Opiliones in Belgium: a word about the samples

Our Opiliones clearly don't face extinction caused by intensive sampling.
The graph shows the number of samples from each year starting with the oldest bottle I have seen.

The first captured (and preserved in the collections in the Institute) is a male Trogulus nepaeformis
taken on April 29th of 1910 in Hastière (UTM=FR26). There was no legit-name on the label.
This first male did not gave birth to a wide interest in Belgian Opiliones. For many years harvestmen
were only sampled by accident, it seems. It took sixty more years before they were studied on a more
regular base. And even now the number of data is not really impressive. I resisted the temptation to
add recent year-round pitfall actions: they count for only one sample.
graph with number of samples each year

map indicating latest sample in square
A further point is that we have almost no recent
information on the southern part of the country.

My conclusion is that the maps on this site give
only a picture of our sampling effort and nothing
more. When a map shows a species present in
some square, we know it is there. The reverse is
not true.

Because we can safely state that we have no real
information on the years before 1975, the maps
are not suited for studies on trends.
Take f.e. Trogulus nepaeformis. The map suggests
big succes for this formerly rare species.
You know better: we simply put some targetted
pitfalls during 1997.

Although the situation did improve, we still have no reason
for outburst in congratulations. The map (left) shows when a
square has been sampled for the last time. For many squares
this coincides with the first time! Check it out on the map below.
Only 12 squares have been sampled in all three periods.
A meagre 35 enjoyed two times the visit of an opilionologist.

map with sampling history

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