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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Bakernema

Bakernema Wu, 1964 (ref. ID; 5832, 5968)

Family Criconematidae (ref. ID; 5968)

ref. ID; 5832

Diagnosis (emended from Ebsary 1981)

Female body 0.50-0.58 mm. Annules 65-85, rounded or slightly retrorse with short to moderately developed membranous cuticular outgrowths which appear spine-like. Head annules two or three, submedian lobes small, separate. Stylet 65-96 µm. Vulva closed with strongly developed overlapping anterior vulval lip or open. Vagina sigmoid or straight. Tail of four to eight annules, rounded conical or conical rounded. (ref. ID; 5832)

ref. ID; 5968

Diagnosis (emended)

Female body 0.51-0.55 mm. Annules 65-70 rounded with membranous cuticular outgrowths which appear spine-like. Head annules three, submedian lobes small. Stylet 65-70 µm. Vulva with strongly developed overlapping anterior vulval lip. Vagina sigmoid. Tail four to seven annules, rounded conical. (ref. ID; 5968)
  • Juveniles (Fourth stage): Annules smooth to crenate. (ref. ID; 5968)
  • Males: Lateral incisures four, bursa small, spicules 36-48 µm. (ref. ID; 5968)

    Remarks

    The possibility exists that Macroposthonia axeste, M. basili, and M. longistyleta should be placed in Bakernema because of the extra cuticle illustrated respectively by Fassuliotis and Williamson (1959), DeGrisse (1969), and DeGrisse and Maas (1970). Such action, however, is not taken herein pending further study of these problematic species. (ref. ID; 5968)

    Type species

    Bakernema inaequale (Taylor, 1936) Mehta & Raski, 1971 (ref. ID; 5968)
    1. Bakernema bakeri (Wu, 1964) Wu, 1964
      See; Bakernema inaequale (ref. ID; 5968)
    2. Bakernema inaequale (Taylor, 1936) Mehta & Raski, 1971 (ref. ID; 5968) reported author and year? (ref. ID; 5832)
      Syn; Bakernema bakeri (Wu, 1964) Wu, 1964 (ref. ID; 5968); Criconema bakeri Wu, 1964 (ref. ID; 5968); Criconema inaequale Taylor, 1936 (ref. ID; 5968)
    3. Bakernema variabile Raski & Golden, 1966
      See; Neobakernema variabile (ref. ID; 5968)
    4. Bakernema yukonense Ebsary, 1981 (ref. ID; 5832 original paper)

    Bakernema yukonense Ebsary, 1981 (ref. ID; 5832 original paper)

    Descriptions

    Body tapers anteriorly to slightly rounded head. Submedian lobes present, separate. Labial annule bilobed dorsally and ventrally. Head annules two. Stylet rigid, stylet knobs 10-12 µm in diameter, anteriorly directed. Base of knobs forming strong concavity. Body annules 80(77-85), retrorse, margins smooth to crenate. Annules covered with external cuticular layer which laterally is developed into rounded spine-like projections. In dorsal and ventral aspect, the external cuticular layer lacks elaboration into irregularly arranged lobes as in B. inaequale but appears as a continuous thin band of smooth to crenate cuticle. Anastomoses zero to three. Number of annules between head and stylet base 14-16, to end of esophagus 20-23, and to excretory pore 21-14. Vulva open, seven (six to eight) annules from terminus, lips prominent, protruding. Anterior vulva lip spined. Vagina straight, oblique to body axis. Anus five (four to seven) annules from terminus. Spermatheca elongate ovoid, length about 1.5 times width, filled with round sperm 1.5-2.0 µm in diameter. Tail terminus variably lobes, with or without external cuticle. Cuticular projections usually absent on tail. (ref. ID; 5832)
  • Juveniles (Fourth stage): Similar to female. Cuticle strongly crenate, extra cuticular layer present, not elaborated into spines. (ref. ID; 5832)
  • Male: Unknown. (ref. ID; 5832)

    Notes

    Bakernema yukonense n. sp. differs from B. inaequale by having more body annules (77-85 versus 65-70), longer stylet (81-96 µm versus 65-70 µm), and by the open vulva and straight vagina (vulva closed, anterior lip strongly overlapping, vagina sigmoid in B. inaequale). (ref. ID; 5832)

    Type host and locality

    Specimens collected July 22, 1981, by Drs. D. Bright and C. Dondale of the Biosystematics Research Institute, Ottawa, from willow growing along the Dempster Highway, near Ogilvier, Yukon, Canada. (ref. ID; 5832)

    Type designations

  • Holotype (female): Slide No. 268 deposited in the Canadian National Collection of Nematodes (CNCN), Ottawa. (ref. ID; 5832)
  • Paratypes (eight females, two juveniles): Slides 268-268a also in CNCN. (ref. ID; 5832)

    Measurements

  • Holotype (female): L=564 µm, a=10.8, b=4.0, c=14.1, V=93. Stylet 86 µm. (ref. ID; 5832)
  • Paratypes (eight females): L=553(501-582) µm, a=11.2(10.3-12.6), b=3.9(3.7-4.2), c=16(12.2-20.2), V=93.5(93-95). Stylet 89(81-96) µm. (ref. ID; 5832)