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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Mylonchulus

Mylonchulus Cobb (ref. ID; ?) or (Cobb, 1916) Altherr, 1953 (ref. ID; 5938)

Family Mononchidae (ref. ID; 5938, 6168, 6740)

Family Mylonchulidae (ref. ID; 6182)

ref. ID; 1663

Stoma with transverse rows of denticles opposite dorsal tooth. Dorsal tooth anteriorly placed in stoma. (ref. ID; 1663)

ref. ID; 1923

Numerous subventral denticles present. (ref. ID; 1923)

ref. ID; 5938

Definition

Buccal cavity goblet shaped, dorsal tooth generally large anterior in cavity. Subventral teeth two, small to large and opposite the base of the dorsal tooth. Denticles in several transverse rows on two subventral sectors of the buccal cavity, forming rasplike areas. Esophagointestinal junction nontuberculate. Females didelphic or monodelphic, ovaries or ovary reflexed. Tails of both sexes similar, short and irregular or broadly rounded. Caudal glands and terminal or subterminal duct present in most species. Males described for many species, either rare or numerous. Spicules short, with or without lateral accessory pieces. (ref. ID; 5938)

Type species

Mylonchulus minor (Cobb, 1893) Andrassy, 1958 (ref. ID; 5938)

Nominal species

36. (ref. ID; 5938)

ref. ID; 6859

Predator. (ref. ID; 6859)
  1. Mylonchulus arenicolus Clark, 1961 (ref. ID; 1311)
  2. Mylonchulus lacustris (Cobb, N.A., in Cobb, M.V., 1915) Andrassy, 1958 (ref. ID; 5938)
  3. Mylonchulus minor (Cobb, 1893) Andrassy, 1958 (ref. ID; 5938)
  4. Mylonchulus montanus (Thorne) (ref. ID; 5938)

Mylonchulus arenicolus Clark, 1961 (ref. ID; 1311)

Descriptions

Body after fixation either coiled ventrad or strongly curved ventrad. Cuticle smooth, with a more or less uniform thickness for most part except around tail where it becomes slightly thicker. Lips distinct, lip region almost continuous with remainder of the body, with six clearly distinct anterior papillae followed by ten barely detectable ones. Amphidial fovea stirrup-shaped but difficult to see in most specimens, situated opposite the tip of the dorsal tooth. Stoma heavily sclerotized, wide anteriorly with the widest part being at three-fifth lip region widths, narrowing posteriorly. Stoma with a strongly developed dorsal tooth. Dorsal tooth-tip is situated around a quarter of the stoma length from the anterior end of the stoma. Stoma length around 1.7 times stoma width. Ventrosublateral walls of stoma each bear six rows of denticles and a small tooth. The first row of denticles is at the level of the tip of dorsal tooth, the last being just anterior to the subventral teeth. Posterior portion of stoma bears fine transverse striae. Anterior end of the cylindrical and muscular pharynx surrounds almost the posterior one-third of the stoma. Nerve ring encircles pharynx at around one-third pharynx length from the anterior end. Excretory pore at less than one-half body width posterior to the nerve ring, cell bodies 76-96 µm posterior to excretory pore. Cardia short and conoid, with a wider anterior part and a transparent more or less funnel-shaped posterior part. Intestine with wide lumen, its cells filled with brown granules. Microvilli well developed. Rectum around 0.8 times anal body width. Tail conoid, ventrally curved, and with well developed caudal glands usually arranged in tandem. Spinneret tubular and terminal in position. A pair of subventral caudal papillae around 14 µm anterior to tail tip. Female reproductive system didelphic, amphidelphic with reflexed ovaries. Anterior ovary situated to the left of the intestine, posterior ovary to the right side of the intestine. Oviduct separated from the uterus by a sphincter. Vagina thick walled, reaching one-third of the corresponding body width. Vulva with refractive lips, very posterior to middle of body. (ref. ID; 1311)
  • Egg: Egg size 119x66 µm. (ref. ID; 1311)
  • Male: Males not found. (ref. ID; 1311)

    Measurements

    Body length 1535.3(1364, 1566, 1676) µm, maximum body width 57.8(54, 59, 62) µm, pharyngeal length measured from the anterior end 466.3(418, 462, 519) µm, tail length 61.3(54, 60, 71) µm, anal body width 39.7(35, 40, 44) µm, lip region width 31.0(30, 31, 32) µm, stoma length 33.0(29, 34, 36) µm, stoma width 18.9(18, 20, 20) µm, nerve ring from the anterior end 121.7(106, 123, 136) µm, rectal length 32.0(29, 30, 37) µm. (ref. ID; 1311)

    Mylonchulus lacustris (Cobb, N.A., in Cobb, M.V., 1915) Andrassy, 1958 (ref. ID; 5938)

    Remarks

    Mulvey and Jensen (1967) synonymized Mylonchulus montanus (Thorne) with M. lacustris. No male was found. (ref. ID; 5938)

    Measurements

    Female: L=2.1(1.9-2.4) mm, c=21(19-23), V=60-64, buccal cavity 32-34x19-20 µm, tail length 100-105 µm (n=7). (ref. ID; 5938)