Heptathelidae

Heptathelidae is a family of spiders. It has been sunk within the family Liphistiidae as the subfamily Heptathelinae, but was accepted by the World Spider Catalog. It is placed in suborder Mesothelae, which contains the most basal living spiders.

Taxonomy
The group was first proposed by Kyukichi Kishida in 1923, when he described a new genus, Heptathela, and suggested creating two tribes within the family Liphistiidae, with Heptathela placed in Heptatheleae. In 1939, Alexander Petrunkevitch raised the tribe Heptatheleae to a separate family, Heptathelidae. In 1985, Robert Raven reunited the two families, a view supported by Breitling in 2022. Other authors have maintained two separate families, a position accepted by the World Spider Catalog.

Phylogeny
Molecular phylogenetic studies have repeatedly shown that the family is monophyletic. One possible relationship between the genera is shown in the following Bayesian cladogram (numbers in parentheses give the number of units in the study):

Genera
, the World Spider Catalog accepted seven genera: The genus Sinothela is considered a nomen dubium (dubious name).
 * Ganthela Xu & Kuntner, 2015
 * Heptathela Kishida, 1923
 * Luthela Xu & Li, 2022
 * Qiongthela Xu & Kuntner, 2015
 * Ryuthela Haupt, 1983
 * Songthela Ono, 2000
 * Vinathela Ono, 2000

Description
Members of the Heptathelidae share features with the other Mesothelae family, Liphistiidae. They are medium to large spiders. They have downward pointing, daggerlike chelicerae. Like other members of the suborder Mesothelae, and unlike all other extant spiders, they have a segmented series of plates (tergites) on the upper surface of all segments of the abdomen and their spinnerets are placed in the middle of the underside of the abdomen, rather than at the end. Their sternum (a plate on the underside of the cephalothorax) is narrow, and there is another smaller ventral plate (the sternite) between the fourth pair of legs. They respire by means of two pairs of book lungs. Unlike members of the Liphistiidae, the palp of the male lacks a tibial apophysis.

They live in burrows closed by trapdoors. Unlike members of the Liphistiidae, heptathelids do not construct signal lines radiating from the burrow.