Pratylenchus penetrans
(Cobb, 1917) Chitwood & Oteifa, 1952
Syn. Tylenchus gulosus Kuhn, 1890; Fischer, 1894;
Tylenchus penetrans Cobb, 1917;
Tylenchus pratensis Steiner, 1927;
Anguillulina pratensis Goodey, 1932;
Pratylenchus pratensis Filipjev & Schuurmans Stekhoven, 1941;
Photo Gallery- Homestead Nat'l Monument
Photo Gallery- Washington state
Photo Gallery- Quebec

Measurements (from C.I.H. Descriptions of Plant-parasitic Nematodes)
L = 348-811 um; a = 19-32; b = 5.3-7.9; c = 15-24; V = 75-84; spear = 15-17 um
L = 305-574 um; a = 23-34; b = 5.4-7.3; c = 16-22; T = 36-58; spear = 13-16 um; spicules = 14-17 um;    gubernaculum = 3.9-4.2 um

Description (from C.I.H. Descriptions of Plant-parasitic Nematodes)
 Female: Body moderately slender, almost straight when killed by gentle heat.  Cuticular annulation fine.  Lateral field normally with four incisures, outer bands may be partly areolate, central field sometimes with oblique striae near vulva, becoming areolate behind vulva, not extending to tail tip.  Lip region slightly set off, low, flat in front, with rounded outer margins, 3 annules.  Head with strong, conspicuous skeleton.  Basal knobs of spear broadly rounded, sometimes cupped anteriorly.  Oesophagus overlapping intestine ventrally in a lobe about 1.5 body-widths long.  Excretory pore about opposite oesophago-intestinal junction with hemizonid occupying about two body annules immediately in front of it.  Post-uterine sac short, undifferentiated, about 1 or 1.5 vulval body-widths long.  Spermatheca spherical, or nearly so.  Tail generally rounded, tip smooth, with 15-27 annules on ventral surface.
 Male: Common.  Slightly smaller than female, but similar in form.  Lateral field with four incisures ending on the bursa, occasionally with oblique lines in central field near mid body.  Spicules slender, with well-marked manubria and ventrally arcuate shafts, 14-17 um long; gubernaculum simple, 3.9-4.2 um long.  Tail about twice as long as anal body diameter; bursa irregularly crenate along edge, enveloping tail tip.
Type host and locality: Greenhouse soil, Rhinebeck, New York, USA



Measurements (from Sher & Allen, 1953)
L = 0.43-0.56 mm; a = 17-30; b = 5.7-6.5; c = 15-21; V = 78-83 ; spear = 17-19 um
L = 0.44-0.56 mm; a = 23-30; b = 5.2-6; c = 15-20; T = 43-52; spear = 16-18 um

Descriptions (from Sher & Allen, 1953)
    Female: Lateral field marked by four incisures.  Lip region slightly set off from head bears three annules.  Outer margins of heavily sclerotized labial framework extend into the body about one body annule.  Spear-guiding apparatus extends posteriorly from basal plate about three body annules.  Spear 18 um long, well develoed, broadly rounded basal knobs.  Dorsal esophageal gland orifice about 2 um behind spear base.  Esophagus opens into intestine near level of excretory pore.  Hemizonid about two annules long situated about one annule in front of excretory pore.  Ovary does not extend to esophagus consists of a double row of oocytes except for posterior and anterior end which is single.  Spermatheca round, oviduct cellular about twice as long as spermatheca, uterus about as long as spermatheca.  Posterior uterine branch short, about equal to the width of body at vulva.  Phasmids slightly posterior to middle of tail.  Four lateral lines extend past phasmid.  Tail rounded, no striations around terminus.
    Male: Similar to female.  Single outstretched testis consists of spermatocytes arranged in double row.  Phasmids slightly posterior to middle of tail, extend only slightly into bursa.  Spicula arcuate, hafted, rest upon trough-shaped gubernaculum.
Type host: From greenhouse soil.
Type locality: Rhinebeck, New York.



Description (from Seinhorst, 1968)
 According to Sher & Allen (1953) this species has three annules on the lips, a round spermatheca and a smooth tail tip.  Males are present.  Populations with these characters appeared to belong to one of two groups: either (1) nematodes with a 15 um long stylet and about 15 annules on the tail or (2) nematodes with a 17 um long stylet, females with 15 to 27 annules on the tail.  In different populations different proportions of the females may have 20 or fewer annules on the tail.  No other differences were found between the different populations of this species.  Neither were there consistent ecological differences.  All are therefore considered to be P. penetrans.  The specimen figured by Sher & Allen (1953) has 18 annules on the tail.  In all populations the distance between vulva and spermatheca is between 45% and 75% of that between vulva and anus.  The postvulvar uterine sac is 26% to 41% of the latter distance long.  In the Netherlands the species occurs on sandy and peat soils and only in association with cultivation, especially of ornamental plants, apples and strawberries.  Small numbers may occur on apple in heavier soils.

Description (from Roman, Hirschmann, 1969)
 Females: Lateral field often marked by four incisures, but may exhibit all variations described above.  Some specimens with straight rows of punctations in center of outer bands, in addition to diagonal lines in inner band.  Lip region slightly set off from body, bearing three annules.  Anterior end of vestibule with slight refractive "ornamentation."  Stylet knobs varying from rounded to anteriorly concave.  Glandular lobe of esophagus overlapping laterally.  Hemizonid two to three annules long, located immediately in front, or up to three annules in front of excretory pore.  Gonad measuring 139.6 to 234.0 um.  Spermatotheca rounded, usually containing spermatozoa.  Postvulvar uterine branch 15.0 to 36.0 um long.  Tail variable in shape, annulations not extending completely around terminus.
 Males: Similar to females.  Stylet knobs variable in shape.  Hemizonid two to three annules long, located immediately in front, or up to two annules in front of excretory pore.  Gonad 165.0 to 336.5 um long.

DNA Sequences Obtained
Specimen: Collected:
OLD 6A-6 in culture, University of Wisconsin
Samac 11-07 in culture, University of Wisconsin
Samac 11-08 in culture, University of Wisconsin
PA-9 in culture, University of Wisconsin
PA-10 in culture, University of Wisconsin
SJBR-16 in culture, University of Wisconsin
MI-18 in culture, University of Wisconsin
SJBR-17 in culture, University of Wisconsin
MI-19 in culture, University of Wisconsin
Lauer 1-21 in culture, University of Wisconsin
Aartz 3-22 in culture, University of Wisconsin
Aartz 3-23 in culture, University of Wisconsin
OSU Logon 7-28 in culture, University of Wisconsin
LL-Orleans 29 in culture, University of Wisconsin
Malek-31 in culture, University of Wisconsin
Malek-32 in culture, University of Wisconsin
Lauer 2 Wisconsin