Rev 09/25/2023

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Morphology and Anatomy Life Cycle
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            Schistonchus (Cobb, 1927) Fuchs, 1937

Type species of the genus:  Schistonchus caprifici (Gasperrini, 1864) Cobb, 1927


Note: Davies et al., 2017 transferred most of the species described under the gaenus Schistonchus by Bajaj and Tomar (2014) to Ficophagus

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Morphology and Anatomy:

Schistonchus is characterised by having the excretory pore opening in the region of, or posterior to, the metacorpus; Ficophagus  by having the excretory pore opening very near the cephalic region; and Martininema  by having it opening at the anterior end of the metacorpus. Several species of Schistonchus have a labial disc but there is no evidence of a labial disc in either Ficophagus or Martininema (Davies et al., 2015).

  • Slender, 400-800 μm long
  • Cuticle finely annulated. Three to four lateral lines or indistinct,
  •  Cephalic region off set or tapering,
  •  Stylet robust, 13-39 μm long, strong basal knobs present, conus forming 50-80% of total stylet length.
  • Esophageal procorpus cylindroid, metacorpus strong, aphelenchoid, muscular, with post-median valve. One or two esophageal glands, dorsal gland lobe well developed and overlapping intestine
  •  Excretory pore opening from level of metacorpus to posterior to nerve ring. .
  • Rectum a short narrow tube.
  • Vulva a simple transverse slit at 65-90% of body length, usually with slightly protruding lips; vagina drected anteriorly.
  • Genital tract monodelphic, prodelphic, ovary outstretched or reflexed
  • Spermatheca usually distinct, post-uterine sac spresent.
  • Female tail tip variable in form, with or without mucron; male tail region sharply recurved.
  • Spicules paired, separate,  rose-thorn shaped with prominent rostrum and relatively high, broadly rounded condylus. Gubernaculum present in some species
  •  Sperm usually amoeboid, apparently flagellate in some species
  • Male tail short, conoid, may be mucronate, tip rounded; two or three pairs of caudal papillae.
  • Caudal alae absent.
Ref: Nickle, 1970; Davies et al., 2015.  

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

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Frequently found associated with sycones (enclosed infrutescences) of Ficus spp.  Probably transported by fig wasps.

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Biology and Ecology:

Schistonchus spp. are probably transported by fig wasps. Some Ficus spp. are dependent on wasps for pollination. Thse syconium of a fig is an urn-shaped fleshy receptacle containing many simple male and female flowers; it opens to the exterior via a pore or ostiole. Wasps enter a syconium through the ostiole for egg deposition; they transfer pollen from male to female flowers and then die. A gall forms around each wasp egg and, within the gall, a male or female wasp develops. Male wasps are the first to emerge from galls, and they then fertilize the female wasps before the females emerge. Female wasps escape from the fig via the ostiole and fly to developing figs where the cycle is repeated. Many species of nematodes mature and reproduce within figs, and are transported among figs by pollinating wasps (Martin et al., 1973).

Many species of Schistonchus have been reported to grow and reproduce within the syconia of various Ficus spp.Some Ficus spp. can host more than one species of Schistonchus (Bartholomaeus et al., 2012).


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Life Cycle:

For Ecophysiological Parameters for this genus, click 

The nematodes feeding on fig epidermal cells, mature and lay eggs which develop into males and females. These adults produce a new generation of entomophilic females which mate, and penetrate the new generation of female wasps. Thus when the wasps emerge, ready to seek fresh sycones, they carry fertilised entomophilic nematodes in their haemolymph. The pre-reproductive female nematode, which is the  dispersal stage of Schistonchus and related genera, use volatiles and cuticular hydrocarbons from the female pollinating wasps to select the appropriate wasp vector (Davies et al. 2015).

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Ecosystem Functions and Services:



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Bartholomaeus, F., Davies, K.A., Ye, W. and Giblin-Davis, R.M. 2012. Schistonchus (Aphelenchoididae) from Ficus benjamini in Australia, with description of S. benjamiina sp.n. Nematology 13:1005-1013.

Davies, K.A., Ye, W.,  Kanzaki, N., Herre, E.A., Esquivel, A.  & Giblin-Davis, R.M. 2017. Two new species and three morphospecies of Ficophagus Davies & Bartholomaeus, 2015 (Nematoda: Aphelenchoididae) from Ficus subgenus Pharmacosycea (Moraceae) in Central America. Nematology19:351-374. DOI: 10.1163/15685411-00003055

Davies, K.A., F. Bartholomaeus, D.M. Li, Z.Q. Zhao, W. Ye and R.M. Giblin-Davis. 2020. Schistonchus macrophylla (Nematoda: Aphelenchoididae): an enigmatic taxon from sycones of Ficus section Malvanthera in eastern Australia, with description of a new subspecies. Nematology 22:999-1013.

Martin, G.C., Owen, A.M., Way, J.I. 1973. Nematodes, figs and wasps. J. Nematology 5:77-78.

Nickle, W.R. 1970. A Taxonomic Review of the Genera of the Aphelenchoidea (Fuchs, 1937) Thorne, 1949 (Nematoda: Tylenchida) . J. Nematology 2:375-392.


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Copyright © 1999 by Howard Ferris.
Revised: September 25, 2023