Filenchus acutus
(Siddiqi, 1979) Raski & Geraert, 1987
Syn.: Duosulcius acutus Siddiqi, 1979
Photo Gallery- Konza Prairie

Measurements: 10 female (paratypes): L = 0.48-0.66 (0.54) mm: a = 39-46 (41.7); b = 4.5-5.3 (4.8); c = 5-6 (5.5) c' = 10.4-14.6 (12); V = 64.7-66.6 (65.4); spear = 6-7 (6.5) um; MB (distance from anterior end of body to centre of median oesophageal bulb as percentage of the oesophageal length) = 40-45 (42.7); MBB (distance from anterior end to base of median oeophageal bulb as percentage of the oesophageal length) = 45-50 (47.7); T/V-A (Tail length divided by vulva-anus distance) = 1.0-1.24 (1.1); Rex (annules between anterior end of body and excretory pore) = 87-118 ( 101); Roes (annules between anterior end and oesophageal base) = 122-155 (138); RVan (annules between vulva and  anus) = 93-115 (104).
        Holotype female: L = 0.53 mm; a = 41; b = 4.6; c = 5.4; c' = 11.5; V = 66.6; spear = 7 um; MB = 41.7; MBB = 47.8; T/V-A = 1.25; Rex = 101; Roes = 142; RVan = 106.

Description- Female: Body slender (maximum width usually 12-13 um), straight to arcuate.  Annules fine but distinct, 0.8-0.9 um wide at mid-body.  Lateral fields 1/10 to 1/12 body-width, originating 26-30 um behind spear base as a narrow streak and ending on tail a little anterior to its middle, with two crenate incisures.  Cephalic region continuous, rounded, low, circular in cross-section, 4.5-5 um wide and 2 um high, with four to five fine transverse striae; sclerotization light; amphids close to oral opening, indistinct in lateral view.  Spear slender, 6-7 um long; conus tiny, about 2 um long; basal knobs minute, rounded, 1.3 um across.  Orifice of dorsal oesophageal gland close to spear base.  Oesophagus 103-125 (113) um long.  Precorpus slender, slightly enlarging at base to a spindle-shaped non-muscular, non-valvate postcorpus; width of precorpus and postcorpus about 1.7 um and 3 um respectively.  Isthmus enlarges behind nerve ring very gradually so that anterior end of basal bulb is not demarcated.  Basal bulb elongated, sac-like, 5.5-6.5 um at its widest, with flat to rounded base having a rounded to discoidal cardia.  Nucleus of dorsal oesophageal gland 6-11 um anterior to oesophageal base.  Nerve ring about one corresponding body width behind postcorpus. Excretory pore 75-85 (80) um from anterior end, less than a body width behind nerve ring; excretory duct prominent, sclerotized.  Deirids 8-11 um behind level of excretory  pore, on a slightly expanded area of lateral field.  Hemizonid distinct, four to five annules long, zero to two annules anterior to excretory pore.
Vulva a depressed closed slit, without epiptygma and lateral flaps.  Vagina curved, about 3/4 body-width long, its anterior two-thirds strongly cuticularized, refractive.  Post-vulval uterine sac absent.  Uterus with a glandular quadricolumellar and a muscular part.  Spermatheca rounded, offset, with minute rounded sperm-like bodies.  Ovary outstretched, with oocytes in one or two rows.  Phasmids three to seven annules anterior to vulva.  Body diameter at anus two-thirds of that at vulva.  Rectum about one anal body width long; anus distinct.  Tail straight to slightly arcuate, regularly tapering to terminus which is abruptly narrowed and sharply pointed, 89-122 (100) um long, finely annulated except at the terminus.

Male: Not known.

Type habitat and locality:  Bush soil in Block F, International Institute of Tropical Agriculture, Oyo Road, Ibadan, Nigeria

Type material:  Collected by Dr. F.E. Caveness in 1974.  Holotype female and 4 female paratypes at C.I.H., St. Albans, England; 2 female paratypes at Nematology Department, Rothamsted Experimental Station, Harpenden, England; 1 female paratype at each of these nematological centres:  Landbouwhogeschool, Wageningen, Holland; Instituut voor Dierkunde, Ghent, Belgium; USDA Nematode Collection, Beltsville, Maryland, USA and Indian Agricultural Research Institute, New Delhi, India.
(Description- Siddiqi, 1979)