A little mite for a similar amount of time

A tiny, but complex mite: Nanorchestes sp.

I’m still swamped at work with too many mites and not enough time to appreciate them. So here’s a tiny example of what mites have to offer when one can take the time to look closely. Although scarcely more than a tenth of a millimetre in length when full grown, this mite comes complete with a highly ornamented cuticle, numerous highly branched (dendritic) setae, 2 pairs of simple eyes, 2 pairs of ciliated trichobothria (one of which forms a latch-trigger setacomplex), mysterious mouthparts, and an astounding ability to jump several times its body length.  Nanorchestes species also have an astounding ecology – a mysterious ability to thrive in cold deserts, including some of the coldest places in the World.

Most mites in this genus are poorly studied, but Nanorchestes antarcticus Strandtmann is well known.  Herds of hundreds of thousands of these mites roam parts of the Antarctic continent, presumably grazing on algae (lacking solid gut contents, the feeding behaviour of these mites is a bit murky).  As tiny as they are, Bill Block has been able to measure individual oxygen consumption rates (Oikos 27: 320-323), which at 5C in an adult female is around 368 micro-litres of O2 per gram per hour.  That may sound like a lot of CO2 entering the Antarctic atmosphere, but on a good day, a full grown mite weighs only about 3.6 micrograms, so no need to dob them in to  Al Gore.  It’s not 5C in Antarctica all that often.

D. E. Rounsevell and Penny Greenslade have a hypothesis  (Hydrobiologia 165: 209-212) that the ornate cuticle in Nanorchestes enables the mites to hold a layer of air around their bodies that increases their respiratory efficiency in seasonally waterlogged soils and perhaps keeps the ice away from their cuticle when they refreeze. Most of the two dozen or so described species in the genus are known from extremely cold areas of the World – but I think this is an artifact of funding. If you want to study animals living in Antarctica, then your are pretty much limited to mites, springtails, nematodes, and rotifers.  Well, I exaggerate, there are a couple of chironomids and I guess a few vertebrates must show up now and then, but who has the time for every little taxon. All those Nanorchestes living outside the Antarctic are pretty much ignored too. You can find Nanorchestes anywhere you can find a dry bit of soil, from the beach to a treehole in a rainforest. I can even find them in my city yard, but then this is Alberta, winter is on the way, and I know they are more cold-adapted than I am. I’d much rather be looking for Nanorchestes on a Queensland beach.

A Long Bite from Oz

Athiasella - a genus named for Claire Athias-Heniot

What with all the digression for ants, Canada Day, and the 4th of July, Australian mites have been few and far between here for awhile. So here is a toothy Australian predatory ologamasid mite to tide me over until I have more time. The genus was named after the great French acarologist, Claire Athias-Henriot.

UPDATE – Speaking of great French acarologists, and there have been many, Michel Bertrand, Seige Kreiter and their colleagues put together a Power Point presentation on French acarology for the 6th Symposium of the European Association of Acarologists last year.  Great fun for anyone interested in the history of acarology (and a couple of my images are used for decoration – along with lots from others).

Re: Ologamasidae – the family that Athiasella belongs to – this is yet another example of an early derivative group (within the most successful radiation of the Mesostigmata) that shows very different diversities in the continents derived from ancient Southern (Gondwanan) and Northern (Laurasian) ’supercontinents’.  Ologamasids are rare and low in diversity in the north, but are a dominant groups of predatory mites in southern continent soils and have even managed to hang on in Antarctica (although just on the Peninsula).

American Mite

A patriotic zerconid mite from Idaho

It’s Independence Day in the USA and freedom is always worth celebrating, so here is a somewhat gaudy mite celebration of July the 4th.  This mite is a predator, probably specializing in nematodes and other soft-bodied prey (based on the few species that have been studied), and the family is very well represented in the Northern Hemisphere, especially in boreal and montane systems. This particular mite was collected by a colleague from Idaho and sent to me in Australia to help in producing a key to families.

Most of my mite art gallery is comprised of Australian mites, but a few yanks have made it into the mix.  I can’t go beyond family for this mite, because the Zerconidae is absent from Australia and I’m not familiar enough with its representatives to put a name on it from a lateral view.  Actually, even when they are on slides, I have difficulty putting names on most Zerconidae. The family is extraordinarily diverse in the Northern Hemisphere with about 37 genera and subgenera currently recognized.  Unfortunately, as yet no one has pulled the literature together into a coherent whole, so the novice must deal with a plethora of languages, generic concepts, chaetotactic nomenclature, and proliferating hairs.

Chaetotaxy – the taxonomy of setae – is one of the most useful tools in the morphological analysis of mites.  ’seta, setae’ – is a fancy term for ‘hair, hairs’.  I sometimes forget that students don’t necessarily know this and it takes a few minutes of uncomprehending stares to remind me to explain, but the term is used primarily for the hair-like mechanoreceptors that jut out all over the body and appendages of arthropods.  Like a cat’s whiskers, setae use contact to pass information to a mite’s nervous system about what is around them.  In this zerconid, the setae on the dorsal shield are short and bushy – densely covered in short, barb-like processes. Setae can take all kinds of forms from simple, needle-like hairs to highly branched, tree-like structures. One likes to think that these various forms have somewhat different functions, but supporting data is rare.

For most mites, every seta has a name, or rather several names, since there are usually two or three major systems in the literature for any particular group – a taxonomic Tower of Babel. Zerconids can be especially confusing because they appear to be basal to one of the major radiations of mites (the gamasine Mesostigmata) and like many ‘primitive’ groups, tend to have lots of structures. In the Zerconidae this has been complicated by a tendency to multiply their setae, making assigning a name to any particular seta somewhere between difficult and arbitrary. Fortunately, a Canadian (Lindquist) and a Spaniard (Moraza) have been working together to make sense of the Zerconoidea and seem to have made excellent progress.  Now, if they would only take the time to produce a decent key to genera, I could start handing out names.

Full Stop on Canada Day

Synchthonius crenulatus (Jacot) on a Times-Roman 12 pt Period

Samples have been pouring in to work for the last month, so the time, and more importantly, the extra energy for blogging have been in short supply.  Sorry to any readers who need new posts on a more regular basis, but today I offer you Synchthonius crenulatus (Jacot).

Presenting a mite in a way that makes sense from the perspective of a viewer is always difficult.  Most people do not grasp just how small mites are and this is especially true for children.  Supposedly, those of us with average eyesight can resolve down to about 0.1 mm.  So, in theory, you could actually see many of the mites around you as tiny flecks.  But once one has gotten past the stage of watching ants and eating dirt, why would you?  Mites are only really interesting when you can see them up close and personal.

The best way to make a mite personal would be to associate it with a familiar object.  A friend suggested the obverse of a Canadian penny might set off the golden coppery colours of this mite and the Maple Leaf would be a good image for Canada Day.  Unfortunately, if scaled to their true relative sizes, this mite would essentially disappear.   According to my quick back-of-the-envelope calculations, you could squeeze about 9,467 of these mites on to a Canadian penny (19 mm diameter), give or take a few thousand legs.

I know I could do this in Photoshop, but I just don’t have the energy (see above) and I would have to do it on my own nickle, so to speak, because if my employers asked me to do it, I would quit.  So, what would be an object of appropriate size?

I chose a Times Roman 12 point font period in the assumption that everyone who can read would be familiar with full stops (as we call the period in Australia).  I know from too much experience with marking student essays that commas, semicolons, and colons are on their way to extinction (or strictly random insertion), but most students still come up with a full stop every sentence or four.  As well as often seen, the 12 pt period has a nice 0.5 mm diameter (5x what the average eye can resolve).

Times Roman or another similar serif font should be familiar to most readers because the little feet on the letters help the eye move along a row of print, increase comprehension, and (with the exception of people with macular degeneration and some other eye problems) reduce eye strain during reading.  As a result, almost everything printed (at least by a competent printer) is in a Roman serif font.  [NB - on the computer screen and on the web, serif fonts are not so easy on the eye and san serif fonts along the lines of Ariel or Helvitica are more commonly used.]

Alas, tests with 2^nd Graders are tending to falsify my hypothesis that even children can relate to a period.  Good news is that they really like the pictures of mites; bad news is that they don’t seem to understand the perspective of the period.  Ah well, why be pessimistic?  Perhaps an understanding will grow with them and mites will have done their small bit to save the period from extinction.

Does a fly itch?

A couple of larvae from the Cohort Parasitengonina

Trombiculoidea are mites with a dubious distinction – most languages have one or more common names for them.  In Australia we would tend to call the hexapod larval stage ’scrub itch mites’ for the intensely annoying rash-like erruptions they leave after biting – an all too common result of a pleasant stroll through the bush.  In North America they are better known as chiggers, red mites, or harvest mites (i.e. common in the Fall).  I imagine readers of this blog with a knowledge of non-English languages could supply a host of other sobriquets.  Anyone with actual experience of scrub itch, or as it is technically known – trombiculosis,  might be tempted to add some colourful modifiers.

Because a large wheal may develop at the spot that a chigger bites, some think that they are burrowing in the skin.  Alas, no, they are ectoparasites that digest our skin and lymph for their feed.  There’s nothing to dig out to reduce the itch and the best thing you can do is not scratch and help avoid secondary infections.  The first scratch is probably good, since it will crush or dislodge the mite, but the mite leaves behind all the enzymes it has been injecting into your skin, and that can take a week or two for your body to deal with.  The more you scratch, the longer it will take to heal. 

If you live in an area where the rickettsial disease scrub typhus is endemic, then it is a good idea to watch out for any large black scabs that form on a chigger bite.  A large black scab or eschar is a sign of infection and all it takes is one infected bite.  In Queensland scrub typhus is a problem, but one good thing about Edmonton is that both chiggers and scrub typhus seem to be absent.

It may be of some comfort to know that only two families of chiggers feed on vertebrates – about a dozen other families of related mites feed on insects, millipedes, spiders, harvestmen, scorpions, and the like.  The two-winged flies (Diptera) seem to be especially lucky when it comes to collecting chiggers.  A possible example of one is above on the viewers right (Microtrombidiidae?).

Only the larval stage (i.e. the first active stage which has only 3 pairs of legs) is parasitic in the Cohort Parasitengonina (chiggers and their relatives and the water mites).  The nymphs and adults are predators – and they may have common names too.  In English, the terrestrial species are often called Red Velvet Mites and they can be quite large (up to 16 mm – the largest known mites outside the ticks) and are covered in a dense pelage of hairs, typically red but sometimes red & white patterned, orange, or another colour or combination.  Alex Wild at MyrmecosBlog has posted a striking picture of one of the red species.

A headless mite - adult Calyptostoma sp.

I don’t have any good SEMs of a red velvet mite – they are as hairy as a mammal and one would go bonkers trying to mask around all the hairs.  However, I do have an adequate picture of a member of the Subcohort Erythraiae, a species of Calyptostoma (Calyptostomatidae) with short setae.  These rather sluggish mites are thought to be predators of fly larvae as nymphs and adults.  The mouthparts (capitulum or gnathosoma) are retracted into the body and can be shot out to impale a maggot.  The mite larvae are parasites of adult Diptera (BugGuide has some good pictures of craneflies infested with the larvae).  So, the next time you come home with a case of scrub itch, think about all those poor flies out there that couldn’t scratch even if they wanted to – and emulate them, don’t scratch.

Strumigenys or Pyramica?

A rainforest litter ant that may eat mites

Over at MyrmecosBlog there is an interesting example of why Wikipedia isn’t a good idea as a reference source.  Whatever their proper name, and I always thought of this Queensland rainforest ant as a Strumigenys, I think this is one of the ants in question.  Of course, relying on Macromite as a source of ant identifications is about as good an idea as using Wikipedia for a term paper, but I thought a post to all those organisms that make themselves more interesting by eating mites was in order.  And while I am at it, a doulbe hurrah for the poison dart frogs that gain their noxious toxins from eating both ants and mites.

Re the ant: I can’t remember if this is a black ant or a red ant, but red constrasts with the background.  This isn’t a great job of masking, but ants have way too many hairs.  If anyone wants to  see some better SEMs of ants and their parts, they should check out Roberto Keller’s Archetype Blog.

Living the straight and narrow

When a bird is your habitat, you have to fit in and hold on.

Sometimes it seems like birds get all the barracking in the carnival of life, but they get more than their fair share of mites too.  In fact, birds provide mites with a host of microhabitats into which they inveigle themselves.  Some of these you might expect, such as nostrils, lungs, air sacs, around the cloaca, in the skin, or under the scales of the feet.  Others take some imagination, such as the several radiations of quill mites that enter the small opening of the umbilicus of a developing feather and spend their lives – usually several generations worth – inside the feather quill.  Most of the mites living on birds, however, are not so nasty and may be useful – the vane-dwelling feather mites – which seem to glean their living from the debris and oils that accumulate on feathers.

As one might expect, vane-dwelling mites live on the surface of the flat flight feathers of birds – mostly in the narrow lanes formed by the barbules, the parallel channels that run out from barbs that run out from the rachis.  These feather mites seem to fit their barbule widths to a T, especially on the wing feathers, where aerodynamic forces are uncompromising.  Actually, feather lice have been shown to fit their spaces, but except for those mites that live on birds that dive or swim under water, it is just an assumption for feather mites.  However, finding and holding on to a potential mate in these circumstances is clearly a challenge as these complexed mites from the feathers of a Pale-headed Rosella (Platycercus adscitus) show.  You can see the expanded posterior of the male (with suckers underneath for holding on) and the energetic grip of legs IV on the larger female, but what happens next is a bit of a mystery.

A Simple Example of Complexity

A Eupheredermous Oribatid Nymph

Blogging has been light because the sun has returned to Edmonton and all my extra energy has been going into the garden.  In celebration of the late, but better than never Spring, I offer you one of my earliest and simplest exemplars, an arboreal member of the family Cepheidae from a rainforest tree in Queensland.  This was taken as a single grab on a predigital camera and later the negative was scanned in, masked, and colourized.

The reason that a single picture was adequate, is that the top of this mite is relatively flat and with a large spot size and long working distance, one picture caught most of the detail.  The detail, however, is relatively complex.  Many oribatid mites exhibit a developmental behaviour called eupheredermy (eu-phere-dermy = good-carry-skin).  Each time they moult their cuticle, a more or less circular patch of cuticle (the scalp) remains attached to their back (the notogaster).  As they continue to moult (oribatid mites shed their skin 3 times before becoming adults: larva to protonymph, protonymph to deutonymph, deutonymph to tritonymph), the scalps accumulate in a pagoda like fashion.   I can see at least three layers of scalps, so this mite was nearing the end of its development when it donated its all to Science (and possibly to Art).  Some mites continue this pattern into the adult, but in this family, the Cepheidae, the scalps are shed at the adult moult and replaced by a thick and typically highly ornamented cerotegument.

Cerotegument litterally means ‘wax cover’ and is an example of more or less logical jargon.  Noto-gaster, or back-belly, seems oxymoronic to me, but reminds me of an old song about a Zombie Jamboree.  Perhaps whoever coined this term was in a festive mood? Of all the jargn in this posting, however, I like ’scalp’ the best.  It is simple and a bit bloody minded.

Christmas Mite for a Snowy Spring

A Peacock Mite - Tuckerella - From Queensland

All the snow and freezing temperatures the last few days have made Edmonton look more or less like it usually does on Christmas. So, here’s a Santa mite to ward off any more of the white stuff.

The mite actually looks pretty much exactly like the image – but that is because I laboriously drew in the long tail setae.  The original image that Caroline Meacham and I first worked up many years ago was chopped off at the rear, but was still striking enough to be picked up by the old Science Netwatch column (Mad about mites.  Netwatch (J. Kaiser, ed.).  Science 286: 1047), and led to an exchange of information with my friend at the USDA, Ron Ochoa, that helped explain the function of those long setae out the rear. 

You can see an even more beautiful image of a Tuckerella and a video of it in action at Ron’s Peacok Mite page.  Check out the rest of the stunning low temperature SEM images in his galleries.

PS – I believe the video was taken by my former student and postdoc, Jenny Beard, who is now the leading specialist on Tuckerella.  Hi Jenny, wherever you are out there, and where is that manuscript on the spider mite with the monster front legs?

Update: For anyone interested in seeing what a Tuckerella might inspire in an artist, check out this Ornamentomology exhibit page.

Tortoise Mites, but usually not the biting kind

Selection of uropodine mites – center and lower right are ant associates

I just noticed an error in my posting on ‘A mite with a mite problem’ – the lizard was covered with deutonymphs of a uropodid mite, not of an astigmatan (see Domrow, R. 1981. A small lizard stifled by phoretic deutonymphal mites (Uropodina). Acarologia 22:247–52).  However, that gives me an excuse to post on the Uropodina, a fascinating, if poorly studied group.

 Early derivative uropodines have a variety of plates and often a thick covering of highly ornamented cerotegument (e.g. the long mite with the tail in the plate and the mite in the viewer’s upper righthand corner).  The more derived lineages, however, use shiny armour for defence and sometimes add detritus to the mix, e.g. the yellow Basket Mites (probably species of Clausiadinychus) in the lower left (ventral view) and upper right region (lateral view).  These mites have a basket formed of raised setae into which they deposit little balls of detritus.  Most higher uropodines, however, look more like turtles than baskets, and are sometimes called Tortoise Mites (not to be confused with the mites that are parasitic on tortoises or other turtles).

 The Uropodina is a massive radiation of mesostigmatans (Acari: Parasitiformes: Mesostigmata) that is most diverse in species and ecological associations in the southern lands that once composed Gondwana.  The elf hat mite is one that I have already posted on.  Mostly what these mites do is a mystery.  For example, I commonly get sent samples of Uroactinia agitans (probably better known as Fuscouropoda agitans) from people with earthworm colonies where these mites can build up tremendous populations.  As far as I know, these mites do no direct damage to the worms, although they may feed on dead or dying worms and possibly compete for resources.  But that is as far as I know – and a search on BIOSIS this morning failed to find any recent studies that support this relatively benign interpretation (the paper I read was from 1953).  So, if a no one is sure what a common synanthrope does, what we know about most Gondwanan species is probably minimal.

 One partial exception are the uropodine mites associated with doryline and ecitonine army ants in the Neotropics.  The diversity and extent of these associations was first documented by the late Carl Rettenmeyer (see Myrmecos Blog for a thoughtful review of his influence on ant people) during his PhD studies.  Since then, Richard Elzinga (see list of papers below) has described many of these fascinating myrmecophiles (under a variety of family and generic names now mostly treated as subgenera of Trichocylliba).  Unlike most higher uropodines, these mites attach to the ants as adults, rather than deutonymphs.  Some just hold on tightly with well developed claws to the mandibles, head or body of the ant.  Others, though, have bizarre modifications to facilitate attachment to specific spots on their ant hosts.  Some have toothed lobes of the body that clasp an ant leg segment or have the entire body modified to fit a leg or antennal segment.  Elongate mites of one genus (Habeogula) clamp the ant’s neck and align themselves under the labial region of the host’s head, presumably to steal food.

This is just a taste of the mesostigmatan associates of ants which include groups outside the Uropodina and such strange forms as the Larvamimidae, which look like army ant larvae and are treated as such by the ants, including lugging them around (Elzinga 1993).  Other mites are known to be kleptoparasites, e.g. Antennophorus grandis on the ant Lasius flavus (Franks et al. 1991).  True ectoparasitism has been demonstrated for one uropodine mite, Macrodinychus sellnicki (Dinychidae), which slowly suck the pupae of the Neotropical ant, Paratrechina fulva into shriveled little husks (Krantz et al. 2007).  A partial list of references follows.

Elzinga, R. J. 1978. Holdfast mechanisms in certain uropodine mites (Acarina: Uropodina). Ann. Entomol. Soc. Amer. 71: 896–900.

Elzinga, R. J. 1982. The generic status and six new species of Trichocylliba (Acari: Uropodina). Acarologia 23:3–18.

Elzinga, R. J.1982. The genus Antennequesoma (Acari: Uropodina) and descriptions of four new species. Acarologia 23:319–25.

Elzinga, R. J. 1982. Th e genus Coxequesoma (Acari: Uropodina) and descriptions of four new species. Acarologia 23:215–24.

Elzinga, R. J. 1989. Habeogula cauda (Acari: Uropodina), new genus and species of mite from the army ant Labidus praedator (F. Smith). Acarologia 30:341–44.

Elzinga, R. J. 1991. Two new elongate species of Planodiscus (Acari: Uropodina) with a key to the known species. Acarologia 32:109–14.

Elzinga, R. J. 1993. Larvamimidae, a new family of mites (Acari: Dermanyssoidea) associated with army ants. Acarologia 34:95–103.

Elzinga, R. J. & C. W. Rettenmeyer. 1970. Five new species of Planodiscus (Acarina: Uropodina). Acarologia 12:59–70.

Elzinga, R. J. 1974. Seven new species of Circocylliba (Acarina: Uropodina). Acarologia 16:595–611.

Franks, N. R., K. J. Healy, & L. Byrom. 1991. Studies on the relationship between the ant ectoparasite Antennophorus grandis (Acarina: Antennophoridae) and its host Lasius flavus (Hymenoptera: Formicidae). J. Zool. Lond. 225:59–70.

Gotwald, W.H. Jr.  1996.  Mites That Live with Army Ants: A Natural History of Some Myrmecophilous Hitch-Hikers, Browsers, and Parasites. Journal of the Kansas Entomological Society, Vol. 69, No. 4, Supplement: Special Publication Number 2: Proceedings of the Eickwort Memorial Symposium (Oct., 1996), pp. 232-237.

Krantz, G. W., L. A. Gomez, and V. E. Gonzalez. 2007. Parasitism in the Uropodina: A case history from Colombia. In Morales-Malacara et al., 29–38. Acarology XI, Proceedings, XI International Congress of Acarology. Mérida, Universidad Nacional Autónoma de México.

Rettenmeyer, C. W. 1961. Arthropods associated with Neotropical army ants with a review of the behavior of these mites (Arthropoda: Formicidae: Dorylinae). Ph.D. diss., Univ. Kansas.

Rettenmeyer, C. W.  1962. Notes on host specifi city and behavior of mymecophilous macrochelid mites. J. Kans. Entomol. Soc. 35:358–60.