A morphologically heterogeneous group of harvestmen. Legs longer than compact body, coloration typically black or grayish (unlike many Eupnoi which are often orange/brown). Pedipalps without capture spines or terminal claws.
Chelicerae with diaphanous teeth, but this feature is difficult to see without a high-magnification microscope.
US + Canadian Dyspnoi are reclusive predators, almost always found in forested upland habitats under rocks and/or logs, in leaf litter, or in caves. Several taxa seem to have an affinity for stream-side or riparian habitats (e.g., Acuclavella, Appalachian Sabacon, Acropsopilio). Unlike Eupnoi, it is rare to find Dyspnoi species "exposed" or wandering on the surface. Find Dyspnoi by searching under rocks and/or logs, by sifting leaf litter, or by using a Berlese funnel.
Dyspnoi is separated into 3 well-supported subgroups, including Ischyropsalidoidea, Troguloidea, and Acropsopilionoidea
Groh, S. & Giribet, G. (2015), Polyphyly of Caddoidea, reinstatement of the family Acropsopilionidae in Dyspnoi, and a revised classification system of Palpatores (Arachnida, Opiliones). Cladistics, 31: 277–290. doi:10.1111/cla.12087 (online PDF
Gruber, J. 2007. Dyspnoi - Historical systematic synopsis. In: Pinto-da-Rocha, R., G. Machado, G. Giribet., eds. Harvestmen: the biology of Opiliones. Harvard University Press, Cambridge
Schönhofer AL. 2013. A taxonomic catalogue of the Dyspnoi Hansen and Sørensen, 1904 (Arachnida: Opiliones). Zootaxa 3679, 1-68. (online PDF