Tetrablemmidae

Tetrablemmidae, commonly referred to as armored spiders, represents a family of araneomorph spiders that primarily inhabit tropical regions. This family was first formally described by Octavius Pickard-Cambridge in 1873. The known distribution of Tetrablemmidae spans across Southeast Asia, with additional species found in parts of Africa and the Americas.

Key Characteristics

The family is known to encompass approximately 150 described species, organized into 27 distinct genera. A significant and distinctive trait observed in many Tetrablemmidae, particularly within the genus Tetrablemma, is the presence of only four eyes. This ocular reduction is a rare characteristic among spiders, shared only with certain members of the Caponiidae family. Some cave-dwelling species within this family exhibit further adaptations to subterranean life, such as a loss of eyes and reduced sclerotization of their exoskeleton.

Habitat and Distribution

The majority of Tetrablemmidae species are collected from ground-level habitats, specifically within leaf litter and soil. This includes the soil found in association with epiphytic plants, indicating a preference for moist, concealed environments. While their primary stronghold is Southeast Asia, their presence in Africa and the Americas suggests a broader, though perhaps less dense, tropical distribution.

Taxonomy

Historically, the family Pacullidae was integrated into Tetrablemmidae in 1981. However, subsequent phylogenetic research conducted in 2016 led to the restoration of Pacullidae as a separate taxonomic family. The family includes numerous genera, some of which are known only from fossil records, such as those found in Burmese amber dating back to the Cenomanian stage.