Call for paratypes!

Acmaeodera n. sp. (Santa Cruz Co., Arizona)

Earlier this year, I featured this small jewel beetle in the genus Acmaeodera (family Buprestidae).  It was collected a few years ago in southeastern Arizona by my hymenopterist friend Mike Arduser, who over the years has given me a great variety of buprestid and cerambycid beetles that he has encountered on flowers while collecting representatives of his chosen specialty – apoid bees (bee specialists are often great collectors of flower visiting insects across many taxa!).  This particular specimen is perhaps the most exciting of all of those, as it appears to represent an undescribed species.  Unfortunately, it is the only specimen known, and describing new species based on a single specimen in a genus such as Acmaeodera – diverse, variable, and with ill-defined species limits – is not advisable.  I have enlisted the help of a few insect collectors to try to find more specimens of this species to allow proper description; however, so far no additional specimens have turned up.  The summer monsoons have begun this season in southeast Arizona, thus the next few weeks will once again provide the opportunity to encounter this beetle.  I am hoping that this post, with precise locality data, information on the circumstances of its collection, and photographs of the beetle and its habitat, will prompt any entomologists reading this to scour the mountains of Arizona during the next month (or the accumulation of undetermined material in their collections) in the hopes of encountering additional specimens to allow formal description of this species.

Label data for the specimen are as follows: “ARIZONA Santa Cruz Co. | Atacosa Mountains | along Ruby Road [E of #100 Trailhead], 6,000 ft. | August 2, 2003 10-1200 [hrs] | Aloysia flwrs – Arduser”.  The first person to search for additional specimens was my friend Paul Kaufman, who searched for the beetle in August 2007.  Here is what he had to say afterwards:

Well, we found the site based on the GPS readings you gave me.  We could not find any of the Aloysia in that location, but there were some other leguminous plants with white flowers a-buzz with bees.  No beetles however.  The area has had a fire burn through it in fairly recent history – several years maybe?  It’s hard to tell, but that could have changed things a bit.  Anyway, we drove west on Ruby Rd a few tenths of a mile and did find a drainage full of Aloysia!  This was the only location along Ruby Rd where we found any growing.  Three of us checked it very carefully uphill and downhill from the road (rough scrambling).  There were lots of bees, flies and leps, but no beetles!

The following year, North American Acmaeodera guru Rick Westcott himself went to search for this species – also without success.  He wrote:

If you remain in touch with the collector of the latter, please ask him if he got it up on the pinyon-juniper zone, or were there just oaks and junipers?  If he was at 6000′, I am quite certain there had to be pinyon.  The trail (#100) starts on the Ruby Road at 4700′ and goes to the lookout that is at 6200′.  I decided not to go to the latter, but I was close.  I did not see any flowers that were suitable for Acmaeodera, let alone did I see an Aloysia bush.  Much of the area had been burnt, though some years ago.

I sent this information to Mike Arduser, who replied as follows:

It appears now that I  must have  misinterpreted the elevation on my topo map and carried that error onto the label, because though I walked up almost to the lookout I did not do any collecting up that high. My collecting (hand net and malaise traps) was done adjacent to Ruby Rd., then upslope approximately 100 meters or so, all of it east of the #100 trailhead (which is where I parked). The only woody plants in the immediate vicinity I noted were Aloysia (in narrow rocky drainages) and a legume (forget the genus at the moment). However, I think there were a few oaks scattered around (I believe there was one where I parked). There was no evidence of fire at the time I was there.

Mike also sent me the photo shown here taken near the collection site (if nothing else, the spectacular scenery makes a visit to this place seem like a good idea), noting:

Attached is a photo from the Atacosa Mtns. Area where the new buprestid was found – the photo was taken about 100ft. elev.  above the collection site and about a ¼ mile to the west.

I’ve included a Google Map at left that shows the location of the Atascosa Lookout (#100) Trailhead.  It’s not the best overhead photo, but it does give an idea of the landscape relief and rather precisely pinpoints its location via GPS coordinates in the lower lefthand corner.  If the beetle truly does occur at lower elevations (~4,700′), then it is probably not terribly specific about this particular locality.  Perhaps it is a Mexican species that only occasionally makes it into the U.S. depending on the season. The repeated comments about apparent fire in the area by Paul and Rick suggest potential vegetational differences in the area from the time the beetle was collected compared to their subsequent visits. Although the single specimen was collected on Aloysia flowers, it is also possible that the species does not actually show a particular preference for this plant – although it does seem likely that it visits flowers of some type.  The only way to answer these questions is by finding more specimens!

Copyright © Ted C. MacRae 2010

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Aaack!-maeodera

Warning: post contains hardcore, taxonomic, sciencey geekiness!

Just as there is seasonality in the lives of insects, there is seasonality in the work of those who study them.  For the collector/taxonomist, everything revolves around the collecting season — time spent on anything else is time not available for collecting. As a result, I spend a good deal of my time during the summer in the field and on its associated planning and organizing activities, leaving the winter months for processing and identifying collected specimens, incorporating them into the permanent collection, generating reports to fulfill permit requirements, and ultimately preparing manuscripts for publication — the raison d’être.  Winter is also the time when I identify specimens sent to me by other collectors.  I do this not only because I’m such a nice guy (at least I hope I am), but also because such material often contains species I haven’t seen before or that represent new distributions and host plant associations that I can use to augment the results of my own studies.  Such work has occupied much of my time during the past several weeks, and I now find myself close to finishing the last of the nearly dozen batches of beetles sent to me since the end of last winter.

Of the three groups of beetles that I actively study — jewel beetles, longhorned beetles, and tiger beetles — it is the jewel beetles that are taxonomically the most challenging.  Tiger beetles can often be indentified in the field (especially with the publication of Pearson et al. (2006), or “the Bible” among cicindelophiles), and North American longhorned beetles have been reasonably well worked by a strong contingent of both professional and amateur taxonomists over the past several decades.  Jewel beetles on the other hand, despite their dazzling colors and popularity with collectors, continue to befuddle even the most dedicated collectors due to their extreme variability and poorly-defined species limits.  Of the 822 species and subspecies known from North America, fully three-fifths of them belong to one of just three hyperdiverse genera — Acmaeodera, Agrilus, and Chrysobothris.  No recent taxonomic treatments are available for any of these genera, thus, identifying species belonging to them requires access to primary literature, a well-represented and authoritatively-identified reference collection, and extraordinary patience!  This is particularly true of the genus Acmaeodera, the North American members of which were last treated collectively more than a century ago (Fall 1899) (at which time less than half of the current 149 species/subspecies were known to science).  The recent explosion of web-based images has helped matters (a particularly useful site for those interested in North American Acmaeodera is Acmaeoderini Orbis, with its galleries of Harvard type specimens and BugGuide photos); however, images are still lacking for many species, and others are not easily distinguished from the images that do exist.

Acmaeodera robigo Knull (Val Verde Co., Texas)

It is precisely this taxonomic challenge, however, that makes the group so interesting to me.  Opportunities for discovery abound, as basic information is incomplete or totally lacking for many species regarding their geographical ranges and life histories.  One of the species I encountered in a batch of material sent to me by cerambycid-specialist Jeff Huether contained three specimens that I eventually determined to represent Acmaeodera robigo.  Josef Knull (1954) first described this species from specimens collected at Lake Corpus Christi in south Texas, and nothing more was recorded about the species until Nelson et al. (1996) reported a single specimen cut from its pupal cell in the base of Dalea formosa (Fabaceae) at White River Lake in far northern Texas — a range extension of almost 500 miles!  Obviously, I didn’t have this species in my collection, and it was only after a series of eliminations that led me to the original description (and confirmation of my ID by Nearctic Acmaeodera-guru Rick Westcott based on the photos shown here) did I know for sure what it was.  These specimens were collected at Seminole Canyon State Historic Park, thus, extending into west Texas the species’ known range, and they exhibit variability in the elytral markings and punctation that was not noted in the original description.  While only an incremental increase in our knowledge of this species, collectively such increases lead to greater understanding of the genus as a whole, and Jeff’s generosity in allowing me to retain examples of the species increases my U.S. representation of the genus to 130 species/subspecies (87%).

Acmaeodera n. sp. (Santa Cruz Co., Arizona)

The opportunity for discovery is not limited to range extensions and new host records, but includes new species as well.  A few years ago I received a small lot of specimens collected in Arizona by my hymenopterist-friend Mike Arduser (hymenopterists, especially those interested in apoid bees, are excellent “sources” of Acmaeodera, which they encounter frequently on blossoms while collecting bees).  Among the material he gave to me was the single specimen shown here that immediately brought to my mind Acmaeodera rubrovittata, recently described from Mexico (Nelson 1994) and for which I had collected part of the type series.  Comparison of the specimen with my paratypes, however, showed that it was not that species, and after much combing through the literature I decided that the specimen best fit Acmaeodera robigo (despite being collected in Arizona rather than Texas and not matching the original description exactly).  This was before I had true A. robigo with which to compare, so I sent the specimen to Rick Westcott for his opinion.  His reply was “good news, bad news” — the specimen did not represent A. robigo, but it didn’t represent any known species either!  While the prospect of adding a new species to the U.S. fauna is exciting, basing a description on this single specimen would be ill-advised.  Only through study of series of individuals can conclusions be made regarding the extent of the species’ intraspecific variability and its relation to known species.  Until such specimens are forthcoming, the specimen will have to sit in my cabinet bearing the label “Acmaeodera n. sp.”  For all of you collector-types who live in or plan to visit southeastern Arizona, consider this a general call for potential paratypes!  The specimen was collected in early August on flowers of Aloysia sp. near the Atascosa Lookout Trailhead on Ruby Road in Santa Cruz Co.

REFERENCES:

Fall, H. C.  1899.  Synonpsis of the species of Acmaeodera of America, north of Mexico.  Journal of the New York Entomological Society 7(1):1–37.
[scroll to “Journal of the New York Entomological Society”, “v. 7 1899”, “Seq 12”]

Knull, J. N. 1954. Five new North American species of Buprestidae (Coleoptera). Ohio Journal of Science 54:27–30.

Nelson, G. H. 1994. Six new species of Acmaeodera Eschscholtz from Mexico (Coleoptera: Buprestidae). The Coleopterists Bulletin 48:272–282.

Nelson, G. H., R. L. Westcott and T. C. MacRae. 1996. Miscellaneous notes on Buprestidae and Schizopodidae occurring in the United States and Canada, including descriptions of previously unknown sexes of six Agrilus Curtis (Coleoptera). The Coleopterists Bulletin 50(2):183–191.

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.

Copyright © Ted C. MacRae 2010

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A Silver Anniversary

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

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

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

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.

Copyright © Ted C. MacRae 2009

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Tragidion confusion

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

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

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.

Copyright © Ted C. MacRae 2009

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Review of Calodema and Metaxymorpha

ResearchBlogging.orgNylander 2008Insects are not only the most diverse group of animals in the world, they are also among the most beautiful.  Beetles, of course (with apologies to any lepidopterists that may be reading this), are responsible for a hefty slice of this majestic diversity, with the most spectacular of these belonging primarily to a few select families.  Longhorned beetles, who combine vibrant colors with grossly elongated antennae and legs.  Scarabs, upping the anty by sporting a monstrously wonderful array of horns or just sheer size to go along with their bright colors.  Tiger beetles, whose elaborate designs and vivid colors are further augmented with toothy-jawed, behavioral charisma.  Yet, it is the Buprestidae upon which the moniker “jewel beetles” has been bestowed, despite their lack of obvious morphological gimmicks – a testament to their bright, sparkling, even gaudy colors and exquisite surface sculpture.

Calodema spp.Some of the most beautiful buprestids in the world are found in the rainforests of southeast Asia, Indonesia, New Guinea and northern Australia.  Genera such as Catoxantha, Chysochroa, Megaloxantha, and Chrysodema come to mind – big, beautiful beetles with screaming iridescence of green, red, yellow and blue.  Living jewels!  These and related genera comprise the great tribe Chrysochroini – the “classic” jewel beetles.  Not as well known but perhaps even more spectacular than the chrysochroines are two genera with strictly Australasian affinities – Calodema (left) and Metaxymorpha (below).  These two genera are the subject of a review authored by Swedish entomologist Ulf Nylander and published in the journal Folia Heyrovskyana by Kabourek.  This gorgeously printed, copiously illustrated, and handsomly bound volume is as much a work of art as it is a technical review.

Metaxymorpha spp.Calodema and Metaxymorpha are among several genera comprising the tribe Stigmoderini in the subfamily Buprestinae.  Six genera, including Calodema and Metaxymorpha, are strictly Australasian, while another five genera are of southern Neotropical occurrence.  This now-disjunct tribal distribution suggests an origin on Gondwana prior to its break up beginning about 167 million years ago during the mid-Jurassic.  Calodema and Metaxymorpha are restricted to New Guinea and its associated islands and the northern and northeastern coastal areas of Australia.  The two genera share certain features that distinguish them from other stigmoderines, notably elongated mouthparts adapted to feeding on nectar and a streamlined, aerodynamically-shaped body with the prosternum (ventral sclerite behind the head) curiously prolonged into a large conical process.  Nylander discusses the possible function of this process in serving as a ballast to help stabilize the flight of these large beetles as they fly through branches and other obstructions in the upper forest canopy searching for flowers on which to feed.  This thought is based on the observation that adult beetles dropped from any angle are able to quickly right themselves and fly away before hitting the ground, while stigmoderines in other Calodema ribbeigenera – lacking the prosternal process – more often drop to the ground and feign death (presumably an adaptation for predator avoidance in the more open environments where they occur).  Calodema and Metaxymorpha are clearly related to each other but are distinguished by the smaller scutellum and nonoverlapping elytra of Calodema versus larger scutellum and distinctly overlapping elytra (in the apical area, usually left over right) of Metaxymorpha.

Fifteen species of Calodema and 18 species of Metaxymorpha are recognized, with comparative tables, figures, and keys provided to differentiate the species and species groups within each genus.  Four species are described as new, including Calodema hanloni, C. longitarsis and Metaxymorpha alexanderiensis from Papua New Guinea, and M. hanloni from Australia.  Species treatments include synonymies, information on type specimens and type localities, label data for specimens examined, detailed descriptions, and comments on distribution and flight periods when known.  Metaxymorpha nigrofasciataHigh quality, full color photographs are provided for every species.  In many cases, multiple specimens are illustrated to show the degree of intraspecific variation encountered in the specimens studied, as shown in the examples included here for Calodema ribbei (above) and Metaxymorpha nigrofasciata (right).  These fabulous plates would almost be enough to justify ‘coffee table book’ status, were it not for the decidedly technical nature of the text itself.  Lest you think this makes for a strictly dry read, there are additional comments for several species regarding historical localities and collection circumstances.  One of the more fascinating is this passage for Calodema vicksoni from Papua New Guinea:

The holotype was captured by a native lady who found this specimen feeding on flowers near her house in the jungle in a very remote location in the Owen Stanley Range.  She caught the beetle and gave it to her husband.  Sadly enough, shortly afterwards she was bitten by a Papuan Blacksnake and died.

The morbid origins of this species become even more gruesome, as Nylander further explains that the species was named to honor the memory of the late Vickson Kotaseao – an associate at the Wei Institute in Papua New Guinea who was the first person to discover the larva of Calodema, and who was later brutally murdered in an ambush while on duty.  The book concludes with a summary of the meager biological information recorded for species of Calodema and Metaxymorpha, including observations of larvae presumed to be Calodema ribbei and their host tree.  As a special bonus, the book comes with a DVD that includes videosequences of adults of several species (Calodema regalis, C. blairi, C. ribbei, C. hudsoni, Metaxymorpha nigrosuturalis, and M. meeki) feeding on their flower hosts in the Australian and Guinean rain forests.  While the color photographs in the book are truly stunning, seeing these beetles on video emphasizes their true spectacularity as living, behavioral creatures and not just dead, pinned specimens.

This book is a beautiful assemblage of all that is currently known about some of the world’s most gorgeous beetles.  Sadly, it also emphasizes just how incomplete that knowlegde really is.  Of the 33 species now recognized in these two genera, 20 of them (60%) have been described in just the past 15 years, and virtually nothing is known of the biology of the vast majority of them.  Seven species are known from just a single specimen, and several more are known by only a very small handful.  In an age where advanced molecular genetic techniques offer great promise for unlocking stores of knowledge about evolutionary relationships among earth’s biota, Calodema and Metaxymorpha offer a sobering reminder that there is still much to do in the less glamorous world of alpha taxonomy.  As noted by Nylander, the center of diversity for these spectacular buprestids appears to be in the Papua New Guinea central highlands – primary rain forests that are increasingly threatened by both legal and illegal logging.  To destroy such a biodiversity “hotspot” would be a sad legacy to leave – but to destroy it without even knowing what was there to begin with would be simply shameful.

I thank Ulf Nylander for granting me permission to scan and post these gorgeous plates, representing but a few of the many beautiful illustrations that can be found in his book.

REFERENCE:

Nylander, U. (2008). Review of the genera Calodema and Metaxymorpha (Coleoptera: Buprestidae: Stigmoderini) Folia Heyrovskyana, Supplementum 13, 1-84.

Two new species of Agrilus from Mexico

ResearchBlogging.orgThe enormous, cosmopolitan genus Agrilus (family Buprestidae – commonly called jewel beetles or metallic woodboring beetles) contains nearly 4,000 described species (Bellamy 2008). With many more still awaiting description, it is perhaps the largest genus in the entire animal kingdom (Bellamy 2003). Agrilus species are primarily twig and branch borers, utilizing recently dead wood for larval development – although there are notable exceptions, e.g. Agrilus anxius (bronze birch borer), A. bilineatus (twolined chestnut borer), and A. planipennis (emerald ash borer), which attack the trunks of living trees and, thus, are of significant economic importance in forest and ornamental landscapes. Host specificity among Agrilus species ranges from highly monophagous – associated exclusively with a single plant species – to rather oliphagous – utilizing several, usually related, plant genera. Adults of Agrilus species are most often found on the foliage of their larval hosts and do not generally visit flowers, as is common in some other genera (e.g., Acmaeodera and Anthaxia). Interestingly, despite the diversity and worldwide distribution of the genus, no species of Agrilus are known to be associated with coniferous plants – a fact that has limited their expansion into the vast northern boreal forests.

Texas, Bexar Co., San Antonio, nr. Fort Sam Houston, em. 25.iv-14.v.1997 ex Phoradendron tomentosum coll. ii.1997, D. Heffern & D. W. SundbergAs can be imagined by its enormity, a comprehensive understanding of the genus will remain a distant goal for many years. Progress will come incrementally, as formal descriptions of new species gradually improve our knowledge of the fauna that exists in each of the world’s main biogeographic provinces. In a recent issue of the online journal Zootaxa, Dr. Henry Hespenheide (UCLA) describes two new species of Agrilus from Mexico. These two species are interesting because of their association with ‘mistletoe’ plants in the genus Phoradendron (family Viscaceae1), obligate hemiparasites that attach to branches and stems of various woody trees and shrubs in tropical and warm temperate regions of the New World. Plants in this genus are known to support a variety of host-restricted insect herbivores, principally in the orders Hemiptera, Coleoptera and Lepidoptera. A single buprestid species has been associated with Phoradendron to this point – Agrilus turnbowi, recently described from specimens reared from dead stems of Phoradendron tomentosum attached to mesquite (Prosopis glandulosa) in southern Texas (Nelson 1990) and pictured here from a specimen in my collection that was reared from dead mistletoe collected at the type locality. At the time of its description, this species was not relatable to any of the other known species in the genus.

1 The Angiosperm Phylogeny Group (2003) includes the Viscaceae in a broader circumscription of the family Santalaceae. However, recent molecular studies suggest the Santalaceae are polyphyletic, with strong support for Viscaceae as a distinct, monophyletic clade (Der & Nickrent 2008).

The two new Mexican species – A. andersoni from Guerrero and Puebla (Figs. 1-3), and A. howdenorum from Oaxaca (Figs. 4-6) – are apparently related to A. turnbowi, which they resemble by their purplish-red coloration and complex pattern of golden setae on the elytra. They are also superficially very similar to each other but differ most notably in size and the overall color and pattern of setae on the elytra.

Figures 1–3. Agrilus andersoni Hespenheide: 1. dorsal habitus; 2. lateral habitus (scale bar indicates 2.0 mm); 3. genitalia of male (scale bar indicates 0.5 mm) (from Hespenheide 2008).

Figures 4–6. Agrilus howdenorum Hespenheide: 4. dorsal habitus; 5. lateral habitus (scale bar indicates 2.0 mm); 6. genitalia of male (scale bar indicates 0.5 mm) (from Hespenheide 2008).

Hespenheide speculates that the color and pattern of the golden setae on the elytra may serve to make the beetles less conspicuous by disruptive coloration, noting the similar coloration of the setae to the leaves of Phoradendron as seen in the photograph of Agrilus howdenorum on its host plant (Fig. 7). This form of crypsis may also be enhanced by the purplish-red ground coloration of the adult, which resembles that of the small, darkened blemishes often observed on the foliage of these plants.

Figure 7. Agrilus howdenorum adult on mistletoe host plant near Diaz Ordaz, Oaxaca, México. The golden setae on the elytra are similar in color to the leaves of the mistletoe and may function as a disruptive color pattern. Photograph by C.L. Bellamy (from Hespenheide 2008).

REFERENCES

Angiosperm Phylogeny Group. 2003. An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG II. Botanical Journal of the Linnean Society, 141: 399-436.

Bellamy, C. L. 2003. The stunning world of jewel beetles. Wings, Essays on Invertebrate Conservation, 26(2): 13-17.

Bellamy, C. L. 2008. A World Catalogue and Bibliography of the Jewel Beetles (Coleoptera: Buprestoidea), Volume 4: Agrilinae: Agrilina through Trachyini. Pensoft Series Faunistica No. 79, 722 pp.

Der, J. P. & D. L. Nickrent. 2008. A Molecular Phylogeny of Santalaceae (Santalales). Systematic Botany, 33(1):107-116.

Hespenheide, H. A. (2008). New Agrilus Curtis species from mistletoe in México (Coleoptera: Buprestidae) Zootaxa, 1879, 52-56

Nelson, G. H. 1990. A new species of Agrilus reared from mistletoe in Texas (Coleoptera: Buprestidae). The Coleopterists Bulletin, 44(3):374-376.

A new species of Xenorhipus from Baja California

ResearchBlogging.orgA few months ago I discussed Trichinorhipis knulli of the tribe Xenorhipidini (family Buprestidae). Members of this tribe exhibit highly sexually dimorphic antennae, with the distal segments of the male antennae highly modified into a very extended flabellate or lamellate condition. The surfaces of the flabellae/lamellae are covered with numerous, presumably olfactory sensillae that are lacking on female antennae (which retain the unmodified serrate condition), strongly suggesting a function involving detection of female sex pheromones. Although chemosensory structures are present on the antennae of nearly all buprestids, the extreme modification exhibited by the males of species in this tribe is not a common occurrence. Nevertheless, similar modifications have evolved independently in a few other genera within the family, including Knowltonia (four species in western North America), Mendizabalia and Australorhipis (monotypic genera in South America and Australia, respectively), and two species of the enormous Australian genus Castiarina. Indeed, males of Knowltonia and the two Castiarina species possess what might be termed ‘bipectinate’ or ‘biflabellate’ antennae due to dual projections from the terminal antennomeres (see Bellamy & Nylander 2007 for a more complete discussion of male antennal modifications in Buprestidae). The tribe Xenorhipidini is the most diverse group in which these modifications have arisen, comprised of the monotypic Trichinorhipis from California and the closely related Hesperorhipis (four species in Arizona and California) and Xenorhipis (until now, 14 species from North and South America and the West Indies).

Xenorhipis bajacalifornica Westcott, 2008 – holotype ♂ (1) & allotype ♀ (2).
Photos by Steve Valley (Oregon Department of Agriculture).

In a recent issue of the online journal Zootaxa, Rick Westcott (Oregon Department of Agriculture) describes a new species of Xenorhipis from the Cape Region of Baja California Sur, Mexico. Although assigned to the genus Xenorhipis, the new species – X. bajacalifornica – seems to bridge the gap between the genera Xenorhipis and Hesperorhipis. As currently recognized, Xenorhipis is distinguished from Hesperorhipis by the shape of the posterior coxal plates, which are scarcely narrowed laterally in the former genus, while in the latter genus they are triangular and with the hind margin strongly oblique. In X. bajacalifornica the posterior coxal plates are somewhat triangular but not as acute laterally as in some species of Hesperorhipis. Xenorhipis bajacalifornica also differs from other described Xenorhipis in its strongly abbreviated elytra, which in males barely reach the second ventrite – similar to species of Hesperorhipis. Other described Xenorhipis exhibit less abbreviated elytra, which cover at least the first three ventrites and in some species almost the entire abdomen. Despite these similarities to Hesperorhipis, a consistent distinguishing character between the two genera was found in the male antenna – in Xenorhipis the flabellar processes begin with the second antennomere, while in Hesperorhipis they begin with the third. It was on this basis that the new species was assigned to the genus Xenorhipis. (The genus Trichinorhipis differs from both Xenorhipis and Hesperorhipis by its rounded rather than quadrate pronotum and its unabbreviated elytra that cover the entire abdomen and has, as a result, been placed in its own subtribe.)

Xenorhipis brendeli ♂Xenorhipis brendeli ♀The photos left show the male (L) and female (R) of Xenorhipis brendeli, the only species in the tribe occurring in eastern North America (west to Minnesota and eastern Texas). Adults of this species are not commonly encountered and have been collected on a variety of deciduous hardwoods but reared almost exclusively from species of hickory (genus Carya). These individuals were reared from dead branches collected in southeastern Missouri – the male from pecan (Carya illinoensis) and the female from shellbark hickory (Carya laciniosa). The male exhibits the scarcely abbreviated elytra that cover almost the entire abdomen (as discussed above). Stan Wellso reported large numbers of males attracted to caged live females in Texas, apparently responding to sex pheromones released by the females.

Xenorhipis osborni ♀Xenorhipis osborni ♂This is another species in the genus – Xenorhipis osborni – known from west Texas. Joseph Knull described the species in 1936 from specimens collected in the Davis Mountains on whitethorn acacia (Acacia constricta), but larval hosts remained unknown until I reared a series of these specimens from dead branches of black acacia (Acacia rigidula) collected above the Pecos River in Val Verde County. I’ve also reared a few specimens from dead branches of catclaw acacia (Acacia greggii) collected in Big Bend National Park, and I wouldn’t be surprised if it breeds in other species of acacia. Again, in this speices the elytra are only slightly abbreviated, though more so than in Xenorhipis brendeli above and also more so in the male (L) than in the female (R). The male of this species is one of the prettiest I’ve encountered in the tribe.

Hesperorhipis albofasciatus ♂Hesperorhipis albofasciatus ♀The genus Hesperorhipis is illustrated here by these photos of H. albofasciatus. These specimens were reared by Rick Westcott from dead branches of walnut (Juglans sp.) – its only known host – collected in Tulare County, California. The elytra in this species are much more abbreviated than in Xenorhipis brendeli and X. osborni but similar to those of X. bajacalifornica – again with the male (L) exhiting greater abbreviation than the female (R). The three remaining species of Hesperorhipis exhibit even more highly abbreviated elytra than H. albofasciatus.

Dr. Charles Bellamy (California Department of Food and Agriculture) is currently revising the tribe. It will be interesting to see how, ulimately, he treats Xenorhipis and Hesperorhipis, given the blended characters exhibited by some species.

REFERENCE

Westcott, R. L. (2008). A new species of Xenorhipis LeConte and of Mastogenius Solier from Mexico, with a discussion of Chrysobothris ichthyomorpha Thomson and its allies and notes on other Mexican and Central American Buprestidae (Coleoptera) Zootaxa, 1929, 47-68

New species and a review of the genus Tragidion

ResearchBlogging.orgSpecies of Tragidion are among the larger and more attractive cerambycids in North America, making them popular among collectors. Their bright orange and black coloration clearly functions in mimicking spider wasps (family Pompilidae) in the genera Pepsis and Hemipepsis – the so-called “tarantula hawks.” Unfortunately, species of Tragidion have been difficult to identify due to a high degree of morphological similarity between species, wide range of variation across geographic areas within species, unusually high sexual dimorphism and dichromatism, and apparent potential for hybridization in areas of geographic overlap. This has confounded efforts to delimit species boundaries, resulting in a confusing assortment of names whose proper application has eluded even the most esteemed of North America’s cerambycid taxonomists. Recently, some much needed clarity was provided by Ian Swift and Ann M. Ray in the journal Zootaxa. Their taxonomic review of Tragidion – the first systematic treatment of the entire genus – recognizes seven species in North America and another four restricted to Mexico. Two species – T. agave from California and Baja California and T. deceptum from montane areas of the southwestern U.S. and northern Mexico (both pictured) – are described as new, and a third – T. densiventre from desert areas of the southwestern U.S. and northern Mexico – is raised from synonymy under T. auripenne. Four new synonymies are also proposed, and dorsal habitus photographs and a key to all species are provided. Life history information is limited for most species of Tragidion. One species – T. coquus – occurs broadly across the eastern and central U.S., where it breeds in a variety of dead hardwoods, especially oak. Several species occur in the southwestern U.S. and northern Mexico – some are found in xeric lowland desert habitats, where they breed in dead branches of Prosopis glandulosa and Acacia greggii (T. densiventre) or dead flower stalks of Yucca and Agave (T. agave and T. armatum), while a fourth (T. deceptum) is found in more montane habitats mining the heartwood of recently dead branches of Quercus. Adults of another species in California and Baja California, T. annulatum, are strongly attracted to brushfires and burning vegetation, and individuals have been observed landing on still-burning and smoldering shrubs, causing their legs and abdomens to melt to the surface of the branches. At several post-burn sites, the melted bodies of this species were common on the charred branches of their hosts, and females have been observed ovipositing on woody shrubs that have been burned. This species likely plays an important role in the decomposition of burned woody material in coastal areas of California. The remaining U.S. species – T. auripenne – is known from only a handful of specimens collected in xeric habitats in the Four Corners region of the southwestern U.S. It’s life history, as well as those of the four strictly Mexican species, remains essentially unknown.

Tragidion agaveTragidion agave Swift & Ray 2008, ♂ & ♀ – California & Baja California. Tragidion deceptumTragidion deceptum Swift & Ray 2008, ♂ & ♀ – southwestern U.S. and northern Mexico.

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