Monday 27 May 2019
Saturday 25 May 2019
Friday 24 May 2019
Dicymbium nigrum
I have been running a pitfall trap in grass in Leicestershire and over the past week and this has collected several specimens of the following spider, all female. Overall I think the evidence confirms that these are Dicymbium nigrum but I would appreciate confirmation from experts. Click on the images for larger photos:
Small squares = 1mm
Roberts (Roberts, M. (1993) The Spiders of Great Britain and Ireland, Compact Edition (2 vols) Brill) says of the two UK species of Dicymbium:
Numbers of dorsal spines on tibia I, II, III, IV: 2211 - YES
Femur I shorter than prosoma - YES
Fovea clearly visible as darkened groove - YES
No dorsal spines on femur I - YES
Posterior eye row: straight - ?? - see below
Anterior median eyes: distinctly smaller than ALE - ??
Sternum rugose - YES
Position of TmI by range 0.50-0.59 - see below
Metatarsus IV dorsally: trichobothrium present - YES
No dorsal spines on metatarsus I - YES
Tibia IV one dorsal spine - YES
Femur I shorter than prosoma:
Posterior eye row: straight - looks straight when viewed from above (is that right?)
Anterior median eyes: distinctly smaller than ALE - I'm not sure about this??
Position of TmI by range: 0.50-0.59: I measure it as 0.64 - ??
Metatarsus IV dorsally: trichobothrium present:
The epigyne is key to separating female specimens of Dicymbium nigrum and Dicymbium tibiale - these specimens have the short epigynal fissure of D. nigrum rather than the longer fissure of D. tibiale:
UPDATE: This was kindly conformed by Matt Prince, BAS, with the proviso that it could be Dicymbium brevisetosum, which may or may not be a separate species and which can only be identified in males (none of which I have found yet).
Small squares = 1mm
Roberts (Roberts, M. (1993) The Spiders of Great Britain and Ireland, Compact Edition (2 vols) Brill) says of the two UK species of Dicymbium:
Numbers of dorsal spines on tibia I, II, III, IV: 2211 - YES
Femur I shorter than prosoma - YES
Fovea clearly visible as darkened groove - YES
No dorsal spines on femur I - YES
Posterior eye row: straight - ?? - see below
Anterior median eyes: distinctly smaller than ALE - ??
Sternum rugose - YES
Position of TmI by range 0.50-0.59 - see below
Metatarsus IV dorsally: trichobothrium present - YES
No dorsal spines on metatarsus I - YES
Tibia IV one dorsal spine - YES
Femur I shorter than prosoma:
Posterior eye row: straight - looks straight when viewed from above (is that right?)
Anterior median eyes: distinctly smaller than ALE - I'm not sure about this??
Position of TmI by range: 0.50-0.59: I measure it as 0.64 - ??
Metatarsus IV dorsally: trichobothrium present:
The epigyne is key to separating female specimens of Dicymbium nigrum and Dicymbium tibiale - these specimens have the short epigynal fissure of D. nigrum rather than the longer fissure of D. tibiale:
UPDATE: This was kindly conformed by Matt Prince, BAS, with the proviso that it could be Dicymbium brevisetosum, which may or may not be a separate species and which can only be identified in males (none of which I have found yet).
Monday 20 May 2019
Andrena scotica
It's #WorldBeeDay, apparently. Too bad beetles, wasps, flies, dragonflies, you're out of luck.
Friday 17 May 2019
Ruby Tiger
For the first time this year it felt like it was worth putting the trap out last night - more species in one night than the rest of the year to date, including this smart Ruby Tiger, Phragmatobia fuliginosa.
Thursday 16 May 2019
Subscribe to:
Posts (Atom)