Holotype female: L = 435um; a = 35; b = 5.8; c = 4.1, c' = 12;
V = 60; V' = 79, esophagus = 76um; tail = 107 um; stylet = 9.5um.
Paratype females (n = 10): L = 452.5um + 23.4 (415-500); a = 35.6 + 2.3 (32-39); b = 5.9 + 0.2 (5.6-6.2); c = 4.7 + 0.6 (4.2-6); c' = 11.5 + 1.3 (10-13.5); V= 62.7 + 2.0 (60-65.5); V' = 80.0 + 1.3 (78-82); G1 = 19.8 + 1.5 (17-22); esophagus = 77.1um + 2.9 (72-83); tail = 98.3um + 9.2 (79-107); stylet = 9.9um + 0.6 (9-11).
Paratype males (n= 8): L = 458um + 17.3 (425-480); a = 38.4 + 2.3 (34-41); b = 5.8 + 0.2 (5.6-6.2); c = 4.2 + 0.2 (4.0-4.6); c' = 11.1 + 4.6 (8-16); T = 28.1 + 2.5 (24-32).
Body from almost straight to slightly ventrally curved in glycerine preserved animals. Body annuli wide, 2.1um + 0.2 (1.9-2.6), but not very pronounced. Lateral field 3.8um + 0.3 (3-4) wide with a single median line, lateral field usually protruded, offset by deep constrictions; in lateral view the edge of lateral field is often seen as a double line, the more inner line probably showing the thickness of the outer cuticular layer; as a result fve lines are frequently observed but the specimen studied by SEM and the male and female sectioned prove that the normal Aglenchus structure is present (i.e. two ridges).
Head slightly offset by constriction, 2.6um + 0.4 (2-3.5) high and 5.9um + 0.5 (4.5-6.5) wide; framework not sclerotized except for the cheilorhabdia. SEM study of the female head shows a trapozoid labial plate with involutions dorsally and ventrally; amphidial apertures rounded with a longitudinally oriented offshoot. Male head diferent; labial plate obliquely ventrally elongated having shape of a boomerang; amphidial apertures follow elongation of plate; on the ventral side two large papillae present. Stylet short, in a recent collection amore delicate than in 1972 slides (could be the result of difference in processing). Median bulb oval, 9.4um + 1.0 (8-10.5) long and 5.1um + 0.5 (4-6.5) wide with small valved in middle.
Terminal bulb pear-shaped, slightly larger in female than in male (females: length 14.5um + 1.0 (13-16.5) width: 6.1um + 0.5 (5.5-7); males length 13.7um + 0.9 (12.5-15.5), width: 5.7um + 0.7 (5-7)). Excretory pore at 67.4um + 2.2 (65-71), i.e. at level of terminal bulb, usually not very distinct; excretory pore anterior, through or posterior to hemizonid; deirids at same level. Oesphageal-intestinal valve distinct, usually a flat disc. Intestine with small sinuous lumen. Rectum small, curved; anus often indistinct.
Tail conical, tip variously shaped: pointed, irregular, rounded; as pointed tail (length 100-120um, n = 11) is longer than irregular tail (length 95-96um, n = 2) and rounded tail (79 -104um; n = 5) it is presumed that pointed tail is the typical shape of the completely developed tail. Irregular tails not present in the 1972 collection. Female reproductive system only anteriorly developed, with lateral vulval flaps about two annuli long; vagina straight inwards or obliquely anteriad with a thick wall (especially near the vulva); no post-vulval uterine sac. Spermatheca partly offset, usually filled with rounded sperm (about 1.7 um diameter), length 13.1 um + 2.2 (10-16); no eggs observed.
Male reproductive system with sliughtly curved spicules (length 12.6um + 1.0 (11-14)), dorsally longer than ventrally; gubernaculum not always distinct, curved, from about 4um to about 5.5um long. Cloacal tube 1.5 um long, cylindrical with terminal slit. Bursa well developed, 30.4um + 2.7 (26-35) long.
Differential diagnosis: Aglenchus dakotensis can be differentiated from the remaining Aglenchus species by its small body (max. 0.5mm), small tail (max 120um), small stylet (9-11um), spicule shape +cloacal tube regular and also by end-on view. A. dakotensis is very similar to A. mardanensis Maqbool, Shahina, and Zarina, 1984. A study of two paratype females did not show differences with the original description except for spear and oesophageal length: both were slightly larger. For A mardanensis no males have been described and no SEM views are available. The females differ in annular width: 1.2-1.5um in A. mardanensis and 1.9-2,6um in A. dakotensis (in A. mardanensis the annuli are indistinct); they could also differ in lateral field structure: in the original description two inner lines are drawn and described (but in the two paratype females the lateral field could not be observed), in A. dakotensis only one inner line is present. Tail, oesophagus, and stylet are slightly smaller in A. dakotensis. The two paratype females of A. mardanensis have no vulval flaps, although they are described and drawn in the original publication.
A. agricola differs in measurements, the main differences being stylet (11-13um) and tail (134-179 um); A agricola males have equal spicular limbs and the cloacal tube is more irregular (e.g. slightly posterior offset). The SEM pictures of A. agricola do not show the characteristics found in A. dakotensis.
Type Locality: Native sod near Rugby, North Dakota, U.S.A.