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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Helicotylenchus

Helicotylenchus Steiner, 1945 (ref. ID; 6575, 7197)

Order Tylenchida (ref. ID; 6180)

Suborder Tylenchina: Family Hoplolaimidae (ref. ID; 3547)

Family Hoplolaimidae (ref. ID; 5933, 6182, 6740, 7197)

Rotylenchoidinae (ref. ID; 7634, 7639, 7646)

ref. ID; 1923

Dorsal esophageal gland orifice 1/3 or more stylet length posterior to base of stylet. (A small genus, about 3 species, primarily terrestrial) (ref. ID; 1923)

ref. ID; 6153

Herbivore. (ref. ID; 6153)

ref. ID; 6155, 6691, 6859

Plant parasite. (ref. ID; 6155, 6691, 6859)
  1. Helicotylenchus abunaamai Siddiqi, 1972 (ref. ID; 7197)
  2. Helicotylenchus aerolatus Van den Berg & Heyns, 1975 (ref. ID; 7197)
  3. Helicotylenchus agricola Elmiligy, 1970 (ref. ID; 7197)
  4. Helicotylenchus amplius Anderson & Eveleigh, 1982 (ref. ID; 6575 original paper)
  5. Helicotylenchus anhelicus (ref. ID; 6575)
  6. Helicotylenchus aquili Khan & Nanjappa, 1972 (ref. ID; 7197)
  7. Helicotylenchus arachisi Mulk & Jairajpuri, 1975 (ref. ID; 7197)
  8. Helicotylenchus astriatus Khan & Nanjappa, 1972 (ref. ID; 7197)
  9. Helicotylenchus bambesae Elmiligy, 1970 (ref. ID; 7197)
  10. Helicotylenchus bihari Mulk & Jairajpuri, 1975 (ref. ID; 7197)
  11. Helicotylenchus caipora Monteiro & de Mendonca, 1972 (ref. ID; 7197)
  12. Helicotylenchus californicus Sher, 1966 (ref. ID; 5933)
  13. Helicotylenchus canadensis (ref. ID; 6575)
  14. Helicotylenchus caribensis (ref. ID; 7639)
  15. Helicotylenchus coomansi Ali & Loof, 1975 (ref. ID; 7197)
  16. Helicotylenchus cornurus Anderson, 1975 (ref. ID; 7197) reported author and year? (ref. ID; 6575)
  17. Helicotylenchus craigi Knobloch & Laughlin, 1973 (ref. ID; 7197)
  18. Helicotylenchus crassatus Anderson, 1974 (ref. ID; 7197) reported author and year? (ref. ID; 6575)
  19. Helicotylenchus delhiensis Khan & Nanjappa, 1972 (ref. ID; 7197)
  20. Helicotylenchus digonicus (ref. ID; 6575)
  21. Helicotylenchus dihystera (ref. ID; 6575)
  22. Helicotylenchus elegans Roman, 1965 (ref. ID; 7639) reported year? (ref. ID; 7646)
  23. Helicotylenchus erythrinae (Zimmermann, 1904) Golden, 1956 (ref. ID; 5933)
  24. Helicotylenchus gramiophilus Fotedar & Mahajan, 1973 (ref. ID; 7197)
  25. Helicotylenchus girus Saha, Chawla & Khan, 1974 (ref. ID; 7197)
  26. Helicotylenchus haki Fotedar & Mahajan, 1973 (ref. ID; 7197)
  27. Helicotylenchus hoplocaudus Manjredar, 1972 (ref. ID; 7197)
  28. Helicotylenchus hydrophilus Sher, 1966 (ref. ID; 6575)
  29. Helicotylenchus identicaudatus Mulk & Jairajpuri, 1975 (ref. ID; 7197)
  30. Helicotylenchus impar Prasad, Khan & Chawla, 1965 (ref. ID; 7197)
  31. Helicotylenchus imperialis Rashid & Khan, 1974 (ref. ID; 7197)
  32. Helicotylenchus jammuensis Fotedar & Mahajan, 1973 (ref. ID; 7197)
  33. Helicotylenchus krugeri Van den Berg & Heyns, 1975 (ref. ID; 7197)
  34. Helicotylenchus leiocephalus (ref. ID; 6575)
  35. Helicotylenchus macronatus Mulk & Jairajpuri, 1975 (ref. ID; 7197)
  36. Helicotylenchus mangiferensis Elmiligy, 1970 (ref. ID; 7197)
  37. Helicotylenchus microlobus (ref. ID; 7639)
  38. Helicotylenchus mucronatus Siddiqi, 1963 (ref. ID; 7197)
  39. Helicotylenchus multicinctus (ref. ID; 7639)
  40. Helicotylenchus nannus (ref. ID; 7639)
  41. Helicotylenchus orientalis (Siddiqi & Husain, 1964) Geraert, 1976 (ref. ID; 7197)
    Syn; Rotylenchus orientalis Siddiqi & Husain, 1964 (ref. ID; 7197)
  42. Helicotylenchus oscephalus Anderson, 1979 (ref. ID; 7197 original paper) reported author and year? (ref. ID; 6575)
  43. Helicotylenchus paracanalis Sauer & Winoto, 1975 (ref. ID; 7197)
  44. Helicotylenchus paraconcavus Rashid & Khan, 1974 (ref. ID; 7197)
  45. Helicotylenchus paragirus Saha, Chawla & Khan, 1974 (ref. ID; 7197)
  46. Helicotylenchus pasohi Sauer & Winoto, 1975 (ref. ID; 7197)
  47. Helicotylenchus persici Saxena, Chhabra & Joshi, 1971 (ref. ID; 7197, 7634 original paper)
  48. Helicotylenchus phalerus Anderson, 1975 (ref. ID; 7197) reported author and year? (ref. ID; 6575)
  49. Helicotylenchus platyurus (ref. ID; 6575)
  50. Helicotylenchus pseudorobustus (ref. ID; 1751, 6575, 7634)
  51. Helicotylenchus punicae Swarup & Sethi, 1968 (ref. ID; 7197)
  52. Helicotylenchus regularis Phillips, 1971 (ref. ID; 7197)
  53. Helicotylenchus reynosus Razjivin in Razjivin, O'Relly & Perez Milian, 1973 (ref. ID; 7197)
  54. Helicotylenchus rohtangus Jairaijpuri & Baqri, 1973 (ref. ID; 7197)
  55. Helicotylenchus rotundicauda (ref. ID; 6575)
  56. Helicotylenchus sacchari Razjivin in Razjivin, O'Relly & Perez Milian, 1973 (ref. ID; 7197)
  57. Helicotylenchus sandersae Ali & Loof, 1975 (ref. ID; 7197)
  58. Helicotylenchus serenus Siddiqi, 1963 (ref. ID; 7634)
  59. Helicotylenchus sharafati Mulk & Jairajpuri, 1975 (ref. ID; 7197)
  60. Helicotylenchus sieversii Razjivin, 1971 (ref. ID; 7197)
  61. Helicotylenchus solani Rashid & Khan, 1974 (ref. ID; 7197)
  62. Helicotylenchus spitsbergensis (ref. ID; 6575)
  63. Helicotylenchus steineri Fotedar & Mahajan, 1973 (ref. ID; 7197)
  64. Helicotylenchus stylocercus Siddiqi and Pinochet, 1979 (ref. ID; 6575)
  65. Helicotylenchus teleductus Anderson, 1975 (ref. ID; 7197) reported author and year? (ref. ID; 6575)
  66. Helicotylenchus teres Gaur & Prasad, 1973 (ref. ID; 7197)
  67. Helicotylenchus thornei Gupta & Chhabra, 1966 (ref. ID; 7634)
  68. Helicotylenchus trivandranus Mohondas, 1976 (ref. ID; 7197)
  69. Helicotylenchus tumidicaudatus Phillips, 1971 (ref. ID; 7197)
  70. Helicotylenchus urobelus Anderson, 1977 (ref. ID; 5933 original paper, 6575) or 1978 (ref. ID; 7197)
  71. Helicotylenchus variabilis Phillips, 1971 (ref. ID; 7197)
  72. Helicotylenchus vulgaris (ref. ID; 7639)

Helicotylenchus amplius Anderson & Eveleigh, 1982 (ref. ID; 6575 original paper)

Diagnosis

Females of H. amplius appear to have more characters in common with those of the bisexual species H. hydrophilus Sher, 1966 and H. stylocercus Siddiqi and Pinochet, 1979. Helicotylenchus hydrophilus differs in having a smoothly rounded, shorter, and less robust ventral tail projection (4-7 µm in five paratypes versus mucronate and 5-11 µm), a closed versus open-ended lateral field, a more anterior dorsal esophageal gland orifice (O = 36-42 versus 43-46 in H. amplius), and a longer stylet conus (M = 45-49 versus 41-46). The characters that distinguish H. stylocercus are its larger (11-16 µm) more heavily annulated ventral tail projection, regular annules around the tail end, a more broadly rounded head, shorter stylet averaging 25 versus 28 µm, a closed-ended lateral field, and a less well developed uterus. The most similar parthenogenetic species are H. digitiformis Ivanova, 1967, H. solani Rashid, 1972, and H. microbulus Perry, in Perry, Darling and Thorne, 1959. These species differ from H. amplius in having a less pronounced ventral tail projection with an irregular or smoothly rounded tip, regular annules on the midend of tail, closed-ended lateral field, and a hemispherical, or more conoid head. (ref. ID; 6575)

Descriptions

  • Holotype (female): L=716 µm, a=24, b=5.8, b'=4.4, c=36, c'=1.3, V=61. Stylet length 28 µm, M = 41, O = 48. Body in an open spiral, annules on dorsal surface 1.9 µm wide at midbody. Lateral field narrow, 5 µm wide, a sixth of body diameter, inner incisures convergent with outers at termination on tail. Head conoid, apex rounded, sometimes slightly flattened, marked by four fine, distinct annules. Posterior cephalids minute, 15 µm posterior to head apex. Stylet knobs 5 µm in diameter, anterior surfaces indented. Metacorpus oval, subventral basal esophageal glands well separated, cylindroid, and narrow. Excretory pore 118 µm posterior to head apex, anterior to esophgointestinal valve. Hemizonid indistinct, at level of excretory pore. Ovaries outstretched, extending 193 µm, anterior, 155 µm posterior to vulva. Spermathecae spherical, axial, contents largely cytoplasmic, sperms not observed. Uterus large, occupying most of body cavity. Vulva atrium depressed deeply; cuticular lining thickened, vulva-vagina depth about half body diameter. Tail with a large, double mucronate ventral projection. Ventral surface of tail with 13 annules, midened of tail finely annulated. Phasmids at seventh annule anterior to level anus. (ref. ID; 6575)
  • Paratypes (47 females, 19 larvae; 14 adults measured): L=761(694-894) µm, a=27(23-31), b=6.0(5.0-7.2), b'=4.6(3.8-5.5), c=36(30-42), c'=1.2(0.9-1.5), V=61(59-62). Stylet length 28(27-29) µm, M = 43(41-46), O = 51(43-62). Body usually in a tight spiral when relaxed, width at midbody 28(24-33) µm; annule width 1.8-2.0 µm on dorsal surface, 1.5 µm along ventral surface. Lateral field narrow, 4.5-7.0 µm wide, seldom more than a fifth of body diameter, open ended at termination on tail with outer incisures continuous with body striae of tail. Head rounded, slightly narrower than adjoining body, with four, sometimes five fine distinct annules. Cephalids indistinct. Stylet knobs 4.0-5.5 µm in diameter, anterior surface indented. Dorsal esophageal gland duct 14(12-18) µm between stylet. Esophagus 164(146-185) µm long, 128(123-141) µm to esophagointestinal valve. Metacorpus oval, valve 91(81-108) µm posterior to head end. Excretory pore 125(113-140) µm posterior to head end, rarely posterior to esophagointestinal valve. Spermatheca axial, contents largely cytoplasmic, cavity always small, sperms not observed. Uterus large, consistently occupying most of body cavity in all specimens. Vulva-vagina depth 14-18 µm, morphological features as described for holotype. Tail 22(18-25) µm long, ventral surface with 8-14 transverse annules. Tail terminus dorsally convex, midened with a finely annulated, often elevated sector. Ventral tail projection of 40 females 8(5-11) µm long, 29-70% of total tail length, cylindroid, surface smooth or with coarse annules on ventral surface only. Tip of projection broadly rounded, mucronate in all but one adult and in all larve. Phasmids minute, centered in lateral field or ventrally offset, preanal in 60% of paratypes at 5(1-10) annules anterior to level of anus, on tail in rest of specimens and in most larvae. (ref. ID; 6575)

    Type host and habitat

    Collected from the rhizosphere of indigenous grasses at Ramsey Lake, Gatineau Park, Quebec. Additional specimens in the type series collected from grass and willow soil substrate at Deschenes, Quebec. Most specimens were collected in moist soil in close proximity to freshwater. (ref. ID; 6575)

    Type designations

    Holotype (female), type slide No.257, collection No.7591. Paratypes (Ramsey Lake), type slide Nos.257a-m, collections Nos.4863, 7591; (Deschenes), type slide Nos.257n-q, collection Nos.7516, 7620, 7645. Deposited in the Canadian National Collection of Nematodes, Ottawa, Canada. Five paratypes each deposited in the United States Department of Agriculture Nematode Collection, Beltsville, Maryland, and the Rothamsted Nematode Collection, Harpenden, Hertfordshire, England. (ref. ID; 6575)

    Helicotylenchus elegans Roman, 1965 (ref. ID; 7639) reported year? (ref. ID; 7646)

    Descriptions

    Life history (at 25 degrees C): Helicotylenchus elegans completed its life-cycle in five stage. It has been found to reproduce parthenogenetically as only the female specimens were found around the roots. The developmental stages are described and measurements related to the identification of different larval stages are given below.
  • Egg. The eggs are oval, pale and transparent. The average size (n=10) of the egg is 56.6+/-2.2 µm in length and 32.2+/-2.1 µm in width. Each egg consists of a shell on outer-side and a mass of undifferentiated granular protoplasm inside. (ref. ID; 7639)
  • First stage larva. The first stage larva was observed inside the egg 6 to 8 days after its deposition. It moulted inside the egg and emerged out of the egg-shell as the second stage larva after 3 to 4 days leaving the moulted cuticle inside the egg-shell. The head of the first stage larva was distinctly visible and the second stage larva occupied almost the entire space inside the egg before hatching. Just before hatching, the second stage larva became very active and moved its head in various directions within the egg. (ref. ID; 7639)
  • Second stage larva. The body measurements (average of 10 larvae) L=312.1+/-13.6 µm, a=20.5+/-1.8, b=3.4+/-0.5, c=58.5+/-6.2, Stylet 17.9+/-0.83 µm. The body of the larva is cylindrical, tapering both anteriorly and posteriorly. Head-region not set-off and stylet measures 17.9+/-0.83 µm in length. Oesophageal bulb overlappig the intestine ventrally, orifice of dorsal oesophageal gland about 6 to 8 µm behind the spear-knobs. Nerve ring surrounds the isthmus and excretory pore just below the level of nerve ring. The genital primordium could not be seen. Tail convex-conoid and digitate. Cuticle striated. The total duration of the second stage larva was 8 to 10 days. At the time of moulting shedding of the cuticle started from the head and progressed towards tail. (ref. ID; 7639)
  • Third stage larva. It is similar to the second stage, but comparatively longer. Body measurements (average of 10) L=384.7+/-11.8 µm, a=22.6+/-1.7, b=3.5+/-0.73, c=63.2+/-1.8, Stylet 20.0+/-0.9 µm. The stylet of the third stage larva is more prominent and body increases in length. The genital primordium is distinct in the centre of the body, lying in the body cavity. The vulva could not be observed. This stage lasted for 6 to 7 days only. It moulted just like the second stage larva. (ref. ID; 7639)
  • Fourth stage larva. The body measurements (average of 10 larvae) L=449.7+/-12.7 µm, a=26.1+/-2.1, b=4.4+/-0.7, c=62.1+/-3.6, V=54.7+/-3.2, Stylet 20.7+/-0.95 µm. In this stage the body length increases considerably and the style is more prominent measuring 20.7+/-0.95 µm in length. The striations on the cuticle are prominent. Lateral fields are marked by four incisures. The gonads increase considerably in size on both sides. The vulva is visible. This stage lasted for 3 to 5 days. In this stage also the moulting occurs on the plane observed in the previous stages. (ref. ID; 7639)
  • Adult stage. This stage appeared 26 to 34 days after the egg was laid. Measurements of the adult (average of 10) L=607.1+/-23.1 µm, a=26.3+/-2.7, b=5.0+/-0.74, c=71.5+/-5.5, V=62.3+/-2.9, Stylet 23.3+/-0.9 µm. The body and stylet increase in length in the final stage. The opening of dorsal oesophageal gland is about 8 to 10 µm behind the base of spear-knobs. The gonads also increase in size. Vulva is prominent and in the form of a depressed transverse slit. The tail is convex-conoid, digitate and marked with 9 to 10 annules. The adult stage may be differentiated from the fourth larval stage on the basis of body length, stylet length and the development of reproductive organs. (ref. ID; 7639)

    Helicotylenchus oscephalus Anderson, 1979 (ref. ID; 7197 original paper) reported author and year? (ref. ID; 6575)

    Diagnosis

    Helicotylenchus oscephalus n. sp. is distinctive by its broadly rounded (hemispherical) head and heavy sclerotization of the head skeleton with a deeply depressed septum. It is most similar to H. rohtangus Jairajpuri & Baqri, 1973, also from a high altitude, from which it is readily separated by length of the stylet (32-34 vs. 25-28 µm in H. oscephalus). Helicotylenchus oscephalus differs from the closely related H. platyurus Perry, in Perry, Thorne and Darling, 1959 and H. paraplatyurus Siddiqi, 1972 by head shapes (hemispherical vs. conoid), number of head annules (six to eight vs. four or five), positions of the hemizonid (three to six vs. zero to two annules anterior to the excretory pore), and in values of (21-33 vs. 33-48 for H. platyurus and H. paraplatyurus). (ref. ID; 7197)

    Descriptions

  • Holotype (female): L=842 µm, a=30, b=5.8, b'=4.9, c=29, c'=1.5, V=59. Stylet length 27 µm, M=49, O=32. Head broadly hemispherical, bearing six fine transverse annules. Head skeleton strongly sclerotized with markedly depressed septum. Stylet knobs with concave anterior surfaces. Cephalids 9 and 18 µm posterior to head apex. Lateral field 7 µm wide, incisures uniformly spaced. Excretory pore 135 µm posterior to head apex, hemizonid distinct, four body annules anterior to excretory pore. Ovaries extending 217 µm anterior and 211 µm posterior to vulva. Spermatheca set off dorsally, without sperms 59 µm anterior and 57 µm posterior to vulva. Tail 29 µm long, terminus broadly rounded, with regular annules. Ventral surface of tail to middle of terminus marked by 21 annules. Phasmid centered, at six and nine body annules anterior to level of anus. (ref. ID; 7197)
  • Paratypes (12 females): L=857(782-927) µm, a=32(28-35), b=6.2(5.7-6.6), b'=5.1(4.6-5.5), c=33(27-39), c'=1.3(1.1-1.7), V=61(58-63). Stylet length 27(25-28) µm, M=48(45-53), O=28(21-33). Body typically in a tight spiral when relaxed, width 25-28 µm at midbody, annules mostly 1.4-1.9 µm wide. Lateral field 7(6-9) µm wide. Head broadly hemispherical, marked by six to eight fine, distinct annules, equal in size to those along side of basal ring. Head skeleton strongly sclerotized, septum deeply depressed. Cephalids 8-10 and 17-18 µm posterior to head apex. Stylet knobs with concave or indented anterior surfaces. Dorsal gland orifice 6-9 µm posterior to stylet. Esophagus 169(156-185) µm long, 139(128-153) µm to esophagointestinal valve. One subventral esophageal gland always free, the other contiguous with the dorsal gland. Excretory pore 135(127-143) µm posterior from head apex, located usually no more than 5 µm anterior to level of esophagointestinal valve, rarely slightly posterior. Hemizonid distinct, at three to six body anules anterior to excretory pore. Anterior ovary extending to 240(216-257) µm, 26-31% of body length; posterior ovary extending to 232(192-303) µm, 22-35% of body length. Spermatheca markedly set off dorsally, without sperms, located at 55(33-64) µm anterior and 53(44-59) µm posterior to vulva. Tail 26(21-29) µm long, dorsally convex-conoid, terminus broadly rounded, bearing annules as large or larger than other tail annules. Ventral surface of tail to middle of terminus marked by 20 (13-24) annules. Outer incisures closed at termination on tail, inner incisures convergent or sometimes fused for short distance. Phasmid centered, 9(3-14) annules anterior to level of anus. (ref. ID; 7197)
  • Male: Male unknown. (ref. ID; 7197)

    Type locality

    Collected in soil from mixed shrub cover on southeast slope of Siver Star Mountain, British Columbia, at an elevation of 1524 m. (ref. ID; 7197)

    Type designations

  • Holotype (female): Type slide No.400, collection No.4983. (ref. ID; 7197)
  • Paratypes (12 females): Type slide Nos.400a-400f, collection No.4983. Deposited in Canadian National Collection of Nematodes, Ottawa. Three female paratypes deposited in United States Department of Agriculture Nematode Collection, Beltsville, Maryland. (ref. ID; 7197)

    Helicotylenchus persici Saxena, Chhabra & Joshi, 1971 (ref. ID; 7197, 7634 original paper)

    Diagnosis and relationship

    Helicotylenchus persici n. sp. comes close to H. serenus Siddiqi, 1963 and H. thornei Gupta and Chhabra, 1966. It differs from H. serenus by a smaller spear and body, posteriorly located phasmid and from H. thornei in the shape of the lip region and a longer tail with a short unstriated process on the ventral side. (ref. ID; 7634)

    Descriptions

  • Female: Body cylindrical, forming a single spiral when relaxed in hot water tapering towards both the ends. Cuticle coarsely annulated with striae averaging 1.5 µm apart on the mid-body. Lateral fields marked by four incisures, about 1/3rd as wide as the body. Deirids not visible. Phasmids pore-like, located at the anal latitude. Lip-region hemispherical, slightly set-off from the body and marked by 4 annules (4-5 annules in the paraytypes). Labial frame-work sclerotized. Buccal spear well developed, 20 µm long with rounded basal knobs. Orifice of the dorsal oesophageal gland half of spear length behind the spear base. Oesophagus with weakly developed median bulb. Isthmus narrower than procorpus, enveloped by the nerve ring in the centre. Excretory pore slightly posterior to the nerve ring, located at 115 µm from the anterior end. Oesophageal glands lobe-like overlapping around the anterior end of intestine on its ventral side. Intestine filled with food globules. Vulva in the form of a transverse slit, vagina at right angle to the body axis. Gonads didelphic, amphidelphic, outstretched; spermathecae empty and continuous. Tail dorsally convex conoid with a short unstriated terminal process. (ref. ID; 7634)
  • Male: Not found. (ref. ID; 7634)

    Type habitat and locality

    Collected from the soil around the roots of peach tress, Prunus persica Stokes near Khanna (Punjab). (ref. ID; 7634)

    Type material

    Holotype female deposited with the Department of Zoology-Entomology, P.A.U. Ludhiana on slide No. Nem. 1 paratypes with the authors. (ref. ID; 7634)

    Measurements

  • Holotype: L=0.5 mm, a=18.5, b=8, c=21, V=60, spear 20 µm. (ref. ID; 7634)
  • Paratypes (female, n=4): L=0.5-0.7(0.59) mm, a=16-18.5(17.1), b=7.0-8.1(7.5), c=18-21(19.1), V=55-62. (ref. ID; 7634)

    Helicotylenchus urobelus Anderson, 1977 (ref. ID; 5933 original paper, 6575) or 1978 (ref. ID; 7197)

    Diagnosis

    Helicotylenchus urobelus n. sp. is most similar to H. erythrinae (Zimmermann, 1904) Golden, 1956 as based on the descriptions by Sher (1966) of topotypes and specimens from a California population he identified as H. erythrinae. Females of H. urobelus n. sp. differ from those of H. erythrinae in having a larger, more pronounced ventral tail projection and reduced, rather than regular, annules on the tail end. Other differences including number of head annules, body size, length of the stylet conus, position of the excretory pore, clarity and position of the hemizonid, and position of the phasmids are moderated by the species designated as synonyms of H. erythrinae by Sher (1966) and Siddiqi (1972). The male of H. urobelus is distinctive by its larger spicules (24-27 vs. 18-22 µm) and shape of the proximal end and by the rounded tail terminus which is not mucronate and does not extend beyond the bursa as is typical for H. erythrinae. Helicotylenchus urobelus is not as closely related to Helicotylenchus californicus Sher, 1966 as suggested by more recent keys. The former is differentiated most readily by the large conoid tail projection of females, which is comparatively short and irregularly rounded in H. californicus. Females of H. urobelus also are more openly spiral when relaxed, the posteriormost cephalids are more posterior (16-18 µm from head apex vs. less than 14 µm in H. californicus), they have a wider lateral field (less than vs. more than one-fifth of body diameter), the inner incisures are more widely spaced and the phasmids are more anterior (8-14 body annules anterior to level of anus in 77% of paratypes vs. 2-7 annules in those of H. californicus). (ref. ID; 5933)

    Descriptions

  • Holotype (female): L=673 µm, a=29, b=6.6, b'=5.2, c=27, c'=1.6, V=60. Stylet length 25 µm, M=45, O=40. Head hemispherical, bearing four annules. Stylet knobs flattened on anterior surfaces. Excretory pore 97 µm posterior from head end. Hemizonid indistinct, three annules anterior to excretory poree. Ovaries extending 152 µm anterior and 151 µm posterior to vulva. Anterior spermatheca axial, 45 µm from vulva, filled with sperms. Posterior spermatheca slightly set off dorsally, 42 µm from vulva, filled with sperms. Lateral fields 5 µm wide at midboby, inner incisures fused for about 1 µm at termination on tail. Tail with 11 annules along ventromedian surface, dorsally convex-conoid, tapering to a prominent, pointed ventral projection bearing a short mucro 1.5 µm long. Phasmids four and seven annules anterior to level of anus. (ref. ID; 5933)
  • Paratypes (13 females): L=748(669-819) µm, a=27(25-33), b=6.1(5.7-6.6), b'=4.9(4.5-5.4), c=35(30-42), c'=1.3(1.1-1.6), V=62(59-66). Stylet length 26(24-28) µm, M=44(42-47), O=36(29-42). Egg (one intrauterine)=82x21 µm. Body usually in a loose spiral when relaxed, but with more curvature in posterior half than shown in Fig. 1A. Annules at midbody 1.5(1.2-1.9) µm wide, body width 21-31 µm. Lateral fields 5.6(4.8-6.7) µm wide. Head hemispherical, usually with four and sometimes three coarse annules which are rarely finer than body annules. Cephalids observed in nine females, posterior cephalids 16-18 µm from head end. Stylet knobs with anterior surfaces flattened or slightly indented, conus (metenchium) shorter than rest of stylet. Dorsal gland orifice 7-10 µm posterior to stylet. Esophagus 154(137-174) µm long, 121(105-137) µm to esophagointestinal valve. Valvular apparatus of metacorpus small, not exceeding 3 µm in length. Esophageal glands distinctly separated into lobes of about equal length. Excretory pore 120(106-131) µm posterior from head end, located anterior to esophagointestinal valve in six specimens, at same level in three specimens and posterior in four specimens. Hemizonid one to three body annules anterior to excretory pore, generally indistinct. Anterior ovary extending to 181(156-200) µm, posterior ovary to 171(148-176) µm, to 254 µm in one specimen with intrauterine egg. Spermathecae containing sperms, usually set off dorsally, rarely axial. Anterior spermatheca 14(12-17) µm in diameter, at 53(43-74) µm from vulva. Posterior spermatheca 14(11-18) µm in diameter, at 50(44-67) µm from vulva. Vaginal walls and lining of vulval atrium uniformly thin. Tail with slight ventral curvature, dorsally convex, tapering to a prominent, pointed ventral projection 4-11 µm long, smoothly rounded projection in three specimens, bearing a mucro in seven specimens. Ventromedian surface of tail with 10(7-13) annules, annules on end of tail about half width of others. Phasmids minute, centered, 8(4-14) annules anterior to level of anus. Inner incisures often fused for short distance at termination on tail (ref. ID; 5933)
  • Allotype (male): L=670 µm, a=35, b=6.2, b'=4.9, c=31, c'=1.6, T=49. Stylet length 21 µm, M=47, O=53. Head subcylindrical, apex rounded, marked by fine, indistinct annules. Lateral fields 4.3 µm wide near midbody. Stylet knobs rounded. Excretory pore 111 µm posterior from head end, near level of esophagointestinal valve. Spicules 25 µm long, gubernaculum 7 µm long. Phasmids 6 and 13 µm anterior to level of cloacal opening. (ref. ID; 5933)
  • Paratypes (seven males): L=678(636-715) µm, a=35(31-37), b=6.1(5.6-6.5), b'=4.8(4.6-5.3), c=30(28-32), c'=1.9(1.6-2.2), T=39(32-47). Stylet length 22(21-23) µm, M=46(43-50), O=47(36-59). Body ventrally arcuate to varying degrees when relaxed, 17-23 µm wide near midbody. Head subcylindrical, apex rounded, with four to five fine or sometimes indistinct annules. Stylet knobs rounded, anterior surfaces may slope slightly posteriorly. Dorsal gland orifice 8 to 14 µm posterior to stylet. Esophagus 141(133-151) µm long, 112(107-121) µm to esophagointestinal valve. Valvular apparatus of metacorpus 2 µm or less in length. Esophageal glands distinctly separated into lobes. Excretory pore 101 to 114 µm posterior from head end, anterior or sometimes posterior to esophgointestial valve. Reproductive system extending anteriorly 263(213-328) µm. Spicules 25(24-27) µm long, proximal end cylindroid, distal end oblique. Gubernaculum 7 to 9 µm long. Tail 23(20-25) µm long, posterior third or more of tail digitate, tip rounded, never spicate or mucronate. Bursa enveloping entire tail. Postcloacal lip bearing a pair of submedian protuberances. (ref. ID; 5933)

    Type locality & host affiliation

    Collected at Callander Beach, Kouchibouguac National Park, New Brunswick, from Carex sp. growing in sand 20 m from Northumberland Strait. No other species of Helicotylenchus was present. (ref. ID; 5933)

    Type designations

    Holotype (female) type slide No.235. Allotype (male) type slide No.235a. Paratypes (female) type slide Nos.235b-235h, (male) type slide Nos.235i-235m. Collection No.7109. Deposited in Canadian National Collection of Nematodes. Two male and female paratypes deposited with the U.S. Department of Agriculture Nematode Collection, Beltsville, Maryland. (ref. ID; 5933)