The spider family Hahniidae (comb-tailed spiders) includes 250 described species (Platnick 2013), 58 of which occur in North America north of Mexico (Bennett 2005). The common name "comb-tailed spiders" refers to the fact that many hahniids share the unusual feature that all six of their spinnerets are arranged in a line (Bradley 2013), although this is not so for those in the subfamily Cryphoecinae, which accounts for two thirds of the North American hahniids (however, of these only Calymmaria and Cryphoeca are commonly encountered; Bennett 2005 and references therein). Like so many groups in the "RTA clade", the hahniids have a checkered taxonomic past, with many species formerly placed in other families, including Agelenidae and Dictynidae, and unresolved questions about the systematics and taxonomy of these spiders remain (Bennett 2005 and references therein; Miller et al. 2010; Platnick 2013)
Hahniids are typically ground dwellers, most often encountered when searching through leaf litter or sorting pitfall trap samples, but spiders in some genera build webs (e.g., Calymmaria, which place their webs beneath and between bark, beneath moss on rocks and living trees, beneath fallen tree trunks, in caves,and especially along streams; Heiss and Draney 2004). Among Nearctic members of the subfamily Hahniinae, only Neoantistea have been observed to build webs. These webs are small simple sheets, without retreats, which are built in moss or over small depressions in the ground--they can often be found in footprints left by animals walking on soft ground (Bennett 2005).
Opell and Beatty (1976) review the morphology and distribution of the North American and Mexican species of Hahniinae (which they treat as being the only members of the family Hahniidae). Roth and Brame (1972) review the morphology, distribution, and habitat associations of the Nearctic cryphoecine genera (which they includ in the Agelenidae).
Dwarf sheet spiders (Hahniidae) is a family of araneomorph spiders, first described by Philipp Bertkau in 1878.[1] Their bodies are about 2 millimetres (0.079 in) long, and they build extremely delicate webs in the form of a sheet. Unlike many spiders the web does not lead to a retreat. The silk used in these webs is so fine that they are difficult to spot unless they are coated with dew. They greatly favor locations near water or near moss, and are often found in leaf litter and detritus or on the leaves of shrubs and trees.[2]
They are characterized by the arrangement of their six spinnerets in a transverse row. The last segment of the outer spinnerets is quite long and stands out above all the others.[2]
Hahniidae are a worldwide family. The genera of the Northern Hemisphere and Africa tend to differ in their genital structures from those of the Southern Hemisphere. Very few species have been described from southeast Asia, although quite a number seems to be yet undescribed.[2]
The family is named after the type genus Hahnia, which is dedicated to German zoologist Carl Wilhelm Hahn.[1]
As of April 2019, the World Spider Catalog accepts the following genera:[3]
Dwarf sheet spiders (Hahniidae) is a family of araneomorph spiders, first described by Philipp Bertkau in 1878. Their bodies are about 2 millimetres (0.079 in) long, and they build extremely delicate webs in the form of a sheet. Unlike many spiders the web does not lead to a retreat. The silk used in these webs is so fine that they are difficult to spot unless they are coated with dew. They greatly favor locations near water or near moss, and are often found in leaf litter and detritus or on the leaves of shrubs and trees.
