Hydromermis floridensis sp. n. (Nematoda: Mermithidae), a Larvicidal Parasite of Glyptotendipes paripes (Edwards) (Diptera: Chironomidae)

Abstract

Hydromermis floridensis sp. n. is described from Glyptotendipes paripes (Edwards) larvae obtained from Lake Cannon, Florida. The species is closely related to H. conopophaga Poinar. A distinction is made between the new species and all other species that possess a subventral mouth in the genera Hydromermis and Gastromermis. Some aspects of the life history are included. The values of esophageal length, esophageal length as a percentage of total length, and the distance of the vulva from the anterior end as a percentage of total length as taxonomic criteria are discussed. In March and April of 1965 Dr. R. S. Patterson of the Midge Research Project of the Florida State Board of Health sent the author mermithids collected from eutrophic Lake Cannon, Florida. Some of the nematodes were fixed in 5% formalin, others were shipped alive and subsequently fixed in the above fixative. The nematodes were taken from the marginal benthic area of the lake in which the predominant midge larva was Glyptotendipes paripes. Ten adult males, 10 adult females, one postparasitic larval male, and several postparasitic larval females were examined in glycerine jelly and measured. Two males and females were sectioned. The organisms differed both quantitatively and qualitatively from the species with subventral mouths currently placed in the genera Hydromermis and Gastromermis. The measurements given below are in microns unless otherwise indicated. The first measurement given is the mean. The measurements in parentheses represent the range. Hydromermis floridensis sp. n. (Figs. 1-8)