We update a species list of reptile diversity at the Reserva Natural Laguna Blanca, with four additional species of snakes, Drymarchon corais Boie, 1827, Dipsas cisticeps (Boettger, 1885), Oxyrhopus rhombifer rhombifer Duméril, Bibron & Duméril, 1854, and Phimophis guerini (Duméril, Bibron & Duméril, 1854). This additional data qualifies San Pedro department as the most diverse department in Paraguay for reptiles. We build upon the already strong case for the reserve, which had its official protection lapse after five years, to be redeclared as a protected area and recognised as an “Important Area for the Conservation of Amphibians and Reptiles”.