Ischyropsalis hellwigii (Panzer, 1794), photo Copyright © Ulla N., from fotocommunity 
The Dyspnoi are a suborder of harvestmen, with about 40 genera, and about 370 described species.
Several fossil species are known, including two extinct families.
The superfamilies Ischyropsalidoidea and Troguloidea are monophyletic. However, the families Sabaconidae and Ceratolasmatidae were not; amongst other inconsistencies, Taracus (Sabaconidae) was a sister group to Hesperonemastoma (Ceratolasmatidae). This has been corrected by Giribet et al. (2010).
The Dyspnoi are one of the most conserved biogeographically conserved higher groups of harvestmen. Few occur in the Southern Hemisphere, and most families are restricted along temperate regions. The exceptions are some Ortholasmatinae (Nemastomatidae) inhabiting the tropics on high mountains in Mexico (Ortholasma bolivari) and northern Thailand (Dendrolasma angka); and species of Acropsopilionidae occuring in Australia, Chile and South Africa. Some Troguloidea were also found in tropical regions during the Cretaceous.
Fossil incertae sedis
Acropsopilionoidea Roewer, 1923
- Ischyropsalididae (1 genus, 39 species)
- Sabaconidae (1 genus, 35 species, 4 subspecies)
- Taracidae (3 genera, 14 species)
- Dicranolasmatidae (1 genus, 18 species)
- † Eotrogulidae Petrunkevitch, 1955 (fossil, 1 genus, 1 species)
- Nemastomatidae (20 genera, 198 species)
- † Nemastomoididae (fossil: 1 genus, 3 species)
- Nipponopsalididae (1 genus, 4 species)
- Trogulidae (7 genera, 48 species)
Schönhofer & Hedin, excellent Tree of Life Article.