Filenchus terrestris
Raski & Geraert, 1986
Photo Gallery- Konza Prairie

Holotype female:  L = 0.613 mm; a = 46; b = 6.8; c = 3.6; c' - 18.2; V = 60; V' = 82.6; VL = 370 um; stylet = 10 um; cone = 5.0 um; excretory pore = 75 um; oesophagus = 90 um; V-a = 73 um; tail = 169 um.
Paratype females (n = 12): L = 0.593 +  0.035 (0.540 - 0.651) mm; a = 38 + 3.94 (33-46); b = 6.5 + 0.30 (5.9 - 6.8); c = 3.8 + 0.14 (3.3 - 4.0)  (n = 8); c' - 16.8 + 2.35 (12.6 - 18.8)  (n = 7); V = 60.9 + 2.02 (58.7 - 66.2); V' = 82 + 1.57 (78 - 83) (n = 7); VL = 361 + 22.33 (317 - 405) um; stylet = 9 + 0.59 (8 -10) (n = 11) um; excretory pore = 75 + 5.12 (68-83)  (n = 9) um; oesophagus = 91 + 5.31 (83 - 98)  (n = 8) um; MB = 39 + 1.89 (37-43) %; V-a = 76 + 2.12 (73-78) (n = 7)  um; tail = 158 + 6.12 (150-169) (n = 8) um.
Paratype males (n = 12): L = 0.567 + 0.043 ( 0.500-0.631 mm; a = 43 + 3.22 (37-47); b = 6.5 + 0.28 (5.9-6.8); c = 3.4 + 0.16 (3.2-3.7); c' = 17 + 0.97 (16-18) (n = 8); stylet = 9.2 + 0.67 (8.5-10.5) (n = 9) um; excretory pore = 71 + 5.17 (62-80) (n = 10) um; oesophagus = 85 + 5.08 (76-90) (n = 10) um; spicules 19 + 1.28 (18-21) um; gubernaculum = 5.1 + 0.74 (4-6) (n = 11) um;  tail = 163.5 + 10.01 (151-172) (n = 10) um.

Female:  After killing, fixing, mounting in glycerine body almost straight to vulva, angles slightly ventrally then straight again, gently curving ventrally near end of tail; cylindrical from vulva anteriorly, tapering slightly in oesophageal region to bluntly rounded, almost hemispherical outline.  Sclerotization of head delicate, arched.  Head about 5.5 um wide at base, and  half as high.
SEM photos show fine annuli continue onto head ending at squarish cephalic plate with rounded corners, slight indents on dorsal and ventral borders.  Circumoral plate set off by depression, rounded corners, slightly rectangular, innervations around slit-like oral aperture appear to be eight in number.  Amphid apertures begin near oral plate, continue as simple slits posteriorly with slight curvature.  No evidence of four cephalic papillae.  Sylet delicate, knobs small but distinct, backwardly directed.  Dorsal gland opening near stylet knobs.  Metacorpus distinctly rounded, well-developed valvular apparatus.
Isthmus slender, posterior, glandular region bulb-like pyriform 15-21 um long.  Excretory pore at level of hemizonid.  Oesophago-intestinal valve simple, low rounded.  Gonad outstretched; spermatheca large, ovate to elongate, filled with sperms about 2 um in diameter.  Uterus with four rows of four cells.  Postuterine sac rounded, 11-19 um long, 0.83-1.16 VBD.  Vulva slit simple, no lateral membranes or hypoptygmata.  Lateral field two prominent lines forming plain band occupying 15-21% body diameter; by SEM band is protruding slightly, rounded; fine irregular longitudinal lines (probably artefact) present on band.  Body tapers slightly from vulva to anus, then more abruptly but regularly to form an elongate, finely conoid outline on tail.
Male:  Similar to female. Body narrows markedly at level of anterior end of spicule, slightly rounded protrusion; anterior lip of cloacal opening seems to extend slightly beyond posterior lip.  Caudal alae low rounded, adanal, 28-42 um long; begin at about narrowing of body at spicule head, extend equal distance posterior to cloaca.
Ventral edge of lateral field merges with beginning of caudal alae, dorsal edge continues posteriad; lateral field becomes two lines again about 21/2 ABD posterior to cloaco then continues posteriad; exact termination of lateral field not determined.

Diagnosis:  The fine body annuli of Filenchus terrestris are similar to F. helenae but F. terrestris differs by its greater size [L = 0.43 (0.35-0.49) mm for F. helenae]; by its larger stylet (= 6-7 um for F. helenae); and by its cephalic morphology (head more bluntly rounded, labial plate a prominent squarish shape, oral disc strongly concave with six prominent labial papillae).  F. terrestris sp. n. is also very similar to F. cabi (Siddiqi & Hawksworth, 1982) comb. n. but differs in tail length (90-120 um in F. cabi vs. 150-169 um in F. terrestris) and vulva position (F. cabi has a very posterior V of 66-71 and V' of about 85%).
(Description- Raski & Geraert, 1986)