Two new species of imagocidal Hydromermis (Nematoda: Mermithidae) from Endochironomus subtendens (Townes) (Diptera: Chironomidae).

Hydromermis viridis n. sp. and Hydromermis gastroviridis n. sp. are described from June and August emerging imagos, respectively, of Endochironomus subtendens (Townes) in Lake Itasca, Clearwater County, Minnesota. The position of the mouth, shape of the posterior end, structure and size of the spicule, absence of an excretory pore, arrangement of male tail musculature, and measurements separate the new species form other species of Hydromermis as well as from one another. The 2 species are placed in the genus Hydromermis though having a rounded tail and only 6 hypodermal cords at midbody. An anomalous double vagina condition is reported in H. viridis.