Figure 1. (a) Sections of the Protura record reported by Imadaté (red), Nakamura (blue),
and others (green); (b) Species density distribution was estimated using the inverse distance
weighted (IDW) interpolation method of ArcGIS; (c) Species distribution in the northern
part of Honshu (Main Island composed of Tohoku, Kanto, Chubu, Kinki, and Chugoku)
(enlarged). Color indicates estimated species richness in each locality in (panels b,c).