All species described here are considered to have a North American coastal temperate rainforest distribution (Fig. 39). Ceratoppia indentata and C. longicupsis are the dominant Ceratoppia for temperate rainforests on the west coast of North America. Ceratoppia tofinoensis has a restricted distribution within the Pacific Northwest, however, this may reflect sampling bias due to a strictly arboreal habitat. All species except C. valerieae appear endemic to this rare ecozone. Ceratoppia valerieae is frequently encountered in coastal forests, generally occurring in low abundance, yet is the dominant Ceratoppia for interior southern British Columbia through to southwestern Alberta. The distribution range of C. offarostrata appears limited to coastal locations on Vancouver Island and Haida Gwaii, British Columbia, but could be due to habitat specificity. Variation in body size and relative lengths of posterior setae were observed in northern and southern range for C. valerieae, and southern populations of C. indentata. Ceratoppia offarostrata exhibited variation in posterior setae length on Haida Gwaii, where specimens collected had slightly shorter posterior setae and reduced rostral bump.
North American coastal temperate rainforests have high tree and other plant diversity, high habitat heterogeneity and diversity of microhabitats compared to other temperate or boreal forest systems. Well-developed forest floor organic layers, long-lived trees with complex architecture, and epiphytic plant and lichen habitats may also help explain the high oribatid mite diversity encountered in these forests. However, why Ceratoppia and other members of the family Peloppiidae are especially species rich in these systems remains unclear.
In addition to the five new species I describe, C. quadridentata arctica was observed on the west coast of Vancouver Island, British Columbia within the temperate rainforest biogeoclimatic zone, however, only in alpine and high elevation areas. Hammer (1955) first described the subspecies of C. quadridentata (C. quadridentata arctica Hammer, 1955) from Alaska. In Canada the subspecies has been found in the three northern territories, and northern areas of Alberta, Quebéc, and Newfoundland, however a wider distribution of C. quadridentata arctica is suspected. For example, in collections for western Canada, C. quadridentata arctica was found in samples from northern British Columbia (Charlie Lake, Fort St. John), as well as high elevation and subalpine areas of the British Columbia temperate zone (Heather Mt. subalpine, Vancouver Island, at 1097m; Comox Glacier meadow, Vancouver Island, at 1840m; Lost Shoe Creek at Hwy 4, Vancouver Island; Manning Provincial Park, at 1768m).
Increased sampling efforts will reveal more robust distribution patterns for all species of Ceratoppia in North America. For example, in Canada, C. bipilis (Hermann, 1804) is known from all provinces and territories except British Columbia and Saskatchewan, but given its holarctic distribution (e.g. Sweden, England, France, Germany, Italy, Holland, Switzerland) (Trägårdh 1910) and presence in northern regions of other Canadian provinces, further sampling will probably reveal this species in the northern areas of these provinces. Other Ceratoppia listed for Canada appear well defined, but less common. For example, C. sexpilosa has been recorded from eastern Russia, and Yukon Territory, while C. sphaerica is listed in Canada from the northern territories, and has a Boreal forest distribution (Siberia, East Greenland) (Trägårdh 1910). Additionally, there are possibly three (or more) undescribed