Nesticidae

Scaffold Web Spiders (Nesticidae)

Scaffold web spiders, scientifically classified as Nesticidae, are a family of araneomorph spiders recognized for their close evolutionary ties to tangle-web spiders (Theridiidae). A defining physical characteristic of this family is the presence of a specialized 'comb' composed of serrated bristles located on the hind tarsi. These bristles play a crucial role in the spiders' silk manipulation, enabling them to draw silk bands from their spinnerets.

Diversity and Distribution

The Nesticidae family is a diverse group, currently encompassing 16 genera and approximately 300 known species. A significant portion of these species are notably associated with subterranean environments, frequently inhabiting caves and rocky overhangs. The genus Nesticus serves as the type genus for the family and exhibits a widespread distribution across the globe. Other genera, such as Eidmannella, have demonstrated significant speciation within specific geographic regions, like the caves of Texas, where some species are considered highly localized and potentially threatened. The species Eidmannella pallida, for instance, while often found in caves and under overhangs, also demonstrates adaptability to more varied habitats, including agricultural fields.

Taxonomy and Extinct Relatives

In addition to extant species, several extinct genera have been placed within the Nesticidae family, primarily known from fossilized remains in amber deposits. These include genera such as †Balticonesticus, †Eopopino, †Heteronesticus, and †Hispanonesticus, dating back to the Palaeogene and Neogene periods. This lineage highlights a long evolutionary history for this group of spiders.