The middle Eocene Ku, Maloob, and Zaap (Kumaza) Calcarenites Member is formally proposed to describe a calcareous unit represented by one to three, calcite-cemented packstone to grainstone calcarenites in a thick undescribed sequence of shales that occur in the subsurface of Campeche Shelf, southeastern Gulf of Mexico. These calcarenite bodies are here called units 1-A, 1-B, and 1-C; they are separated by one to two shale layers denominated as units Lu-1 and Lu-2. The type section is in the Maloob 97 well. The Kumaza Member has been studied using seismic data, core, chip samples, and log information from 57 wells drilled in the Kumaza fields in the Campeche Shelf. The Kumaza Member contains the most important reservoir rocks in this region and is mappable more than approximately 100 km2 (39 mi2). These calcarenite banks are here inferred to have originated on a shallow water platform and were later redeposited in deeper waters from a restricted area. The age of the rock units in the Kumaza Member is established from foraminifera, including Morozovella lenheri, Morozovella spinulosa, Truncorotaloides rohri, Orbulinoides beckmanni, and Lepidocyclina (Polylepidina) antillea.