We describe a new species of marine associated oribatid mite, Ameronothrus twitter Pfingstl and Shimano, sp. nov., from a wharf of fishing port (Choshi Outer Fishing Port), Chiba, Honshu, Japan. This species was spotted for the first time ever on photographs posted on Twitter. Ameronothrus twitter Pfingstl and Shimano, sp. nov. is characterized by a specific cuticular notogastral pattern consisting of distinct nodules that are fused to irregular ridges in the median anterior and the median posterior region. Additionally, it features a unique combination of fused lamellar keels, presence of primilateral setae on tarsus I, presence of dorsal companion setae on genu I, II, III and all tibiae and tarsal distal setae ending with a small nodule. Ameronothrus twitter Pfingstl and Shimano, sp. nov. is the second species of this genus found on Japanese islands, which represents the southernmost occurrences of this taxon in the Asian Pacific region.
