Helicotylenchus digonicus
Perry, 1959
L = 0.7 mm; a = 26; b = 5.8; c = 45; V = 51
Body
spiral when relaxed. Lip
region truncate with 4 annules. Spear
25u
long with cupped knobs. Dorsal
esophageal gland opening 10u-14u behind spear knobs.
Spermagonia conspicuous with thick cellular walls, sperms often present
during reproductive period.
Tails bluntly conoid to rounded, rarely with slight
projection. Phasmids 2-8 annules anterior to anus.
The spermagonia, so prominent in this and
related species, have created considerable controversy. Hirschman
and Triantaphyllou, 1965, consider them degenerate spermathecae, and Sher,
1966, concurs with this veiwpoint. However, the author agrees with
Perry, 1959, that cells of thick walls produce sperms which fertilize eggs
as they move from the ovary into the uterine tract. True spermathecae
do not have thick cellular walls and it appears highly improbable that
during degeneration they should develop into such elaborate cellular structures.
Helicotylenchus
usually has very definite periods of reproduction which last for 4-6 weeks
and only during this time are sperms observed.
Habitat: Bluegrass lawn, Brookings, South Dakota
(Thorne and Malek, 1968 description)
DNA Sequences Obtained
