Rickia wasmannii everywhere

Thanks to John Pontin for pointing out the Rickia infested ant in one of this years Wildlife Photographer of the Year competition. I had the portfolio at home, but hadn't noticed the fungus on the ant. It's a bit hard to tell from the online image, but is really quite clear when it's a bit bigger.

I'm thinking that the ant is probably Myrmica rubra. As far as I know, R. wasmannii has not been recorded on this species before. Perhaps the photographer, András Mészáros, would be able to help establish whether I'm right?

I'm starting to think that R. wasmannii is actually quite common in Europe, but just under-recorded. Has anyone else made Rickia sightings?

Rickia wasmannii in the UK

Did anyone else notice the photograph on Plate 8 of the 'Ants of Surrey', captioned 'A rare variety of M. sabuleti with unusually shaped hairs? I'd had the book for ages and not paid any attention to it until a few weeks back. The unusually shaped hairs looked remarkably familiar to me.

I emailed John Pontin, to see if he had any specimens of these ants. After a bit of a mix-up over my address (which has changed since the last BWARS newsletter, by the way) I finally retrieved the two specimens he sent to me. They are covered with Rickia wasmannii, as I suspected, more so than the specimens I collected in Bavaria. This fulfils my ambition of finding it first in the UK, even if I didn't collect it. It also means probably two more papers to write (one for the mycologists, one for the myrmecologists).

Rickia wasmannii

Fairly regularly something comes along and completely stumps me, but it doesn't normally happen with European ants.

I thought I knew Myrmica well, especially M. scabrinodis, which is one of the species I most regularly encounter. This Bavarian specimen really has caused me to do a disproportionate amount of work to resolve it's identity.

First of all I wasn't even 100% certain that it was a Myrmica. It has unusually large mandibles and, particularly, it appears to be covered with rather strange clavate hairs. I had to get my BIG eyepieces out to check the tibial spurs on the middle and hind legs (which were dubiously pectinate) and then count the palp segments, which always takes a lot of effort to get the position and lighting good enough to see anything. The result was that it is definitely a Myrmica.

By this stage I had already decided that it had the antennal scape and overall shape of M. scabrinodis, but those hairs were peculiar. I worked my mounted specimen through Seifert (1988) and his new book (2007), both of which suggested clearly that the specimen is M. scabrinodis¹.

I then really started asking questions about those hairs and, once I had thought of fungi as a possibility, I quickly found was seems to be the most likely answer: Rickia wasmannii. This was described from Germany, though I've no idea how common recorded it is. It was only recently collected from Hungary and Romania (Tartally, et al, 2007), and does not appear to be known from the UK. All five specimens in this collection are covered in these little growths on almost every part of their bodies.

I haven't actually confirmed this, but I suspect that species of Rickia are host specific and that R. wasmannii is the only one that is known from Myrmica sp. However, if anyone has any additional information on Rickia sp. I'd be very grateful to hear about it. In the meantime I will spend a lot more time looking at British Myrmica in the hope that I can get the first UK record of R. wasmannii!

I sure know how to have fun on a Friday evening.

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¹ For those who are interested in such things, the standard measurements and indices used to make the identification were as follows:
     Head length (HL) = 996 µm
     Head width (HW) = 952 µm
          HL/HW = 1.047
     Scape length (SL) = 763 µm
          SL/HL = 0.767
     Minimum distance between frontal carinae (FR) = 310 µm
          HW/FR = 3.071
     Maximum distance between frontal lobes (FL) = 443 µm
          FL/FR = 1.428
     Length of propodeal spines (SP) = 310 µm
          SP/HW = 0.311
     Petiole width (PE) = 266 µm
          PE/HW = 0.279
     Postpetiole width (PP) = 376 µm
          PP/HW = 0.395