The 'Mesothelae' are one suborder of
spiders (Order Araneae) that includes the extinct families Arthrolycosidae and Arthromygalidae, and the only recent family
Liphistiidae.
Recent Mesothelae are characterized by the narrow
sternum on the ventral side of the
prosoma. Several
plesiomorphic characters may be useful in recognizing these spiders: there are
tergite plates on the
dorsal side and the almost-
median position of the
spinnerets on the
ventral side of the
opisthosoma. They lack a venom gland and duct, which almost all other spiders feature.
[1] All Mesothelae have four pairs of spinnerets. Like
mygalomorph spiders, they have two pairs of
book lungs.
[Scharff, N. & Enghoff, H. (2005). Arachnida. ''Zoological Museum, University of Copenhagen''.]
The ''Heptathelidae'' were once considered their own family, today they are considered a subfamily of the Liphistiidae (as ''Heptathelinae''). As opposed to all other recent mesothelids, these do not have fishing lines in front of their entrances. Therefore, they are more difficult to find. They also have a paired
receptaculum (unpaired in other liphistiids), and have a conductor in their
palpal organ.
Before mating, the male creates a sound (inaudible to humans) to induce the female to appear at her trap door. Then mating may take place.
Distribution
Liphistiidae spiders are distributed in
Myanmar,
Thailand, the
Malayan peninsula and in
Sumatra. Heptathelidae are found in
Vietnam, the Eastern provinces of China, and Southern Japan.
In Popular Culture

Mesothelae chasing a small reptile, Petrolacosaurus
In the
BBC documentary ''
Walking with Monsters'' (2005), one
Carboniferous era species of mesothelae was described as being as large as a human head and hunted
reptiles the size of today's
cats. It lived like the
tarantulas in
burrows, and would either lie in wait for its prey, or chase it through the
jungle. In reality no spider that large has ever been found, but when the series began production, the
eurypterid ''
Megarachne'' was still mistakenly thought to have been a spider. Its correct identity wasn't discovered until ''Walking With Monsters'' was well into production, and the giant spider was left in and called "''Mesothelae''" instead of "''
Megarachne''".
References
1. Haupt, J. (2004). The Mesothelae - a monograph of an exceptional group of spiders (Araneae: Mesothelae). ''Zoologica'' 154:8 , ISBN 3-510-55041-2 (Abstract)
External links
★ http://insects.tamu.edu/research/collection/hallan/acari/Araneae1.htm