PhD Arthur Decae 2010 - Ghent Ecology - Universiteit Gent

The external respiratory organs of mygalomorph spiders are located on the anterior half of the
ventral abdomen as two pairs of book lungs (visible as roughly circular light colored patches).
Most araneomorph spiders have only the anterior pair of book lungs and a more posterior
located tracheal opening that is missing in mygalomorph spiders.
The external spinning organs (spinnerets) of mygalomorph spiders differ from those of other
spiders in the absence of anterior median spinnerets or their homolog, the reduction or
absence of anterior lateral spinnerets and the sub-segmentation of the basal segment of the
posterior lateral spinnerets (Raven 1985).
Table 2. All sixteen currently recognized orthognate spider families with notes on their principal
lifestyles after Jocqué and Dippenaar-Schoeman 2006. Note that in 11 out of 16 families the
production of silk-lined burrows is the dominant lifestyle. Regarding the 6 families that are not
primarily burrowing; three families (Theraphosidae, Dipluridae and Hexathelidae) are known to
contain at least some species that excavate burrows (personal observations) and only three are not
known to excavate burrows at all. These last three families ( Mecicobothriidae, Microstigmatidae and
Paratropididae) are also the families of which very little is known about their habits.
FAMILY LIFESTYLE
1 Actinopodidae Silk-lined burrow with trapdoor
2 Antrodiaetidae Silk-lined burrow with trapdoor or silk collar
3 Atypidae Silk-lined burrow with sock-like extension
4 Barychelidae Silk-lined burrow (retreat) with trapdoor
5 Ctenizidae Silk-lined burrow (retreat) with trapdoor
6 Cyrtaucheniidae Silk-lined burrow with trapdoor
7 Dipluridae Silk-lined retreat in crevices
8 Hexathelidae Silk-lined retreat in crevices
9 Idiopidae Silk-lined burrow with trapdoor
10 Liphistiidae Tubular burrow with trapdoor
11 Mecicobothriidae Silk-line retreat in crevices
12 Microstigmatidae Free-living encrusted with earth
13 Migidae Silk-lined burrow (retreat) with trapdoor
14 Nemesiidae Silk-lined burrow (retreat) with trapdoor
15 Paratropidae Cursorial in leaf litter
16 Theraphosidae Silk-lined burrow, arboreal retreat or cursorial
Fig. 3 Distinguishing Mygalomorphae
from Araneomorphae. A-C ventral views,
B-D frontal views. Differences in
morphology of chelicerae, book lungs and
spinnerets.