Description of

Description of Marylynnia puncticaudata n. sp. (Nematoda, Cyatholaimidae) from Bizerte Lagoon, Tunisia.— A new free–living marine nematode species of Cyatholaimidae, Marylynnia puncticaudata n. sp. from Bizerte Lagoon (Tunisia) is morphologically described. Males are characterized by a slightly larger body than females, a cephalic ring followed by ten subcephalic setae, modified cuticular punctuation, caudal lateral differentiation of large dots, and strongly cuticularized gubernaculum with a unique shape and bidenticulated distal half. The cuticle ornamentation of females is similar to the males. However, their caudal lateral differentiation is composed of smaller and more spaced dots. An updated morphological key to species of Marylynnia is given. Key words: Free–living marine nematodes, Bizerte Lagoon, Marylynnia puncticaudata n. sp. Resumen Descripción de Marylynnia puncticaudata sp. n. (Nematoda, Cyatholaimidae) del lago de Bizerta, Túnez.— Se describe morfológicamente una nueva especie de nematodo marino de vida libre de la familia Cyatholaimidae: Marylynnia puncticaudata sp. n. del lago de Bizerta (Túnez). Los machos se caracterizan por tener un cuerpo ligeramente más grande que las hembras, un anillo cefálico seguido de diez sedas subcefálicas, puntuación distinta de la cutícula, diferenciación laterocaudal de grandes puntos y gubernáculo muy cuticularizado con un