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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Mononchus

Mononchus Bastian, 1865 (ref. ID; 5938)

Order Dorylaimida (ref. ID; 7909)

Rhabditida (ref. ID; 6180)

Family Mononchidae (ref. ID; 880, 5938, 6740)

ref. ID; 1663

Longitudinal ridge without denticles opposite dorsal tooth. Common species. (ref. ID; 1663)

ref. ID; 1861

The genus is large predatory nematode. Mononchus feeds on small metazoans, including other nematodes. (ref. ID; 1861)

ref. ID; 5938

Definition

Lips and labial papillae poorly developed. Buccal cavity twice as long as wide, walls fairly straight. Dorsal tooth anterior with apex directed forward in cavity, ventral ridge absent. Esophagointestinal junction nontuberculate. Female didelphic, ovaries reflexed. Male spicules long and thin. Tails of both sexes similar, elongate with rounded terminus. Caudal glands and terminal duct present. Generally found in aquatic habitats. (ref. ID; 5938)

Type species

Mononchus truncatus Bastian, 1865 (ref. ID; 5938)

Nominal species

13 (7 of these are considered species inquirendae by some authors including myself). (ref. ID; 5938)

ref. ID; 6691

Predators. (ref. ID; 6691)
  1. Mononchus angarensis Gagarin, 1984 (ref. ID; 7909)
  2. Mononchus aquaticus (ref. ID; 1751)
  3. Mononchus bastiani De Man
    See; Mononchus papillatus (ref. ID; 2592)
  4. Mononchus brachyuris Butschli, 1873 (ref. ID; 3439)
  5. Mononchus brevicaudatus Cobb, 1917 (ref. ID; 2588)
  6. Mononchus dolichurus Ditlevsen, 1911 (ref. ID; 2592)
  7. Mononchus maduei Schneider, 1925 (ref. ID; 5938, 7909)
  8. Mononchus (Sporonchulus) micoletzkyi Meyl, 1954
    See; Prionchuloides micoletzkyi (ref. ID; 5938)
  9. Mononchus muscorum (Dujardin, 1845) (ref. ID; 2588, 2592)
  10. Mononchus niddensis Skwarra, 1921 (ref. ID; 5938)
  11. Mononchus nudus Gagarin, 1991 (ref. ID; 7909 original paper)
  12. Mononchus papillatus Bastian, 1865 (ref. ID; 2588, 2592)
    Syn; Mononchus bastiani De Man (ref. ID; 2592)
  13. Mononchus propapillatus (ref. ID; 1751)
  14. Mononchus superbus Mulvey, 1978 (ref. ID; 5938 original paper)
  15. Mononchus tajmiris Gagarin, 1991 (ref. ID; 7909 original paper)
  16. Mononchus tridentatus De Man, 1876 (ref. ID; 2588, 2592)
  17. Mononchus truncatus Bastian, 1865 (ref. ID; 5938, 7909) reported year? (ref. ID; 1795)
  18. Mononchus zschokkei Menzel, 1913 (ref. ID; 2592 original paper, 3439)

Mononchus maduei Schneider, 1925 (ref. ID; 5938, 7909)

Descriptions

Head rounded, dorsal tooth apex 80-83% from base of buccal cavity. Walls of buccal cavity fairly thick, cavity approximately three times as long as wide. Female didelphic, amphidelphic, ovaries reflexed. Vulval papillae absent. Spermatheca filled with sperm. Caudal glands three, leading to a terminal, armed spinneret. Male spicule long and slender, accessory pieces with bifurcated distal ends. Spicule tips bidentate, male tail with a series of small serrations anterior to tail terminus. Supplements many, well developed, and evenly spaced. Male tail cylindroid tapering suddenly in posterior third, spinneret terminal and armed. (ref. ID; 5938)

Remarks

An aberrant form which I have tentatively identified as Mononchus maduei was found with two normal slender spicules measuring 120 µm in length and with 22 supplements. In addition, there was a third spicule measuring 82 µm and a large gubernaculum. This spicule is not characteristic for the male of this genus but resembles that found in some dorylaimid species. (ref. ID; 5938)

Measurements

  • Female: L=3.2(2.8-3.4) mm, a=40(35-44), b=3.0(2.8-3.3), c=17(16-20), V=55(50-60), buccal cavity 54-58x20-23 µm, tail length 183(170-200) µm; egg 98-100x82-90 µm (n=5). (ref. ID; 5938)
  • Male: L=2.9(2.7-3.0) mm, a=30-33, b=3.1-3.3, c=20-23, buccal cavity 52-57x20-22 µm, tail length 136(130-150), spicule length 120(110-130) µm, amphid width 6-7 µm, supplements 22-26 + 6 (n=6). (ref. ID; 5938)

    Mononchus nudus Gagarin, 1991 (ref. ID; 7909 original paper)

    Diagnosis

    This species is very similar to Mononchus truncatus Bastian, 1865, but the tail has a different shape-thick, saclike. In terms of the shape of the tail, it is close to Mononchus maduei Schneider, 1925, but is smaller (in females of M. maduei L=3.5-3.7 mm) and tail relatively longer (in females of M. maduei, c=17-20). (ref. ID; 7909)

    Descriptions

    Nematodes of average size. Lips and labial papillae well pronounced. Stoma measures 26-44x17-21 µm, buccal index 1.5-2.2. Tip of dorsal onchium situated 22-24 percent of the length of the stoma away from its anterior margin. Amphid openings 5-6 µm wide localized at the level of the anterior third of the length of the stoma. Esophagus muscular, lumen lined with cuticle. Mean length of oesophagus 411 µm. Bulbs absent. Nerve ring encircles 25-27 percent of the length of the esophagus. Females didelphic, ovaries reflexed. Lips of vulva sclerotized. Vagina extends deep into the body a distance equal to half the body diameter. Rectum short, its length less than the anal diameter of the body. Tail thick, saclike, its end only 2.5-2.8 times narrower than the anal body diameter. Mean length of tail 176 µm. (ref. ID; 7909)

    Remarks

    Distributed in Rybinsk and Sheksninskoye reservoirs (both are part of the composition of the Volga-Baltic aquatic system). Previously, the species was erroneously identified for the fauna of these reservoirs as Mononchus maduei Schneider, 1925 (Gagarin and Velichko 1982; Gagarin 1986). (ref. ID; 7909)

    Examined materials

    Six (female, female) from Rybinsk Reservoir. Collected in July 1982 (mouth of Suda River, depth 0.2 m, ground-muddy sand)-2 (female, female); collected in June 1983 (mouth of the Kes'ma River, depth 0.5 m, ground-sand)-4 (female, female). Holotype (female) (preparation "P-104"): L=2015 µm, a=23.43, b=3.88, c=11.92, V=57.42 percent, c'=2.83. Paratypes, 5 (female, female), L=1619-2148(1804) µm, a=22.52-34.65(28.14), b=4.09-4.57(4.38), c=9.01-12.07(10.17), c'=3.11-4.08(3.67), V=48.98-57.42(52.05) percent. (ref. ID; 7909)

    Type specimens

    Type specimens are deposited in the collection of the Laboratory of Biology and Systematics of Aquatic Organisms of the USSR Academy of Sciences Institute of Inland Waters Biology (Borok village). (ref. ID; 7909)

    Mononchus superbus Mulvey, 1978 (ref. ID; 5938 original paper)

    Differential diagnosis

    Mononchus superbus differs from all species in this genus by its very long body and large buccal cavity. It differs from M. niddensis in the position of the dorsal tooth apex (76-77% vs. 83-88 from the cavity base in M. niddensis) and very long female tail. The male of M. superbus differs from M. niddensis in buccal cavity size, position of the dorsal tooth, shape of the tail, spicule length, and number of supplements. (ref. ID; 5938)

    Descriptions

    Dorsal tooth large, apex 76-77% from base of buccal cavity. Indentation of ventral wall of cavity at level of dorsal tooth apex. Buccal cavity walls fairly thick, cavity about twice as long as wide. Female didelphic, amphidelphic ovaries reflexed with spermatheca containing many small sperm. Vulval plates distinct, vulval papillae absent. Caudal glands three, leading to a terminal opening. Tail cylindroid tapering to a bluntly rounded terminus fitted with a terminal seta. Male with many well-developed equidistant supllements, accessory pieces long with bufurcated distal ends. Spicule long and slender. Tail cylindroid tapering abruptly midway to a terminal spinneret. Tail terminus provided with a small seta. (ref. ID; 5938)

    Examined materials

  • Holotype (female): L=5.6 mm, a=47, b=4.0, c=13.2, V=53, buccal cavity 74x38 µm, tail length 420 µm; collection No.6552, type slide No.236 deposited in the CNCN Ottawa, Ontario, Canada. Collected by Environment Canada from mud. (ref. ID; 5938)
  • Allotype (male): L=5.0 mm, a=40, b=4.2, c=20.5, buccal cavity 78x40 µm, spicule length 160 µm, tail length 230 µm, supplements 39; collection No.6552, type slide No.236a deposited in CNCN Ottawa, Canada. Same data as holotype. (ref. ID; 5938)
  • Paratypes: Eight females and 10 males deposited in CNCN Ottawa, Ontario, Canada. Collection Nos.6552, 6799, and 6702. (ref. ID; 5938)

    Measurements

  • Female: L=5.3(5.0-5.6) mm, a=44-47, b=3.8-4.5, c=13.0-13.2, V=51-53, buccal cavity 72-80x33-40 µm, tail length 410(400-420) µm (n=8). (ref. ID; 5938)
  • Male: L=5.2(4.5-6.0) mm, a=43.2(39-46), b=4.2(4.0-4.6), c=20.9(19.5-24.0), buccal cavity 70-80x24-40 µm, spicule length 170(160-180) µm, tail length 235(225-240) µm, accessory piece 55 µm, amphid width 6-7 µm, cuticule at midbody 10-11 µm, supplements 36-40 (plus 7-9 vestigial) (n=15). (ref. ID; 5938)

    Mononchus tajmiris Gagarin, 1991 (ref. ID; 7909 original paper)

    Diagnosis

    This species is closest to Mononchus angarensis Gagarin, 1984. Differs from it in having a smaller body size (in females of M. angarensis L=5.09-5.30 mm), larger stoma (in M. angarensis, the stoma measures 81-86x36-40 µm), more supplements in males (in males of M. angarensis, 37-39 supplements), and a more evenly proportioned tail. (ref. ID; 7909)

    Descriptions

    Rather large nematodes. Body long, well proportioned. Cuticle smooth, its thickness in the region of the stoma 8-10 µm. Lips distinct from one anoher, deep; labial papillae distinctly pronounced. Stoma wide, measures 105-123x45-56 µm, buccal index 2.0-2.7. Tip of dorsal onchium situated 16-27 percent of the stoma length from its anterior margin. Openings of the amphids are narrow, 5-8 µm wide, localized at the level of the tip of the dorsal onchium. Esophagus muscular, not constricted, with a strongly cuticularized inner lumen. Its mean length in females in 1148 µm and 1075 µm in males. Bulbs are absent. Nerve ring encircles 25-30 percent of the length of the esophagus. Females are didelphic, ovaries are reflexed. The lips of the vulva bear cuticularized bodies. The vagina takes up more than half the diameter of the body. In the uterus, there are usually 1-3 eggs measuring 180-210x140-170 µm. Males are armed with 41-47 tubular supplements. Spicules slender, long, measuring 285-300 µm, pointed at the tip. Lengtht of accessory piece (gubernaculum) 90-110 µm. Rectum with well-developed rectal glands. Tail weakly tapered, almost cylindrical; its end bears two papillae. Mean length of tail in females 253 µm, in males 211 µm. Caudal glands well developed, ducts of glands at exit expanded in the form of an ampulla. (ref. ID; 7909)

    Examined materials

    5 (male, male), 4 (female, female), 12 juveniles from Lake Taimyr (depth 10-17 m, ground-mud) 24.VIII.1988.
  • Holotype (female) (preparation "Taimyr-30"), L=4130 µm, a=17.88, b=3.53, c=16.20, c'=2.36, V=56.66 percent. (ref. ID; 7909)
  • Allotype (male) (preparation "Taimyr-35"), L=3630 µm, a=19.31, b=3.36, c=17.29, c'=1.87, spic.- 312, suppl.- 41. (ref. ID; 7909)
  • Paratypes: 4 (female, female), L=3240-4410(3868) µm, a=17.04-17.99(17.57), b=3.22-3.41(3.36), c=13.0-19.60(15.43), V=54.92-60.14(59.60) percent, c'=1.92-2.46(2.27); 3 (male, male), L=3443-4226(3791) µm, a=17.80-20.87(19.28), b=3.36-3.89(3.55), c=15.79-19.81(18.00), c'=1.73-2.01(1.86), spic.- 285-300, suppl.- 41-47. (ref. ID; 7909)

    Type specimens

    Type specimens are deposited in the collection of the Laboratory of Biology and Systematics of Aquatic Organisms of the USSR Academy of Sciences Institute of Inland Waters Biology (Borok village). (ref. ID; 7909)

    Mononchus truncatus Bastian, 1865 (ref. ID; 5938, 7909) reported year? (ref. ID; 1795)

    Measurements

    Female: L=1.4-2.4 mm, c=7.8(7.2-8.7), V=53(52-55), buccal cavity 25-43x12-18 µm, tail length 160-250 µm (n=10). (ref. ID; 5938)