Euctenizidae, a group of mygalomorph species, are mostly indigenous to parts to the U.S. as well as Mexico. Presently they are said to be more closely connected to the Idiopidae or armored trapdoor spiders family. As per the 2019 April records, the WSC (World Catalog Spider) acknowledges 83 species distributed in 7 genera.


Spiders Belonging To This Family



  • Aptostichus angelinajolieae
  • Aptostichus atomarius
  • Aptostichus barackobamai
  • Aptostichus bonoi
  • Aptostichus miwok
  • Aptostichus simus
  • Aptostichus stanfordianus
  • Aptostichus stephencolberti
  • Eucteniza relata
  • Myrmekiaphila comstocki 
  • Myrmekiaphila neilyoungi
  • Neoapachella rothi
  • Promyrmekiaphila clathrata
  • Promyrmekiaphila winnemem

Physical Description & Identification


Size: The size varies from spiders of one genus to the other. For instance, members of the Eucteniza genus reach a length of 1.08 inches (27.5 mm). On the other hand, those of the Aptostichus genus is 0.11 – 0.29 inches (3 – 7.5 mm) long. Like most other species, females are bigger than their male counterparts.

Color: The primary colors range from brown to reddish-brown to yellowish-red. The stripes and patterns differ as per the species. Some possess brownish-yellow legs, while some also have dusky abdominal lines.

Other Characteristic Features: The Eucteniza species have a long, oval cephalothorax arranged in a rectangular manner in rows of two. The Myrmekiaphila species posses a modified palpal tibia.


Most females are likely to lay their eggs inside the burrow.


They also build burrows on their own and dwell there after maturation.

The Web

They do not spin webs; instead, they build burrows,  some create wafer-like doors at the entrance, while others make cork-like ones.

Are Euctenizidae Spiders Venomous

They are not venomous, with their bite not harming humans, apart from localized pain and swelling.

Quick Facts

Distribution Different parts of U.S.A and Mexico
HabitatDeserts, dry forests (Eucteniza)
Diet Mostly insects
Lifespan 5 – 10 years

Did You Know

  • The most prominent genus of this family is Eucteniza.
  • It derives its name from “eu”, a Greek prefix translating to good or valuable.