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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Paraplectonema

Paraplectonema Strand, 1934 (ref. ID; 3571)

Araeolaimida De Coninck & Stekhoven, 1933: Family Leptolaimidae Orley, 1880: Subfamily Leptolaiminae Orley, 1880 (ref. ID; 3571)

Family Leptolaimidae (ref. ID; 6740)

ref. ID; 1923

Stoma elongated, collapsed, possibly 2-part in tandem; amphids unispiral; male unknown. (One species, aquatic) (ref. ID; 1923)

ref. ID; 3571

Type species

Plectus pedunculatus Hofmanner 1913, designated by Filipjev 1929 (ref. ID; 3571)
  1. Paraplectonema canadianum Hopper, 1968 (ref. ID; 3571, 7916)
  2. Paraplectonema multitubiferum (Imamura, 1931) (ref. ID; 7916), (Imamura, 1931) Loof & Jairajpuri, 1965 (ref. ID; 3571)
    Syn; Plectus multitubiferus Imamura, 1931 (ref. ID; 3571)
  3. Paraplectonema pedunculatum (Hofmanner, 1913) (ref. ID; 7916), (Hofmanner, 1913) Strand, 1934 (ref. ID; 881) or (Hofmanner, 1913) Filipjev, 1929 (ref. ID; 3571)
    Syn; Cylindrolaimus aberrans Micoletzky, 1915 (ref. ID; 3571); Plectus pedunculatus Hofmanner, 1913 (ref. ID; 3571)

Paraplectonema multitubiferum (Imamura, 1931) (ref. ID; 7916), (Imamura, 1931) Loof & Jairajpuri, 1965 (ref. ID; 3571)

Synonym

Plectus multitubiferus Imamura, 1931 (ref. ID; 3571)

Descriptions

Body diameter at the level of the stoma 10-11, at middle of body 27-28.2 (at vulva 34-39), anus. 17-26. Cuticle annulated, lateral field two-lined. Cephalic setae are small. Amphids are single-spiral, slightly produced transversely. In males, they are larger (5.2-5.7) than in females (4-4.5). Esophagus is cylindrical, only at the base slightly thickened, its length 132-142 µm. The cardiac-intestinal region is equal to the transverse section of the esophagus at the base. Renette gland is pyriform, its base (10-12x5-6) is at the level of the cardia. The pore of the renette gland is at the level of the nerve ring. The distance from the cephalic end to the micro-onchium 20-24 µm, to the nerve ring 78-84 µm, excretory pore 92-106 µm, vulva 491-506 µm. Testis is to the left of the intestine, its length 200-215 µm. Spicules with heads, are narrow, arched, 31-32 µm in length. Gubernaculum with dorsal apophyses (10-13). Supplements consist of two arched segments: the end, as a rule, protrudes outwardly. The length of the supplements is from 16 to 21 (anterior ones are smaller). The supplemental field extends 172-193 µm. The characteristic feature of the species is the spiral shape twist of the tail. The female reproductive system is didelphic, amphidelphic. Length of the anterior ovary 105-110 µm, posterior 94-106 µm. Reproductive tubules are of equal length, 232-243 µm. Eggs 58-62x26-34 µm. Vulva transverse. Hindgut 24-29 µm. Tail is bifurcated, its anterior part is conical, posterior is cylindrical with a small swelling apically. Length of tail in males is 110-127 µm, in females 157-173 µm, that is, 5-6 and 6-9 times greater than the anal diameter, respectively. In males, there is a pair of subventral and one dorsal setae on the tail. (ref. ID; 7916)

Remarks

In addition to the described species, the genus Paraplectonema contains two additional species: P. pedunculatum (Hofmanner, 1913) and P. canadianum Hopper, 1933. All species are diagnosed with difficulty because there is no description of the male of P. pedunculatum. We included this species with the male characters (from southern Caspian, material of A.V. Chesunov) in the key. (ref. ID; 7916)

Examined materials

Sixteen males, 15 females, 9 larvae. Southwestern part of Lake Khanka, mouth of the Mel'gunovka River; depth around 1 m, muddy sand, July-August 1987. (ref. ID; 7916)

Type specimens

The specimens are deposited in the Department of Zoology of the Far East University. (ref. ID; 7916)

Measurements

  • Male: Body length 910-1120 µm, a=34-39, b=6-8, c=7-9. (ref. ID; 7916)
  • Female: Body length=994-1086 µm, a=27-31, b=6.6-7.1, c=6-7, V=46.5-49.1 percent. (ref. ID; 7916)