Leiobunum rotundum species account
Leiobunum rotundum
This page is, for now, created as an experimental extra to the main article "British Harvestmen" to see if it's a good way of providing a more detailed species account next to the more generalist main text.
Also for now, it'll be mostly a parking place for extra images that may document the various development stages and colour variety of the species, but we hope to add more specific info on the morphology and biology of the species as we go along. No timeframe though
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Intro
As noted in the main article both British species of the genus Leiobunum (L.rotundum and L.blackwalli) are fairly easily set apart from other species by their extremely long and fine legs compared to the, rather smallish to medium body size, which is even more notable on L. rotundum than on L. blackwalli and especially on the males. On adults (!) the legs are also very conspicuously dark, almost black, but on juveniles these are still brighter and patchy.
L.rotundum male (center) and two females found under a rock on bank of river.
Length of second leg indicated on male.
Other species with long legs, but just a tad shorter, both relatively and absolutely, include the very closely related genus Nelima, and the species Dicranopalpus ramosus (which is easily set apart by other features), but most confusingly probably Opilio canestrinii which also shares the dark/black legs on adults and the often orange-reddish body colour.
In the British Leiobunum sp. males and females can be quite easily told apart by their distinctive colouring and habitus: Males have a smaller, almost roundish body that is usually coloured quite brightly orange-red (more brownish on occasion) with an almost indistinguishable "saddle" pattern on the back, whereas the females have a much taller oval body that is usually more brown than reddish with a clear, much darker saddle pattern.
The two Leiobunum species can be told apart, in adults, most 'scientifically prudent' by their gentials (male penis preferably), but can also usually be distinguished quite reliably by the colouring of the ocularium, which is mostly entirely dark/black on L. rotundum and carries a clear/white band over each eye on L. blackwalli (when viewed from above one could easily think the ocularium is white with a small black band in the middle (a little black wall
).Furthermore, the females have fairly distinctive body shapes (in healthy adult animals) and saddle markings: L.rotundum taller, more oval (or rectangular with rounded edges if you will) with an almost straight dorsal band that only has minor zig-zags and a feeble "T" shape toward the rear. L.blackwalli shorter and much more "pear" shaped, with a triangular (or rather "Christmas tree" shaped - thanks Hay
) dorsal band that clearly widens posteriorly. Both body shape and dorsal 'saddle' markings are somewhat variable though, so should be used with some care as ID-ing characters.
Leiobunum rotundum (top) and blackwalli (bottom); females left, males right.
As noted above, the juveniles and even the sub-adults can look quite distinctive from the adults as many 'features' are not yet fully developed. For one thing the colouring of the legs is not clearly blackish yet, much more transparent and even has clear patches or rings if you will, but also the ocularium is not necessarily 'recognizable' as shown nicely in this image of a sub-adult female.
Sub-adult female, note the relatively clear ocularium! : Original Date/Time = 2008:07:14 14:05:34
On the real juveniles even the total colouring is such that any association with the adults would be wishful thinking.
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Biology
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Some Images
This is (for now?) simply a collection of images to 'document' the species - mostly based on availability rather than quality or their purposefulness for showing special features ...