Steinernema cumgarense

Steinernema cumgarense

Phan, Spiridonov, Subbotin & Moens, 2006

Description

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Male<= /b>

        &= nbsp;   Body C-shaped in heat-relaxed specimens, tapering towards anterior end. Annules 1-1.3 μm wide, indis= tinct under LM. No lateral fields visible but irregular anastomoses of cutic1e annulation present along lateral body. Anterior extremity rounded with f1attened area just around oral aperture. Six labial papillae and more prominent cephalic papillae present. Cheilorhabdions thick, strongly cuticularised, 2-3 μm long ring 6-6.5 μm diam. forming middle part of stoma. Additional thinner cuticular ring situated posterior to thicker one, embedded into pharyngeal tissue. Corpus cylindric= al, without visible metacorpal swelling. Basal bulb subpyriform. Nerve ring situated on anterior slope of basal bulb in most males. Valves in shape of platelets of thin folded cutic1e. Cardia spherical, protruding for 18-22 μm into intestine proventriculus. Excretory channel strongly cuticularised for 10 μm from pore. Intestinal = lumen open up to mid-body. Separate spermatocytes poorly distinguishable, even in ref1exed testis part, being replaced with complex rachis structure in testis middle, with characteristic patterns of spermatogenesis up to vas defere= ns. Genital papillae with a row of usually nine pairs of subventral papillae extending from tail terminus to body middle, single, large, precloacal papi= lla in midventral position, one pair of papillae in lateral position at manubri= um level when spicules retracted, and one pair of papillae in dorso-lateral position in postcloacal area. Latter pair usually closer to equatorial part= of tail. Spicules (Fig. 1)<= /a> with elongate, funnel-shaped manubrium, tapering towards distal end, with round extremity and more or less pronounced terminal duct. All four main ribs of spicule prominent, separated by gaps visible in lateral aspect. Spicule body gradually narrowing from rostrum to distal end. Cloacal opening covered with f1ap when spicules retracted. Two papilla-like structures on cloacal margin. Gubernaculum usually straight with ventrally curved proximal end, often with cuticular knobs on inner surface. Mucron spike-like.

        &= nbsp;   Some measurements: Spicule length= =3D 76 (68-81) μm, gubernaculum le= ngth =3D 58 (48-66) μm, D% =3D 45 (35-52).

Female

Annules 1.5 μm wide, prominent near vulva lips. Cephalic extremity with six labial and four cephalic papillae. Cuticular ring forming main part of stoma walls 5-6 μm thick a= nd 7-7.5 μm long. Stoma= tal cavity 10 μm wide. E= xcretory duct strongly cuticularized, entering body at almost 90° to the longitudinal axis. Vulva equatorial, epiptygmata present. Vulva lips equal = in size, protruding up to 20-25 = 56;m. Tail terminus dome-shaped, bearing peg-like, 3-5 μm long, mucron.

Infective juvenile

Body of heat-relaxed juveniles moderately C-shaped, tapering towards anterior end. Annules 1 μm wide visible throughout body. Lateral field in anterior half= of body with four ridges, two pronounced marginal ridges and poorly discernible submarginal lines. Such regular pattern not observed in posterior half of b= ody, with ventral gap between central and marginal ridges disappearing. Lateral field 8.5-9.5 μm wid= e at mid-body. Cuticle swollen near anterior end forming 4-5 μm long cephalic capsule. Frontal surface or anterior = end always regularly rounded. Labial papillae indistinct, four cephalic papillae and amphidial pouches occasionally visible. Corpus slender anteriorly, slig= htly widening to metacorpal part. Nerve ring always located about corpus-isthmus junction. Hemizonid in isthmus level. Basal bulb with poorly visible valves= and large nucleus in dorsal anterior half. Cardia about 10 μm long, narrowing to posterior end. Bacterial vesicle elliptical, 10-13 μm= long and 5-6 μm width. Re= ctum about two anal body width long. Genital primordium 50 μm long. Phasmids at one-third of tail length posterio= r to anus (phasmid - mucron distance about 25-26 μm), with aperture near ventral edge of ventral marginal line. Lateral field lines disappearing at level of phasmids. Tail = with pronounced ventral concavity, ventrally curved with terminus pointed to fin= ely rounded. Hyaline region comprising about half of tail length.

Some measurements= : L = =3D 402 (384-432) μm, EP =3D 35 (33= -38) μm, T =3D 36 (34-38) μm, D% =3D 41 (38-43), E% =3D 99 (87-103).

=

Type host and locality

=

Natu= ral host unknown as nematodes were obtained by Galleria mellonella baiting method. Collected near the village Cu M'Gar in the Daklak province of Vietnam= (longitude 108°02'E, latitude l2°29'N, altitude 600 m a.s.l.) from = the red basa1t soil of highland coffee plantations.

Type material

=

Holo= type male and seven paratype males deposited at Insti= tute of Parasitology of Russian Academy of Sciences, Leninskii prospect 33, Moscow, 119071, Russia. Slides with paratype males, first generation females and infective juveniles deposited in Department of Nematology, Institute= of Ecology and Biological Resour= ces, National Center for Science and Technology, Hoang Quoc Viet 18, Nghiado, Caugiay, Hanoi, Vietnam.

Relationships

=

Male= s have two papilla-like structures on the cloacal margin, the spicules have an elongate manubrium and developed rostrum and there is a short, spike-like, caudal mucron in both generations. The first generation female has a dome-shaped tail and a minute, peg-like, mucron. Epiptygmata are present. T= he infective juveniles belong to the shortest group with an average body lengt= h of 402 μm and the hyaline region comprises about half of the tail length. The lateral fiel= ds have four ridges in the mid-body region.<= /span>

        &= nbsp;   In I= J body length, this species is similar to S. eapokense (L =3D 402 (370-434) μm) and S. siamkayai (L =3D 446 (308-495) μm), but is shorter than S. sasonense (L =3D 471 (437-516) μm), S<= /i>. carpocapsae (L =3D 546 (427-640) μm= ), S. scapterisci (L =3D 572 (517-609) μm), and S. tami (L =3D 530 (400-600) μm).
This species can be distinguished from the closely related S. eapokense by the D% value (38-43 vs 32-37) = and hyaline region of the IJ tail which is 38 (38-43) vs 53 (47-57)%. Th= e IJ of S. cumgarense has a thicker body than S. siamkayai (17-19 vs 19-23 μm). Steinernema cumgarense differs from= S. backanense by the length= of the spicule and gubernaculum (68-81 vs 53-62 μm and = 48-66 vs 36-48 μm, respectively). The IJ also differs from S. sasonense by the shorter pharynx length (80-91 vs 94-104= μm) and shorter ta= il length (34-38 vs 43-49 μm).

Molecular characterisation

S= teinernema cumgarense is characterised by seque= nce lengths of ITS regions (ITS1 + 5.8S + ITS2) bp, ITS1 =3D 269 bp, ITS2 =3D 3= 06 bp and its composition, A =3D 0.22877, C =3D 0.16301, G =3D 0.21917, T =3D 0.3= 8901. The sequence of ITS regions is deposited in GenBank under accession no. = AY487920.

Reference

Phan, K.L., Spiridon= ov, S.E., Subbotin, S.A. & Moens, M. (2006). Four new species of Steinernema Travassos, 1928 with short infective juveniles from Vietnam. Russian Journal of Nematology 14, 11-29.