Cosmetid harvestman with parasitic/phoretic mites in Argentina

Metalibitia sp. poss. paraguayensis | Corrientes Province, Argentina

While searching logpiles last month in a relatively intact tract “Selva Paranaense” near Paso de la Patria (Corrientes Prov., Argentina), the most interesting find for me was , a bizarre longhorned beetle that is either amazingly cryptic or a curious mimic (I couldn’t decide). There wasn’t much else to be seen in the logpiles—it had been a very dry summer in northern Argentina, but I did find this interesting species of harvestman (class Arachnida, order Opiliones) huddled together in one of the punkier piles of wood.

Knowing little about harvestman taxonomy (but knowing of several specialists who do), I sent the photos around for expert opinion. Everyone responded with the same opinion—family Cosmetidae, apparently distinguished by its spoon-shaped pedipalps. Marshal Hedin compared them to this similar-looking species photographed in Bolivia, Christopher Taylor (Catalogue of Organisms) thought they might be a species of Metalibitia and Ricardo Pinto-da-Rocha suggested M. paraguayensis as having been recorded from the province of Corrientes (although a specimen would need to be examined to confirm the identification). My thanks to each of these gentlemen for weighing in on a possible ID.

Argentina represents the southernmost extent of this strictly New World family of harvestmen, while to the north the family extends up to the southern U.S. (genus Vonones). In between, the family is diverse and comprises up to one-third to one-half of the harvestman fauna (Kury & Pinto-da-Rocha 2007). Many species in the family are ornately marked, giving rise to the family name which is derived from the Greek kosmetós (= ornate)—check out this gallery of photos at Flickr to see some truly spectacular examples.

While I was photographing these individuals, and even when I first began processing the photos, I thought that they were quite dirty and debated whether to clean them in PhotoShop. Then I realized that the numerous white spots were not debris, but mites! Whether these represent a parasitic or phoretic relationship is not clear to me, however, and none of the gentlemen I sent the photos to offered any comment about them. Erythraeid and thrombidiid mites are well documented as harvestman ectoparasites during their larval stage, with recorded hosts including Neotropical species of Cosmetidae (Townsend et al. 2008). The tiny, white mites on these individuals, however, do not resemble the large, red erythraeid mites (probably genus Leptus) that I have seen parasitizing our North American harvestman species, and their numbers on multiple individuals is, to me, more indicative of a phoretic relationship. If you want to become thoroughly confused by the tremendous diversity of mites the parasitize harvestmen, see the comprehensive review by Cokendolpher (1993).


Cokendolpher, J. C. 1993. Pathogens and parasites of Opiliones (Arthropoda: Arachnida). The Journal of Arachnology 21:120–146.

Townsend, V. R., D. N. Proud, M. K. Moore, J. A. Tibbetts, J. A. Burns, R. K. Hunter, S. R Lazarowitz & B. E. Felgenhauer. 2008. Parasitic and phoretic mites associated with Neotropical harvestmen from Trinidad, West Indies. Annals of the Entomological Society of America 101(6):1026–1032.

Kury, A. B. & R. Pinto-da-Rocha. 2007. Cosmetidae Koch, 1839. Pp 182–185. In: R. Pinto-da-Rocha, G. Machado & G. Giribet (Eds.). Harvestmen: The Biology of the Opiliones. Harvard University Press, Cambridge and London, x + 597 pp.

Copyright © Ted C. MacRae 2012

Answer to Super Crop Challenge #1

Seemingly correct answers came quickly to yesterday’s inaugural Super Crop Challenge, which featured a curious structure atop a harvestman (class Arachnida, order Opiliones) that I encountered while hiking the lower North Fork Section of the Ozark Trail in extreme southern Missouri. “Seemingly” I say, because even though some points were earned, others remained left on the table – the organism was rightly recognized as a harvestman, and the structure in the photo does indeed contain the ocelli (or eyes).  However, nobody actually named the structure itself (see update below) – the ocularium (ocular or optical tubercle would also have been accepted).  Hey, I’m pedantic and proud!

As near as I can tell, this individual belongs to the genus Leiobunum (family Sclerosomatidae).  Species in this genus are notoriously difficult to identify; however, the super long legs, dark dorsal stripe, pointed abdomen, and very long palps with “knees” that extend dorsally to a level well above the ocularium suggest a male L. vittatum or one of its close relatives (Schulz 2010). Leiobunum vittatum is a common inhabitant of wooded habitats across the eastern U.S.

I took this shot with an MP-E 65mm macro lens at about 2.5X. The short working distance of the lens at this level of magnification makes it difficult to photograph these longer-legged species in lateral profile due to their habit of “waving” their especially elongate 2nd pair of legs in the air as pseudo-antennae – one touch of any part of the camera sends them scampering. I chased this guy back and forth across a downed tree trunk for some time before I finally got lucky when it encountered some prey (note the long structure extending down from the mouth area – I believe it is the antenna of a tiny, nymphal blattodean) and became distracted just long enough for me to close in and fire off a couple of close shots. He was actually closer to the underside of the log, so when I took this photo I was leaning far over the log with the camera almost upside-down!

Okay – Art earns points for being the first to identify it as a harvestman, while Geek snaps rare duplicate ID points for using the order’s scientific name (no complaining – scientific names will always get points on this blog).  Art, Aniruddha, and Geek also get half-points for mentioning (in order of correctness) eye, ocelli (technically more correct, but wrong plurality), and ocellus (yes, only one is visible – did I mention my pedantic tendencies?).  However, I’m going to declare arachnologist and Opiliones specialist Chris as the winner of this round for his impressive display of generic-level identification based on the meagerest of evidence!

Update 11/22, 11:00 a.m. – actually, Chris did name this structure in an email sent to my office address while the comments box was unchecked and, thus, earns a clean sweep of this challenge.

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


Schulz, J. W. 2010. The Harvestmen of Maryland (accessed 20 November 2010).

Copyright © Ted C. MacRae 2010

Super Crop Challenge #1

ID quizzes and challenges seem to have become an increasingly popular subject for natural history blogs. I’ve done a few of my own, but my straight up ID challenges are starting to seem a little unimaginative compared to the DNA sequence, crypsis, mimicry, taxonomy fail, and other challenges being offered up by bug blogdom’s more creative types. To step it up a notch, I offer the first Super Crop Challenge. Small structures that we take for granted within a larger context often take on alien qualities when viewed in isolation. Can you identify this structure and the organism that possesses it?

Copyright © Ted C. MacRae 2010

Phreaky Phalangid

While searching through shortgrass prairie atop the Pine Ridge in northwestern Nebraska in hopes of finding Cicindela nebraskana (prairie long-lipped tiger beetle), this harvestman caught my eye.  Harvestmen are, of course, arachnids related to spiders, but they lack fangs and poison or silk glands and are placed the separate order Opiliones (Phalangida when I was in school).  Admittedly, I haven’t paid much attention to harvestmen before now, but this one seemed different from any I’d seen before – nearly black with relatively short legs and distinctive orange intersegmental articular membranes at the base of the legs.  Harvestmen are known to employ chemical defenses through special repugnatorial glands that produce phenols, quinones, ketones, and/or alcohols, and this individual seemed to display a clear example of aposematic coloration to warn any potential predators of its distastefulness.

Trachyrhinus favosusAlthough beetles are my focus, I normally try to do my own identifications in other groups as well.  However, some rather persistent searching through the extensive harvestman holdings at BugGuide failed to turn up a good match.  In gestalt it seemed to belong to the family Sclerosomatidae, but even that was just guessing on my part.  So, I did what I’ve done only a few times before and posted the photos to BugGuide’s ID Request.  A day and a half later I had my answer – Trachyrhinus favosus.  BugGuide Contributing Editor V. Belov had sent the photos to harvestman expert Marshal Hedin, who had this to say in response:

Cokendolpher describes males as ‘body ranging from solid black…’ with bases of femora ‘yellow-brown’. The species is also known from western Nebraska. Cool.

I was pleased to learn that these photographs represented a new species for BugGuide and no longer felt bad about not being able to find a good match.  Further, my leanings toward the family Sclerosomatidae had been confirmed.  According the Cokendolpher (1981), T. favosus ranges in a narrow band from North Dakota south to north-central Texas and is active only during fall.  I had intended to try to get an even closer photograph, but after taking the second photograph above I accidentally disturbed the critter and then watched in amazement as it began bouncing up and down vigorously.  This apparently is a defensive behavior that functions to blur the body form.  I watched it bounce and became even more amazed as it began calmly walking away while continuing its vigorous bouncing – quite a spectacle!

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


Cokendolpher, J. C.  1981. Revision of the genus Trachyrhinus Weed (Opiliones, Phalangioidea).  Journal of Arachnology 9:1–18.

Copyright © Ted C. MacRae 2010

Circus of the Spineless #47

When I started participating in blog carnivals last year, Circus of the Spineless was – for me – the pinnacle of blog carnivals.  I wanted to take my shot at hosting this venerable celebration of creepy crawlies, and even though the waiting list for hosting was almost a year long, I offered my services and settled in for the long wait until February 2010.  Ten months have passed and the time has come.  In the meantime, I did my blog carnival host début with Berry Go Round #21 and snatched the sophomore slot for nature blogging’s newest carnival with House of Herps #2.  Through those efforts, I learned that blog carnival hosting is an incredible amount of work/fun, and while plants and herps are fascinating, inverts are my true love.  It is, thus, with great pride that I join the ranks of previous hosts in presenting this, the 47th edition of CotS.  Featured below are 16 submissions by 14 contributors that cover representatives from 5 classes in 3 invertebrate phyla.  A humorous look at some of the personalities behind invertebrate study is presented as a bonus for those who make it to the end.

If you missed last month’s issue, you can find Circus of the Spineless #46 at Kate’s Adventures of a Free Range Urban Primate, and next month’s edition will be hosted by Matt Sarver at The Modern Naturalist.


Coral Reefs
The Voltage GateJeremy at The Voltage Gate reports on peer-reviewed research on the impact of herbivorous fish on the recovery of coral reefs in his post, Protecting herbivorous fishes significantly increases rate of coral recovery.  Coral reefs have been hard hit by the challenges of bleaching and disease, pressures likely linked to climate change, and macroalgae, when given the opportunity to dominate, provide even further challenges.  This can happen when populations of herbivorous fish, major grazers of macroalgae, are reduced through commercial harvest.  The study authors evaluated ten sites over a two-and-a-half year period in and around the Exuma Cays Land and Sea Park (ECLSP), which was established as a no-take marine reserve in 1986, finding an increase of coral cover during the study period from 7 percent to 19 percent.  However, ECLSP reefs were responsible for all of this increase, with no net recovery occurring outside the ECLSP.  These results illustrate the importance of reserves as a refuge for biodiversity and the service they provide in keeping marine systems intact.

—-“Informal Group” OPISTHOBRANCHIA

Sea slug (Glaucus atlanticus)
Deep-Sea NewsThis gorgeous nudibranch species got a foul slandering when they started washing up on Gold Coast beaches in Australia.  Miriam Goldstein debunks this unfair treatment in her post, Sea slugs have self esteem too, at Deep-Sea News, noting its absolutely stunning iridescent blue and silver color with gorgeous feathery tentacles.  Further exception is taken with such descriptors as “slimy”, “venomous”, “blue-bottle eating”, and “cannibals” – with the truth behind each of these terms far more fascinating than the visceral reaction their use was intended to elicit.  Good news as well – you don’t have to travel to Australia to see these things – they live throughout the world’s open oceans (but you will have to get far from shore, where the pelagic jellys upon which they feed can be found).

—-“Informal Group” PULMONATA

Iron-clad snail (Cyrsomallon squamiferum)
Deep-Sea NewsI’ve known about iron-clad beetles, species of Zopheridae whose exoskeleton is so hard and thick it is almost impossible to impale them with an insect pin.  I’d never heard of an iron-clad snail, however, until I read Dr. M’s post, The Evolution of Iron-Clad Samurai Snails With Gold Feet, at Deep-Sea News.  Unlike the seemingly iron-impregnated beetles, these snails actually utilize iron sulfide in a series of armor plates covering the “foot.”  Just described in 2003 from a hydrothermal vent in the Indian Ocean, it is the only known animal known to use iron sulfide as skeletal material.  Only time will tell if these snails achieve the same popularity as living jewelry as the beetles.

¹ The taxonomy of the Gastropoda is under constant revision, as the results of DNA studies increasingly reveal as possibly polyphyletic many of the former orders (including the Opisthobranchia and Pulmonata, now known as “informal groups”).


Samurai crab (Heikea japonica)
ArthropodaMike Bok at Arthopoda shares two stories about this crab – one an ancient Japanese legend, the other a modern piece of scientific folklore – in his post, Samurai Crabs: Transmogrified Japanese warriors, the product of artificial selection, or pareidolia?  In the first, popular legend alleges that these crabs were transformed from drowned samurai warriors, each one identifiable by the face of the fallen samurai that it bears on its backs and for whom the crab searches in the depths of the oceans around Japan.  This ancient legend has led to a modern scientific quibble about whether the stylized face that can be seen on the crab’s carapace is the result of artificial selection by generations of superstitious Japanese fishermen, who have selectively released crabs bearing any resemblance to a human face.  This may make for compelling scientific debate, but Mike counters even the considerable eloquence of Carl Sagan in providing his own thoughts on why this likely is not true.


Amphipod (Phronima spp.)
ArthropodaIn another example of the intermixture of science and culture, Mike Bok (Arthopoda) asks, Did Phronima inspire the design of the Alien Queen?  Mike agrees with the claim that the original “soldier” alien morph seen in “Alien” (1979) was based on a painting by artist H. R. Giger, but he thinks that Phronima more likely influenced the design of the queen alien morph in “Aliens” (1986).  The truth may remain hidden at Stan Winston Studios, but the broad crest atop the head of Phronima, bearing tubular, upward-pointing eyes, its “necro-parasitic” tendencies, and a chillingly suggestive photograph of the beast from a 1981 paper lend an air of plausibility to Mike’s hypothesis.


Harvestmen, daddy-long-legs
Kind of CuriousJohn at Kind of Curious follows up on David Attenborough’s Life in the Undergrowth Episode 1 with his post, Daddy Long Legs Daddies (aka Harvestman).  Looking like spiders but lacking their venomous and silk-spinning abilities, it seems that nobody can agree on the proper name for these spider relatives.  Brits call them “harvestmen”, but Americans call them “daddy-long-legs”, a term that in the UK refers rather to crane flies (which less informed Americans simply call “giant mosquitoes”).  Let’s not even mention the daddy-long-legs spider (Pholcus phalangioides), which actually is a spider.

—-Order ARANEA

Neoscona crucifera (barn spider)
XenogereAnyone who hikes along woodland trails in the eastern U.S. during autumn knows what a “spider stick” is – i.e., any handy stick that can be waved probingly in front of one as they hike, lest they run smack into the web of any number of orb weavers that are fond of stretching their large webs across such natural insect flyways. Jason, at Xenogere, has some biggun’s in his neck of the woods, which he describes in intriguing detail in his post, Walking with spiders – Part 3. Barn spiders are some of the biggest, allowing one to fully appreciate their polychroism and polymorphism. I challenge even the most arachnophic of readers to look at Jason’s photographs and not be mesmerized by their beauty.


Autumn meadowhawk dragonfly (Sympetrum vicinum)
Rambling Woods~The Road Less TraveledMichelle at Rambling Woods~The Road Less Traveled presents a stunning series of photographs of this gorgeous red dragonfly in her post, Circus of The Spineless~Curiosity will conquer fear even more than bravery will.~James Stephens.  Perching on her hanging basket of pink-flowered begonias, colors matching perfectly, it was almost as if the dragonfly has staked a claim on the hanging basket as it own personal territory.  Where there is one, there are others, and her neighbor’s deck had both a red male and a blue female doing… well, see Michelle’s diagram.


Horned passalus (Odontotaenius disjunctus)
Anybody Seen My Focus?Joan Knapp at Anybody Seen My Focus?  shows photographs of this beetle in her post, Bess Beetle: Horned Passalus (Odontotaenius disjunctus), as it lumbered slowly and gracefully over a fallen tree branch.  Perhaps the cool temperatures were the reason for its sloth.  Or perhaps the missing antenna indicated a feeble, old individual on its last (six) legs.  A brief interruption for photographs seemed not to deter the beetle from its destination, somewhere in the leaf litter beyond the log…


Skipper butterflies (family Hesperiidae)
Nature of a ManRandomtruth at Nature of a Man loves skippers (are they butterflies, or aren’t they?), and you’ll love his photographs of these delightful little half-butterflies in his post, Day Skippers.  While there is some slight doubt about the identity of individuals he sees in his backyard (skippers are notoriously difficult to identify in the field), there is no doubt that these little guys are loaded with personality.  You won’t believe the “natural history” moment he caught on film (er… pixels?) and presented in the final photo sequence.

Monarch butterfly (Danaus plexippus)
GrrlscientistGrrlscientist summarizes a recent peer-reviewed paper in her post, Migratory Monarch Butterflies ‘See’ Earth’s GeoMagnetic Field.  The paper reports on photoreceptor proteins in monarch butterflies known as “cryptochromes” that not only allow the butterflies to see ultraviolet light, but also allows them to sense the Earth’s geomagnetic field.  These highly conserved proteins evolved from the light-activated bacterial enzyme phytolase, which functions in DNA damage repair.  Most animals have one of two types of cryptochromes, but monarchs have both – providing the first genetic evidence that the vertebrate-version of cryptochrome is responsible for the magnetoreception capabilities in migratory birds.  Further research may provide insight on the workings of the circadian clock, which could lead to better understanding of sleep disorders and mental illnesses such as depression and seasonal affective disorder, as well as development of new treatments for jet lag and shift-work ailments.


Ants (family Formicidae)
Wild About AntsKatydids, grasshoppers, cicadas – what do ants have on these singers of the insect world?  Plenty, as Roberta at Wild About Ants points out in her post, Ants: No Longer the Strong Silent Types.  It turns out that ants have patches of ridge-like structures on their gaster, which they rub against a curved ridge (called a “scraper”) on the petiole to communicate with each other via stridulation.  While lacking the decibel level of a cicada, these sounds are nevertheless in the audible range for human ears and are thought to have alarm, mating, and recruitment functions.  Even more fascinating, stridulation is not the only tool in the ant music chest – drumming and rattling have also been documented.  Curiously, however, ants do not possess ears, rather likely sensing sounds through their legs or by specialized hairs on their antennae.  Check out the provided links to SEM photographs and a sound recording.

Bald-faced hornet (Dolichovespula maculata)
Hill-Stead's Nature BlogDiane Tucker, Estate Naturalist at the Hill-Stead Museum in Farmington, Connecticut, writes at Hill-Stead’s Nature Blog. In her post, Be it ever so humble, she takes a look at some of the different animal nests that become revealed during autumn’s leaf drop – particularly those made by the bald-faced hornet (and also birds such as oriole’s).  From its start as simple cluster of chambers, to its growth over the course of the summer – growing fatter until the summer’s apex of warmth and light, then tapering off with the approach of fall, these insect homes are a marvel of nature – intricately constructed homes made entirely of paper.


Common green bottle fly (Lucilia sericata)
Bug Girl's BlogBug Girl discusses the resurging use of bottle fly larvae in her post, Maggot therapy.  The academic among us will appreciate her discussion of the mechanisms that allow these seemingly disgusting vermin to function as incredibly delicate microsurge0ns in cleaning and disinfecting open wounds.  The morbid among us will appreciate the links to the most entertainingly disgusting medical photos one can imagine.  Check it out – but not over your lunch hour!


Wanderin' Weeta (With Waterfowl and Weeds)Wanderin’ Weeta (With Waterfowl and Weeds) was going to make an owl out of Douglas fir cones, but instead she found globular springtails, a crab spider, and a ladybug in a sprig of fir.  We’re glad she has an interest in little hitchhikers such as these, even if the kids at school when she was growing up didn’t.


Bug Girl shows that entomologists have a sense of humor with her post, Monday Morning bug jokes – a video compilation of jokesters from the recent Entomological Society of America Annual Meeting in Indianapolis.  My favorites were the best dung beetle pickup line (“Is this stool taken?”) and Marvin Harris’ rendition of the minimum number of insects needed to elicit control (1 pubic louse, or 1/2 codling moth larva :)).  J. McPherson was equally, if unwittingly, hilarious due to his Christopher Lloyd-esque mannerisms.  My favorite entomological joke of all, however, was not featured, so I offer the following addendum to Bug Girl’s post:

Copyright Ted C. MacRae 2010

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