Description (from Seinhorst, 1968)
According to Loof's (1960) description, P. crenatus has
a short postvulvar uterine branch and no spermatheca. However, all
specimens investigated had a long postvulvar uterine branch and a sometimes
obscure spermatheca which did not contain sperms or similar bodies (the
"spermagonium" of Dickerson, 1962). Loof indicated as type specimen
of P. crenatus Sher & Allen's (1953) neotype of P. pratensis.
Dr. Merlin Allen was so kind as to compare specimens of two Dutch populations
with this type. A population with a long postvulvar uterine branch,
an empty spermatheca and without males appeared to be conspecific with
P.
crenatus.
The descriptions of P. crenatus as given by Sher &
Allen (1953) and Loof (1960) need the following emendations and additions:
Spermatheca small and empty, situated anterior to vulva about 50% to 90%
of distance from vulva to anus. Postvulvar uterine branch occupying
40% to 50% of distance between vulva and anus (about two body diameters
long, as stated by Sher & Allen, 1953). The tail bears 20 to
24 annules.
P. crenatus can be distinguished from other species with
crenate tails and three annules on the lips by the absence of males and
the long postvulvar uterine branch.