Ariadna/Dysdera species

Fact Box Species: Ariadna species or perhaps Dysdera crocota (see notes below) Family: Segestriidae (or Dysderidae if spider actually is Dysdera crocota) Body length: female: at least 15 mm for adults male: about 12 mm Habitat: In a tube-like retreat in dry vegetation or under stones; a larger diameter cavity just inside the entrance to the retreat is also used as a brood chanber Toxicity: Unknown but some instances of envenomation of humans by D. crocota are alleged to have required hospitalisation

In its retreat Its retreat Its eggs

This page is unusual in displaying a spider as possibly belonging to either of two different families: Segestriidae and Dysderidae. For many years taxonomists have debated whether or not these two families should be combined. Both have species with the same general body shape and with porrect fangs (i.e. fangs that point forward rather than down), 6 eyes instead of the usual 8 eyes (this distinguishes it from the otherwise quite similar miturgid genus Cheiracanthium, which has 8 eyes), and distinct tracheal spiracles (small 'breathing' holes) located on the underside of the abdomen and lying just behind the books lungs to which they are quite similar in appearance.

The spider shown on this page is perhaps more likely to be an Ariadna species than a dysderid since the only known member of the Family Dysderidae is Dysdera crocota, a species that apparently has been introduced from Europe but is said to be present only in New South Wales, Victoria, South Australia and Tasmania. The evidence that this spider is an Ariadna species includes the wider spread of the 6 eyes across the head (they are tightly clumped on D. crocota) and the more hirsute (hairy) legs and body.

On the other hand, the spinnerets appear to be those of Dysdera and the lack of mottling of the dorsal abdomen also favours this species rather than Ariadna. The colour pattern of the spider shown on this page does not match either Dysdera or Ariadna particularly well. An important distinguishing feature is that for Ariadna and other segestriids the first three pairs of legs point forwards whereas for Dysdera only Legs I and II are forwards directed. Unfortunately, it is not clear from the above photos which way this spider's Leg III is pointing.

The images of this spider's retreat are not typical of Ariadna, which normally uses an existing small hole in a tree or on the ground and has a ring of radiating threads around its entrance. In fact the images more nearly match those expected for Dysdera crocota.

Spider(s) with a very similar appearance: Ariadna species.