Remarks on the type species of Rhigonema Cobb, 1898 (Rhigonematoidea: Rhigonematidae) and Heth Cobb, 1898 (Ransomnematoidea: Hethidae)

Abstract

Additional information onRhigonema brevicollum, the type of the genusRhigonema, and onHethjuli, the type of the genusHeth, is presented based on original, hitherto unpublished, descriptions held in the Cobb Archive at the USDA, Beltsville, MD, USA. Both species were originally published as small annotated illustrations in a general work, although the promised full descriptions were never published by Cobb. The genusRhigonemais shown to be based on a species lacking a vaginal diverticulum in the female genital system, but having a long, Type 2, ovejector. The genusDudekemia, originally differentiated fromRhigonemaon an assumed (and erroneous) difference in female genital tract form, is confirmed as a junior synonym ofRhigonema. A full description of both sexes ofHethjuliis also provided, again based on Cobb’s original notes, thereby defining the type species with greater precision than was previously possible.