Ogma seymouri
(Wu, 1965) Siddiqi, 1986
Photo Gallery- Pachaug State Forest, CT
Criconema seymouri Wu, 1965
Crossonema (Seriespinula) seymouri (Wu) Mehta & Raski, 1971
Seriespinula seymouri (Wu) Mehta & Raski, 1971
Seriespinula seymouri (Wu) Khan, Chawla & Saha, 1976

     Body of heat-killed specimens almost straight.  Head set off, consisting of two annules.  First annule slightly wider than the second (17.2 - 21.2 and 15.8 - 17.5 um respectively).  First annule thin and broad, margin slightly irregularly crenate.  Second annule appears as an irregular band and, in one specimen, short spines were present.  Lip region prominent, mostly concealed by first head annule.
     Total number of body annules 61 or 62 (not including head annules).  Posterior margin of body annules with spines, which are oblong with blunt ends.  The length of spines varies, near midbody the longest spine is about 8 um long.  At both extremities spines are in a continuous fringe.  On other annules spines arranged in groups, usually in two or three, some in four or five, or even single.  The number of rows near middle of the body appears to be about 10-12.  The distance between groups of spines varies from quite distinct to rather close, which sometimes makes it difficult to determine the number of rows of spines on each annule.
     Spear 63.2 - 65.5 um long, spear base 8-9 um in diameter, extending through 9 or 10 body annules from anterior end. Esophagus 0.095 to 0.102 mm, extending through 13 body annules from anterior end. Excretory pore on 17th or 18th body annule from anterior end.
     Vulva on 13th annule and anus on 6th - 8th from posterior end.  Anterior vulval flap a simple arch, occupying most of the width of the annule.  Tail 23.2 - 31.0 um long, terminus pointed, ending in a single lobe.  Ovary 0-.247 - 0.274 mm long, free and reaching about 36-55 um behind basal esophageal bulb.
     (N = 3): L = 0.450 - 0.472; a = 9.6 - 11.6; b = 4.5 - 5.0; c = 15.2 - 19.4; V = 85.6 - 86.9%
     Holotype female:  L = 0.465; a = 10.1; b = 4.6; c = 17.6; V = 86.9%.  Anus on seventh annule.  First head annule = 21.2 um; second annule = 17.5 um.  Excretory pore on 18th annule.  Spear 63.2 um (proportion 52.2:11).
     Body of specimens killed by gentle heat curved ventrally.  Head flat in front with four to six annules.  Spear absent.  Esophagus weakly developed, about 76-91 um long; median bulb present, anterior end slightly broader than posterior end.  Excretory pore about 0.101 - 0.120 mm from anterior end.  Annules at middle of body about 3 or 4 um long.
     Lateral field about 4.5 um wide with two incisures.  Short ridges of cuticular thickening may appear on the lateral field.  Occasionally one or two additional lines appeared faintly, but it is doubtful whether these are regular incisures.  Tail 42-47 um long, tip pointed, cuticle of terminus generally with a rough appearance.  Spicules 40-47 um long, slightly arcuate.  Gubernaculum about 8 um long.  Caudal alae low.  Testis 0.144 - 0.175 mm long, outstretched, except one with a short reflexure near free end.
     (N = 8): L = 0.425 - 0.460; a = 18.9 - 22.0; b = 4.8 - 6.2; c = 8.8 - 10.5; T = 33.9 - 40.9.
     Allotype male: L = 0.460; a = 21.7; b = 6.2; c = 10.5. Spicule 45 um. Testis 0.175 mm.
     This new species resembles C. tenuicaudatum Siddiqi, 1961 and C. hungaricum Andrássy, 1962.  It differs from both species in having a much shorter spear, the location of the excretory pore more anterior (on the 17th or 18th annule against the 24th and the 21st - 23rd, respectively), the spear extending through only 9 or 10 annules, and the esophagus extending through 13 annules. It differs from C. tenuicaudatum in having the anterior vulval flap in the form of a simple arch, instead of being somewhat rectangular in shape as figured by Siddiqi.  It differs from C. hungaricum in having the second head annule slightly smaller than the first, instead of subequal as figured by Andrássy.
Host and Locality
     From soil under a cedar tree (Thuja plicata Donn), Mt. Seymour, near Vancouver, British Columbia, Canada.
(Description- Wu, 1965)

Measurements (10 females): L = 457 um (388-510); stylet = 61 um (58-67); V = 84.1% (80.7 - 86.0); Rv = 13 (11-15); R = 57 (53-67); Rex = 18.
Associated plants and localities.  Soil around roots of Acer rubrum L. at the beginning of the Calamity Brook Trail near the Upper Works parking lot, Essex Co., N.Y.
The original description by Wu (1965b) was adequate, but the range of measurements was expanded by Mehta and Raski (1971) when more specimens were found.  This species was found only once in this study and all specimens agree well with the existing descriptions.
The most identifiable features of C. seymouri are the two offset crenated head annules, short stylet, and the 10 to 12 rows of divided hand-like spines on the body.  This species is most closely related to C. hungaricum and is differentiated from it by having a shorter stylet.
(Description- Hoffman, 1974)

This Species included in the Criconematid Project

DNA Sequences Obtained:
N308 Pachaug State Forest, CT