Ogma octangulare
(Cobb, 1913) Taylor, 1936
Photo Gallery- Mt. Philo, Vermont
Photo Gallery- Governor Dodge State Park, Wisconsin

Length. .4 mm; a = 8.
Tail conoid, ending in a minute knob.  Annules 65-75.  Spines scale-like, rounded, relatively large, arranged in 8 longitudinal rows.  Head of two annules, first of which is plate-shaped disc.  Second rounded.  Lips 6, small, flat.  Middle bulb of oesophagus elongated, isthmus and terminal bulb cylindrical with only slight swelling at base.  Stylet large, stout.  Length 63 um, or 16% of body length, extending through 12 annules. Nerve ring oblique, near base of oesophagus.  Intestine thin-walled, occupying most of body cavity.  Anus at about 7th annule in front of terminus, inconspicuous.  Vulva prominent, at 12th annule in front of terminus.  Vagina extending inward and forward one body diameter.  Uterus in young specimen extending through 10 annules.  Single ovary outstetched or only short end reflexed, lying in dorsal portion of body cavity with blind end near oesophagus.  Excretory pore at exterior margin of 19th annule, distinct when seen in ventral, less distinct in lateral view.  Male unknown.
Habitat:  Soil, Dismal Swamp, Virginia, U.S.A.
(Description- Taylor, 1936)

Female (n = 1): L = 378 um; a = 10.3; V = 85; stylet = 68.4 um; R = 67; RSt = 15; ROes = 20; RV = 13; Ran = 8; RVan = 4; VL/VB = 1.1; St % L = 18.1.
Larva (n = 1): L = 281 um; a = 8.4; stylet = 57.4 um; R = 69; RSt = 16; St % L = 20.4.

Female:  Body almost straight.  Labial disc with submedian lobes, protruding slightly beyond first annule.  Lip region consisting of two annules, rounded laterally with a few larger marginal indentations; first annule 11.8 um and second annule 14.0 um wide respectively.  Succeeding two body annules 19.9 um and 22.8 um wide respectively.  All body annules thick, retrorse, bearing 8 longitudinal rows of scales.  Width of annules at midbody 6.3 um; margins of scales appearing smooth.  Excretory pore not seen.  Body width at midbody 36.8 um.   Hemizonid not seen.  Stylet slender with cupped basal knobs, the latter being 6.6 um wide and 3.3 um high.  Front part of stylet 56.3 um long and posterior part 12.1 um long.   Spermatheca not seen.  Tail tapering gradually to a narrow tip.

Larva:  Similar to female except that there are 10 to 11 longitudinal rows or more trianularly shaped and posteriorly pointed scales.  First and second head annules 11.0 um and 12.9 um wide respectively, followed by first two body annules which are 15.8 um and 18.0 um wide respectively.  Width of annules at midbody 4.4 um.  Hemizonid and excretory pore not seen. Body width at midbody 33.5 um.  Stylet slender with stylet knobs 5.2 um wide and 2.9 um high.  Front part of stylet 48.2 um long and posterior part 9.2 um long.  Tail tapering gradually to a narrow tip.
(Description- Van Den Berg, 1983)

This species included in the Criconematid Project

DNA Sequences Obtained
Specimen: Collected:
NID 27 Mt. Philo,VT
NID 28 Mt. Philo,VT
NID 29 Mt. Philo,VT