Arthropoda

Arthropods – insects, arachnids, crustaceans, myriapods, & relatives

Saltatorial sidetracks

/ Ted C. MacRae / 6 Comments

One thing I’ve realized during these past several years of fall collecting is that there are more than just tiger beetles to capture my interest as the field season enters its final days.  The late season floral burst of goldenrods (Solidago spp.) and tall thoroughwort (Eupatorium altissimum) brings forth a multitude of bees, flies, wasps, and soldier beetles.  Megacyllene robiniae, the locust borer (family Cerambycidae), is also a pleasant, if not pedestrian sight on the goldenrod as well, but if one is lucky to find goldenrod near a patch of Amorpha fruticosa (indigo bush), then its larger, more boldly marked and infinitely more exciting congener M. decora (indigo borer) might also be seen.  Nothing, however, seems to match the diversity and abundance during fall of the great order Orthoptera – grasshoppers, katydids, and crickets.  This is particularly true in the Ozark glades and Great Plains grasslands where I’ve spent the majority of my fall collecting time.  Perhaps it is because of their size – for the most part they are relatively large insects compared to the beetles I normally study, or maybe it is their pervasive reliance on sound – singing in the grass, rasping in the trees, snapping their wings in flight.  Bold and conspicuous, they demand attention.

Increasingly, I’m finding these fall hoppers harder and harder to resist, especially grasshoppers of the family Acrididae.  Until now I don’t think I’ve given grasshoppers their due respect – compared to my beetles they always seemed so… primitive.  No horns, no jeweled, metallic sculpturing, no over-sized jaws, no unique morphological specializations of any kind other than enlarged, saltatorial (modified for jumping) hind legs – they sport the quintessential ‘general’ insect body plan (open up any college introductory entomology textbook, and what do you see illustrated in the general morphology chapter… a grasshopper!).  Even their movements seemed to me somehow mechanical and robotic.  I always brushed them off as just basic insects, unrefined and uninteresting.

Of course, they are anything but uninteresting – in fact, orthopterans as a whole are among the most popular of insect groups if the number of recently published field guides is any indication.  One of these is The Grasshoppers (Orthoptera: Acrididae and Romaleidae) of Nebraska (2008), authored by Matthew L. Brust and colleagues, and a copy of which I received as a gift from the senior author during my recent collecting trip to Nebraska and surrounding areas.  According to this book, the grasshopper in these photographs is Hippiscus ocelote – the wrinkled grasshopper, a large, handsomely robust species distinguished by the single cut in the pronotum and its surface sculpturing, the orange hind tibia, and the triple-banded and basally blue inner surface of the hind femur.  The species is generally brownish throughout, but this particular individual – seen in the White River Hills of southwestern Missouri in early September – sported a decidedly reddish head and pronotum that contrasted beautifully with its spotted wings and forced me to stop searching for tiger beetles and spend some time photographing it.

There are many reasons why I should not let myself get interested in grasshoppers – they’re big and take up a lot of space (a premium in most private collections such as mine), and by any standard my interests are already spread too thin.  Still, I think it is better to have too many interests than not enough, and a Schmidt box or two full of some of the more interesting grasshoppers that I’ve encountered – properly curated and identified – wouldn’t take too much away from my beetle efforts.  I already have a few specimens of Trimerotropis saxatilis (lichen grasshopper) from Missouri’s igneous glades and the related T. latifasciata (broad-banded grasshopper) from Oklahoma’s Glass Mountains, so a small assortment of other notable species in addition to them couldn’t hurt, right?

Photo Details: Canon 50D w/ 100mm macro lens (ISO 100, 1/250 sec, f/16-f/20), Canon MT-24EX flash (1/2 ratio) w/ Sto-Fen + GFPuffer diffusers. Typical post-processing (levels, minor cropping, unsharp mask).

REFERENCE:

Brust, M. L., W. W. Hoback and R. J. Wright.  2008. The Grasshoppers (Orthoptera: Acrididae and Romaleidae) of Nebraska.  University of Nebraksa-Lincoln Extension, 138 pp.

Copyright © Ted C. MacRae 2010

Missouri’s disjunct population of Cicindela obsoleta vulturina

/ Ted C. MacRae / 18 Comments

Although I’ve been collecting insects since I was a kid (and seriously for nearly three decades), it has only been in more recent years that fall has become an important part of the collecting season for me. With the notable exception of Fall 1978, when the Systematic Entomology course I was enrolled in sent me on a frantic quest to become one of the few undergraduate members of the exclusive “200 family” club (I got 205!), I long viewed fall as a time to hang up the net and begin the winter-long process of mounting, labeling, and curating the hundreds – sometimes thousands – of specimens I had collected earlier in the year during spring and summer.  This has primarily been a reflection of my taxonomic interest – woodboring beetles in the families Buprestidae and Cerambycidae, which occur at their overwhelmingly greatest abundance and diversity throughout most of North America during spring and summer but are found only sparingly later in the season.  Tiger beetles (family Cicindelidae) changed all that, and when I first began serious study of the group around 10 years ago, I found the combination of gorgeous weather and multitude of “spring/fall” species that emerge briefly during fall an irresistible siren call to the field. I’ve not looked back, and the Annual Fall Tiger Beetle Collecting Trip™ is now an established and eagerly anticipated event.

Cicindela obsoleta vulturina - the prairie tiger beetle (Blackjack Knob, Taney Co., Missouri).

No species embodies all that I love about fall tiger beetle collecting more than Cicindela obsoleta vulturina, the prairie tiger beetle. I first learned of the occurrence in Missouri of this large, dark green species back in 2000, when I saw a single specimen in the Enns Entomology Museum collected in Protem, Taney Co.  I was just beginning my tiger beetle studies and would later learn what the Tiger Beetle Guild already knew – that the occurrence of this species in Missouri was restricted to cedar glade habitats in the White River Hills region in the extreme southwestern part of the state, and that the population occurring there and in adjacent northern Arkansas was disjunct by 300+ miles from the main population in Texas and Oklahoma.  I couldn’t wait to see it for myself and eventually enlisted the help of Eric Eaton, living in the area at the time, and asked him to let me know if he saw a large green tiger beetle after the late summer rains began.  That September, I got a message from Eric saying that he had seen just such a beast not far from his home, and the following weekend he and I would enjoy the chance to meet each other in person and the splendor of the season while finding this marvelous species at several locations in the area.  Thus began my love affair with this species, and for several years I returned to the area each fall to document additional localities for this and other tiger beetle species occurring in the area.

Blackjack Knob is part of an extensive xeric dolomite prairie complex (commonly referred to as cedar glades, though the term is not precisely accurate) in the White River Hills subsection of the Ozark Highlands, providing habitat for prairie tiger beetles and other typically southwestern plants and animals.

In fact, until a few weeks ago it had been several years since I had last seen this species in the field.  I did make an attempt to see it again last year but returned home from that early October trip unsuccessful, cold and wet.  Thus, when tiger beetle enthusiast Steve Spomer mentioned to me earlier this summer that he wanted to see our Missouri population, I jumped at the chance to coordinate our visits this fall and show him some of my favorite sites.  The Patron Saint of Cicindela was smiling down upon us that day, as perfect timing and sunny skies combined to bring adults out in an abundance that I’d not seen in any of my previous visits.  I would take advantage of this rare opportunity and spend the next day in the area as well, documenting a number of new localities along the northern and eastern edge of its known distribution, including a far eastern extension of its range to Caney Mountain Conservation Area in Ozark Co. where we had long suspected the beetle to occur but failed in all previous attempts to find it.

Steve Spomer and yours truly at Cane Creek Rd. site.

The prairie tiger beetle is the easternmost subspecies of the large grassland tiger beetle, which along with its other included subspecies covers a geographic range covering most of Texas, New Mexico, and eastern Arizona and extending up through western Oklahoma and Kansas into eastern Colorado.  Individuals of subspecies vulturina, occurring primarily in eastern/central Texas, are distinguished from the other subspecies (nominate in western Texas and eastern New Mexico north into Colorado, santaclarae in New Mexico and Arizona, and neojuvenilis in south Texas) by their generally black to olive-green coloration and reduced, narrow elytral markings, typically with an inverted “V” at mid-elytron.  The Missouri/Arkansas disjunct population is interesting from several standpoints:

  • Individuals mostly dark olive-green – no black individuals.
  • Elytral maculations more completely developed.
  • Adults active in late summer/early fall rather than summer.

These features, in particular coloration and maculation, have fueled speculation that this isolated population might be subspecifically distinct (Pearson et al. 2006).  A recent review of material from throughout its range found these color characters of limited use in unequivocally diagnosing individuals from the Missouri and Arkansas population as a separate subspecific taxon (Mawdsley 2009); however, a molecular systematics approach ultimately may be needed to resolve the status of this population.  Presumably, the Missouri/Arkansas disjunct population represents a hypsithermal relict, left behind when the return of cooler, moister conditions caused a retreat of the formerly more expansive grasslands to their current position.  If true, then the Missouri/Arkansas population has been isolated from the parent population for ~6,000 years.  I suspect that the late summer/early fall adult phenology is an adaptation to local precipitation patterns, relying on more predictable late summer rains to trigger adult emergence after the generally droughty months of July and August.  In this regard it differs fundamentally from the true “fall” species, which emerge briefly in the fall as sexually immature adults before overwintering and re-emerging in the spring for mating and oviposition.  These Missouri/Arkansas disjuncts do not re-emerge in spring, but instead mate and lay eggs in the fall before the onset of cold weather.  The eggs hatch as well (based on my growth chamber observations of this species), so winter also is passed as a larva – either as newly-hatched 1st instars, or as later instars that hatched during the previous year(s) – rather than as adults.

I have noted considerable variation in the coloration and maculations of individuals in this population.  The individual in the first photograph above is typical of the population – dark olive-green with thin but nearly complete maculations.  That individual comes from Blackjack Knob (Taney Co.), which is near the heart of the White River Hills region.  However, the degree to which the maculations are developed is variable, ranging from rather incomplete to even more fully developed due to the presence of a marginal connection.  Additionally, a few individuals can be found that show greater or lesser suffusion of brown on the head, pronotum, and elytra.  At another location in the county closer to the northern distributional limit (Hwy 160/Cane Creek Rd.), this brown suffusion is more common and variably expressed from minimal to nearly complete.  The photographs below show five individuals from this site expressing differing degrees of brown as well as the variable macular development seen throughout the population:

Male (Hwy 160/Cane Creek Rd.) - green w/ trace brown, marginal band incomplete, median band complete.


Female (Hwy 160/Cane Creek Rd.) - green w/ slight brown, marginal band complete, median band incomplete.


Male (Hwy 160/Cane Creek Rd.) - green w/ moderate brown, marginal band incomplete, median band incomplete.


Male (Hwy 160/Cane Creek Rd.) - green w/ heavy brown, marginal band complete, median band complete.


Female (Hwy 160/Cane Creek Rd.) - completely brown, marginal band complete, median band incomplete.

There is another site even further north in the county (Merriam Woods), which I found for the first time on this trip and, to my knowledge, represents the northernmost extent of the population in Missouri.  At this site, nearly all of the individuals show coppery-brown coloration with almost no hint of green.  These fully brown individuals seem to represent an appearance that is completely unlike that seen in any other part of the range of the species.  The individual in the photo below typifies the appearance of the beetles seen at this site:

Male (Merriam Woods) - brown, marginal band incomplete, median band complete.

I’m less familiar with coloration of the population further south in Arkansas, although in my limited collecting in that area I recall that most individuals I encountered exhibited the dark olive-green coloration typical of individuals at Blackjack Knob and other more southern sites in Missouri.  Thus, there seems to a clinal element to variability in coloration in the Missouri/Arkansas disjunct population.  I suspect that the unique coloration of the beetles in this population is related to the soils with which they are associated.  Light gray Jefferson City-Cotter dolomite bedrock forms the core of the White River Hills landscape and is exposed extensively in the glades that dominate its knobs and slopes.  These exposures are weather-stained black and overlain by thin, black soils that support dark, green-black lichens amongst the sparse vegetation, as seen in the following photographs taken at the newly identified northeasternmost site at Caney Mountain Conservation Area:

Thinly soiled dolomite exposures punctuate the glades in the White River Hills. Prairie tiger beetles are found in these exposures.


Dark green-black lichens encrust the thin black soils overlaying the dolomite exposures. Prairie tiger beetle adult coloration closely matches the coloration of the lichens and soil.

The glades and dolomite exposures where these beetles are found in the White River Hills and the dry oak woodlands that surround them have a characteristic look that is not seen once one leaves the area, and I have found many new sites for the beetle in the northern and eastern fringes of the region by stopping at locations where the roadside exposures had the right “look.”  The variation in maculation and coloration seen in this population may be an indication that the population is still adapting to local conditions since becoming isolated from main population.

Currently, I have 3rd-instar larvae that I collected from their burrows at Blackjack Knob (adults mostly green) and Merriam Woods (adults mostly brown) and hope the rear them to adulthood next year.  If I succeed in getting virgin adults from the two sites, I think it would be interesting to do some single-pair crossings and rear the progeny to see how coloration is expressed.  A long term project, for sure, as these beetles probably require at least two seasons to reach adulthood, but rearing them is fun!  A more difficult, yet far more interesting, project would be to secure virgin adults from the mostly black main population in Texas – or even the bright green, thickly-maculated santaclarae subspecies from Arizona – to see how interbreeding them with these Missouri disjuncts would affect coloration and maculation in their progeny – they could be some of the most unusual appearing large grassland tiger beetles ever seen (not to mention their tongue-twisting taxonomic moniker of Cicindela (Cicindelidia) obsoleta vulturina [Missouri disjunct] x obsoleta santaclarae!).  Timing would be a difficulty, since the Texas and Arizona populations exhibit a more normal summer adult phenology, but it would be worth a try if I could secure a source of larvae for rearing.  Anybody?

A male sports his impressive pair of choppers.

Photo Details (insects): Canon 50D w/ 100mm macro lens (ISO 100, 1/250 sec, f/13-22), Canon MT-24EX flash (1/4-1/2 ratio) w/ Sto-Fen + GFPuffer diffusers. Typical post-processing (levels, minor cropping, unsharp mask).

REFERENCES:

Mawdsley, J. R.  2009. Geographic variation in U. S. populations of the tiger beetle Cicindela obsoleta Say (Coleoptera: Cicindelidae).  Insecta Mundi 0094:1–10.

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

Jeepers Creepers, where’d ya get those multilayered retinae?

/ Ted C. MacRae / 28 Comments

A few weeks ago I was fortunate to get a chance to blast down to the White River Hills in extreme southwestern Missouri.  Cicindela obsoleta vulturina (prairie tiger beetle) was my quarry – I had made arrangements to meet up with fellow cicindelophile Steve Spomer (principal author of Tiger Beetles of South Dakota & Nebraska, Spomer et al. 2008) and show him a few of the better sites I had found for this species.  We would have good success due to gorgeous fall weather and perfect timing, and the next day I would be fortunate to extend its known distribution further north and east.  Still, the beetles are not early risers, and I found myself that second morning with some time on my hands while waiting for these sleepy-heads to arise from their slumber and begin their foraging activities.  As I trolled the thinly soiled dolomite exposures of a new site I had identified the previous day, a spot of red jerking erratically through the sparse vegetation caught my eye, and looking closer I was delighted to see this small but brilliantly colored jumping spider (family Salticidae) trying to evade my gaze.

Jumping spiders are perhaps the most diverse of all spider families, but it is their extraordinary visual capabilities and complex predatory and courtship behaviors that they are best known for.  Popular as research subjects, to the rest of us they are simply endearing little animals.  Some of the largest and most colorful jumping spiders belong to the genus Phidippus, which is also one of the most diverse genera in the family and boasts some 60 species in the continental United States (Edwards 2004).  The genus is characterized by details of the eye placement and carapace shape (Richman 1978) but can often be recognized by their relatively large size, numerous erect hairs, and conspicuous iridescent chelicerae just below the front eyes.  The species can be quite difficult to identify, especially the females, but I feel reasonably confident that this individual is a male of the widespread species P. apacheanus.

I wasn’t always so confident – browsing images on BugGuide left me confused after finding images of P. apacheanus and P. cardinalis males that looked almost identical. However, further digging reveals P. apacheanus is characteristically a more intense red, while P. cardinalis is more orangey with lighter bristles which may appear silvery.  Also, P. cardinalis often displays makings on the abdomen – generally a light line running around the anterior part of the abdomen and sometimes tiny light spots on the dorsum – that are absent in P. apacheanus.  (This begs the question as to whether some of the BugGuide photos may be misidentified?)  Another Phidippus species that might be confused with P. apacheanus is P. clarus; however, that species has a black cephalothorax and bright abdominal markings.  According to Herschel Raney, P. apacheanus is most often seen in fall.

This was a very difficult subject to photograph.  He refused to come out in the open, preferring to duck and peek from behind whatever vegetation he could find.  Realizing that my desire to photograph him without any manipulation would be a lesson in futility, I used my finger to prod him towards and onto a small, flat, lichen-encrusted rock, where he would look at me with ever-increasing alarm and try to flee at the approach of the camera.  Lots of failed shots were discarded in the field before I finally got a few I thought I could live with (which, I think, are a decided improvement over my first jumping spider photos).  As I zoomed in for the closeups, I saw for the first time the shimmering of his multilayered retinae moving in the depths of his primary medial eyes.  The retina is the darkest part of the eye, thus, when the eye is at its darkest the spider is looking straight at you!

Photo Details: Canon 50D w/ MP-E 65mm 1-5X macro lens (ISO 100, 1/250 sec, f/13), Canon MT-24EX flash (1/8 ratio) w/ Sto-Fen + GFPuffer diffusers. Typical post-processing (levels, minor cropping, unsharp mask).

REFERENCES:

Edwards, G. B.  2004. Revision of the jumping spiders of the genus Phidippus (Araneae: Salticidae). Occasional Papers of the Florida State Collection of Arthropods 11:i-viii, 1-156, 350 figs.

Richman, D. B.  1978. Key to the jumping spider (salticid) genera of North America.  Peckhamia 1(5):77–81.

Spomer, S. M., M. L. Brust, D. C. Backlund and S. Weins.  2008. Tiger Beetles of South Dakota & Nebraska. University of Nebraska, Department of Entomology, Lincoln, 60 pp.

Copyright © Ted C. MacRae 2010

Quick Business…

/ Ted C. MacRae / 2 Comments

I’ll have a “real” post ready shortly, but I wanted to make a quick note of a few items that have popped up recently:

  • Cylindera celeripes – this, of course, is the swift tiger beetle, a quite rare species of tiger beetle that I’ve been studying for the past two years.  I am preparing a manuscript (now in its final stages) that will review the species’ historical occurrence, document the new records I’ve accumulated for it, and discuss its potential conservation status.  I’ve gotten specimen label data from university collections in IA, KS, NE, OK, and TX (known range of the beetle) and from a number of private tiger beetle collectors.  However, I would like to make the story as complete as possible and am looking for any other repositories that might contain additional specimens.  If you know of such in your local university museum (other than those in the states listed above), I would appreciate knowing about them and getting ahold of their label data.
  • The Southern Fried Science Network has just launched a new group blog called Journeys, which they hope will serve as a central hub for writing about scientific field work and expeditions.  It’s a unique concept where contributors will post updates, stories, discoveries, and observations in the course of conducting their fieldwork.  The site has already been populated with a number of expedition logs (including a couple of my own).  I’m anxious to see if this takes off, as its field-work focus is right up my alley.  A link has been added to my sidebar under the heading “Field Work”.
  • Every now and then, someone asks me why I collect insects.  More specifically, they want to know why I must collect the insects that I find, rather than simply observing them in the field, making notes, and then letting them go on their merry ways.  Some are truly curious, while others adopt the more judgmental stance that collecting insects now is akin to the days of ornithology when birds were observed not through binoculars, but through rifle scopes before being shot!  I have a standard set of responses to this question, mostly dealing with difficulty of field identification, incomplete taxonomy, vouchering of scientific data, etc.  However, next time I am asked the question, I am going to provide a link to this post, a guest contribution by myrmecologist Benoit Guenard on Alex Wild’s Myrmecos.  I can only imagine what Benoit is going through, now realizing that he had found and photographed just the second and third known specimens of a truly rare North American ant, only to let them go because he didn’t realize what they were at the time.

Copyright © Ted C. MacRae 2010

“Colorfull Cockroach” discovered in Panama

/ Ted C. MacRae / 11 Comments

I won’t call this a taxonomy fail, since Patrick is clearly not a taxonomist, or even the first person to confuse a beetle with a cockroach.  Nevertheless, I was amused at Patrick’s amazement with the “colorfull cockroach” that he found and his palpable excitement that it might be a new discovery.

Well, I was amazed about this type of cockroach so, I would like to know if it is a cockroach or what because I know you guys will be also interested about checking out this type of bug.
Thanks please answer fast 🙂
Maybe is a new kind of cockroach not discovered yet.

Fortunately, the folks at What’s That Bug were able to correctly identify this as Euchroma gigantea (giant metallic ceiba borer), a beetle in the family Buprestidae (and the largest such species in the Western Hemisphere).  An interesting note about this photo is that it shows the beetle with some – but not all – of the green pulverulence (dusty coating) that these beetles exhibit over the elytra upon emergence from their host tree.  This coating is quickly worn off as the beetle goes about its activities, and most museum specimens of the species lack it completely – giving the beetle a purplish appearance as seen on the left elytron of the beetle in this photo.  Even handling a freshly-emerged specimen to mount it on an insect pin would likely result in loss of much of the coating, so it is quite difficult to preserve specimens in their lime-green dusty state.

Copyright © Ted C. MacRae 2010

Sweet Sixteen!

/ Ted C. MacRae / 16 Comments

The 7th Annual Fall Tiger Beetle Trip™ is officially over – Chris and I rolled back into town a little after midnight last night. It was an amazing trip – perfect weather, unparalleled scenery, and a record-breaking 16 species of tiger beetles seen in 13 localities across four states. Not only does this beat my previous trip record of 13 species, but we did it with only five days in the field. At the time of my previous update, we had visited several locations in the South Dakota Badlands and Nebraska Pine Ridge and found ten different tiger beetle species, including Cicindela pulchra (beautiful tiger beetle) – our top priority for the trip – C. nebraskana (prairie long-lipped tiger beetle), and C. lengi (blowout tiger beetle). Our plan for the next day was to visit the Badlands of Wyoming to look for C. decemnotata (Badlands tiger beetle – appropriately) and the Yampa River Valley of northwestern Colorado to look for C. scutellaris yampae and C. formosa gibsoni, all three of which we managed to find (though with caveats – stay tuned). Our originally planned final field day was to take us back into Wyoming to look for C. longilabris (boreal long-lipped tiger beetle) in the mountains east of Laramie and the Nebraska Sand Hills to look for the delicate little C. limbata before heading back home. However, we were finally paid a visit by “the skunk” and did not see any of these species (although our sighting of C. limbata (common claybank tiger beetle) in Wyoming did officially break the old trip record). Not wanting to end the trip on a disappointing day, we delayed our departure for home yesterday and visited two more sites at the eastern edge of the Nebraska Sand Hills (sites M and N in the above map) – a clay bank site where we saw a robust population of C. denverensis (to augment the single individual we had seen earlier in the trip) and several C. splendida (splendid tiger beetle), and another sand dune/blowout system where we at last succeeded in finding C. limbata.

The day after the end of the Annual Fall Tiger Beetle Trip™ is usually a somewhat depressing day for me. Not only is the trip over, but likely so is the entire insect collecting season. I know I need the down time to process the specimens and knowledge acquired during the season, but the field work itself remains my favorite aspect of this pursuit. Nevertheless, the experiences from this trip will fuel my memories for years to come, and in the next weeks I’ll share some of the stories that unfolded. Until then, I leave you with this portrait of C. pulchra – looking rather annoyed with me for my persistent efforts to take his photograph.

Cicindela pulchra - the ''beautiful'' tiger beetle

Copyright © Ted C. MacRae 2010

Promiscuous Plants

/ jtrager / 22 Comments

Naturalists have long been aware of the greater tendency for plants than for animals to create viable interspecies hybrids. This is attributable not only (as some might expect) to a higher likelihood of passive plants whose mating is mediated by pollen-hungry insects, or the wind, to hybridize more often, but rather to a greater ability of plants, with the simpler design of their anatomies, successfully to build a functioning organism with a Gemisch of genes from parents of different species. Such hybrids occur naturally, and are often reported in regional floras. Further, the advent of modern techniques for characterizing DNA has revealed that hybridizations of yore have given rise to numerous species, and higher lineages, in plants, in fungi, and to a lesser extent in animals.

My recent wanderings in quest of fall flora photos at Shaw Nature Reserve really brought this phenomenon of admixture of species to mind as I was examining populations of the three Gentiana species that live at the reserve. All three are fairly recent introductions at SNR, added to the flora in several locations in our prairie and wetland habitat reconstruction program. Hybridization among these gentian populations was first brought home in my observation over the last three years of increasing numbers of purplish and bluish and outright blue individuals in a population that was originally pure white gentian – Gentiana alba. This population was sowed in the mid-1990s as part of a mesic prairie reconstruction in the watershed of our wetland complex.

Gentiana alba, G. andrewsii and their lavender tinted hybrid growing side by side at Shaw Nature Reserve.

Pale or white bottle gentian, in "pure" form.

A few years later, 50 or so meters distant, separated by a dense row of trees and shrubs, and in a much wetter habitat in which water pools after every rain and seeps subsurficially much of the year, blue bottle gentian – G. andrewsii — was sowed into a wet prairie / sedge meadow reconstruction.

The rich blue flowers of the blue bottle gentian, Gentiana andrewsii

At first the two populations grew independently and remained separate, but what I surmise was a combination of water borne seed transport (along the shore of a pond whose edge both populations are near), and bumblebee borne pollen transport, conspired to bring gametes of the two species together, creating what population geneticists call a hybrid swarm, and what taxonomists call a — well, I can’t write it in polite company such as my readers.

Observe in the sequence of images above how a bumblebee gyne (a potential queen of one of next year’s annual bumblebee colonies) pries open a bottle gentian flower and dives in for a long drink of nectar at the base of the large vessel. Apparently the nectar is copious, because bumblebees may remain in a single gentian flower for up to a minute.

The result of pollen transport among pale and blue bottle gentians, a hybrid of intermediate characteristics.

While there are other populations of both species on the reserve (one hopes, out of bumblebee range from each other) that may retain their genetic integrity, the rampantness of the admixture at this site does give me pause.

And it gets worse! — On drier ground up the slope, among a dense planting dominated by prairie dropseed and little bluestem grasses,  a third gentian known as downy or prairie gentian – Gentiana puberulenta – was established from a seed mix sowed 10 years ago to convert the watershed of the reserve’s wetlands to prairie vegetation.

Unlike the two previously mentioned species and their hybrids, the downy gentian's petals open wide at anthesis, admitting entry to small bees and even to spindly-legged potential pollinators such as syrphid flies.

And now those perverse bumblebees have gone and defied the laws of speciesness and created what appear to be hybrids of this third gentian species with the other two. Honestly, I don’t know whether to feel that I have done some sort of wrong by creating the situation that allowed this to happen … or simply to be intrigued by this unforeseen outcome of my work, and to wonder what will come of it after I’m gone?

The gentian in the upper photo appears to be the offspring of a cross between white and downy gentian parents, while the one in the lower photo appears to be the result of a cross between blue bottle and downy gentian.

2 days, 6 localities, 10 species…

/ Ted C. MacRae / 6 Comments

Here’s an updated itinerary for the 7th Annual Fall Tiger Beetle Trip that fellow cicindelophile Chris Brown and I are in the midst of. We’ve spent the past two days visiting six localities in Nebraska and South Dakota. So far, we’ve found a total of 10 species – including every species we had hoped to see at this point in the trip. The list so far (in chronological order) is:

  • Cicindela (s. str.) tranquebarica kirbyi – ho hum, we’ll see this in several places.
  • Cicindela (s. str.) purpurea audubonii – über common Great Plains species, although the black form is always a treat to see.
  • Cicindela (s. str.) pulchra – YEAH! Seen in good numbers at one of the new South Dakota localities discovered in 2008 by Matt Brust (our personal chaperone for the day). Marvelous field photographs.
  • Cicindela (s. str.) fulgida – Only one seen, but Chris got a nice series of field photographs (I’ve seen good numbers of this species from my previous trips to this area in 2008 and in Oklahoma last year).
  • Cicindela (s. str.) nebraskana – Another “A list” species for the trip, but we’ve only seen one so far.
  • Cicindela (Cicindelidia) punctulata punctulata – also known as Cicindela ubiquita.
  • Cicindela (s. str.) scutellaris scutellaris – even though this is a common Great Plains species in any sandy area, I never tire of its dazzling red elytra and blue/green head and pronotum.
  • Cicindela (s. str.) lengi – The third species on our “A list” that we’ve seen, with some real nice field photographs from Monroe Canyon.
  • Cicindela (s. str.) formosa generosa – another common Great Plains species.
  • Cicindela (s. str.) denverensis – I didn’t expect to see this one on the trip (just a single individual at Monroe Canyon), but I’ll take it!

Tomorrow we’ll hit a Wyoming location where Cicindela (s. str.) decemnotata is known to hang out – a species I’ve not yet seen, either alive or preserved. Most sources regard this species as closely related to C. denverensis, but Matt thinks it is actually more closely related to C. fulgida due to similarity in form and shine but green instead of purple. Afterwards, in a major addition to our planned itinerary (hence the updated Google Map), we’ll go into northwestern Colorado to look for two very cool subspecies of the otherwise widespread species – C. formosa gibsoni and C. scutellaris yampae. If we’re lucky we’ll also see the delicate little sand lover, Cicindela (s. str.) limbata, but if we don’t see it there then we should see it the next day when we finish out the trip back in the Nebraska Sand Hills just east of Alliance. But before that, we’ll veer back up into Wyoming and look around in the high elevations east of Laramie in hopes of finding Cicindela (s. str.) longilabris laurentii. That one may be a stretch, but if we are successful then we have the potential to see a total of 15 species – that would be a trip high for me (literally and figuratively).

Copyright © Ted C. MacRae 2010