Some pointers if your looking to get Bristletails - Order Microcoryphia identified from photos.
Dilta spp...Short antennae; ocelli under outer corners of compound
|Dilta hibernica showing ocelli position under compound eye|
Dilta chateri. A common species in south Wales. Was found new to science by Arthur Chater in 1995 after he undertook a survey of the Thysanura in Cardiganshire. At that time he assumed that the commonest species there was D. hibernica, it was only after he published the survey in the Dyfed Invertebrate Group Newsletter that he realised it was something different. (He has since commented that he's never found true D. hibernica in Cardiganshire). https://yrefail.net/dig/DIG_Vol22.pdf
D. chateri is currently only known from Wales, though probably overlooked elsewhere due to it often being mistaken for D. hibernica? I've seen possible photo evidence of D. chateri around Bath, Bristol and Cornwall areas. Be great to get one confirmed.
|Dilta chateri showing the dark band to rear of the hump|
The above specimen is in what i call
'full splendor' and showing the dark band to rear of the hump -
diagnostic. It won't always be this thick (often with a thin band) and
will occasionally be broken in the middle. T. alternatus will also have a similar band.
|Side on view of fresh moult D. chateri|
|D. chateri showing thin dark band to rear of hump and typical body pattern |
Dilta hibernica. Not so common in south Wales, i don't find it too often in the Valleys. When i do come across it, it tends to be in wooded limestone areas. Hard Fern - Blechnum spicant overhanging path banks, rock ledges etc are a good a place as any to collect these, along with other Bristletails.
|Dilta hibernica in full splendor (photo by Chris Lawrence..one of my specimens)|
If you look close at photo above, you will see a dark V shape band running back from front center of hump down along body sides. There will also be a pale circular patch on body, found just above the pale area at base of tails - looking to be diagnostic?
Note: a similar pale area can occasionally be seen in some fresh moult D. chateri.
|Dark Dilta hibernica showing pale area part way up from tails.|
Ive used this bad pic of a D. hibernica to illustrate how clear the pale circular area can usually be seen. This and the dark V over hump diagnostic in separating it from the other two Dilta spp.
Dilta littoralis. Looks to be scarce in south Wales, known from an handful of sites. It occurs mainly on coastal sites and on
heaths, grasslands, scree slopes etc. Though, it has been found on
heath and a colliery site in the Shirowy Valley (the one below), some 20miles inland from the coast.
|Dilta littoralis with dark broken lines running length of body.|
These don't seem to be as showy as the other two, often seen with dark broken lines running length of body, as shown in photo below.
Full splendor specimens will show light brown
between these lines. Image of one hear...
Note: Dilta littoralis specimens that have lost their scales are possibly black and not cream-pinkish when 'bald' as in D. chateri and possibly D. hibernica? Needs more checking.
Petrobius spp...Antennae longer than body, ocelli 'hour glass' shaped under compound eyes.
Petrobius brevistylis. A common species considered to be confined to the coast. It likes to occupy sites with access to large continuous rocky surfaces immediately above the high tide mark. Regularly found in same areas where you would find Sea-slaters - Ligia oceanica.
|Petrobius showing long antennae |
Not possible to separate P. brevistylis from P. maritimus on body pattern. A close look at the face is needed to check for scales or lack of.
|Petrobius brevistylis. Scales clearly visible face; face looks darker (Photo by Matt Prince).|
A look at the face head on, you will see dark scales on the frons; area by outer corner of compound eye etc; (see Mick's Microcoryphia key in above link for better understanding or where to look) head looking generally darker in appearance.
Petrobius maritimus. A common coastal species that can also be found inland, have been known to enter homes. In areas where these two species occur together, a considerable degree of habitat separation can often be noticed. P. brevistylis will occupy sites with large areas of rocky surfaces, while P. maritimus usually occupies the upper surfaces of smaller stones. The average population density is greater in P. brevistylis than in P. maritimus. P. brevistylis is considered the more successful of the two species in Britain (Davies and Richardson, 1970).
Petrobius maritimus. Head generally paler with darker areas absent from frons and area by outer corner of compound eyes etc (see Mick's Microcoryphia key in above link for better understanding or where to look). A black marking is present on the pleural fold.
Trigoniophthalmus...Antennae same length as body; ocelli beneath middle of compound eyes.
Trigoniophthalmus alternatus...a scarce
species in south Wales and the rest of Britain for that matter. This
one often turns up in gardens and will venture into homes.
|Trigoniophthalmus alternatus from a garden wall in Tongwynlais|
Pale hump with dark band over rear. Overall body pattern seems consistent in this species? Some side on shots can have an appearance of Dilta chateri. Though, if you manage to get a look at the ocelli position, then it will be unmistakable..especially if you have a worn specimen.
Extra info, images, habitat photos and species info below. Any confirmed images, extra info etc would be most welcome. Will keep updating this post as going along.
|An overwintered Dilta chateri showing a bronze colour|
|Dilta chateri and D. hibernica habitat|
|Dilta hibernica (image by Sarah Patton)|
|Dilta chateri and D. hibernica habitat|
|Petrobius maritimus habitat |