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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Eutylenchus

Eutylenchus Cobb

Family Atylenchidae (ref. ID; 5966)

ref. ID; 1923

With 4 cephalic setae; primarily aquatic species. Cuticle of body without numerous longitudinal ridges. (One named species) (ref. ID; 1923)

ref. ID; 5966

Andrassy (1976) included Pleurotylenchus Szczygiel, 1969 in the Atylenchidae, an action which is not accepted herein. Pleurotylenchus is considered to be distinct from Atylenchus and Eutylenchus because of the absence of head setae. This genus is apparently most closely related to Coslenchus Siddiqi, 1978 and to Campbellenchus Wouts, 1978 in the Tylenchidae. (ref. ID; 5966)
  1. Eutylenchus africanus (ref. ID; 5966)
  2. Eutylenchus excretorius Ebsary & Eveleigh, 1981 (ref. ID; 5966 original paper)
  3. Eutylenchus setiferus (ref. ID; 5966)
  4. utylenchus vitiensis Orton williams, 1979 (ref. ID; 5966)

Eutylenchus africanus (ref. ID; 5966)

Descriptions

Cephalic lobes 6. Excretory pore posterior to hemizonid, stylet 20-24 µm. (ref. ID; 5966)

Eutylenchus excretorius Ebsary & Eveleigh, 1981 (ref. ID; 5966 original paper)

Differential diagnosis

Eutylenchus excretorius n. sp. is most closely related to E. vitiensis but differs by having a shorter stylet (21 µm (20-22) versus 26 µm (24-28)), excretory pore 94-105 µm from head located in posterior half of isthmus (excretory pore 68-81 µm from head, located in anterior half of isthmus in E. vitiensis), hemizonid 2-4 annules posterior to excretory pore (hemizonid 6-16 annules posterior to excretory pore in E. vitiensis), and by the presence of a prominent elevated vulval disc which is absent in E. vitiensis. (ref. ID; 5966)

Descriptions

  • Female: Body nearly straight, tapering anteriorly from base of esophagus to head and posteriorly from vulva to tail terminus. Cuticle with 12 longitudinal ridges of rectangular blocks separated by deep transverse and longitudinal striae over most of body. Two ridges begin on each midlateral aspect one or two annules posterior to head. Dorsal and ventral areas of body each have three ridges beginning about five annules posterior to head. The final two ridges begin about midprocorps where the lateral ridges diverge. Annules about 1.5 µm wide at midbody. Head nonannulated, set off by deep constriction from body. Prominent perioral disc present. Head with four distinct lobes in en face, each lob separated by distinct incisures dorsoventrally and laterally. Each lobe with one seta 10(8-12) µm long. Each seta has an expanded, slightly pedunculate basal portion and finely pointed distally tapered tip. Esophagus with distinctly valvate, fusiform metacorpal bulb, occupying most of adjacent body cavity, 47-55 µm from head. Isthmus slender, 43-53 µm long gradually expanding into an elongate, pyriform basal bulb, 26-37 µm long. Esophageal base 136-152 µm from head. Deirid 6-11 annules posterior to excretory pore, centered in a cuticular block. Stylet with a finely pointed, slender, strongly cuticularized conus 9-10 µm long and with 12-12.5 µm shaft which is less cuticularized and difficult to resolve. Stylet knobs 3-3.5 µm in diameter. Dorsal esophageal gland duct indistinct. Excretory pore and duct cuticularized, conspicuous, located in posterior half of isthmus, 94-105 µm from head. Hemizonid located 2-4 annules anterior to the excretory pore, 2-3 annules long. Ovar single, outstretched anteriorly. Oocytes mostly in single row. Spermatheca and sperm not seen. Vulva elevated, surrounding area deeply depressed. Vulva covered by a thickened disc of cuticle. Low lateral vulval membranes present. In ventral view, vulva seen as a transverse slit bissecting the four-plated vulval disc. Anterior and posterior to the disc are the two depressions seen in lateral view. Lateral vulval membranes distinctly crenate. Post uterine sac 1.6(1.5-1.9) times as long as vulva body width. Vulva to anus distance 120(117-124) µm. Tail 106(103-110) µm long, 10(9.2-10.7) times anus body width tapering to a finely rounded or pointed terminus. Cuticular ridges and blocks end about midtail, remainder of tail finely to minutely transversely striated to terminus. (ref. ID; 5966)
  • Juvenile females (fourth stage): Similar to adult female except for gonad development. (ref. ID; 5966)
  • Males: Unknown. (ref. ID; 5966)

    Type locality and habitat

    Specimens were collected October 16, 1980, by the authors from a grass growing in water in the Ottawa River near Deschenes, Quebec. (ref. ID; 5966)

    Type designations

    Holotype female and five paratypes deposited in the Canadian National Collection of Nematodes in Ottawa, slide number 260. Two additional paratypes and three juveniles also deposited in CNCN, slide number 260a. (ref. ID; 5966)

    Measurements

  • Holotype (female): Length(L)=801 µm, a=48.3, b=5.7, c=8.3, V=73.3, stylet 21 µm. (ref. ID; 5966)
  • Paratypes (7 female): L=885(837-911) µm, a=42.8(41-45), b=6.2(6-6.3), c=8.3(8.1-8.8), V=74.1(72.9-75.8), stylet 21(20-22) µm. (ref. ID; 5966)

    Eutylenchus setiferus (ref. ID; 5966)

    Descriptions

    Cephalic lobes 6. Excretory pore anterior to hemizonid, stylet 18-21 µm. (ref. ID; 5966)

    Eutylenchus vitiensis Orton williams, 1979 (ref. ID; 5966)

    Descriptions

    Cephalic lobes 4. Excretory pore anterior to hemizonid, 68-81 µm from head, stylet 24-28 µm. (ref. ID; 5966)