Order: Opiliones, Harvestmen

Family: Nemastomatidae

Paranemastoma quadripunctatum

Overview species:

Family: Nemastomatidae, 5 species in the Netherlands
Mitostoma chrysomelas (Hermann, 1804)
Nemastoma bimaculatum (Fabricius, 1775)
Nemastoma dentigerum Canestrini, 1873
Nemastoma lugubre (Mueller, 1776)
Paranemastoma quadripunctatum (Perty, 1833)

Mitostoma chrysomelas

Mitostoma chrysomelas is pretty easy to recognize on the two pedipalps that forms a kind of fork that is pointing forward. The pedipalps are densely covered with sticky hairs. It is a small harvestman, body length females up to 2mm, males up to 1.6mm. It has long legs I usually find it under old wood and old loose bark but also under stone. It often runs pretty fast and than it is difficult to make good pictures of it. Is it sitting for a while, then it is a very photogenic animal.
You can download an article (English) with comments on the Systematics of this species group by J. Meijer (Meijer 1973) pdf from the Naturalis website.

Mitostoma chrysomelas adult

Mitostoma chrysomelas juvenile

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Nemastoma bimaculatum

A rare species is Nemastoma bimaculatum. It has taken a long time before I find the first. The white spots are in this species very sharp angular and have a distinct notch on the outside. Also look at the species Nemastoma lugubre that looks very much alike. Body length females to 2.5mm, males up to 2.2mm.

Nemastoma bimaculatum

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Nemastoma dentigerum

Nemastoma dentigerum also belongs to the smaller species, like this whole family. Body length females to 1.9mm, males up to 1.7mm. There is a little problem with recognizing this species. There also seem to be all black forms of the species that normally have white spots. The result is that you call a whole black harvestman Nemastoma dentigerum, while it is a black version of one of the other species. It is only obvious if you have a male, who has a tooth on the pedipalps.

Nemastoma dentigerum

Nemastoma dentigerum, ♂

Nemastoma dentigerum, just molted

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Nemastoma lugubre

From the family Nemastomatidae I see Nemastoma lugubre the most, even some exemples with a diviant drawing I have found, see the bottom two photos. One has a extra large white spot behind on the back and the other has even two extra spots right behind the two normal. The shape of the spots is round off this is in contrast to the species Nemastoma bimaculatum. I find the animals especially if it has rained and it is very wet on the forest floor. Sometimes there are more than one under a dead branch or bark on the ground. Body length females to 2.7mm, males up to 1.8mm.

Nemastoma lugubre

Nemastoma lugubre, besides a woodlouse

Nemastoma lugubre, abnormal spots, three instaed of two

Nemastoma lugubre, abnormal spots, two more behind the two normal

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Paranemastoma quadripunctatum

Paranemastoma quadripunctatum is a very rare species.
Henk Soepenberg discovered 09-04-2014 an individual near Dalfsen in Overijssel. That is for me a reason to go looking on the marked place, where I find one and can make some photos. Later I find them also in Eys and Winterswijk. It's a pretty big harvestman compared to the other of this family. Both, male and female are up to 4 mm long. There are bright spots on the body and there are two rows of bumps on the back. The animal is therefore very easy to stand out from the other black harvestmen.

Paranemastoma quadripunctatum

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literature:

Meijer, J. 1973. Some remarks on the systematics of the Mitostoma chrysomelas group (Arichnida, Opilionida Nemastomatidae) — Zoologische mededelingen Leiden deel 46 no 9 blz 117-127