C. cachecreekensis was based on the part and counterpart holotype, specimen numbers F-1545 & F-1546, housed in the collections of the Thompson Rivers University in Kamloops, British Columbia.

[1] Cuspilongus cachecreekensis was one of three sawfly species described in Archibald & Rasnitsyn's 2015 paper, the other two being Ulteramus republicensis and Ypresiosirex orthosemos, from the Klondike Mountain Formation and the McAbee fossil beds respectively.

[1] Alexandr Rasnitsyn (1988) had described the species Mesocephus ghilarovi based on the holotype PIN 3559/652 female fossil, part of the Paleontological Institute, Russian Academy of Sciences collections.

[2] In the type description for Cuspilongus, Archibald and Rasnitsyn opted to include it in the living Cephidae subfamily Cephinae based on the darkened intercostal wing area and the downward curved to the ovipositor sheath.

Located 5–8 km (5,000–8,000 m) south of Böön Tsagaan Lake in the Gobi Desert, Bon-Tsagan is a outcrop of the Dzun-Bain Formations[3] Khurilt Member dated to be Aptian.

[2] The unnamed formation outcropping at the McAbee Fossil Beds preserve an upland temperate flora that was first interpreted as being Microthermal,[4] although further study has shown them to be more mesothermal in nature.

[5] The plant community preserved in the McAbee Fossil Beds site is mostly broadleaf pollen with alder and elm dominating, and may represent a successional forest involving multiple volcanic ash eruptions.

[5][6] The broader Eocene Okanagan Highlands likely had a mesic upper microthermal to lower mesothermal climate, in which winter temperatures rarely dropped low enough for snow, and which were seasonably equitable.