Dyspnoi

Dyspnoi can be distinguished from other Opiliones suborders by the presence of prosomal defensive scent glands with ozopores hidden in a depression (atrium) formed by a dorsal integumental fold of the carapace and dorsal parts of coxae I, rather than exposed ozopores as seen in Laniatores, Cyphophthalmi, and some Eupnoi. The scent gland ducts possess a specific closing mechanism with a pad-like tissue valve and associated musculature for secretion discharge. Some genera, such as Nipponopsalis and Ischyropsalis, exhibit notably enlarged chelicerae in both sexes used for crushing snail shells. Members of the family Nemastomatidae within this suborder often show reduced body size and eye regression in cave-dwelling (troglobitic) species.

Predominantly temperate forest and woodland habitats, with many species associated with moist microhabitats including leaf litter, soil crevices, and decaying wood. Several lineages have independently adapted to cave environments (troglobitic), showing troglomorphic features such as eye reduction and elongation of appendages. Some Ortholasmatinae (Nemastomatidae) occur in tropical high-elevation habitats, including cloud forests in Mexico and montane regions in northern Thailand.

Primarily distributed in the Northern Hemisphere temperate regions, with exceptional biogeographic conservation among harvestmen groups. The suborder does not occur in the Southern Hemisphere except for Acropsopilioidea. Major centers of diversity include Europe, North America, and temperate Asia. The Hadzinia-Nemaspela complex in the Balkans and Caucasus represents relictual paleo-European mainland fauna that survived Pleistocene climatic changes in southern refuges. The genus Nemaspela is primarily Caucasian with disjunct occurrence in the Dinaric region.

Specialized feeding habits documented in some lineages: Nipponopsalis and Ischyropsalis possess enlarged chelicerae adapted for crushing and consuming snails. General feeding ecology for most Dyspnoi remains poorly documented, though likely includes small invertebrates and detritus based on related harvestmen groups.

Defensive behavior involves chemical defense via prosomal scent glands. The secretion discharge mechanism is complex and unusual: enteric fluid is directed toward ozopores via cuticular grooves on coxapophyses of legs I, then sucked into scent gland reservoirs by dorsal dilator muscles creating negative pressure. After dilution of naphthoquinone-rich gland contents, secretion-loaded fluid is discharged via transversal compressor muscles. This represents a derived mechanism distinct from other Opiliones suborders.

Predatory and scavenging roles in soil and leaf litter food webs; specialized snail predators in certain lineages. Troglobitic species contribute to nutrient cycling in cave ecosystems.

• EupnoiBoth are suborders of long-legged harvestmen (Palpatores), but Eupnoi lack the hidden ozopore structure and complex scent gland closing mechanism characteristic of Dyspnoi; Eupnoi typically have exposed ozopores.
• LaniatoresShort-legged harvestmen with exposed ozopores and different scent gland morphology; Laniatores often possess enlarged pedipalps for defense rather than the enlarged chelicerae seen in some Dyspnoi.
• CyphophthalmiMite-like harvestmen with exposed ozopores and generally reduced body size; lack the distinctive atrium-enclosed ozopores and associated gland musculature of Dyspnoi.

• harvestmen
• arachnids
• chemical defense
• temperate
• relict fauna
• troglobites

• BugGuide
• Wikipedia
• iNaturalist taxon
• Catalogue of Life
• Answer to Super Crop Challenge #1 | Beetles In The Bush
• Functional anatomy of scent glands in Paranemastoma quadripunctatum (Opiliones, Dyspnoi, Nemastomatidae)
• Nemaspela ladae sp. n., a new troglobitic nemastomatid (Opiliones, Dyspnoi, Nemastomatidae) from a Dinaric cave