Не зря я все-таки состою в общетаксономической рассылке TAXACOM!
Хоть и приходится каждый день удалять из почты 10, а то и 50 ненужных писем, которые не имеют отношения к нашему сайту; но часто удается получить очень интересную информацию.
Вот в этот раз удалось увидеть редкие фотографии микроскопического клеща на эдеагусе жужелицы из рода Platycoelus. Жука нашел Kipling W. Will из Калифорнийского университета в поездке по Iron Range National Park (Квинсленд, Австралия). Им же сделаны фотографии.
Род Platycoelus (в письме допущена ошибка) относится к трибе Pterostichini (за уточнение названия и указание систематической принадлежности жука - огромное спасибо Б.М.Катаеву!). Клещ, скорее всего, из группы Astigmata.
Появление фотографий вызвало вот такую дискуссию ученых (см. выдержки из писем ниже)
Fri, 13 Jan 2012 14:43:31
Always something new, or at least new to me. Everyone knows that mites are very common on carabids, externally and under the elytra, but in all the countless dissections I have done, I have never seen one parked up and inside, within the telescoped genitalia, on the median lobe of a male as in the attached images. Has anyone encountered this? This same beetle also has what looks like mite larvae in "burrows" in/on its wings, which are highly damaged. I haven't paid much attention to wings, so this may be common. The species of carabid is an undescribed Platycaelus from the Iron Range, NQLD. I hand collected the specimen into EtOH during a trip with Geoff Monteith of the QM to the Iron Range.
Kipling W. Will
University of California
Fri, 13 Jan 2012 18:08:35
I found them in the vaginal trac of Brachinus during my dissertation days. I'll check to see if I mentioned that in my revison.
Terry L. Erwin
Department of Entomology
Fri, 13 Jan 2012 10:36 PM
Never see, perhaps an accident ?
I thought that the mites were only transported, but not parasites!
Sat, 14 Jan 2012 10:05:13
Yes, many mites on carabids are just riding around and getting a meal of scraps (i.e.phoretic), I have seen masses of mites on big pterostichines and pamborines that swarm off the body and onto the head and the prey item the beetle is eating to get their own meal. But there are some true parasites as well. There is a pretty large, but scattered literature on this, which I am only slightly familiar with.
As for this being an accident, if you mean that it isn't where the mite would normally ride and it just happened to get pulled into the male when the beetle retracted its aedeagus, then perhaps so. But since I collected this specimen and one female of the same species into a clean 95% EtOH vial and when I did the dissection the male was closed up tight, it wasn't contamination. Not like you might expect from a big pit fall trap sample where everything is sloshing around together.
Sun, 15 Jan 2012 20:59:33
The only mite that I can remember from the genitalia of carabid beetles is the genus /Ovacarus /(Acari: Tarsonemoidea: Podapolipidae). Members of this family are all obligate ecto- and sometimes endoparasites of insects. The mites under the elytra of carabids are likely from this family too, and several genera are found on carabids. They're extraordinary mites, showing moderate to massive reductions in morphology, relating to their parasitic life. They're fairly grotesque, but to an acarologist they have their charms!
That said, this mite in the picture doesn't look like a podapolipid, which are (from those I've seen) soft bodied, pale creatures. This looks more like the non-feeding, phoretic life stage of an Astigmata. These mites stick limpet-like to their hosts with their ventral suckers. They're usually common externally, but I've not come across them internally. However, a general rule in Acarology is that if an animal has a space small enough for a mite to crawl into, they will.
I am, of course, happy to look at the mites. At the very least I could work out who would be most interested in them! Carabid beetles have some extraordinary mites. They're not the most mite-infested of beetles (passalids, scarabaeids & perhaps scolytids beat them), but they win hands-down for the most bizarre mites.