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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Coomansus

Coomansus Jairajpuri & Kahn, 1977 (ref. ID; 5938)

Family Mononchidae (ref. ID; 5938)

ref. ID; 5938

Definition

Lips and labial papillae well developed. Buccal cavity barrel shaped. Dorsal tooth located in anterior half of cavity, apex directed anteriorly. Buccal cavity without ventral ridge. Esophagonintestinal junction nontuberculate. Female didelphic, ovaries reflexed. Males described for about half known species. Tails of both sexes similar, conoid and ventrally arcuate. Caudal glands and terminal duct absent. (ref. ID; 5938)

Type species

Coomansus parvus (de Man, 1880) Jairajpuri & Kahn, 1977 (ref. ID; 5938)

Nominal species

11. (ref. ID; 5938)
  1. Coomansus campbelli (Allgen, 1929) (ref. ID; 5938)
  2. Coomansus fletcherensis Mulvey, 1978 (ref. ID; 5938 original paper)
  3. Coomansus gerlachei (de Man, 1904) Jairajpuri, 1970 (ref. ID; 5938)
  4. Coomansus parvus (de Man, 1880) Jairajpuri & Kahn, 1977 (ref. ID; 5938)

Coomansus fletcherensis Mulvey, 1978 (ref. ID; 5938 original paper)

Differential dignosis

Coomansus fletcherensis n. sp. is closest to C. campbelli (Allgen, 1929) but differs significantly in buccal cavity size (70-76x39-43 vs. 47-55x27-31 µm for C. campbelli) and in length and shape of the female tail (c=22-25 vs. 10-14 for C. campbelli, and c=23-29 vs. 17-21 µm for the male of C. campbelli). The male of C. campbelli as described by Clark (1963) has 10 or 11 supplements while that of C. fletcherensis n. sp. has 18-20 plus 10 or more vestigial supplements. (ref. ID; 5938)

Descriptions

Dorsal tooth large, apex 68-71% from base of cavity. Walls of cavity thick without ventral ridge opposite dorsal tooth. Amphid aperture obscure. Female didelphic, amphidelphic, reproductive tract with a spermatheca containing sperm and a well-developed sphincter muscle between the uterus and oviduct. Ovaries reflexed, vulval plates distinct, vulval papillae absent. Male with fairly long spicules and accessory pieces with bifurcated distal tips. Supplements many, small. Rectal and ejaculatory glands present. Tails of both sexes conoid, ventrally arcuate to acutely rounded terminii. (ref. ID; 5938)

Examined material

  • Female (holotype): L=3.4 mm; a=34; b=3.8; c=23; V=59; buccal cavity 73x38 µm; tail length 145 µm; egg 160x90 µm; collection No.7005, type slide No.237 deposited in the Canadian National Collection of Nematodes (CNCN) Ottawa, Ontario, Canada. Collected by members of the Freshwater Institute, Environment Canada, from Lake Bottom mud of Stanwell Fletcher Lake Somerset Island, N.W.T. (ref. ID; 5938)
  • Male (allotype): L=3.2 mm; a=40; b=3.6; c=26; buccal cavity 70x29 µm; tail length 125 µm; spicule length 125 µm; supplements 18+10; collection No.7005, type slide No.237a deposited in the CNCN Ottawa, Canada. Same habitat and locality as holotype. (ref. ID; 5938)
  • Paratypes: Five females and 12 males all deposited in the CNCN Ottawa, Canada. Same data as holotype. (ref. ID; 5938)

    Measurements

  • Female: L=3.5(3.4-3.6) mm; a=32(31-37); b=3.9(3.8-4.1); c=24(22-25); V=57-60; buccal cavity 70-75x39-43 µm; tail length 148(140-160) µm; eggs 150-175x70-100 µm (n=5). (ref. ID; 5938)
  • Male: L=3.3(3.0-3.5) mm; a=37(33-40); b=3.7(3.3-3.9); c=26(23-29); buccal cavity 70-76x39-45 µm; tail length 125(115-140) µm; spicule length 120(115-130) µm; supplements 18-20 (plus 10 or more vestigial) (n=6). (ref. ID; 5938)

    Coomansus gerlachei (de Man, 1904) Jairajpuri, 1970 (ref. ID; 5938)

    Descriptions

    Buccal cavity with thick walls, dorsal tooth apex 82% from base of cavity. Spicules bulky with indented distal ends. Accessory pieces long (38 µm) with bifurcated distal ends. Supplements large with echinulate tips. (ref. ID; 5938)

    Remarks

    This is the first record of this species from Canada. I have examined may males and females of C. gerlachei from the Antarctic and find very little morphological difference between these and the male specimen from the Canadian Arctic. de Man (1904) shows three longitudinal grooves in the walls of the buccal cavity of this C. gerlachei and one of these appears to be a ventral ridge. Examination of Antarctic specimens indicates that this structure is not a ridge such as that found in Clarkus papillatus and other species in that genus. (ref. ID; 5938)

    Measurements

    Male: L=3.3 mm; a=40; b=5.5; c=26; buccal cavity 40x22 µm; tail length 125 µm; spicule length 150 µm; supplements 8+1 (n=1). (ref. ID; 5938)