Nematode of the Week

Ecumenicus monohystera

Ecumenicus monohystera (de Man, 1880) Thorne, 1974 
Syns. Dorylaimus monohystera de Man, 1880
Dorylaimus gibbero-aculeatus Kreis, 1930
Eudorylaimus monohystera (de Man, 1880) Andrassy, 1959
Indokochinema ekramullahi Jana & Baqri, 1983
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Ecumenicus monohystera is distinctive among members of the Qudsianematinae (Dorylaimoidea: Qudsianematidae) for its single, posteriorly-directed ovary.  The only other genus in this subfamily expressing this character is Indokochinema Darekar & Khan, 1979, one species of which has been synonymized with E. monohystera.  Indokochinema itself may be synonymous with Ecumenicus (Jairajpuri and Ahmad, 1992), although the status of its one remaining species, I. conicauda Darekar & Khan, 1979 remains to be determined.  Specimens of E. monohystera have been recovered from our survey site at Konza Prairie, as well as from a bison wallow at Konza.  This nematode has also been found at 9 Mile Prairie, near Lincoln, NE, as well as from agricultural fields in Texas. E. monohystera is considered an omnivore, but like other Qudsianematinae may very well be predaceous. 

Peter Mullin


Descriptions:

Thorne, 1974: 

        "Ecumenicus new genus

        Dorylaimidae:  Nemas 1.0-1.4 mm long.  Lateral field a single line of cells
        and from each a minute tubule leads to a pore at the surface.  Dorsal gland
        nucleus located almost adjacent to its pore.  Vulva at 33-37%, a transverse
        slit with slightly sclerotized labia and vagina extending posteriorad.  Ovary
        single, reflexed.  No anterior uterine branch.  Tail bluntly digitate.  Only a
        single species known.

    Type species: Ecumenicus monohystera (de Man, 1880) n. comb.
    Synonyms: Dorylaimus monohystera, de Man, 1880
                   Eudorylaimus monohystera (de Man, 1880) Andrassy 1959
               Dorylaimus gibbero-aculeatus  Kreis, 1930

    L = 1.1 mm; a = 30; b = 4.5; c = 28; V = 35 
    Lips distinct, the region set off by slight expansion.   Spear 11u long with
    aperture 1/3 its length.  Guiding ring refractive, about 1/3 head width.
    Esophagus a slender, nonmuscular tube in anterior 3/5, then about half neck
    width in posterior 2/5.  Dorsal esophageal gland nucleus only slightly 
    behind its pore.  Pairs of submedian gland pores arranged similar to those 
    of Eudorylaimus.  A slight isthmus joins esophagus and cardia.  Cardia 
    discoid, then bluntly conoid.  Small hyaline structures in cardiac region.
    Cells of intestine with scattered dark granules.  Gonad as described above.
    Prerectum length 2-3 times width body.  Tail as illustrated.  Eggs 2-3 times
    as long as body width.

    Ecumenicus monohystera is world-wide in distribution.  Morphological
    characters and measurements of specimens from different continents are 
    most remarkable for their similarity."
     

Thorne and Swanger, 1957:
    "Kreis reports a male, the only one ever collected: Length 1.0 mm; width 3.8;
    esophagus 25.0; and tail 3.8 per cent of total length; supplements eight; tail
    form and supplement arrangement very similar to that of Dorylaimus  microdorus.
    The principal diagnostic characters of Dorylaimus gibbero-aculeatus Kreis,
    1930, are: A single circlet of labial papillae and the appearance of the 
    vestibule and spear.  Since all dorylaims possess two circlets of labial 
    papillae and the appearance of the vestibule and spear apparently is due to
    a fixation artifact, the species is synonymized with D. monohystera."
     
    Measurements of Konza Prairie specimens (n = 3):
    L a b c c' V Odontostyle Aperture Lip region
    1123 31.78 4.77 34.47 1.54 34.67 11 3.33 11.33

     
  • References:
    • Jairajpuri, M.S. and Ahmad, W.  1992.  Dorylaimida: Free-living, Predaceous, and Plant-parasitic Nematodes. E.J. Brill, Leiden.  458 pp.
    • Thorne, G. 1974. Nematodes of the Northern Great Plains. Part II  Dorylaimoidea in part (Nemata: Adenophorea).  South Dakota State University Technical Bulletin 41.  120 pp.
    • Thorne, G. and Swanger, H.H.  1957.  A monograph of the Nematode Genera Dorylaimus Dujardin, Aporcelaimus n.g., Dorylaimoides n.g. and Pungentus n.g.  Martinus Nijhoff, The Hague, Netherlands.   225 pp.