Shell with regular prominent ribs, colour predominantly white, the spatula and interior margin dark. TYPE SPECIES Patelloida rugosa Quoy & Gaimard, 1834.

According to Lindberg & Vermeij (1985), Patelloida consists of at least two groups. One group includes species characterized by a low to medium shell profile, a few strong radial ribs or many fine riblets in the shell surface and reduced third lateral radular teeth, and inhabits various substrata. The other group, which was called the P. profunda group by Christianes (1975) and Lindberg & Vermeij (1985), consists of species with a moderate to high shell profile, many riblets on the shell surface and equal-sized lateral radular teeth, and is restricted to calcareous substrata. Recently, Nakano & Ozawa (2007) assigned the P. profunda group to the new genus Eoacmaea, since it is distinct from other species of Patelloida both morphologically and genetically. Although Eoacmaea has morphological characters shared with the other group of Lottiidae, it is also genetically distant from the other lineages. Based upon these facts, Nakano & Ozawa (2007) proposed a new family, Eoacmaeidae, for Eoacmaea.

Patelloida extended its distribution westwards from its likely origin in the tropical Tethys Sea (Nakano & Ozawa, 2004). The earliest fossils of this genus have been found in the Late Cretaceous of California (Lindberg, 1983). Furthermore, Patelloida species commonly occurred in nearshore sediments in North America and Europe during the Tertiary (MacClintock, 1967; Lindberg, 1983; Lindberg & Hickman, 1986). These fossil records support the argument that Patelloida reached Europe and North America during the Late Cretaceous. However, this genus disappeared in Europe and North America following the onset of a cool period (Lindberg, 1988).