Cuticular-respiration
Guides
Acerentomidae
coneheads
Acerentomidae is a family of minute, wingless, eyeless soil-dwelling hexapods in the order Protura. Members lack tracheae and rely on cuticular gas exchange for respiration. The family exhibits exceptional diversity in the northeastern Palearctic, with 31 species documented from Siberia and the Russian Far East, and 19 species in 13 genera in Arctic regions alone. Arctic species typically possess more setae than temperate relatives and show high endemism with restricted distributions.
Nanorchestidae
Nanorchestidae is a family of small soil-dwelling mites in the order Endeostigmata. The family contains two recognized genera, Nanorchestes and Speleorchestes, which show distinct ecological partitioning: Nanorchestes dominates cold desert and polar habitats, while Speleorchestes inhabits hot deserts. This distribution correlates with structural differences in the cuticle. Members of this family may achieve high numerical abundance in extreme desert soils.