Eggs of Huffmanela markgracei sp. n. infected one of three Atlantic sharpnose sharks, Rhizoprionodon terraenovae (Richardson) (Carcharhiniformes: Carcharhinidae) captured by bottom long-line in the northwestern Gulf of Mexico off Padre Island, Texas. Eggs in the skin formed sinuous tracks (1-8 eggs wide; 1-4 eggs deep; 150 eggs/mm2) occupying a swath of the skin 22 cm × 2 cm on the tongue, branchial arches and the dorsal surface of the buccal cavity. Eggs had transverse eggshell ridges (branching and non-branching), had shells that were clear, amber or brown, and measured 90-113 µm (x = 102 ± 4; n = 190) long, 38-54 µm (43 ± 3; 190) wide, 3-5 µm (4 ± 0; 190) in eggshell thickness with protruding polar plugs 8-12 µm (10 ± 1; 190) wide. Apparently fully developed larvae in eggs were 255-335 µm (299 ± 26; 30) long, 8-10 µm (9 ± 1; 30) wide, and in-folded 5-6 (6 ± 0; 30) times. Some of these larvae were emerging from eggs in the skin. The new species differs from congeners by the combination of having a large, spindle-shaped egg, transverse eggshell ridges, an envelope that is smooth, tightly-apposed to the eggshell and surrounds the entire eggshell inclusive of the polar plugs, and a large larva. This is the first report of a species of Huffmanela Moravec, 1987 from a chondrichthyan in the Gulf of Mexico and from a shark not assigned to Carcharhinus.