During the last week of August, I teamed up with fellow longhorned beetle enthusiast Jeff Huether to look for species in the genus Crossidius. This exclusively North American genus contains a number of colorful species in the tribe Trachyderini that are associated with woody composites in the genera Ericameria and Chrysothamnus (rabbitbrush) and Gutierrezia (snakeweed). While centered in the vast Great Basin in the western U.S., many species occur further east into the Great Plains, west to the Great Central Valley and deserts of southern California, north into southwestern Canada, and south into mainland Mexico and Baja California.¹ Adults of most species emerge during late summer or fall to coincide with the profusion of yellow blooms that appear on their host plants and upon which the adults can be found feeding, mating, and resting. A conspicuous feature of most species in the genus is extreme polytopism—a consequence of discontinuous host plant distributions across the basin and range topography that has resulted in more or less insular local populations. Not surprisingly, the taxonomic history of the genus is complex, but many of the Great Basin taxa are now regarded as subspecies of two widely ranging species—C. coralinus and C. hirtipes (the latter being, perhaps, the most highly polytopic species of Cerambycidae in all of North America).²
¹ Morris & Wappes (2013) recently described and assigned to this genus a species apparently restricted to relict sand formations in southern Georgia. Its highly disjunct distribution, however, along with significant differences in morphology, habits and biology compared to other species of Crossidius suggest that it might more properly be regarded as a distinct genus.
² Not all longhorned beetle enthusiasts accept the current taxonomy, arguing that species such as C. coralinus and C. hiripes merely reflect clinal patterns of variability. I concede the genus needs further work, as did Linsley & Chemsak (1961), whose generic revision forms the basis for current species/subspecies concepts. I will note, however, that the aforementioned authors examined more than 12,000 specimens during the course of their study, and wholesale dismissal of the subspecies they recognized might be premature until a significantly larger amount of material, preferably supplemented with series of specimens from lesser known geographies as well as molecular data from across their ranges, can be examined.
We flew into Reno and spent the first several days in western Nevada. Jeff arrived the night before I did and, thus, had the chance to scope out Davis Creek Park south of Reno during the morning of my arrival. It must have been to his liking, as after he picked me up at the airport we went straight back to the park and found good numbers of what we consider to be C. hirtipes immaculatus on the stands of rabbitbrush at the park. There were at least two types of rabbitbrush present, with the beetles showing a distinct preference for one over the other (vouchers of both plant species were collected for ID confirmation). Thick haze from the ongoing Rim Fire to the south in the Sierra Nevada had settled over the area, greatly limiting visibility and reducing adjacent Mt. Rose to a faint silhouette but allowing some rather spectacular sunset photos of one of my favorite western jewel beetle species, Agrilus walsinghami, which we found in small numbers on both types of rabbitbrush.
Haze from the Rim Fire settles over Davis Creek Park | Washoe Co., Nevada
The following day we drove to several areas further east near Fallon (Churchill Co.) and along Coal Canyon Road near Lovelock (Pershing Co.), where we found good numbers of C. coralinus temprans on gray rabbitbrush (Ericameria nauseosa). In most spots only a few individuals were found—mostly males, but in one spot south of Fallon we encountered good numbers of the beetles (and the heaviest numbers of mosquitoes from nearby Carson Lake that I have ever experienced!). We were skunked in our attempt to find C. h. bechteli, which has been collected at a few spots across northern Nevada, but we knew it would be a long shot since known records of the subspecies are from mid- to late September. Our visit to the area, however, was not for naught, as the sinking sun in the still smoke-filled sky presented a short window of opportunity for more stunning photos of insects at sunset.
Using the “left wrist” technique for Crossidius coralinus temprans on Ericameria nauseosa | Pershing Co., Nevada
Day 3 was spent dropping south along US-95A in western Nevada towards Yearington and Wellington (Lyon Co.). We made a number of stops and encountered C. c. temprans at most of the rabbitbrush habitats we sampled, but our real quarry was several named subspecies of C. hirtipes—C. h. rubrescens, and in adjacent Douglas Co., C. h. immaculipennis and C. h. macswainei. For much of the day it looked as though we might not find any of the C. hirtipes subspecies, but finally as we approached Yearington we found what we consider to be C. h. rubrescens hiding among the flowers of yellow rabbitbrush (Chrysothamnus viscidiflorus). (In fact, we were actually walking back to the car to leave the spot when we finally spotted a mating pair on a flower. It turns out that we were focusing on the larger Ericameria plants preferred by C. coralinus, rather than the smaller Chrysothamnus plants preferred by C. hirtipes.) Considerable effort was required to collect a decent series and obtain field photographs before the setting sun caused the beetles to retreat and become too difficult to find. It would also be my last opportunity to take dramatic sunset photos, this time with C. hirtipes.
Sage grasslands with established stands of rabbitbrush is perfect Crossidius habitat | Lyon Co., Nevada
Preparing to photograph a mating pair of Crossidius coralinus temprans | Lyon Co., Nevada
We continued our hunt for the other two C. hirtipes subspecies mentioned above on Day 4 in the area around Wellington in Lyon Co. and adjacent Douglas Co. Those of you who think Nevada is desolate and monotonous desert should take the drive south of Yearington through Walker Canyon and then south of Wellington through Toiyabe National Forest to Sweetwater Summit. I guarantee this will be some of the most spectacular countryside you have ever seen. As with C. h. rubrescens the previous day, it took some effort and trying several spots before we found a population in Douglas Co. west of Wellington that we consider to represent C. h. immaculipennis. They were co-occurring with almost equal numbers of C. ater, a widespread, all-black species that shows no appreciable variation across its range but which has been implicated in providing melanism to several C. hirtipes subspecies through introgressive hybridization (Linsley & Chemsak 1961). Eventually we decided we had sufficient material of C. h. immaculipennis and drove back through Wellington and south towards Sweetwater Summit, stopping at several spots along the way but finding nothing on either the Ericameria or Chrysothamnus. Finally, at the summit we found a single individual of C. h. macswainei, which I photographed later that evening. At the time we thought it was the only individual of this subspecies that we had collected on the trip, but closer examination of the material collected north of Yearington since returning home suggests that it may actually be a mixture of C. h. rubrescens and C. h. macswainei. [Clearly the taxonomy needs to be adjusted if this is the case; either the two taxa are not valid subspecies (in which case intermediates should also be found), or they actually represent two closely related but nevertheless distinct and partially sympatric species.]
Toiyabe National Forest, Nevada—what people think…
Toiyabe National Forest, Nevada—the real thing (made even more dramatic by the setting sun)!
On Day 5 we continued our southward march, crossing over the Nevada-California border along US-95 and dropping south along the eastern flank of the Sierra Nevada—first into Mono Basin and then into Owens Valley. For me it was a return to one of my favorite places on earth, which I last visited way back in 1995 while living in California. We stopped briefly at Topaz Lake and found a few Cicindela o. oregona that proved to be extremely wary (white box photography alert), but our real target was C. h. flavescens, known only from the area around Kennedy Meadow in Inyo Co. Unfortunately, we didn’t pay attention to the county and went instead to Kennedy Meadows in Tuolomne Co.! Needless to say, while we did find some stands of Ericameria we did not find any Crossidius beetles, and it would not be until after the trip was over that we discovered our error. Nevertheless, the drive up the eastern flank of the Sierra Nevada, over Sonora Pass, and partway down the western flank to Kennedy Meadows allowed us to “clean up” on C. ater and offered spectacular scenery despite the continued cloaking of haze from the now much nearer Rim Fire. Jeff also managed to find the only specimen of C. punctatus that we would see on the trip.
Sonora Pass | Mono/Tuolomne Co., California
Lodgepole pine (Pinus contorta murrayana) cadaver at Sonora Pass
We continued south along US-95 into Mono Basin towards a locality near Mammoth Lakes to look for the spectacular orange subspecies C. c. monoensis. Of course, one cannot drive right through the Mono Lake area without stopping and every Vista Point and at the lake itself to admire its strange, almost moonscape-like tufa towers. It was getting late in the day, so I found myself in a bit of a race to photograph the towers before they were covered by the advancing shadows from the Sierra Nevada to the west. I did not succeed completely, but the resulting photos with contrasting “black and white” towers made for nevertheless interesting photos.
Mono Lake Vista Point along US-395 | Mono Co., California
Great Basin fence lizard (Sceloporus occidentalis longipes) at Mono Lake Vista Point
Tufa towers at Mono Lake | Mono Co., California
Late afternoon shadows create an interesting “black/white” contrast between shaded and sunlit tufa.
Eventually we resumed our southward trek and, with daylight waning rapidly, arrived at a spot near Mammoth Lakes where Jeff had taken C. c. monoensis in the past. We were rewarded with a few males and females, and I was able to take some rather spectacular field photographs of each. Until now, all of the C. coralinus I had seen were deep red and black, but these were bright orange with only a little bit of black—gorgeous! After failing in our attempt to find C. h. flavescens, finding this subspecies rescued the day as a success, and we were able to complete our drive into Bishop and spend the next day focusing on additional subspecies in Owens Valley and the White Mountains.
The eastern slopes of the Sierra Nevada rise dramatically in the distance | Mono Co., California
Mono Basin near Mammoth Lakes (7000 ft)—locality for Crossidius coralinus monoensis | Mono Co., California
Our first stop on Day 6 was just a short 2.5 drive north from our hotel in Bishop, where we found a very nice population of C. c. caeruleipennis. If you think C. c. monoensis is spectacular, wait until you see this subspecies bearing the same bright orange coloration as C. c. monoensis but larger and even less maculated with black—the males are almost pure orange! I presume we were on the early side of things (as with most of the populations we found), as the plants were just on the early side of blooming and the majority of individuals encountered were males (which tend to emerge earlier than females). The occasional E. nauseosa plant in full bloom often had several individuals on it, including mating pairs.
Owens Valley near Bishop (4000 ft)—locality for Crossidius coralinus caeruleipennis | Inyo Co., California
With success already in hand, we continued south into the White Mountains to the area around Westgard Pass where a particularly dark subspecies—C. h. nubilus is known to occur. As we experienced earlier in the week, success did not come until we stopped searching the larger, more conspicuous Ericameria plants and focused on the much smaller and less conspicuous C. viscidiflorus plants. While I did manage to take some field photographs, the beetles were not numerous and I held some alive for photographs in the hotel room later than night. The beetles also seemed to be curiously patchy in their occurrence, with large stretches of seemingly good plants hosting none and the majority found in two small, localized spots in the area west of the pass.
Pinyon-juniper zone near Westgard Pass—locality for Crossidius hirtipes nubilus | Inyo Co., California
Under normal circumstances, I would have been content to close out the day looking for additional beetles to strengthen my series in the hopes of getting a good representation of the variation present in the population, but these were not normal circumstances—we were only a short drive from Ancient Bristlecone Pine Forest. Despite living in California for five years back in the 1990s, I never took the opportunity to visit this place and explore its incredible stands of Great Basin bristlecone pine (Pinus longaeva). The oldest non-clonal tree in the world, dated to nearly 5000 years old, occurs in this area, and many of the trees in the forest range from 1000–2000 years old. Indescribable is the only adjective that I can offer for one’s first sight of these trees, many gnarled and grotesquely twisted by age and wind, the older ones often with nothing but a narrow strip of living wood connecting the roots to a small group of live branches on an otherwise dead tree.
Great Basin bristlecone pines (Pinus longaeva) | Ancient Bristlecone Pine Forest, Inyo Co., California
Sitting next to an ancient cadaver—who knows how old it is?
Spectacular vistas around every bend at Ancient Bristlecone Pine Forest.
Female cones bear longish, incurved bristles on the tips of their scales.
Great Basin bristlecone pines are restricted to high elevations in California, Nevada, and Utah.
On Day 7 we left Bishop and headed back north to Mono Basin to take another shot at C. c. monoensis and also look for C. h. rhodopus, the latter being a particularly reddish subspecies known only from Mono Basin. We had not seen the latter in our cursory look at Mono Basin habitats two days ago, and it continued to elude us at several stops in areas supporting the C. viscidiflorus host plants on which we expected it to occur (although we did manage to find a few more C. c. monoensis at the locality near Mammoth Lakes). I had collected C. h. rhodopus almost 20 years ago—my last trip to the Mono Basin—at a spot in the Benton Range at the south end of the Mono Basin (which also happens to be the type locality for the jewel beetle Nanularia monoensis, described by my late friend Chuck Bellamy in his 1987 revision of the genus). As a remembrance of Chuck I thought it would be nice to find and photograph N. monoensis as well, so we headed towards the Benton Range as our last stop in California before heading east through the Great Basin to look for additional C. hirtipes and C. coralinus subspecies. As we drove, we saw robust stands of C. viscidiflorus in Adobe Valley stretching south of Mono Lake towards the northern terminus of the White Mountains and decided to stop on the chance we might find C. h. rhodopus there. It’s a good thing we did, as the beetles were out in force. I tried photographing some individuals in the field, and while I did get some decent shots the beetles were generally too flighty and active to justify the effort. I was also anxious to look for N. monoensis, so I put a live male and female in a vial with a piece of host for photography later that evening and we continued towards the Benton Range.
Adobe Valley near the White Mountains—locality for Crossidius hirtipes rhodopus | Mono Co., California
Despite its close proximity to the comparatively lush Adobe Valley, conditions in the Benton Range were exceedingly dry. We searched around a bit, but it was apparent by the lack of any herbaceous plants or fresh growth on perennial plants that the area had not received rain for an extended period of time. In fact, I could not even find a single buckwheat (Eriogonum kearneyi var. monoensis) plant on which to search for jewel beetles. The only beetles seen were an aggregation of ~15 C. ater and C. h. rhodopus adults on a single E. nauseosa plant that, unlike the other plants in the area, somehow managed to achieve full bloom. Nevertheless, it was great to visit the locality and rekindle memories after so many years absence. Once we convinced ourselves that there were truly no more beetles to be had, we began the first leg of our long, 2-day drive across the southern Great Basin for the final phase of the trip.
The Benton Range is the type locality of Nanularia monoensis | Mono Co., California
The White Mountains form a dramatic backdrop behind the Benton Range | Mono Co., California
The author takes a “pensive” selfie | Benton Range, Mono Co., California
We spent the night in Tonapah, Nevada and began Day 8 by driving east along US-6, stopping along the roadsides periodically whenever particularly promising-looking stands of Ericameria/Chrysothamnus were seen. We had expected to begin finding populations assignable to subspecies C. h. brunneipennis as soon as we left Tonapah, but for the most part searching during the morning hours was fruitless. We did find single male and female examples from south-central Nevada of what seems to best fit C. coralinus coccineus (known mostly from southwestern Utah), but it was not until late morning when we were within about 30 miles of Ely in east-central Nevada that we began finding adults of C. hirtipes brunneipennis. At first they were scarce and difficult to find, ensconced as they were within the flowers of their C. viscidiflorus hosts, but shortly they began to appear in great numbers and offered opportunity for field photographs and good series. We had observed on several days of the trip that C. hirtipes began ‘disappearing’ during late afternoon, in contrast to C. coralinus which tended to settle down within the flowers of their host plant where they could be found even at dusk (and perhaps all night had we searched for them at that time). I now believe that C. hirtipes tends to crawl down to the base of the host plant to spend the night and requires some period of warming temperatures before they come back up to the flowers the following morning, and that this is the reason why we did not succeed in finding populations further to the west in the areas we searched after leaving Tonapah in the morning. In contrast, we rarely failed to succeed in finding C. coralinus in the locations where they occur during early morning or early evening hours.
A short drive further east to Ely got us within range of the darkened subspecies C. h. cerarius, and at the first stop south of town sporting a good stand of C. viscidiflorus we found this one also in good numbers. Another short drive further east to near the Utah border brought us within the western limit of the final C. hirtipes subspecies that we were targeting—C. h. wickhami. Unlike the previous subspecies, which has an extremely limited distribution in east-central Nevada, C. h. wickhami is widespread from east-central Nevada across western Utah and northern Arizona. We waited until we crossed the Utah border, stopped at the first stand of C. viscidiflorus that we saw, and found decent numbers of this subspecies distinguished by its light coloration and distinct sutural stripe.
Yellow rabbitbrush (Chrysothamnus viscidiflorus) host for Crossidius hirtipes wickhami | Millard Co., Utah
We needed to make it to Moab, Utah in the evening, so we began the long trek across southern Utah. There is another C. coralinus subspecies known from southwestern Utah that we could have targeted—C. c. coccineus, but we had both already collected examples of this subspecies in Cedar City, Utah during a tour of the Great Western Sand Dunes two years ago. Finding a male and a female of what seem to be this subspecies fulfilled my desire for photography subjects, and there were additional C. coralinus subspecies to be had further east that I had not yet collected. As I first learned two years ago, and which was again confirmed on this trip, southern Utah has some of the most dramatic scenery in all of the western U.S. Period! The photos below are but two examples of the many spectacular sights that I saw, and more now than ever I hope to return to this area in the future for serious exploration.
A thunderstorm settles over the Cricket Mountains behind Sevier Lake | Millard Co., Utah
A late afternoon rainbow dissipates over Devil’s Canyon | Emery Co., Utah
The last field day of a trip is always a bit melancholic—I’m never happier than when I’m in the field, and when I’m having particularly good luck it makes the end of the trip even harder to think about. The best cure for melancholy, however, is more success in the field, and Day 9 started off with a bang. We had driven less than 40 miles south of Moab when we saw good looking stands of E. nauseosa and C. viscidiflorus, and on the very first plant we checked sat a spectacular female representing the robust, bright red and heavily marked nominotypical C. coralinus. Only a few more were found during the ensuing search until I found a “mother lode” plant hosting two mating pairs and three singletons. As it was still fairly early in the morning, the beetles were quite calm and I was able to fill my photographic quota of the subspecies with nice field shots of both sexes. We stopped at several more spots as we approached and crossed into Colorado, including Cortez where we found nice numbers of super-sized individuals. Mindful of the time, we tore ourselves away and continued east to the area around Fort Garland in south-central Colorado, where Jeff had previously seen C. c. jocosus—similar to C. c. coralinus but unusually diminutive in comparison. Anticipation, however, got the better of us before we made it to Fort Garland, for after passing through the San Juan Mountains we stopped at a few spots around Monte Vista on the western side of the San Luis Valley (Fort Garland lies further east on the opposite side of the valley). Good fortune awaited us, as we found a handful of individuals at two sites that appeared to represent C. c. jocosus, reducing the importance of getting to Fort Garland and finding them there. The sites where we found these beetles might represent the western limit of distribution for the subspecies, which would seem to be isolated from C. c. coralinus by the intervening San Juan Mountains. It’s a good thing we stopped at those sites, as further east near Fort Garland nearly all of the plants were past peak bloom and no beetles were seen. Only a last ditch stop at a stand of plants just east of Fort Garland produced a single male and single female to add to those we had collected earlier, but it was enough to put a smile on the face and make it easier to accept that a long, successful trip had finally come to an end. We recounted our successes during the 3-hour drive to Denver: 14 of 16 targeted taxa successfully located, plus an additional three taxa not targeted for a total count of 17 named taxa.
Photographing insects on Ericameria nauseosa | San Juan Co., Utah
In closing this report, I should note a few caveats:
- Identifications are preliminary and based primarily on expected geographical occurrence along with cursory comparison to descriptions and diagnoses published in Linsley & Chemsak (1961). Some modifications to these identifications might occur after collected material has been examined more closely (e.g., the possible co-occurrence of C. h. rubrescens and C. h. macswainei at a locality just north of Yearington, Nevada). This also applies to host plant identifications; however, voucher samples were collected from almost every location and will be submitted to specialists for ID confirmation.
- All of the photos in this post were taken with my iPhone. This does not mean that I have no photos taken with my ‘real’ camera to share—these will be forthcoming in future posts that examine many of the above mentioned subjects in more detail (as well as a few additional subjects not mentioned above). This also does not mean that these photos are ‘straight from the phone’—they have been post-processed in much the same way I process photos taken with the digital SLR to emphasize their good qualities and minimize their bad ones. I choose to include only iPhone photos in this post since the iPhone is what I mostly use to document a general ‘flavor’ of the trip, saving the digital SLR for true macro-photography or subjects requiring the highest possible quality. Aw heck, here’s a ‘real’ photo of one of the insects I found on the trip to whet your appetite for posts to come:
Crossidius coralinus temprans (female) on stem of Ericameria nauseosa | Churchill Co., Nevada
REFERENCES:
Bellamy, C. L. 1987. Revision of the genera Nanularia Casey and Ampheremus Fall (Coleoptera, Buprestidae, Chalcophorinae). Contributions in Science, Los Angeles County Museum of Natural History 387:1–20.
Linsley, E. G. & J. A. Chemsak. 1961. A distributional and taxonomic study of the genus Crossidius (Coleoptera, Cerambycidae). Miscellaneous Publications of the Entomological Society of America 3(2):25–64 + 3 color plates.
Morris, R. F., III & J. E. Wappes. 2013. Description of a new Crossidius LeConte (Coleoptera: Cerambycidae: Cerambycinae: Trachyderini) from southern Georgia with comments on its biology and unusual distribution. Insecta Mundi 0304:1–7.
Copyright © Ted C. MacRae 2013
