Scanning electron microscopy of the cystidicolid nematode Ascarophis mexicana Moravec, Salgado-Maldonado et Vivas-Rodríguez, 1995 enabled the first detailed study of its cephalic structure. In contrast to most Ascarophis species, its pseudolabia are highly reduced and sublabia are unlobed and weakly developed. Similascarophis is considered a synonym of Ascarophis, to which two its species are transferred as A. maulensis (Muñoz, González et George-Nascimento, 2004) comb. n. and A. chilensis (Muñoz, González et George-Nascimento, 2004) comb. n.