We report Eryngium arenosum (Apiaceae, Saniculoideae), a new species from Texas, USA. This new species is differentiated from E. nasturtiifolium, the most similar species, by characters of the capitule (color, shape, size, number of flowers), lengths and shapes of the involucral and floral bracts, presence or absence of a coma, length of the calycine scales relative to the sepals, and habitat preferences. We describe and illustrate these differences, and provide a morphological description, information on phenology, geographical distribution, and habitat, and illustrations of the new species.