Variation of Tail Shape of Cylindrocorpus curzii (Nematoda:Cylindrocorporidae).

Populations of Cylindrocorpus curzii (T. Goodey, 1935) T. Goodey, 1939 (1,2)isolated f rom filter effluent of the sewage treatment plant Urbana, Illinois, were propagated on Aerobacter aerogenes (Kruse) Beijerinck. A single gravid female was transferred to sterile distilled water containing .01 ~g /ml sodium hypochlorite. After 20 min, during which time several eggs were deposited, the female was removed. The sodium hypochlorite solution, containing eggs, was changed after 4 h and replaced with two changes of sterile distilled water. Larvae that hatched were immersed briefly in .01 #g /ml actidione, rinsed in sterile distilled water and transferred to fresh A. aerogenes cultures. Thus, the resulting nematode population, derived f rom a single female to ensure genetic uniformity, was established monoxenically on A. aerogenes. Over a 3-year period during which monoxenic cultures of C. curzii were studied, adult males and females o c c a s i o n a l l y e x h i b i t e d considerable variation in tail shape. These aberrant forms were only seen in old stock cu l tu res s to red at r o o m t e m p e r a t u r e . Normally, the female tail was long and finely pointed (Fig. l-A), whereas the male tail was ventrally curved and tapered rapidly to a terminus which had a comparat ively short narrow process (Fig. I-E). The variation in females ranged f rom short, bluntly rounded tails, terminating the body just behind the anus, to short conical and apiculate forms (Fig. I-B to D). Occasionally, males were seen without the terminal process on the tail (Fig. l-F). In subsequent mating tests, involving virgin female variants, mated with normal males or male variants, or normal virgin females mated with male variants, the resulting progeny possessed normal tail shape, indicating that the observed variations were probably due to environmental rather than genetic factors. Undoubtedly, the occurrence of these variants