prey upon the many other small insects and mites found there, and it would be reasonable to presume that their most effective means of dispersal to new habitats (i.e., dead trees) would be by “hitching a ride” with adult woodboring beetles as they emerge and fly to these new sites. As obvious as this explanation might seem, few data have actually been generated to demonstrate it is actually the case, and several competing hypotheses such as accidental boarding (hitching a ride by accident), obligate symbiosis (the pseudoscorpions live exclusively on the beetles), and phagophily (preying upon other beetle associates such as mites) have been offered as alternative explanations. However, at least one fairly recent investigation on the pseudoscorpion, Cordylochernes scorpioides, a frequent inhabitant under the elytra of the giant harlequin beetle, Acrocinus longimanus (family Cerambycidae), does seem to not only support the dispersal hypothesis, but also suggests that large male C. scorpioides even defend a beetle’s abdomen as a strategic site for intercepting and inseminating dispersing females (Zeh and Zeh 1992).

REFERENCES:

Farish, D. J. and R. C. Axtell. 1971. Phoresy redefined and examined in Macrocheles muscaedomesticae (Acarina: Macrochelidae). Acarologia 13:1629.

Haack, R. A. and R. C. Wilkinson. 1987. Phoresy by Dendrochernes Pseudoscorpions on Cerambycidae (Coleoptera) and Aulacidae (Hymenoptera) in Florida. American Midland Naturalist 117(2):369–373.

Linsley, E. G. 1963. The Cerambycidae of North America. Part IV. Taxonomy and classification of the subfamily Cerambycinae, tribes Elaphidionini through Rhinotragini. University of California Publicatons in Entomology 21:1–165, 52 figs.

MacRae, T. C. 1994. Annotated checklist of the longhorned beetles (Coleoptera: Cerambycidae and Disteniidae) known to occur in Missouri. Insecta Mundi 7(4) (1993):223–252.

MacRae, T. C. and M. E. Rice. 2007. Distributional and biological observations on North American Cerambycidae (Coleoptera). The Coleopterists Bulletin 61(2):227–263.

Perry, R. H., R. W. Surdick and D. M. Anderson. 1974. Observations on the biology, ecology, behavior, and larvae of Dryobius sexnotatus Linsley (Coleoptera: Cerambycidae). The Coleopterists Bulletin 28(4):169–176.

Zeh, D. W. and J. A. Zeh. 1992. On the function of harlequin beetle-riding in the pseudoscorpion, Cordylochernes scorpiones (Pseudoscorpionida: Chernetidae). Journal of Arachnology 20: 47–51.

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Friday Flower – Pawpaw

May 7, 2010October 10, 2011 / Ted C. MacRae / 28 Comments

As my friend Rich and I stood in the verdent understory admiring the spectacular panicles of red buckeye punctuating the green lushness, a small brown flower on a leafless branch above me caught my eye. “Pawpaw!” I exclaimed, perhaps partly in amazement that it took us awhile to notice the trees that were, in fact, all around us. Pawpaw (Asimina triloba) is a member of the only temperate genus in the otherwise exclusively tropical and subtropical family Annonaceae (Custard Apple Family). Although not nearly as restricted in occurrence in Missouri as the red buckeyes with which they were growing, they are nevertheless always a treat to see. Scattered throughout the state, they can be found growing in bottomland forests, ravines in mesic upland forests, along woodland streams, and at bases of bluffs (Yatskievych 2006).

Pawpaws are, of course, famous for their large edible fruits, sometimes called Indian bananas, Missouri bananas, Michigan bananas, [insert eastern state here] bananas, etc. Technically, however, the pawpaw fruit is a berry, since it is derived from a single pistil and has multiple seeds embedded within the pulpy matrix. I’ve not tried the fruit myself, not for lack of desire but rather an inability to find them when they ripen in fall before the birds and mammals get to them. Some effort has been made to cultivate the plant for fruit production, but low fruit set seems to be a persistent problem due to reproductive self-incompatibility.

Pawpaw also famously serves as the larval food plant for the zebra swallowtail butterfly, Eurytides marcellus (family Papilionidae). Beyond this, however, there seem to be not many insects associated with the plant. I have collected dead wood of pawpaw in an effort to determine the species of wood-boring beetle species that are associated with it. The only species I’ve reared is the longhorned beetle, Elaphidion mucronatum (whose common name “spined oak borer” belies the fact that it is one of the most polyphagous of all North American species), and two other longhorned beetles, Eupogonius pauper and Urgleptes querci (also highly polyphagous), have also been reported being reared from dead wood of this plant. I have not associated any jewel beetles with pawpaw, nor have any such associations been reported in the literature. It would appear that woodboring beetles are not fond of the soft, weak wood of pawpaw, perhaps due to the plant’s annonaceous acetogenins with known pesticidal qualities (Ratnayake et al. 1993) (acetogenins are also under investigation as anti-cancer drugs). Other poisonous compounds, chiefly alkaloids, are found in various parts of the plant, especially the seeds and bark, and likely play a role in herbivore defense. Insect pollinators also seem to be infrequent, as I have not noted any insects on its flowers. Most members of the family are pollinated by beetles (Yatskievych 2006), but the meat-colored, downward-facing, not-so-sweet-smelling flowers of pawpaw suggest pollination by flies, perhaps those attracted to carrion.

REFERENCE:

Ratnayake, S., J.K. Rupprecht, W.M. Potter, and J.L. McLaughlin. 1993. Evaluation of the pawpaw tree, Asimina triloba (Annonaceae), as a commercial source of the pesticidal annonaceous acetogenins. p. 644-648. In: J. Janick and J.E. Simon (eds.), New Crops. Wiley, New York.

Yatskievych, G. 2006. Steyermark’s Flora of Missouri, Volume 2. The Missouri Botanical Garden Press, St. Louis, 1181 pp.

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Monday Ménage – Brachyleptura rubrica

February 22, 2010October 10, 2011 / Ted C. MacRae / 12 Comments

Photo details: Canon 100mm macro lens on Canon EOS 50D, ISO 100, 1/250 sec, f/18, MT-24EX flash w/ Sto-Fen diffusers.

This mating pair of longhorned beetles represents Brachyleptura rubrica, one of several so-called “flower longhorns” (including the rare Typocerus deceptus) that I saw on flowers of Hydrangea arborescens last June at Trail of Tears State Park in southeastern Missouri. Flower longhorns collectively represent the subfamily Lepturinae, which among the Cerambycidae are distinguished by their posteriorly tapering elytra and generally narrow pronotum that give them a rather broad-shouldered look. Their conical coxae (basal segment of the leg) and eyes that usually do not surround the base of the antennae distinguish them from the subfamily Cerambycinae, and the prognathous (forward slanting) face distinguishes them from the Lamiinae (flat-faced longhorns). Additionally, a great majority of Lepturinae are diurnal (active during the day) and visit flowers as adults, whereas most other Cerambycidae (with notable exceptions) are nocturnal and seldom active during the day (most often being encountered by their attraction to lights). The subfamily is named for its type genus, Leptura — derived from the Greek word λεπτός (leptos), or narrow, which I presume to be a reference to their relatively more slender appearance compared to other Cerambycidae. Species in the genus Brachyleptura are distinguished from other Lepturinae by their often abbreviated elytra (“brachy” derived from the Greek word βραχύς, or short), although this is only scarcely the case in B. rubrica. I’m confident most of you can determine the derivation of the species name.

Although fairly widespread across the eastern U.S., I can remember being really excited the first time I saw this species back in the mid-1980s when I was beginning my faunal study of the Cerambycidae of Missouri (MacRae 1994). It is by no means rare, but at the same time it is not so routinely encountered as other common flower longhorns in the state such as Strangalia famelica solitaria, S. luteicornis, S. sexnotata, Typocerus octonotatus, and T. velutinus. Unlike those more commonly seen species, B. rubrica shows a distinct preference for plants with white, compound, flat-topped floral structures. No plant in Missouri meets this description better than Hydrangea arborecens, and it is on flowers of this plant that I have most often seen the species. Other flowers on which I have collected it include Ceanothus americanus, Cornus drummondii, Daucus carota, and Parthenium integrifolium — all white, compound, and (except Ceanothus) flat-topped. Larvae have been recorded breeding in a variety of hardwood species such as beech, birch, elm, hickory, and maple; however, I have only reared this species once — a single individual that emerged from a rather punky dead branch of Carpinus caroliniana (blue beech, musclewood, hornbean) (MacRae and Rice 2007). I suspect that the condition of the wood (slightly decayed rather than freshly dead) is more important than the actual tree species (although perhaps it is confined to hardwoods and does not utilize conifers).

There is a related species in Missouri, Brachyleptura vagans, which resembles B. rubrica in form and by its white-annulated antennae, but it is distinguished by the elytra being wholly black except for small (usually) red patches behind the humeri (shoulders). I haven’t encountered this species quite as commonly in Missouri, mostly in shortleaf pine (Pinus echinata) forests of the Ozark Highlands. I’ve collected it on most of the same flowers as B. rubrica, but rather than H. arborescens it seems to be most fond of C. americanus.

REFERENCES:

MacRae, T. C. 1994. Annotated checklist of the longhorned beetles (Coleoptera: Cerambycidae and Disteniidae) known to occur in Missouri. Insecta Mundi 7(4) (1993):223–252.

MacRae, T. C. and M. E. Rice. 2007. Distributional and biological observations on North American Cerambycidae (Coleoptera). The Coleopterists Bulletin 61(2):227–263.

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North America’s most beautiful longhorned beetle

September 28, 2009October 10, 2011 / Ted C. MacRae / 36 Comments

I’ve written a few posts in recent weeks highlighting some of the more interesting finds encountered during two visits this past July to the White River Hills region of extreme southwestern Missouri. It’s a land of extremes, with deeply dissected layers of limestone/dolomite bedrock supporting xeric glades, dry woodlands and riparian watercourses. The hilltop glades (“balds”), in particular, feature prominently in the region’s natural and cultural history and are the most extensive system of such habitat in Missouri. They support a number of plants and animals more characteristic of the grasslands of the south-central U.S., such as the recently featured Megaphasma denticrus and Microstylus morosum, North America’s longest insect and largest robber fly, respectively. Sadly, the glades in this region are much reduced in size and quality compared to their pre-settlement occurrence, primarily due to overgrazing and suppression of fire. These anthropogenic forces have combined to reduce overall vegetational diversity and accelerate encroachment by woody species (chiefly eastern red-cedar, Juniperus virginiana). Nevertheless, there still remain several high quality glade remnants in the area, and the public agencies charged with their conservation are increasingly utilizing mechanical removal of woody growth, controlled burns, and managed grazing in an effort to simulate the natural forces that mediated this landscape for thousands of years.

Chute Ridge Glade, Roaring River State Park, Barry Co., Missouri

My reason for returning to the White River Hills this year was simple—find and photograph the magnificent longhorned beetle, Plinthocoelium suaveolens (family Cerambycidae). This species, occurring across the southern U.S. from Florida and Georgia west to New Mexico and Arizona, is truly one of North America’s most beautiful longhorned beetles due to its large size, brilliant iridescent green coloration, and super-elongate wildly-contrasting orange and black legs. Until recently, this species was known in Missouri only from sporadic records across the southern part of the state (MacRae 1994). I knew of its association with gum bumelia (Sideroxylon lanuginosum [= Bumelia lanuginosa], also called gum bully and woolly buckthorn), which was first noted by Missouri’s first State Entomologist, C. V. Riley (1880) and later discussed in detail by Linsley and Hurd (1959) and Turnbow and Hovore (1979); however, my repeated searches over the years whenever I encoutered this plant came up empty. A few years ago, Chris Brown and I were conducting a survey of tiger beetles in the White River Hills and noted the relatively common occurrence of bumelia on these glades. Bumelia, like P. suaveolens, is one of only a few North American representatives of a largely tropical group, and it is one of the few woody species naturally adapted to the xeric conditions found on these glades. Recalling the association of P. suaveolens with this plant, and also recalling that adults could be attracted to fermenting baits of the type described by Champlain and Knull (1932), we placed fermenting bait traps on several glades in the area and succeeded in trapping a number of individuals during the month of July. When I began searching the bumelia trees at these glades, I found adults perching on the lower trunks of several trees. It was the first time I’d seen live individuals of this species in Missouri. At the time I was not a photographer, and that experience became one of the many moments that I would later look back upon and think, “If only I’d taken a picture of that!” Thus, at the end of June this year, having successfully found Cylindera celeripes in Missouri on the first day of a planned 3-week search, my attention immediately turned to the new goal of finding P. suaveolens and photographing it on its host plant.

Sideroxylon lanuginosum (gum bumelia) at Blackjack Knob, Taney Co., Missouri

I knew this wouldn’t be easy—the beetles were not abundant when I had last observed them, and those that I did find were quite wary to my approach. Getting within striking distance with a net was one thing; doing so with a camera and macro lens would be another thing entirely. In my first trip to the area (early July), I went to Chute Ridge Glade, a magnificently restored glade in Roaring River State Park where I had seen the greatest number of individuals before. I was full of optimism on that first day as I zigzagged across the rough terrain from one bumelia tree to the next, but my optimism began to wane as I cautiously approached each tree and saw nothing. Within an hour, I’d looked at every bumelia tree I could find on the glade and not even seen a beetle, much less attempted a photograph. It would take a 2-hour drive along twisting back roads to reach the other sizeable glade complex where I had seen beetles before (Blackjack Knob in Taney County), and another hour of searching on several dozen trees would again yield nothing. By now I was feeling rather frustrated—the day’s oppressive heat and humidity had taken its toll, and my 4.5-hour drive from St. Louis was looling like it would be for naught. I had noted that the bumelia flowers were almost but not quite open yet—perhaps it was too early in the season still?

Plinthocoelium suaveolens larval frass pile at the base of living Sideroxylon lanuginosa

Plinthocoelium suaveolens larval frass pile at trunk base of living Sideroxylon lanuginosum

The remnant glades at Blackjack Knob are more extensive than those at Chute Ridge, so many more trees still awaited examination—if I could only muster the energy! I trudged back to the truck, guzzled a nice, cold Powerade, and started off in another direction. I looked at a number of trees and still had seen no sign of the beetle, but on one particular tree I noticed an enormous pile of sawdust on the ground at the base of the tree. I looked at it more closely and saw that it had the rough, granular texture so characteristic of longhorned beetle larvae that like to keep their galleries clean, and its bright, moist color suggested that it was being ejected by a larva tunneling through living wood. I looked up into the tree above the pile to find where it was coming from but could find no ejection hole. I checked the base of the trunk itself and still couldn’t find anything. Then I started poking into the pile and felt a root. Further poking revealed a soft spot on the root, and I immediately knew that I had found a P. suaveolens larval gallery—no other cerambycid species is known to bore in roots of living Sideroxylon, especially one as large as this based on the size of the frass pile. I hurried back to the truck and grabbed my hatchet, returned to the tree, and scraped away the soil above the root to find an obvious ejection hole a few inches away from the base of the trunk. I started chipped into the root at the ejection hole and found a large, clean gallery extending down the center of the root away from the trunk. About 18” away from the trunk I found it—a large, creamy-white cerambycid larva.

Plinthocoelium suavelones larva in root of living Sideroxylon lanuginosa

Plinthocoelium suaveolens larva in root of living Sideroxylon lanuginosum

Finding a P. suaveolens larva was gratifying, but it wasn’t what I had come here to do, which was photograph the adult. After placing the larva live in a vial for preservation later on (dropping into scalding water to “fix” the proteins and prevent discoloration when stored in 70% ethanol), I continued searching the trees for adults. I found one tree on which the flowers were just barely beginning to open and collected a few of the pedestrian species of scarabs that are attracted to bumelia flowers in droves when fully open (e.g. Cotinis nitidus and Trigonopeltastes delta)—for the record. There was still no sign of adult Plinthocoelium, and I was on the verge of calling it a day when I approached another tree and saw it! I froze, then slowly geared up with the camera and started stalking slowly towards it. It was not in a very convenient location, down low on the trunk and partially screened by foreground vegetation. I got close enough to start attempting some shots—not ideally composed, but just to ensure that I had something before I tried to get any closer. After the third shot, however, it became alarmed and started to flee, and I had no choice but to capture it for a “studio backup.” That taste of success gave me the motivation to resume my search, but no additional beetles were seen before a dropping sun put an end to the day.

Plinthocoelium suaveolens on lower trunk of living Sideroxylon lanuginosum

Not entirely satisfied with the shots that I’d gotten, I returned to Blackjack Knob the following day and also searched some of the extensive habitat at nearby Hercules Glades Wilderness. I wouldn’t see another beetle the entire day, although encountering a nice series of Cicindela rufiventris (red-bellied tiger beetle) was some consolation for suffering the day’s oppressive heat and humidity. I still had the live beetle, so I placed my hopes on getting better photographs of the beetle in confinement after returning home. That would not come to pass—the beetle refused to sit obligingly on the stick I placed in the large screen cage, and instead clung to the cage itself. For days I watched it, giving it honey-water for sustenance and waiting for an opportunity to photograph it on the stick on which it refused to sit. It became clear to me that studio photographs, at least in the manner I was attempting, would not be possible. Not entirely satisfied with having seen only a single beetle on my trip, and thinking that I may have been too early based on the flowering phenology of the bumelia host trees, I did what any dedicated entomologist would do—I made a second trip to the area two weeks later!

I didn’t mess with Chute Ridge Glade this time, instead making a beeline for Blackjack Knob right away. Unfortunately, the weather was uncooperatively drizzley (I would have preferred hot and humid to rain!). Nevertheless, daughter Madison and I made our way to the glades and began inspecting the trees that I had just examined two weeks earlier. I noted immediately that the bumelias were now in full flower, and it wasn’t long before I saw the first adult flying into these flowers. Exciting for sure, and this was a good sign to see an active adult despite the drizzly weather, but the situation of the beetle on a high branch left no possibility for photographs (and only with a rather acrobatic swing of my fully extended net handle amidst a jumble of dead branches was I able to capture it). This same scenario would replay several times over the next two hours before rain finally drove us back to the car. In total, we saw half a dozen active adults, but in each case they were seen flying to flowers on high branches and could not be photographed. Despite that disappointment, I’ll never forget the spectacularity of seeing these beetles in flight—shimmering green and bold orange, with legs and antennae spread wide in all directions. I was also fortunate to find another tree with a fresh frass pile at its base indicating an active larva. This time, I cut the tree some inches above the ground and extracted the trunk base and root intact for transplanting into a large soil box upon my return home. The appearance of new frass on the soil surface afterwards confirmed that I had gotten the root containing the larva and that it had survived the extraction and transplanting. Hopefully I will be able to successfully rear this individual to adulthood.

Despite the rain, we then went back to Hercules Glades Wilderness to see if luck would follow suite there as it had at Blackjack Knob. It didn’t, as rain continued to doggedly pursue us, but the day was not a total loss as daughter and I got in a nice 7-mile hike through some of Missouri’s most ruggedly scenic terrain and were rewarded with the sighting of a western pygmy rattlesnake. The next day was sunny, much to our delight, and I considered going back to Blackjack Knob where we had seen a good number of adults the previous day. In the end, I decided I’d played that card and rather than continue trying for photographs I’d rather see if the beetle could be found at another glade complex further to the east at Long Bald Glade Natural Area in Caney Mountain Conservation Area. Things didn’t look promising, as I found bumelia trees occurring only sporadically across the main glade complex—with no sign of the beetles. Nevertheless, we enjoyed the day and spent a bit of time chasing after some enormous robber flies that later proved to be Microstylum morosum, a new record for Missouri and a significant northeastern range extension. I thought that would be the highlight of the day, but as we were heading back to the car I spotted a small glade relict on the other side of the road. It was overgrown and encroached, apparently not receiving the same management attention as the glades in the main complex. Regardless, I went over to check it out and immediately spotted several bumelia trees amongst the red-cedars, and within minutes I saw a beetle—low on the trunk of a very small bumelia tree! Once again I froze, then slowly geared up with the camera and began my ultra-cautious approach (remember, this was only my second photo chance after a combined four days in the field). Like last time, I took one shot while still some distance away, then moved in for closer attempts. Unlike last time, there was no bothersome vegetation cluttering the view, and when I moved in for closeups the beetle turned around, crawled up the trunk a short distance, and then paused. I snapped off a small series of shots while it sat there, and then suddenly it became alarmed and flew away. Though still not perfect, these photographs were better than the previous ones I had obtained (check out the pronotal armature in the last photo!), and the finding of this species at Long Bald Glades also represented a new county record.

Plinthocoelium suaveolens on trunk of living Sideroxylon lanuginosum

Missouri populations are assignable to the nominotypical subspecies (southeastern U.S.), which is distinguished from subspecies plicatum (Texas, New Mexico, Arizona, and northern Mexico) by the bronze or cupreous tints and weak transverse rugae on the pronotum (Linsley 1964). The distributional ranges of the two subspecies intermingle in northeastern Texas.

Photo details:
All photos: Canon 100mm macro lens on Canon EOS 50D
Photo 1 (Chute Ridge Glade): normal mode, ISO-400, 1/250 sec, f/16, natural light.
Photo 2 (Sideroxylon lanuginosum): landscape mode, ISO-100, 1/160 sec, f/6.3, natural light.
Photos 3 (P. suaveolens larval frass pile), 6—8 (P. suaveolens adult): manual mode, ISO-100, 1/250 sec, f/9-11, MT-24EX flash 1/2 power through diffuser caps (photo 7 slightly cropped).
Photos 4—5 (P. suaveolens larva): manual mode, ISO-100, 1/60 sec, f/14 (closeup f/25), MT-24EX flash 1/2 power through diffuser caps.

REFERENCES:

Champlain, A. B. and J. N. Knull. 1932. Fermenting bait traps for trapping Elateridae and Cerambycidae (Coleop.). Entomological News 43(10):253–257.

Linsley, E. G. 1964. The Cerambycidae of North America. Part V. Taxonomy and classification of the subfamily Cerambycinae, tribes Callichromini through Ancylocerini. University of California Publicatons in Entomology, 22:1—197, 60 figs., 1 pl.

Linsley, E. G. and P. D. Hurd, Jr. 1959. The larval habits of Plinthocoelium suaveolens plicatum (LeConte). Bulletin of the Southern California Academy of Sciences 58(1):27–33.

MacRae, T. C. 1994. Annotated checklist of the longhorned beetles (Coleoptera: Cerambycidae and Disteniidae) known to occur in Missouri. Insecta Mundi 7(4) (1993):223–252.

MacRae, T. C. and M. E. Rice. 2007. Distributional and biological observations on North American Cerambycidae (Coleoptera). The Coleopterists Bulletin 61(2): 227–263.

Riley, C. V. 1880. Food habits of the longicorn beetles or wood borers. The American Entomologist 3(10):237–239.

Turnbow, R. H. Jr. and F. T. Hovore. 1979. Notes on Cerambycidae from the southeastern U. S. Entomological News 90(5):219–229.

Typocerus deceptus in Missouri

July 17, 2009July 22, 2013 / Ted C. MacRae / 16 Comments

It has been fifteen years now since I published an annotated checklist of the longhorned beetles (families Cerambycidae and Disteniidae) of Missouri (MacRae 1994). That publication (and a similar one on Buprestidae) was the product of eight years of collecting – of specimens in the field and of data in any other public or private collection I could find that contained Missouri specimens – during my stint as a field entomologist with the Missouri Department of Agriculture. I collected during the week while on my rounds. I collected on weekends as well. I visited every college and university in the state that had an insect collection of any size, and a few in neighboring states as well. I made the acquaintance of private collectors with significant Missouri material – most notably Richard Heitzman, Marlin Rice, and the late Gayle Nelson. By the time I left Missouri for a new position in Sacramento, I had documented 219 species and subspecies of longhorned beetles from the state – 66 of which were new state records.

Typocerus deceptus on flower of Hydrangea arborescens

Despite my best efforts, however, I knew the list was not complete – they never are. In the years since returning to Missouri, I’ve documented an additional 10 species and subspecies in the state (MacRae and Rice 2007), and in a newly published paper (McDowell and MacRae 2009) the rare species, Typocerus deceptus, is documented from Missouri for the first time. I cannot take credit for this discovery – that honor goes to the paper’s lead author, Tom McDowell of Carbondale, Illinois. Tom first encountered this species in 2005 at Trail of Tears State Park in southeastern Missouri near Cape Girardeau while conducting routine insect surveys. After seeing additional individuals on a subsequent visit to the park the following year, Tom contacted me to tell me of his find and graciously invited me to join him on further studies of this rarely encountered species. I readily agreed, and in July of last year I met up with Tom at Trail of Tears to see the beetle for myself.

Typocerus deceptus on flower of Hydrangea arborescens

Typocerus deceptus has been recorded sporadically from across the eastern U.S. Nothing is known of its biology other than adult flower hosts and activity periods, and the larva and larval host(s) remain completely unknown. The species is aptly named, as its appearance is deceptively similar to the common and widespread species, T. velutinus. Both of these species belong to the so-called “flower longhorn” group (subfamily Lepturinae), characterized by adults that are largely diurnal (active during the day) and attracted to a great variety of flowers upon which they feed. Tom had found T. deceptus feeding on flowers of wild hydrangea (Hydrangea arborescens) in the company of several other flower longhorns, including T. velutinus. The similarity of T. deceptus to T. velutinus makes distinguishing individuals amongst the vastly more abundant T. velutinus quite difficult. However, Tom was able to recognize the species during his surveys as a result of prior experience with it in Illinois. As Tom and I searched the wild hydrangea plants growing along an intermittent drainage between the road and the park’s unique mesic forest, we succeeded in picking out a total of four individuals of this species amongst the dozens of T. velutinus and other lepturines also feeding on the flowers.

Typocerus velutinus on flower of Hydrangea arborescens

I gradually developed a sense of the subtle differences that distinguish this species from T. velutinus and that allow its recognition in the field. Typocerus deceptus is slightly more robust than T. velutinus, and whereas the transverse yellow elytral bands of the latter are distinct and well delimited, they are weaker and often interrupted at the middle in T. deceptus, giving the beetle a slightly darker brownish appearance. The lateral margins of the elytra are also more strongly emarginated near the apices, giving the beetle a more distinctly tapered appearance. Finally, while both species possess a distinct band of dense, yellow pubescence along the basal margin of the pronotum, this band is interrupted at the middle in T. deceptus. My ability to recognize this species in the field was confirmed a few weeks ago when I returned to Trail of Tears (with longtime field companion Rich Thoma) to attempt what seemed to be an impossible task – photograph these active and flighty insects in the field on their host plants. Conditions were brutally humid, and I only saw two individuals that day – the first I immediately captured and kept alive as a backup for studio photographs should I fail to achieve my goal in the field, but the second individual (not seen until almost two hours later!) posed just long enough for me to whip off a series of frames, two of which turned out well enough to share with you here. The first photo clearly shows the interrupted basal pubescent band, and both photos show the distinctly emarginate lateral elytral margins and weak transverse yellow bands (compare to the uninterrupted pronotal pubescent band and well developed transverse elytral bands of T. velutinus in the third photo).

Me with the discoverer of Typocerus deceptus in Missouri Trail of Tears State Park, July 2008

TCM with the discoverer of Typocerus deceptus in Missouri at Trail of Tears State Park, July 2008

It is possible that T. deceptus is not as rare as it appears and is simply overlooked due to its great resemblance to another much more abundant species. However, I believe this is unlikely given its rarity in collections of eastern U.S. Cerambycidae by casual and expert collectors alike. Moreover, T. deceptus is not the only “rare” longhorned beetle to have been documented at Trail of Tears State Park – a number of other species have also been found there but not or only rarely elsewhere in Missouri (e.g., Enaphalodes cortiphagus, Hesperandra polita, Metacmaeops vittata, and Trigonarthris minnesotana). This may be due to the unique, mesic forest found at Trail of Tears, being one of only a few sites in southeastern Missouri that support more typically eastern tree species such as American beech (Fagus grandifolia), tulip poplar (Liriodendron tulipifera), and cucumbertree (Magnolia acuminata). Whether one of these trees serves as a larval host for T. deceptus is unknown. Nevertheless, I will be returning to Trail of Tears in the future to see what other treasures remain hidden within its unique forests.

Photo details (insects): Canon 100mm macro lens on Canon EOS 50D, ISO 100, 1/250 sec, f/18-20, MT-24EX flash 1/4 power through diffuser caps.

REFERENCES:

MacRae, T. C. 1994. Annotated checklist of the longhorned beetles (Coleoptera: Cerambycidae and Disteniidae) known to occur in Missouri. Insecta Mundi 7(4) (1993):223–252.

MacRae, T. C. and M. E. Rice. 2007. Distributional and biological observations on North American Cerambycidae (Coleoptera). The Coleopterists Bulletin 61(2):227–263.

McDowell, W. T. and T. C. MacRae. 2008. First record of Typocerus deceptus Knull, 1929 (Coleoptera: Cerambycidae) in Missouri, with notes on additional species from the state. The Pan-Pacific Entomologist 84(4):341-343 DOI: 10.3956/2008-23.1

A Silver Anniversary

June 24, 2009June 20, 2017 / Ted C. MacRae / 17 Comments

Twenty-five years ago tomorrow, I discovered my first new species. I didn’t know it at the time – in fact, it would be several years later before the budding, young entomologist that I was would finally conclude that the large, spectacularly beautiful, cerambycid beetle that I was capturing in my fermenting bait traps just south of St. Louis did indeed represent a previously unrecognized species.

In my first job out of school as a field entomologist for the Missouri Department of Agriculture, I worked with nursery growers to identify insect pest problems on their crops and provide recommendations for control. Wood boring beetles – especially the longhorned beetles – are a major problem for growers of trees, and it was that importance, combined with a latent interest in taxonomy, that led to my interest in this group (and the beginnings of my identity as a “coleopterist”). I didn’t just work in entomology – I lived it, and when I wasn’t inspecting rows of trees, checking gypsy moth traps, or scouting for musk thistle weevil release sites in the three counties around St. Louis, I was collecting insects and the primary literature about them. One of the early papers I came across (Champlain and Knull 1932) described the use of fermenting bait traps for collecting Cerambycidae, in particular species in the genus Purpuricenus. I desperately wanted some of these beetles – large, showy, velvety black, with vivid red or orange basal markings on the elytra – but had not yet encountered either of the two species then known in eastern North America. I made a batch of the stuff – basically molasses, beer, yeast, and water – and placed buckets of the slurry at a few spots that I would be able to check periodically while on my rounds. Much to my delight, I quickly began trapping numerous species of Cerambycidae – including the two species of Purpuricenus. Most of these specimens were coming to a trap I had placed at one of my favorite collecting spots – Victoria Glades Natural Area in Jefferson Co., some 30 miles south of St. Louis. Over the next few weeks I acquired a nice little series of the two species, and I increased their number during the following three years with continued trapping.

Purpuricenus humeralis (Fabricius)

The two species were easily distinguished – in Purpuricenus humeralis the basal elytral markings were triangular and covered just the humeri, while in P. axillaris they were transverse and covered the entire basal half of the elytra. As I studied the series of the latter, however, something seemed amiss. Some of the specimens were distinctly larger and more robust, while others were smaller and more gracile. Moreover, the color of the elytral markings on the larger specimens seemed to be consistently more reddish than the pale orange markings of the smaller specimens. At first I dismissed it as variation – common among longhorned beetles, which can vary greatly in size depending on the quality of the larval host. But as I studied them more I noted other consistent differences between the two “forms” – the larger with more well-developed pronotal tubercles (the middle one of which bore a distinctly polished apex and the lateral ones more acutely angled), a distinct “tooth” at the apex of the elytral midline, and coarser punctures at the base of the elytra. It seemed obvious that the two forms represented two different species, but the only other species I could find in Linsley’s (1962) monograph of North American Cerambycidae (my bible!) was P. linsleyi – known then only by the holotype and one paratype from an unspecified location in Texas. Neither series matched the description of that species very well – the shape of the elytral marking was wrong – but I concluded the larger one must be that species and the smaller was axillaris. There was another possibility – but that young entomologist just couldn’t entertain the idea of a large, showy, longhorned beetle still undescribed in eastern North America.

Purpuricenus axillaris Haldeman

Some time later I received a series of a Purpuricenus that my colleague Dan Heffern had collected near San Antonio, Texas. Dan had also taken up collecting cerambycids with fermenting bait traps, and while he was quite proficient with Texas species he wasn’t quite sure what to make of these particular specimens. He sent them to me for my opinion, and it was quite clear – they were the real P. linsleyi. The rediscovery of that rare species was an exciting find in itself, but it rekindled the puzzle of the Missouri Purpuricenus – if they were not P. linsleyi, then what were they? The only conclusion was that two species were masquerading under a single name, and that I would have the privilege of naming one of them. Wow, my first new species – something every amateur taxonomist dreams about, but I had no idea it would happen so soon, or with such a spectacularly beautiful species! By then I was living in Sacramento, so I traveled to nearby Berkeley to meet with the late John Chemsak at the University of California and show him my material. John was a longtime associate of the late, great E. Gorton Linsley, co-authoring with Linsley several later volumes of the North American Cerambycidae monograph, and had managed to borrow type material of P. axillaris from the Museum of Comparative Zoology at Harvard University. We found that both species were present in the small type series, so together we decided which specimen should be designated as a lectotype for P. axillaris – and thus, which of the two species would be named as new.

Purpuricenus paraxillaris MacRae

It would take several more years before I actually published a description of the new species, naming it P. paraxillaris (meaning “near” axillaris) and selecting as holotype the very first specimen I collected – on June 25, 1984. I wanted to know its distribution, which meant borrowing material from museums and willing individuals. I also recognized that some collectors of Cerambycidae might view the description of a large, showy species from eastern North America with some skepticism, so I wanted to be as thorough as possible. (There were a few private collectors that declined to loan their material to me because of such skepticism.) During that process, I learned that P. paraxillaris is quite common across the eastern U.S. – in fact, many of the literature references to P. axillaris actually refer to this species, but it wasn’t until collectors began using fermenting bait traps widely that large series of specimens became available for study. By examining the few available reared specimens, I learned that P. axillaris prefers hickory (Carya) as a host, while P. paraxillaris prefers oak (Quercus) and chestnut (Castanea). With several hundred specimens of the two species at my disposal, I became more convinced than ever that they were distinct, and with the many specimens of other species in the genus that I had borrowed as well, I decided to expand the scope of the paper to a general review of the entire genus in North America. This would allow me not only to describe the new species, but report the rediscovery of P. linsleyi as well. Finally, after several years (remember, I was/am just an amateur), the description was published in the October 2000 issue of The Pan-Pacific Entomologist (MacRae 2000).

For those of you with an interest in such things, I include here a key to the three eastern North American species of Purpuricenus.

Key to adult Purpuricenus in eastern North America
(adapted from MacRae 2000)

1. Posterior margin of basal elytral markings distinctly oblique; apical dark area extending forward along suture and reaching scutellum……………. P. humeralis (Fabricius)

1′. Posterior margin of basal elytral markings more or less transverse; apical dark area not extending forward along suture to scutellum ………………………………………………………. 2

2 (1′). Discal calluses of pronotum weak, median callus without polished apical line; lateral pronotal tubercles small, angles obtuse; basal elytral punctation relatively finer and sparser; elytral apices subtruncate, angles not distinctly dentate; basal elytral markings yellow to orange ………………………………………………………………………. P. axillaris Haldeman

2′. Discal calluses of pronotum distinct, median callus prominent and with polished apical line; lateral pronotal tubercles well-developed, angles acute; basal punctation of elytra relatively coarser and denser; elytral apices emarginate, angles distinctly dentate; basal elytral markings orange to red-orange ………………………………. P. paraxillaris MacRae

REFERENCES:

Champlain, A. B. and J. N. Knull. 1932. Fermenting bait traps for trapping Elateridae and Cerambycidae (Coleop.). Entomological News 43:253–257.

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 Publications in Entomology 20:1–188, 56 figs.

MacRae, T. C. 2000. Review of the genus Purpuricenus Dejean (Coleoptera: Cerambycidae) in North America. The Pan-Pacific Entomologist 76:137–169.

Sanctuary for the Betulaceae

February 25, 2009October 10, 2011 / Ted C. MacRae / 17 Comments

Nestled on the eastern side of the St. Francois Mountains, where the craggy exposures of the Ozarks most ancient rocks begin to subside underneath the Cambrian sandstones laid down over them, lies Hawn State Park – considered by many to be the loveliest of Missouri’s state parks. I have written previously about Hawn – in fact, it was the subject of my very first post on this blog. I have long treasured Hawn for its excellent insect collecting, diversity of plants and habitats, and unbridled beauty. I have hiked the incomparable Pickle Creek and Whispering Pine Trails many times – far more than any other trail in the state, and each time I fall more deeply in love with what, to me, represents the essence of the Missouri Ozarks in their most pristine state.

The charm of Hawn results from a unique combination of geological features. The Lamotte sandstone outcrops that dominate Hawn’s landscape are the oldest sedimentary rocks in the state, formed from coarse sand deposits that were laid down over the Precambrian rhyolites and granites that form the core of the St. Francois Mountains. These sand deposits were themselves buried under limestone and dolomite layers formed at the bottom of vast seas that later covered much of the interior of the continent. Subsequent periods of uplift and erosion once again exposed these sandstones, whose unique ability to hold groundwater has resulted in the formation of spring-fed streams that have cut deep into their soft layers to create canyon-rimmed valleys with tall vertical cliffs. One of these streams is Pickle Creek, which is fed throughout the year by Pickle Spring and has in some places cut all the way down to the underlying igneous rock to form “shut-ins.” In contrast to the slow, sandy bottomed stretches where Pickle Creek is still cutting through sandstones, the water in these igneous shut-ins rushes through narrow openings in the highly resistant rock. The igneous and sandstone exposures found in Hawn are spectacularly beautiful and support a unique flora due to the acid soils they produce. One group of plants that have taken sanctuary in these moist, acid soils is the Betulaceae, or birch family. Missouri is home to five native species of Betulaceae¹, and while none of them are extraordinarily uncommon they are limited in their occurrence to natural communities with sufficient moisture and exhibit a clear preference for acidic soils. This confluence of conditions occurs perfectly along Pickle Creek, allowing all five native species to grow here side-by-side – a betulaceous “hot spot” that represents not only the full diversity of the family in Missouri, but also the total generic diversity of the family in North America. In fact, only one other genus (Ostryopsis, shrubs related to Corylus and restricted to China) is assigned to the family on a global basis (Furlow 2004).

¹ Dr. George Yatskievych, in his recently published Steyermark’s Flora of Missouri (2006), regarded the presence of Corylus cornuta in Missouri as unlikely despite earlier reports of such. Dr. Yatskievych also recorded a single escape of the European species Alnus glutinosa from Springfield, Missouri.

The Betulaceae are deciduous trees and shrubs that occur primarily in the boreal and cool temperate zones of the Northern Hemisphere, although outposts are also known from high elevations in the Neotropics and, as mentioned above, China. Fossils of this ancient lineage of flowering plants are traceable to the late Mesozoic (upper Cretaceous), and the family appears to form a clade with hamamelidaceous plants. As would be expected from a group with boreal affinities, most species exhibit adaptations for survival in cold climates, such as small stature, shrubby growth habits, and small leaves. Several of Missouri’s species have performed well and gained acceptance as ornamental trees and shrubs, while others are important as sources of hazelnuts (genus Corylus) or ecologically for their ability to fix nitrogen (genus Alnus). My interest in these plants has nothing to do with their economic importance, but rather in their role as host plants for several rarely encountered species of woodboring beetles. Often, insects in this group may be collected on foliage of their hosts during the summer, making host identification fairly easy due to the presence of leaves. This is not always possible, however, due to limited periods of adult activity or low population densities. Rearing these insects from their hosts provides additional opportunity to document their occurrence, and winter is often the best time to collect the dead branches in which they breed, since by that time they have nearly completed their development and will be ready to emerge as soon as temperatures rise during spring. Identifying woody plants without foliage can be a challenge, but the ability to distinguish host plants by non-foliage characters such as bark, growth habit, bud shape, etc. greatly facilitates studies of wood boring beetles through rearing. In the past I have relied heavily on Cliburn and Klomps’ (1980), A Key to Missouri Trees in Winter, which utilizes mostly details of the twigs and buds to discriminate among Missouri’s 160+ species of trees. However, after a certain level of familiarity is gained, one eventually learns to recognize winter trees and even downed logs or fallen branches simply by their “look”.

Betula nigra - habit

Betula nigra - old bark

Betula nigra - sapling

Betula nigra (river birch) is the only member of this largely boreal genus found in the middle and southern latitudes of the U.S. and, thus, cannot be confused with any of Missouri’s other betulaceous species². It is the largest of the five and, along with the following species, is the most demanding in terms of keeping its “feet” wet. Trees are usually encountered right at the water’s edge, with tall, slender, often twisted or leaning trunks. Young trees and large branches on older trees exhibit gorgeous reddish brown bark peeling in thin, papery sheets, becoming thick and scaly on the main trunks of older trees. Small branches are dark, purplish brown in color with smooth bark and distinctly horizontal lenticels. I have reared a small jewel beetle from fallen, dead branches of this tree collected at several locations in Missouri – this beetle turned out to be new to science, which I described and named Agrilus betulanigrae in reference to its (then) only known host (MacRae 2003). I have also reared tremendous series of another jewel beetle, Anthaxia cyanella, which at the time was not known to utilize this host and was considered uncommon. As it turns out, Betula nigra is its preferred host, and the rearing of large series from many locations resulted in improved knowledge about color forms and variability in this species (MacRae & Nelson 2003).

² The widely planted but dreadfully non-adapted Betula pendula (European white birch) and B. papyrifera (paper birch) can be recognized by their distinctly white bark. These species are limited to urban landscapes where they rarely achieve significant stature before declining and eventually succumbing to insect pests such as Agrilus anxius (bronze birch borer). River birch provides an equally attractive and much more durable choice!

Alnus serrulata - habit

Alnus serrulata - sapling

Alnus serrulata - old cones

Alnus serrulata (common alder, hazel alder, smooth alder, tag alder…) also demands to be next to (or even in) the water. Unlike B. nigra, however, this species rarely reaches true tree status, instead usually forming shrubby thickets along the water’s edge. Saplings can resemble those of B. nigra due to their smooth brownish bark, but the latter is usually more purplish, and the lenticels of A. serrulata are not distinctly horizontal as in B. nigra. The large purple-red buds also differ from the small brown buds of B. nigra, and during winter A. serrulata is adorned with numerous staminate catkins. The persistent woody cones also cannot be mistaken for those of any other species of Betulaceae in Missouri. Associated with this plant is the longhorned beetle, Saperda obliqua, which reaches its southwesternmost distributional limit in Missouri on the basis of a single specimen collected some 25 years ago right here along Pickle Creek and given to me by lepidopterist George Balogh. Numerous attempts to find this species here since then have not (yet!) been successful.

Carpinus caroliniana - habit

Carpinus caroliniana (blue beech, hornbeam, musclewood) is one of my favorite betulaceous species. The beautifully fluted trunks and smooth, light gray bark are remniscent of the limbs of a sinewy, muscular person – every time I see this tree I cannot resist the temptation to grab and stroke the hard limbs (should I be admitting this?). This character begins to show even in very young trees, making its identification during winter quite easy. These trees also like to be near water, but they are not so demanding to be right at the water’s edge as are the previous two species. They usually form small trees, often in clumps with multiple trunks. There are some notable insect associations that I’ve found with this plant. One is a small jewel beetle, Agrilus ohioensis, which I reared from dead branches of this plant collected along Pickle Creek (Nelson & MacRae 1990), and which after more than 20 years still remain the only known Missouri specimens of this species. Another is the longhorned beetle, Trachysida mutabilis, a single adult of which I reared from a dead (almost rotting) branch of this plant collected not too far from Pickle Creek in Iron Co. This beetle also is the only representative of its species known from Missouri (MacRae & Rice 2007).

Ostrya virginiana - habit

Ostrya virginiana - trunk

Ostrya virginiana (hop hornbean, American hornbeam) has a form and growth habit very similar to C. caroliniana, but its leaves that persist through the winter make it instantly recognizable from afar. In Missouri, this habit is most often seen with the oaks (Quercus spp.). This species can be found even further away from the water than the previous species, and its small stature combines with the orangish, persistent leaves to form a distinctive understory layer during winter. Also, in contrast to the smooth gray bark of Carpinus, this species exhibits scaly, light reddish brown to brownish gray bark. I have succeeded in rearing one of the two known Missouri specimens of another jewel beetle, Agrilus champlaini, from O. virginiana collected along Pickle Creek (the other specimen was reared from wood collected at Graham Cave State Park, another site where sandstone bedrocks favor an O. virginiana understory). Unlike most other jewel beetles, A. champlaini forms galls in small living branches of its host. I have collected the distinctive swellings during winter on many occasions but managed to rear only these two individuals (plus one ichneumonid parasitoid). I have also noted similar swellings on Carpinus but have not yet managed to definitely associated them with this beetle.

Corylus americana (hazelnut, American hazelnut) is the smallest of Missouri’s five betulaceous species, always forming shrubs, sometimes in thickets, and never assuming the form of a tree. Its staminate catkins present during winter immediately identify plants of this species as Betulaceae, but the small, globe-shaped buds are unlike the more pointed buds of Ostrya and the elongated, reddish buds of Alnus. This species is the least demanding in terms of being near water and can be found even in upland prairies and glades. I haven’t yet associated any woodboring beetles with this plant in Missouri, but there are several jewel beetles known from the eastern U.S. that utilize Corylus (Agrilus corylicola, A. fulgens, and A. pseudocoryli) and could occur in Missouri.

The upland habitats at Hawn are of interest as well. Lamotte sandstones are the dominant bedrock, creating acid soils that support a canopy dominated by Missouri’s only native species of pine, Pinus echinata (shortleaf pine), several species of oak, and a diversity of acid-loving shrubs primarily in the family Ericaceae (including the stunningly beautiful Rhododendron prinophyllum, or wild azalea). Historically, so-called “pine savanna” was prevalent in this area, a natural community in which periodic fires maintained an open structure amongst the fire-adapted pines and allowed a diverse herbaceous layer beneath the open canopy. Much of Hawn has closed up after decades of fire suppression; however, the Department of Natural Resources has implemented a rotational burn management regime to recreate pine savanna habitat within Hawn’s Whispering Pines Wild Area. Evidence of what appeared to be very recent burns could be seen at several places as I hiked along the Whispering Pines Trail, and while many visitors might have been alarmed at the apparent “damage” they were observing, my heart sang with the prospect of seeing mature pine savanna communities taking hold throughout my beloved Hawn. As I stood atop this ridge and looked back down from where I had come, I could almost see Henry Schoolcraft and Levi Pettibone in the distance on horseback, perhaps pausing to gaze at an elk.

REFERENCES:

Cliburn, J. and G. Klomps. 1980. A Key to Missouri Trees in Winter, 2nd edition. Missouri Department of Conservation, Jefferson City, 43 pp. (subsequently revised)

Furlow, J. J. 2004. Betulaceae in Flora of North America @ efloras.org. http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=10101.

MacRae, T. C. 2003. Agrilus (s. str.) betulanigrae MacRae (Coleoptera: Buprestidae: Agrilini), a new species from North America, with comments on subgeneric placement and a key to the otiosus species-group in North America. Zootaxa 380:1–9.

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.

MacRae, T. C. and M. E. Rice. 2007. Distributional and biological observations on North American Cerambycidae (Coleoptera). The Coleopterists Bulletin 61(2):227–263.

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.

Yatskievych, G. 2006. Steyermark’s Flora of Missouri, Volume 2. The Missouri Botanical Garden Press, St. Louis, 1181 pp.

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.

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