Helicotylenchus digonicus Perry in Perry Darling & Thorne, 1959

Shokoohi, Ebrahim, Marais, Mariette, Fourie, Hendrika & Panahi, Hadi, 2018, Morphological and molecular characterization of three Helicotylenchus species from Iran, Zootaxa 4388 (2), pp. 207-220 : 209-210

Helicotylenchus digonicus Perry in Perry Darling & Thorne, 1959

( FiguRE 1 )

Helicotylenchus digonicus WaS dEScRibEd fROm Poa pratensis L. in WiScOnSin (USA) and SincE REpORTEd fROm all ThE biOgEOgRaphical REgiOnS.

Measurements: SEE TablE 1.

Description. FEmalE (n=7): HabiTuS SpiRal. Lip REgiOn 4.1±0.4 (3.4–5) µm high and 5.6±1.2 (4–8) µm WidE, anTERiORlY flaTTEnEd and cOnTinuES WiTh bOdY cOnTOuR, WiTh fOuR TO fiVE annulES. ThE labial fRamEWORk iS WEll SclEROTizEd, WiTh OuTER maRginS Of ThE labial fRamEWORk EXTEnding 2–3 µm fROm baSal plaTE. CEphalidS nOT SEEn. STYlET 24.3±1.6 (23–28) µm lOng, lEngTh Of cOnuS 10.7 TO 12.3 µm. STYlET knObS anTERiOR facE flaTTEnEd (32%) TO indEnTEd (68%). POSiTiOn Of dORSal phaRYngEal gland OpEning (DGO) 9.4±2.3 (6–13) µm anTERiOR TO STYlET knObS. MEdian phaRYngEal bulb OVal TO ROund, 13–14 µm lOng and 9–10 µm WidE; ValVE 2–3 µm lOng and 1–2 µm WidE. PhaRYnX lOng, WiTh lEngTh TO End Of gland 120.6±10.3 (102–134) µm. PhaRYnX WiTh an 27–28 µm lOng VEnTRal OVERlap. HEmizOnid lOcaTEd 1 TO 3 annulES anTERiOR TO EXcRETORY pORE. HEmizOniOn nOT SEEn. FaSciculi nOT SEEn. CuTiclE annulaTEd, 1.0 TO 2.0 µm. NERVE Ring aT iSThmuS, aT 62–70% Of phaRYngEal lEngTh. SEcRETORY-EXcRETORY pORE OpEning OppOSiTE iSThmuS, aT 73–86% Of phaRYngEal lEngTh. DEiRidS nOT SEEn; OVaRiES nOT REflEXEd; OViducT appaREnTlY ShORT, lESS Than a half Of ThE cORRESpOnding bOdY diamETER; nOT WEll diffEREnTiaTEd fROm ThE OVaRY; SpERmaThEca OVal TO ROundEd; SpERmaThEca lESS Than ThE cORRESpOnding bOdY diamETER, SpERm nOT SEEn; uTERuS TubulaR, 0.9 TimES ThE cORRESpOnding bOdY diamETER. VulVa WiThOuT pROTRuding lipS and EpYpTigma, lOcaTEd aT 60 % Of bOdY lEngTh. LaTERal fiEld WiTh 4 linES, innER TWO linES End On Tail in u-ShapE paTTERn. REcTum 0.9–1.2 TimES ThE anal bOdY diamETER. InTESTinE nOT EXTEndEd OVER REcTum. PORE-likE phaSmid TWO TO ThREE annulES anTERiOR TO anuS. Tail 15.3±2 (12–18) lOng, ShapE mORE cuRVEd dORSalY; WiTh SEVEn TO ninE VEnTRal Tail annulES. Tail mORE cuRVEd dORSallY, dORSal SidE JOinS VEnTRal SidE, WiTh SlighT VEnTRal pROJEcTiOn.

MalE: nOT fOund.

Locality and habitat. ThE maTERialS EXaminEd WERE cOllEcTEd in BafT (KERman PROVincE), SOuTh Of IRan, fROm ThE RhizOSphERE Of Juglans regia L.

Remarks. ThE cuRREnT SpEcimEnS WERE idEnTifiEd aS H. digonicus bEcauSE Of habiTuS bEing mOSTlY SpiRal, STYlET lEngTh (mEan ValuE: 24 µm), bOdY lEngTh (mEan ValuE: 736 µm), Tail mORE cuRVEd dORSallY, dORSal SidE JOinS VEnTRal SidE aT an anglE and nO malES. ThE cuRREnT IRanian SpEcimEnS Of H. digonicus agREE WiTh ThE TYpE and SubSEquEnT dEScRipTiOnS (ShER, 1966; HaShim, 1982; WOuTS and YEaTES, 1994; MaRaiS, 2001; SubbOTin et al. 2015). In cOmpaRiSOn WiTh ThE IRanian indiVidualS REpORTEd fROm ThE Hamadan PROVincE Of IRan bY HaSSanzadEh et al. (2005), ThERE iS nO SignificanT diffEREncE EXcEpT fOR a SlighTlY ShORTER Tail lEngTh (12–18 vs 7–21 µm). COmpaREd WiTh H. digonicus REpORTEd fROm ThE cEnTRal paRT Of IRan (MaRkazi PROVincE) bY MOhammad DEimi and MiTkOWSki (2010), nO SignificanT diffEREncE WaS, hOWEVER, ObSERVEd. In cOmpaRiSOn WiTh ThOSE STudiEd bY KnOblOch and Laughlin (1973), ThEY diffER in bOdY lEngTh (670–852 vs 590–710), c (40–57 vs 24–35), Tail annuli (7–9 vs 10–14) and phaSmid diSTancE fROm anuS (2–3 vs 5–9). COmpaREd TO ThE SpEcimEnS Of ThiS SpEciES STudiEd bY SubbOTin et al. (2015), ThEY diffEREd in c’ (0.9–1.2 vs 0.9–1.5), V (58–70 vs 61.5–63.7), Tail annuli (7–9 vs 8–15) and phaSmid diSTancE fROm anuS (2–3 vs 0–2 annuli). In cOmpaRiSOn WiTh ThOSE STudiEd bY MaRaiS (2001), ThEY diffEREd in bOdY lEngTh (670–852 vs 525–874 µm), a (25–29 vs 19.1–35.4), c (40–57 vs 28.7–83), c’ (0.9–1.2 vs 0.5–1.6), STYlET lEngTh (23–28 vs 22–31 µm), DGO (6–13 vs 8–16 µm), Tail annuli (7–9 vs 5–8) and phaSmid diSTancE fROm anuS (2– 3 vs 6–14 annuli).

DNA chaRacTERiSaTiOn: ThE 28S RRNA gEnE SEquEncE Of H. digonicus amplifiEd bY ThE TWO pRimERS D2A and D3B WaS 774 baSE paiRS (bp) lOng. WiThin ThiS fRagmEnT, 27 bp diffEREncES diSTinguiShEd ThE IRanian pOpulaTiOn fROm ThE ITalian pOpulaTiOn Of H. digonicus (accESSiOn nR. DQ328758 ; 93% idEnTiTY) and 69 bp diffEREncES fROm H. digonicus (accESSiOn nR. HM014240 ; 88% idEnTiTY) fROm SOuTh AfRica. In addiTiOn, cOmpaREd TO ThE USA iSOlaTE Of H. digonicus (accESSiOn nR. HM014274 ; 88% idEnTiTY), ThE IRanian SpEcimEnS ShOWEd 72 bp diffEREncES.

Figures

FIGURE1. Helicotylenchus digonicus PERRYIN PERRY,DARLING & THORNE,1959.FEMALE:A, B: ANTERIOR END (STOMA AND DGO). C: NECK.D: FEMALE REPRODUCTIVE SYSTEM.E: ENTIRE FEMALE.F–H: FEMALEPOSTERIOR END.