Rev: 01/11/2022

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       Tylocephalus Crossman, 1933


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Morphology and Anatomy:


  • Body length 0.3 to 0.6 mm.
  • Anterior end with bilateral and dorsoventral symmetry.
  • Cervical expansions bulbiform,
  • Amphid aperture circular, located at half of stoma length.
  • Renette cell located ventrally, opposite to isthmus. Excretory gland duct weakly cuticularised, enveloped by renette cell. Excretory pore posterior to nerve ring.
  • Stoma plectoid.
  • Pharynx plectoid, divided into corpus and isthmus by a break in muscular tissue and subventral gland orifices, basal bulb with valves.
  • Vulva equatorial.
  • Reproductive system didelphic, amphidelphic, ovaries reflexed


  • Reproductive system diorchic, testes opposed.
  • Spicules paired, curved ventrad.
  • Tubular supplements, precloacal, postcloacal sensilla and gobernaculum absent.
  • Tail conoid at first, then cylindrical, ventrally curved.
  • Caudal glands present, opening through a terminal spinneret. 

Ref: Holovachov et al (2004).


Tylocephalus cephalatus
B,G: anterior; D,I: Pharyngeal region; H: Female gonad
from Holovachov et al., 2004

For comparisons among genera, go to subfamily Wilsonematinae

Labial region components of Tylocephalus

from Holovachov et al., 2003.

CE = cervical expansion, CORN = cornu; FLAB = flabellum; LR = lateral rim; MP = midlateral projection; MR = median ridge; QUAD = quadrant; RR = radial ridge; YI = Y-shaped incisure.

Body size range for the species of this genus in the database - Click:
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Biology and Ecology:

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Life Cycle:

For Ecophysiological Parameters for this genus, click 
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Ecosystem Functions and Services:

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Holovachov, O., Bostrom, S., Mundo-Ocampo, M. 2004. Description of three known and two new species of the genus Tylocephalus Crossman, 1933 with a revised taxonomy of the genus and key to species of the subfamily  Wilsonema (Plectida). Russian J. Nematol 12:115-130.

Holovachov, O., Bostrom, S., Tandingan De Ley, I., De Ley, P., and Coomans, A. 2003. Morphology and systematics of the genera Wilsonema Cobb, 1913, Ereptonema Anderson, 1966 and Neotylocephalus Ali, Farooqui and Tejpal, 1969 (Leptolaimina: Wilsonematinae) J. Nem. Morph. Syst. 5:73-106.

Copyright © 1999 by Howard Ferris.
Revised: January 11, 2022.