On Saturday I visited the sand dune system at West Wittering with '
The Lyons'. He had surveyed the site last year so had a pretty good idea of what we might find, albeit that there were bound to be new species for the site, even when the fauna is specialist but species-poor. The weather was not too bad for the time of year but an increasingly strong wind made life difficult and my net, which I carried round throughout, remained unused. Instead we relied on tussocking, sieving and his vacuum sampler; techniques that I very rarely use. The resulting catch was primarily spiders and beetles (hence why I rarely use these techniques) and the average size of the specimens was best measured in micrometers!
Graeme was able to identify a lot of what we caught but if I just ticked off everything he said, it would defeat one of the main objects of 'The Challenge' - learning stuff myself. So I took a bunch of specimens of things that I thought I might have a fighting chance of doing and made some notes of Graeme's suggestions so I'd have a pretty good idea if I'd keyed things properly. More than two days later and I'm not even a third of the way through the specimens and I've got three definites, a probable and an 'errrrr' out of the beetles.
Apologies for the poor photos but it's a case of spend time getting decent photos or write the blog.
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Pseudaplemonus limonii - a rather nice weevil off sea-lavender |
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Cordicollis instabilis |
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Coccidula rufa |
All three of these were lifers for me! I then had a look at an
Otiorhynchus weevil. I got as far as
ovatus or
desertus with something vaguely approximating to a degree of confidence. Duff separates these by the tooth on the hind femur being 'long and sharply pointed' or 'very small and obscure'. Well that's bloody helpful, how long, how pointed? The RES key was more helpful in that it says the tooth should be as long as the width of the tibia. Well the tooth is much shorter than the width of the tibia but other features don't fit well with desertus so.....
On to the subject of the blog title. The ladybird in question is less than 1.5mm long but it's a ladybird, how hard can it be? Well, my go-to book for ladybirds is the Naturalists Handbook but a bit of a Google had suggested the best fit for my specimen might be
Nephus redtenbacheri and that isn't in there as it was found in Britain since the book was published. So I tried the Bloomsbury Field Guide which according to the 'celebrity' endorsement on the back is the 'definitive field guide to ladybirds'. Well it is the definitive guide only if your idea of identifying things is to look at a picture and say 'well it looks like that one, that'll do'. For a group of species that are extremely variable in appearance, to have no key, no clear cut features to separate similar species, etc. is far from 'definitive' to my mind. Anyway, Mike Hackston came to my rescue as he so often does; a decent key in intelligible language. So I fumbled my way through to couplet 18 which asks whether there are ridges on the process on the prosternum. Seriously? The whole beetle is <1.5mm! Even at 80x magnification I had no idea so I took a photo and looked at it on the laptop.
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So has it? |
I was hoping for a nice smooth process where it would be easy to see ridges. On this bloody thing I had no real idea but plumped for yes. This eventually took me to a group of
Scymus species, none of which looked like my specimen so I tried no. This took me to the question of how many antennal segments does it have? Oh come on! Again, the whole beetle is less than 1.5mm.
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How many segments then? |
One option took me to just one species and it didn't look right for that, the other took me to a pair which includes
Nephus redtenbacheri. So I guess that's probably what it is but identifying things through a route where you cannot clearly identify features that you need to see is most unsatisfactory. It retains a ? on the label.
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Nephus redtenbacheri? |
Fortunately, I did pick up a few flies which have been much easier to key. Two
Lonchoptera lutea and a
Geomyza tripunctata both provided new families for the year, as did a Chloropid which I haven't tried to key yet.
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Geomyza tripunctata |
Love the lilac weevil. Need to look out for it next time i'm at the north Norfolk coast
ReplyDeleteI found Nephus redtenbacheri over ten years back on a burnt bit of Hambledon Common (conf. Roger Hawkins). It won't appear in the keys but I think the leg colour proved to be diagnostic? Be nice if the keys started "are the legs black or red" but that would be far too simple and common sense-worthy...
ReplyDeleteChloropids...what key(s) are you using? And do you have a spare Sphaerocera RES key??? Having a bugger of a time tracking one down.
ReplyDeleteChloropid was keyed to family only I'm afraid. Can't help with Sphaerocerids I'm afraid but there is probably a key at Dinton when you're down. No mention of leg colour in Hackston's key I'm afraid.
ReplyDeleteI use the 1989 Naturalists' Handbook key to coccinellids but there's much room for improvement. It separates Scymnus (prosternal keels present) from Stethorus and Nephus (prosternal keels absent) but this is clearly wrong, as your photo of Nephus redtenbacheri shows. There are keels on the prosternum of Nephus but they are shorter and only on the process, not running the full length of the prosternum.
ReplyDeleteThe 2013 edition should be better as I did submit a load of comments and corrections to the keys.
ReplyDeleteI suppose it also has to be said that N. redtenbacheri has recently been split on the British list, as there is a very similar species on sea-lavender called N. limonii. I guess yours could be limonii.
ReplyDeleteThanks Mark, I do normally use the 1989 Nat. Handbook. Thanks for the tip about N. limonii, I'll look in to that.
ReplyDelete