Ichneumon Report for 2015
Presented to the YNU Entomological Section Meeting at Wilberfoss on 13th March 2015
I have commented previously on the fact that the UK ichneumon checklist that Dr Gavin Broad, the NHM ichneumon specialist, has placed online is c20% larger than the list published by the RES in 1977, that is c500 more ichneumons. As very few people have studied this group of insects it is difficult to separate those which have simply been overlooked from any that are new arrivals in the UK. Identification guides published some decades ago are becoming more out of date. For example, J.F.Perkins was at the NHM half a century ago and more and published two RES Handbooks dealing with the Ichneumonine subfamily in 1959 and 1960. There are now 50-60 additional ichneumonines in Britain, so we have to use Perkins' keys with caution. From the time I started looking at these insects in the mid-1970s I have found ichneumonines that did not give me a satisfactory answer in Perkins' keys and I now have half a storebox of these insects that I have failed to identify, sometimes after several attempts!
On the other hand, new keys have opened up new possibilities. Take Phytodietus, for example. The Phytodietini is a tribe of the Tryphonine subfamily and is characterised by the sculpture of the propodeum which has no carinae but has fine transverse striae. There are two genera: Netelia, which is nocturnal, orange-yellow with large eyes, long legs and long antennae, and Phytodietus, which has a black body with cream markings and red legs. D.R.Kasparyan of the Russian Academy of Sciences in St Petersburg published a review of the Palaearctic species in 1993 which was translated into English a year later. I caught up with it last year and have sorted out the mounted specimens in my storeboxes. There were two species already on the Yorkshire list, both confirmed, and that has increased to seven, most with several records from multiple vice counties.
One subfamily that has been a problem is the Ctenopelmatinae. These ichneumons are very diverse and some closely resemble ichneumons in other subfamilies but the characteristic feature is that the fore tibia has a tooth projecting from the tip. A handful of them are nocturnal hunters and resemble Netelia in appearance. Mike Fitton and Ian Gauld produced a key to nocturnal ichneumons thirty years ago and Gavin Broad and Mark Shaw at Edinburgh have a new one in circulation. As a result there are plenty of records from all over Yorkshire. The rest of the subfamily consists of black-bodied insects. A major problem is that the key to tribes (of the world) that Henry Townes published 45 years ago really does not work. Gavin Broad has solved the problem by looking at the specimens in the NHM and memorising them!
I decided to follow his example last year when I was working on the Leeds Musuem collection and came across a pair of Hadrodactylus tiphae named by G.J.Kerrich. Kerrich worked at Manchester Museum before moving to the NHM and I regard his identifications as reliable, so I borrowed the specimens to study at home. I noticed that these slender insects had the first tergites long and elongate, so I extracted the specimens with this feature from my storebox. I then noticed that the outer crossveins in the forewings had a strong zigzag shape just below the large areolet, so any specimens without an areolet ot with a straight vein went back in the box. Then I saw that the clypeus was thick, convex and heavily punctured with the punctures continuing up the face, so any insects with smooth faces or thin or impressed clypea went back in the box. That left 50-60 specimens which I compared with Kerrich's specimens and worked out how they fit into Townes' keys. Townes did not mention the shape of the crossvein at all! The Swedish entomologist Mattias Idar had studied Hadrodactylus in the 1960s and 70s and published two papers (in English) 35 years ago. I compared the specimens I named with those at NHM but Gavin Broad drew my attention to a new key by Kasparyan and provided me with a copy. This key is a great improvement on Idar's and has allowed me to sort out nearly all the specimens I have. There were previously three species of Hadrodactylus on the YNU cards and that has increased to 14. The second most common one in Yorkshire was not described until 2009 when Kasparyan found specimens in NMS and he and Mark Shaw named it in honour of Mattias Idar. This demonstrates the difficulty that previous workers will have had if a common ichneumon is not in any keys.
At about the same time I was working on the Sheffield Museum collection and noticed specimens of two Ctenopelmatines that had been collected and named by the Belorussian entomologist Sasha Tereshkin while on a week-long visit to Derek Whiteley in 1996. One was Scolobates auriculatus, the only British representative of the tribe Scolobatini.This insect had the face produced into a pointed snout, the claws had a long, strong pecten on each claw and the propodeum was smooth with each spiracle surrounded by a raised doughnut-shape. Townes does not mention the shape of the face or the characters of the propodeum at all! I looked through the specimens in my storebox and found a specimen collected in Sheffield by Roger Shaw. The only other Yorkshire record is from Allerthorpe in 1923, collected by W.J.Fordham. This specimen is in the World Museum in Liverpool and I need to check that out one day.
Last autumn I took up Gavin's offer to name some specimens to genus for me and I took him a few Ctenopelmatines on each visit to London. He not only named the genera but many of them he named to species as well. This allowed me to learn the characteristics of several genera and I have now taken a few to NHM and checked the features of the species in several genera.
The Yorkshire ichneumon total has now reached 1,000 confirmed species plus 180 others which may be correct but there are no confirmed records.