Building a key to the British Alexeter | Identification Trainers for the Future

In the final post of our short series on the curation placements of our Identification Trainers for the Future, Chloe Rose gives us an insight into the work she has been doing in the Hymenoptera department. The Hymenoptera include all bees, ants and wasps, but Chloe has been focussing her work on the parasitic wasps, of which there are a surprising number in the UK.

I have been spending the last 2 months of my traineeship in the Hymenoptera department with Dr Gavin Broad (Senior Curator of Hymenoptera, specialist in Braconidae and Ichneumonidae). Here I have been working on a genus known as Alexeter, a group of wasps which parasitise sawflies.

Photo showing Chloe picking up a specimen via its pin, using forceps
Chloe in the process of re-curating part of the Hymenoptera collection.

These wasps fall into the Mesoleiini tribe which is part of a large subfamily known as Ctenopelmatinae. There are around 6,000 known species of parasitic wasps in the UK, a staggering number which is a huge portion of our insect diversity. However, little is known about many of these groups and few of these species have well illustrated identification keys available, making the area of study considerably less accessible. This is why I am helping Gavin to construct an easy-to-use identification guide for this poorly understood group of wasps.

During the first few days of the project we got stuck straight in. Gavin pulled out the 2 drawers of specimens and let me spend the first day looking at them through the microscope and familiarising myself with the different species. From Day 2 onwards, I spent my time re-curating the collection, replacing the old cork boards with modern foam trays.

This is a very tricky job when dealing with such fragile specimens and inevitably a few got broken. It’s important that if any are damaged, any lost parts are kept in gel capsules and attached to the specimen. Although there are risks in moving a collection, it is an important curatorial procedure which will help better conserve the specimens in the long term. It was also very helpful for the rest of my work as the older pins had begun to fuse to the cork making them difficult to work with.

Photo of Chloe sitting at her desk with a drawer full of the re-curated specimens in their trays
Now in their new foam trays, the next part of my project was to start creating the identification key

The next part of the project was to start looking at the 9 individual species of Alexeter and noting down their differences. What differentiates one species from another and how can you tell them apart?

I needed to start thinking about which characteristics were the most defining and how these could be interpreted into a key. I initially thought this would be fairly straightforward and envisaged it to be similar to a game of spot the difference! But I was sadly mistaken.

Features that I once thought as constant then began to vary the more specimens I looked at and therefore could no longer be used as a reliable characteristic, sending me back to the drawing board. Differences between males and females also have to be taken into account as colouration for example will often vary between the genders.

Admittedly there were some easier species that I became very quick at identifying, such as the nocturnal ones which are orange and easy to tell apart; for example, Alexeter nebulator, has a black head when looking at it from a dorsal view and Alexeter clavator has an orange head.

When faced with a genus that has a number of similar looking species within it, writing a key for it then becomes tricky as the characteristics you’re looking at become minute and very subtle, such as a slight kink in a vein on a wing or the minor change in pattern on a textured surface.

The next part of the project was to start photographing the specimens so the images could be used to illustrate the key. I took care in picking out specimens, taking preference for ones which were intact and well positioned. I then cautiously, using a fine brush, removed any bits of dust, pollen or tiny specs of fabric (these can’t be seen with the naked eye, but can potentially ruin photos and, in many cases, won’t be visible until after you’ve taken the picture!).

Once they were all looking their best and in position, I began the ‘photo shoot’. The camera I used has software designed specifically for challenging subjects, providing depth of field at microscopic level, ideal for a genus such as this.

I have however, found this group to be particularly challenging to photograph because of their abundance of body parts and gangly nature; legs, antennae and wings sticking out in every direction. Keeping all of the features in focus and making sure all of the important characteristics are visible can be very tricky.

I am new nearing the end of this project and tying up all the loose ends, watch this space for our publication of a key to British Alexeter!

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