Hoplitomeryx is a genus of extinct deer-like ruminants which lived on the former Gargano Island during the Miocene and the Early Pliocene, now a peninsula on the east coast of South Italy.

Its fossilized remains were retrieved from the late 1960s onwards from reworked reddish, massive or crudely stratified silty-sandy clays (terrae rossae), which partially fill the paleo-karstic fissures in the Mesozoic limestone substrate and that are on their turn overlain by Late Pliocene-Early Pleistocene sediments of a subsequently marine, shallow water and terrigenous origin.

Later, after the regression and continentalization of the area, a second karstic cycle started in the late Early Pleistocene, the neokarst, which removed part of the paleokarst fill.

The second model is based upon limb proportions only, but these are invalid taxonomic features for island endemics, as they change under influence of environmental factors that differ from the mainland.

The shared lack of large mammalian predators and the limited amount of food in all niches promoted the development of derived features in all size groups (apomorphies).