Tuesday, 25 March 2008

Monomorium sp. A

When I first attempted to identify this ant I decided that it was Monomorium exiguum, though I wasn't exactly convinced. I was using Bolton (1987), though I find the key fairly vague at times, which isn't helped by the fact that the descriptions aren't exactly consistent and many species lack diagrams.

M. exiguum is the last species in the key - okay, so there aren't that many Afrotropical Monomorium with 11 antennal segments, but even so I feel that if you've got to the end of the key and your not convinced, then chances are you are wrong.

Then I discovered that I had collected specimens that were a perfect match for M. exiguum and very different from this species, so it was clear that I was wrong. I went back to the key and decided that the next best fit was Monomorium dolatu, though I was rather less than convinced - the petiole shape and Cephalic Index appeared to be correct, but there were slight differences in the structure of the clypeus.

My trip to the Natural History Museum, London has thrown the latest spanner in the works, as I've now been able to examine specimens that Bolton identified as M. dolatu closely. It's pretty clear that this isn't M. dolatu, as the petiole shape is not near as conical as on that species and it's generally wrong. I was also able to check and eliminate M. pulchrum, M. taedium, M. fastidium and M. vaguum. I have in my collection and was able to confirm M. rosae, M. exiguum and M. mictilis. The only other species that it could remotely be is M. bequaerti, which was not present in the museum collection, but this should have a postpetiole the same size as the petiole, as in M. pulchrum, which my specimen does not have.

Since I've eliminated all Afrotropical species of Monomorium with 11 antennal segments I'm having to call it 'species A' for the moment, at least until I've checked those species occurring elsewhere. This is the second potentially new species of Monomorium I've encountered in as many months - the first I've already established is definitely new.

M. sp. A was collected once, nesting within an Acacia pod, in Kololi. Because this was within our last few hours in Gambia and I had packed everything to leave, they were collected alive. I had to carry the pod, with the ants, back to the hotel in my hand. This involved dodging the bumsters (notorious in The Gambia) and trying to keep the pod safe whilst I had a chat with a charming young Gambian woman, who invited me to a 'club' and I suspected to be a prostitute. Once I made it back to my room I put the pod and the ants in a bag and in my case, where they remained until I got home.

I kept them alive for a few days before realising all I had were a few workers - not worth the effort of keeping long-term. They were also a pain; they proved to have an incredible ability to walk upside down on a smooth surface and vertically across fluon. This, combined with the fact that they tended to wedge themselves into the small gap between container and lid made them very difficult to contain. Given these recorded habits it seems that this species is well adapted to an arboreal lifestyle.

Incidentally, the droplets of liquid are grease. I will have to do something about this soon, whereupon I may upload some fresh photographs.

Camponotus vestitus subsp. intuens

I originally identified this as Camponotus cosmicus and wrote a nice long blog defending my decision to call it that. I even provisionally synonomised it with a few other species and subspecies. I was wrong!

At the time, I sent photographs to Brian Taylor, who replied, 'Why do you not think this is Camponotus vestitus?' Perhaps I should have recognised that his far greater experience was likely to lead to a correct identification, but I like to learn from my own mistakes.

C. cosmicus was one of the species that I checked when I visited the London Natural History Museum, as the holotype is there. C. cosmicus is a large and fairly stocky ant, even the minors, unlike my specimens. I was also able to check C. vestitus subsp. pectitus, which has all the right features (divergent pubescence on the gaster, same number of setae on the mesosoma, same propodeum shape) and differs only slightly in the colour of the head.

Arnold (1924) stated that Smith's (1858) description of C. cosmicus is useless, and it appears as though he is right. However, none of the authors who have written about C. cosmicus picked up on what I believe is probably the most significant characteristic, as all specimens in the museum had many erect setae on the ventral surface of the head. I can also add that C. cosmicus is predominantly very dark red (not black), with the propodeum rounding smoothly from the metanotal groove, less divergent pubescence on the gaster and a greater number of setae on the mesosoma.

So, maybe it is C. vestitus subsp. pectitus. It gets complicated because Bolton (1995) states that Santschi (1926) suggested that C. vestitus subsp. pectitus and C. vestitus subsp. intuens are the same, but at no point do they appear to have been properly synonymised. Reading Santschi's statement, it seems pretty clear that he has no doubt, so I can only assume that Bolton did not synonymise it because the description of C. vestitus subsp. pectitus post dates this statement! Forel's (1909) description of C. vestitus subsp. intuens is just as ambiguous as the descriptions of C. cosmicus and C. vestitus subsp. pectitus.

Update Nov 2008: My specimens have now been compared with the type specimens from the Naturhistorisches Museum Basel. This allowed me to confirm that they are very clearly C. vestitus subsp. intuens - a completely identical match. Possibly the colour of the head is the key feature in discriminating these subspecies.

I also showed my specimens to Cedric Collingwood, who claimed them to be C. jizani. This is a species from the Middle East, though he admitted that the only reason he named it thus was because he didn't know what else to call it! Possibly, C. jizani is a junior synonym of C. vestitus subsp. intuens or C. vestitus.

This species was collected a number of times only in the grounds of the hotel we were staying at in Kololi, Gambia. Here it could be found nesting in turret nests, so named because there were steep 'craters' of sand piled around the nest entrances, up to about an inch high. These are described by Arnold (op. cit.) for C. vestitus subsp. pectitus, which he states is rare and found nesting in sandy soils. He then describes,
'nest-entrances[s] surrounded by a circular, high and sharp-edged crater... This form of crater is distinctive of this insect.'


Before I disappeared for Easter I visited the London Natural History Museum to compare my some of my Gambian specimens with ant specimens in their collection. As a result, I have a few changes to make, but need to do a bit more work before I make them. Until I change the posts, this will hopefully caution against relying on previous posts.

I had misidentified the following species:
I had correctly identified these species:
These species are perhaps open to debate, as I couldn't conclusively establish whether they were the same species or different:
  • Camponotus rufoglaucus controversus - slight differences in setae and pubescence but the specimens checked were not types and were majors only.
  • Camponotus olivieri lemma and delagoensis - I couldn't check these subspecies.
  • Crematogaster impressa - the specimens present were collected by Donisthorpe and did not appear to be the same as mine or each other. Chances are this species and C. excisa will not be resolved until the taxonomy is revised.

Monday, 10 March 2008

Earth Hour 2008

Here's a really neat idea: everybody, everywhere in the world switches their lights off for a particular hour on a particular day. It seems a bit like the more productive and less-potentially-damaging version of everyone in China jumping all at once (which I've always thought would be fun to try just once).

So, at 8pm on the 29 March 2008 (hopefully) millions of people around the world will switch off their lights. I'm rather disappointed that London isn't listed as one of the cities involved, but that shouldn't stop me or anyone else from getting involved.

For more information, click on the banner at the top.

Sunday, 9 March 2008

Fungal attack - Cordyceps gracilis

In a few months I'm going to let my online gallery close, so I'm taking the opportunity to post some of the more unusual photographs here.

This is Cordyceps gracilis. Cordyceps fungi are parasitic on insects, some of which are quite extraordinary looking.

The common species of Cordyceps within the UK is C. militaris, which can occasionally be found growing out of buried Lepidoptera.

C. gracilis is much rarer and very different in appearance, but also infects Lepidoptera. It was collected during a heathland survey training event at Poors Allotment, nr. Chepstow and was only the second record for Gloucestershire (though there are now four). It was growing in Pteridium aquilinum litter, which meant that I only had to reach down to pick it up and the whole thing came out easily, caterpillar as well. In case you don't believe that it is a caterpillar, I pulled the mycelium away from the caterpillar's head and took the close up photograph below.

Here is a short clip about tropical Cordyceps and ants:

Saturday, 8 March 2008

Tachinus rufipes a myrmecophile?

Tachinus rufipes MJL235I found this rove beetle under a stone in the middle of a Lasius flavus colony. As a potential myrmecophile it was pretty convincing, as it was in a chamber right in the middle of the colony, though at a distance from the ants. I collected it with a few L. flavus and kept it alive with them for a few days before deciding to work out what it is.

I originally thought it might be Lamprinodes saginatus, a species associated with ants, including Lasius. However, I'm not a coleopterist and the Staphylinidae are particularly difficult, so I am indebted to Don from the BWARS forum for suggesting an identity from these pictures and describing a bit about the genus.

Apparently it is most likely a male Tachinus rufipes, a not uncommon species in the UK. Tachinus tend to live in grass tussocks, decaying vegetation, dung, carrion, etc, so seem to be generalists. None are listed in Donisthorpe's The Guests of British Ants (1927) as being myrmecophilous. Whether or not this species should be regarded as a myrmecophile probably depends upon how many other times it's found in ant nests, but it is certainly not a species that is dependent upon ants. Most likely the ants were providing suitable conditions and a possible food source. This relationship may not come without a price to the beetle, as both antennae in this specimen are missing segments at the end.

The site it was collected from is one of my favourites and is usually the first site I visit each year. It is a steep south-facing grassland in a sheltered valley and has a lot of flat stones on the ground under which ants nest. Early in the year whole colonies are easy to find just under these stones, along with their myrmecophiles. It was originally visited by Cedric Collingwood in 1960; I checked it out 40 years later and rediscovered Formica cunicularia. These F. cunicularia all seem to be doing something they shouldn't, as they are polygynous, so this year I collected a colony with five queens to observe. Other species recorded include:
  • Myrmica sabuleti
  • Myrmica scabrinodis
  • Myrmecina graminicola
  • Lasius alienus
  • Lasius brunneus
  • Lasius flavus
  • Formica fusca
  • Claviger testaceus
  • Platyarthrus hoffmannseggi
plus a few as yet unidentified possible myrmecophiles, most of which are more nondescript rove beetles. There aren't that many species of ant in the UK, so any site with eight or more species and frequent myrmecophiles is somewhat exciting.