This suborder is thought to form the sister group to all other living spiders, and to retain ancestral characters, such as a segmented abdomen with spinnerets in the middle and two pairs of book lungs.

Reginald Innes Pocock in 1892 was the first to realize that the exceptional characters of the genus Liphistius (the only member of the group then known) meant that it was more different from the remaining spiders than they were among themselves.

The names refer to the position of the spinning organs, which are in the middle of the abdomen in Liphistius and nearer the end in all other spiders.

[5] Pocock divided his Opisthothelae into two groups, which he called Mygalomorphae and Arachnomorphae (now Araneomorphae), implicitly adopting the phylogeny shown below.

[18] Unlike all other extant mesothelians, heptathelids do not have fishing lines in front of the entrances to the burrows that they construct, making them more difficult to find.

Liphistiidae spiders are mainly distributed in Laos, Malaysia, Myanmar, Sumatra, and Thailand, with two species native to China.

However, Paul A. Selden has shown that most only have "the general appearance of spiders", with segmented abdomens (opisthosomae), but no definite spinnerets.