Steinernema eapokense

Steinernema eapokense

Phan, Spiridonov, Subbotin & Moens, 2006

Description

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Male =

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&= nbsp; Body C-shaped in heat-relaxed specimens, tapering towards anterior end. Annules 1-1.4 μm wide, poorly distinguishab1e throughout body under LM. No lateral fields visible. Anteri= or extremity rounded without prominent flattened area around oral aperture. Six labial papillae and four more prominent cephalic papillae present. Cheilorhabdions present strongly cuticularized, 2 μm long ring of 6-6.5 μm wide, forming midd1e part of stoma. Additional thin= ner cuticular ring situated posterior to thicker one, embedded into pharyngeal tissue. Corpus cylindrical, with visible metacorpal swelling and swelling around basal part of stoma. Basal bulb subspherical. Nerve ring situated on= anterior slope of basal bulb in most males. Cardia flat, 8-10 μm long. Excretory duct strongly cuticularized up to 1= 2-13 µm from pore. Intestinal lumen open throughout body length. Separate spermatocytes poorly distinguishable even in reflexed testis part, being replaced with complex rachis structure in middle region of testis. <= span style=3D'mso-bidi-font-style:italic'>Genital papillae with a row of usually nine pairs of subventral papillae extending from tail terminus to b= ody middle, one unpaired large precloacal papilla in midventral position, one p= air of papillae in lateral position at manubrium 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) with elongate, funnel-shaped manubrium, tapering towards distal end, with round extremity = and more or less pronounced terminal duct. Bifurcation of outer line of velum a= nd ventral rib of spicule visible near rostrum. All four main ribs of spicule discernible, separated by gaps visible in lateral aspect. Spicule body gradually narrowing from rostrum to distal end. Cloacal opening covered with flap when spicules retracted. Two papilla-like structures on cloacal margin. Gubernaculum usually straight with ventrally curved proximal end. Tail mucr= on often cylindrical, with globular inclusion.

&= nbsp; Some measurements: Spicule length= =3D 69 (63-74) μm, gubernaculum = =3D 50 (47-56) μm, SW% =3D 246 (221-282), GS% =3D 73 (69-80).

Female

Annules 1.5 μm wide. Cephalic extremity with six labial and four cephalic p= apillae. Cuticular ring forming main part of stoma walls 5 μm thick and 5-5.5 μm long. Stomatal cavity 10 μm diam. Excretory duct strongly cuticularized, entering body at angle of about 45°. Equatorial vulva with petal-like, 10-12 μm long structures, protr= uding from opening. Vulva lips 1ess than 12-15 μm high, equal in size. Tail end dome-shaped, with conical, 10-= 15 μm long, spike-like mucro= n.

Infective juvenile

Body of heat-relaxed juveniles quite obese, moderate= ly C-shaped, tapering towards anterior end. Annules about 1 μm wide, visible throughout body. Lateral field in anterior half of body with four ridges in center, two pronounced marginal ridges and poorly discernible submarginal lines. Lateral field 8-9 μm wide at mid-body. Such regular pattern not observed in posterior half of body with ventral gap bet= ween central and marginal ridges disappearing. Cutic1e swollen near anterior end forming cephalic capsule. Frontal surface of anterior end always regularly rounded. Labial papillae indistinct, four cephalic papillae and amphidial pouches occasionally visible. Corpus slender, slightly widening to metacorp= al part. Nerve ring always around corpus-isthmus junction. Excretory pore encirc1ed by refractive ring of cutic1e 1-1.5 μm deep. Hemizonid located at isthmus level, usually protruding from body, 3-4 annules long. Basal bulb with poorly developed valves. Cardia about 7 μm long, with rounded posterior end. Bacterial vesicle elliptical, 5-7 μm wide and 10-14 μm long. Rectum ca 1.5 anal body diam. long. Genit= al primordium 50 μm lon= g. Phasmids at one-third of tail length posterior to anus (phasmid-mucron dist= ance =3D ca 25-26 μm). Lateral field lines disappearing at phasmid level. Tail with pronounced dorsal concavity, dorsally curved with terminus pointe= d to finely rounded. Hyaline region comprising approximately half of tail length= .

Some measurements= : L = =3D 402 (370-434) μm, EP =3D 29 (26= -31) μm, T =3D 39-35-45) μm, D% =3D 34 (32-37), SW% =3D 246 (221-282),= GS% =3D 73 (69-80).

Type host and locality

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Type= host unknown as nematodes were obtained by the Galleria mellonella baiting method. The type isolate was collected in Eapok, Daklak province, Vietnam (longitude 106°04'E, latitude 12°48'N, altitude 600 m a.s.l.), from basalt red soils in coffee plantations on the submontane plateau.

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Type material

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Holo= type male and six paratype males deposited at Institu= te 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

The = male has two papilla-like structures on the cloacal margin and the spicules have an elongate manubrium and developed rostrum. A short mucron is present in both male generations and is often cylindrical with globular inclusion. <= span lang=3DEN-GB style=3D'mso-bidi-font-size:12.0pt;mso-bidi-font-style:italic'= >The first generation females possess a pronounced, conical, tail mucron. Infect= ive juveniles belong to the shortest length group with an average body length of 402 μm. The tail tip is dorsally concave and the hemizonid is protuberant in the majority of infective juveniles. The hyaline region comprises about 50% of the tail length and the lateral fields have four ridges in the mid-body region.

Steinernema eapokense differs from the closely related species S. cumgarense in D% and H% values of = IJ. The E% value helps to distinguish S. eapokense from S. sia= mkayai (66-80 vs 85-112%). IJ of S. eapokense (L =3D370-434 μm) are shorter th= an those of S. carpocapsae (438-650 μm), S. scapterisci (517-609 μm) and S. = sasonense (437-516 μm). The spicules of S. eapokense are shorter than those of S. back= anense (63-74 vs 47-62 μm)<= i>.

Molecular characterisation

S= teinernema eapokense is characterised by seque= nce lengths of ITS regions (ITS1 + 5.8S + ITS2), 723 bp, ITS1 =3D 262 bp, ITS2 = =3D 306 bp and its composition, A =3D 0.22544, C =3D 0.15491, G =3D 0.22544, T =3D = 0.39419. The sequence of ITS regions is deposited in GenBank under accession no. = AY487921.

Reference

Phan, K.L., Spiridonov, 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.