Descripteur : Symmetry of the caudal bursa
Symmetry , or lack thereof, in the bursa is an easily observed character and many generic diagnoses have been based on it.
In fact , it is of little value above the species level since asymmetrical bursae have arisen on many occasions in a great number of families. Pronounced asymmetry occurs most commonly in highly coiled species(e.g., members of the Nippostrongylinae). In these forms hypertrophy of one of the latero-ventral lobes probably aidsin holding the female during copulation.
The caudal bursa can present lateral lobes left and right symmetrical in size or no (see images)
Symmetry of the caudal bursa, ventral view.
Hiérarchie
Sex of the nematode | |_ Symmetry of the caudal bursa | |_ Asymmetry of the caudal bursa {Symmetric} | |_ Height of the asymmetry {Symmetric} | |_ Width of asymmetry {Symmetric}