Ten new species of Arrenurus are described from Mexican Lakes. Two species (tamaulipensis, xochimilcoensis) belong to the typical subgenus, seven species (alloexpansus, colitus, champayanus, anae, costeroae, catoi, apizanus) ...

A new water mite species is described, belonging to the genus Piona (Hydrachnidia: Pionidae), collected from a canal at Xochimilco, Mexico City, Mexico. This represents the first family and genus record for Mexico City.