De kleine hooiwagen Nemastoma dentigerum Canestrini (Opilionida, Nemastomatidae)

The small opilionid Nemastoma dentigerum Canestrini (Opilionida, Nemastomatidae). Up till now only a few specimens of Nemastoma dentigerum are known to have been collected in The Netherlands. This species however is very common in a polder near Nijmegen, province of Gelderland. The author assumes that the species is not uncommon in at least the southern parts of the Netherlands and that it may be extending its range to the North. This would fit a general pattern of several species of harvestman that seem to show a tendency of moving northwards during the last decades, e.g. Platybunus pinetorum, Nemastoma bimaculatum, Trogulus nepaeformis, Dicranopalpus ramosus and Opilio canestrinii. The distribution of N. dentigerum near Nijmegen is illustrated and compared with those of Nemastoma lugubre and Nemastoma bimaculatum, which also occur in this area. Some ecological and behaviouristic observations on N. dentigerum are discussed.