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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Neomesomermis

Neomesomermis Nickle, 1972 (ref. ID; 1770)

Family Mermithidae (ref. ID; 1770)

ref. ID; 1770

Diagnosis

Head slightly set off from body, mouth opening terminal. Cephalic papillae six, amphids large, opening located posterior to level of cephalic papillae. Vagina barrel shaped, vulval flap absent, eggs medium sized. Tail terminus bluntly rounded. Male with two medium-sized spicules with or without protuberances on tips. Genital papillae many and large. Tail terminus bluntly rounded. (ref. ID; 1770)

Notes

Nickle (1972) set up this new genus to accommodate species with large amphids, two spicules, barrel-shaped vagina in female, and blunt tail tips in both sexes. He designated Mesomermis flumenalis Welch, 1962 as the type species of his new genus and placed Mesomermis Daday, 1911 in genus inquirendae since the type species Mesomermis zschokkei Daday, 1911 (designated by Chitwood in 1935) was inadequately described. (ref. ID; 1770)

Type species

Neomesomermis flumenalis (Welch, 1962) Nickle, 1972 (ref. ID; 1770)
  1. Neomesomermis flumenalis (Welch, 1962) Nickle, 1972 (ref. ID; 1770)
  2. Neomesomermis leptoderos Mulvey & Nickle, 1978 (ref. ID; 1770 original paper)
  3. Neomesomermis welchi Mulvey & Nickle, 1978 (ref. ID; 1770 original paper)
  4. Neomesomermis yukonensis Mulvey & Nickle, 1978 (ref. ID; 1770 original paper)

Neomesomermis flumenalis (Welch, 1962) Nickle, 1972 (ref. ID; 1770)

Descriptions

Parasitic in insects; described by Welch (1962) from the haemocoele of black fly (Simulium venustum Say) from Number Ten Creek, Hastings County, Ontario, and redescribed by Ebsary and Bennett (1974) from the A valon Peninsula, Newfoundland. (ref. ID; 1770)
  • Male: Head rounded slightly set off from body, mouth terminal. Amphids posterior to level of cephalic papillae, pouch very wide with thick walls. Cephalic papillae six, distinct. Spicule head not flared, shaft of uniform thickness, walls fairly thin, tip of spicule bluntly rounded with several small terminal protuberances. Genital papillae evenly spaced with long inner ducts. Tail uniformly conoid to rounded terminus. Cuticle very thick. Postparasitic male juvenile in final molt does not have a caudal appendage. The spear is well developed and the tips of the spicules are provided with several small protuberances. The amphid aperture is very wide. (ref. ID; 1770)
  • Female: Not found. (ref. ID; 1770)

    Notes

    Welch (1962) in his description of N. flumenalis did not indicate the presence or absence of protuberances on the tips of the spicules. Ebsary and Bennett (1974) remarked that their male specimens of N. flumenalis had spicules with rounded tips bordered by small spines. The presence or absence of caudal appendages in the postparasitic male juveniles was not mentioned by either Welch or Ebsary. (ref. ID; 1770)

    Measurements

    Male (n=1): Body length 10 mm; body width 92 µm; head width 60 µm; amphid aperture 28 µm; amphid pouch 15x22 µm; spicule length 190 µm; spicule head width 10 µm; spicule midshaft width 10um; tail length 210 µm; cuticle width at midbody 18 µm. (ref. ID; 1770)

    Neomesomermis leptoderos Mulvey & Nickle, 1978 (ref. ID; 1770 original paper)

    Diagnosis

    N. leptoderos n. sp. differs from N. flumenalis in spicule tip shape and absence of terminal protuberances and in size of genital papillae and inner ducts; from N. welchil n. sp. and N. yukonensis n. sp. in tail shape and spicule structures. (ref. ID; 1770)

    Descriptions

  • Male: Head rounded, slightly set off from body. Amphids large, well posterior to level of cephalic papillae, walls of pouch thick. Spicule head flared, shaft of uniform thickness to acutely pointed spicule tips. Genital papillae unevenly and widely spaced with short inner ducts. Tail long, uniformly conoid to acutely rounded terminus. Cuticle relatively thin. (ref. ID; 1770)
  • Female: Not found. (ref. ID; 1770)

    Measurements

    Male: Body length 8.0 mm; body width 70 µm; head width 46 µm; amphid aperture 20 µm; amphid pouch 14x21 µm; spicule length 200 µm; spicule head width 11 µm; spicule shaft width 9 µm; tail length 190 µm; cuticle width at midbody 8 µm. (ref. ID; 1770)

    Neomesomermis welchi Mulvey & Nickle, 1978 (ref. ID; 1770 original paper)

    Diagnosis

    N. welchi n. sp. differs from N. flumenalis in spicule tip shape and absence of terminal protuberances, and in size of genital papillae and inner ducts; from N. leptoderos n. sp. in tail shape, arrangement, and size of genital papillae and inner ducts and in shape of spicules which are pointed for N. leptoderos and acutely rounded for N. welchi. (ref. ID; 1770)

    Descriptions

  • Male: Head rounded, not set off from body. Mouth terminal, amphids large with many sensillae located slightly posterior to the cephalic papillae. Spicules with expanded distal ends, shaft of uniform thickness with slightly flared spicule head. Genital papillae evenly spaced with short inner ducts. Tail ventrally arcuate to bluntly rounded terminus. Cuticle very thin. (ref. ID; 1770)
  • Female: Head rounded distinctly set off from body, mouth opening terminal. Amphids large located posterior to level of cephalic papillae. Vulva lips slightly elevated, without vulva flap. Vagina barrel shaped. Tail bluntly rounded. (ref. ID; 1770)

    Measurements

  • Male: Body length 7.1(4.6-9.0) mm; body width 116(95-130) µm; head width 45(40-50) µm; amphid aperture 10 µm; amphid pouch 10-16x20-22 µm; spicule length 131(100-150) µm; spicule midshaft width 6 µm; tail length 170(130-210) µm; cuticle width at midbody 4-5 µm. (ref. ID; 1770)
  • Female: Body length 5.0 mm; midbody width 42 µm; head width 28 µm; amphid aperture width 9 µm; cuticle width at neck 7 µm and at midbody 3-4 µm. (ref. ID; 1770)

    Neomesomermis yukonensis Mulvey & Nickle, 1978 (ref. ID; 1770 original paper)

    Diagnosis

    N. yukonensis n. sp. differs from N. flumenalis in shape of spicule tips and absence of terminal protuberances; from N. leptoderos n. sp. in tail shape, arrangement of genital papillae, and spicule head and tip; from N. welchi n. sp. in size of genital papillae, spicule length, and shape of tip. (ref. ID; 1770)

    Descriptions

  • Male: Head not set off from body, mouth terminal, amphid aperture located slightly posterior to level of cephalic papillae. Walls of amphid pouch thick. Spicule shaft of uniform thickness with thick walls. Spicule tips with small indentations. Genital papillae evenly spaced with short inner ducts. Tail ventrally arcuate to bluntly rounded terminus. Cuticle fairly thick. (ref. ID; 1770)
  • Female: Not found. (ref. ID; 1770)

    Measurements

    Holotype (male): Body length 11.0 mm; body width 105 µm; head width 40 µm; amphid pouch 5x10 µm; spicule length 210 µm; spicule midshaft width 10 µm; tail length 190 µm; cuticle width at midbody 11 µm. (ref. ID; 1770)