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An order of nematodes in which the cephalic region may be adorned with three or six labia or the labia may be replaced by a corona radiata. The variable stoma may be well developed or rudimentary but is never collapsed or inconspicuous. The capacious stoma consists primarily of cheilostome; only the base of the cup is surrounded by esophageal tissue. The stoma even when reduced is represented by the cheilostomal vestibule. The esophagus in larval forms is rhabditiform, and the posterior bulb is valved. The adult esophagus is cylindrical to clavate. In the fourth juvenile stage and the adult the excretory system consists of paired lateral collecting tubules, an excretory cell, and paired subventral glands. Other immatures have a single excretory cell. The females have one or two gonads, and the uterus is heavily muscled. The males have unusual caudal alae, referred to as a bursa copulatrix. The bursa differs from other caudal alae in that it contains muscles and rays. Males have paired and equal spicules. All strongylid nematodes are parasitic.
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An order of nematodes in which the labia are generally well developed; however, many taxa exhibit a smoothly rounded anterior. The labial region is often set off from the general body contour by a constriction. The cephalic sensilla are all located on the labial region. When there is no constriction, the labial region is defined as that region anterior to the amphids. The amphidial pouch is shaped like an inverted stirrup, and the aperture is ellipsoidal or a transverse slit. The stoma is armed with a movable mural tooth or a hollow axial spear. The anterior portion of the tooth or spear is produced by a special cell in the anterior esophagus. The esophagus is divided into a slender, muscular anterior region and an elongated or pyriform glandular/muscular posterior region. There are generally five esophageal glands with orifices posterior to the nerve ring. In some taxa there are three glands, and in others seven have been reported. The esophagointestinal valve is well developed. The mesenteron is often clearly divided into an anterior intestine and a prerectum. Females have one or two reflexed ovaries; when there is only one, the vulva may shift anteriorly. Males have paired equal spicules that are rarely accompanied by a gubernaculum. The males often have the ventromedial preanal supplements preceded by paired adanal supplements.
Industry:Science
An order of nematodes in which the labia are seldom well developed; however, a hexaradiate symmetry is distinct. The external circle of labial sensilla may appear setose, but they are always short, never long or hairlike. The stoma may be slender and elongate, or spacious, or any gradation between. The stoma may be armed or unarmed; the armature may be movable teeth, fossores, or a pseudostylet. The corpus is always muscled and distinct from the postcorpus, which is divisible into an isthmus and glandular posterior bulb. The metacorpus is almost always valved. The female reproductive system may have one or two ovaries, and males may or may not have caudal alae; however, a gubernaculum is always present. The male tail commonly has nine pairs of caudal papillae; three are preanal and six are caudal.
Industry:Science
An order of nematodes in which the labial region is most frequently provided with two lateral labia or pseudolabia; in some taxa there are four or more lips; rarely lips are absent. Because of the variability in lip number, there is variation in the shape of the oral opening, which may or not be surrounded by teeth. The amphids are most often laterally located; however, in some taxa they may be located immediately posterior to the labia or pseudolabia. The stoma may be cylindrical and elongate or rudimentary. The esophagus is generally divisible into an anterior muscular portion and an elongate swollen posterior glandular region, where the multinucleate glands are located. Eclosion larvae are usually provided with a cephalic spine or hook and a porelike phasmid on the tail.
Industry:Science
An order of nematodes in which the labial region is variable and may be distinctly set off or smoothly rounded and well developed; the hexaradiate symmetry is most often retained or discernible. The amphids are porelike, oval, or slitlike, or clefts located on the lips. The internal circlet of six sensilla may be lacking. The external circle of 10 sensilla is often evident; however, these may be reduced to a visible 4 or some may be doubled. The hollow stylet is the product of the cheilostome (conus, “guiding apparatus,” and framework) and the esophastome (shaft and knobs). Throughout the order and its suborders the stylet may be present or absent and may or may not be adorned with knobs. The variable esophagus is most often divisible into the corpus, isthmus, and glandular posterior bulb. The corpus is divisible into the procorpus and metacorpus. The metacorpus is generally valved but may not occur in some females and males, and the absence is characteristic of some taxa. The orifice of the dorsal esophageal gland opens either into the anterior procorpus or just anterior to the metacorporal valve. The excretory system is asymmetrical, and there is but one longitudinal collecting tubule. Females have one or two genital branches; when only one branch is present, it is anteriorly directed. Except for sex-reversed males there is only one genital branch. Males may have one (=phasmid) or more caudal papillae. The spicules are always paired and variable in shape; they may or may not be accompanied by a gubernaculum.
Industry:Science
An order of nematodes in which the number of labia varies from a full complement of six to three or two or none. The tubular stoma may be composed of five or more sections called rhabdions. The three-part esophagus always ends in a muscular bulb that is invariably valved. The excretory tube is cuticularly lined, and paired lateral collecting tubes generally run posteriorly from the excretory cell; some taxa have anterior tubules also. Females have one or two ovaries; when only one is present the vulva shifts posteriorly. The cells of the intestine may be uninucleate, binucleate, or tetranucleate, and the hypodermal cells may also be multinucleate. Caudal alae, when present, contain papillae.
Industry:Science
An order of nematodes in which the oral opening is generally surrounded by three or six labia; in some taxa labia are absent, but the cephalic sensilla are always evident. Usually there are eight cephalic or labial sensilla; the submedians may be fused and then only four sensilla are seen. The stoma varies from being completely reduced to spacious or globose. The esophagus varies from club shaped to nearly cylindrical, never rhabditoid. There may be posterior esophageal or anterior intestinal ceca. The collecting tubules of the excretory system may extend posteriorly and anteriorly. Males generally have two spicules; however, in some taxa there may be none or only one. The gubernaculum may also be present or absent. Though females generally have two ovaries, multiple ovaries do occur. The number of uteri is also variable: two, three, four, or six. Phasmids are sometimes large and pocketlike. Reportedly, the larvae lack a stomatal hook or barb.
Industry:Science
An order of nematodes in which the taxa are readily recognized by their conspicuous body annulation. The annuli may be covered with concretion rings, or the cuticle may be ornamented with scales, warts, or bristles. The cephalic sensilla reportedly are reduced in number. The internal whorl is absent, the second whorl is papilliform, and the four sensilla of the third circlet are setiform. The vesiculate amphids are oval to circular and occupy much of the cephalic region. The somatic setae are tubular, and the open distal ends are often elaborate. The posterior esophagus is only slightly expanded. When pigment spots or ocelli are present, they are just posterior to the esophagus. Females are amphidelphic, and the ovaries are generally outstretched. The male spicules are generally accompanied by a gubernaculum. Both sexes have three caudal glands.
Industry:Science
An order of nematodes in which the variable stoma may or may not be armed with a dorsal tooth which may or may not be opposed by subventral denticles. The variable amphids range from reniform-to-elongate loops to simple or multiple spirals. The cephalic sensilla are generally in three whorls; however, the second and third whorls may be combined. Distinguishing the order is the cephalic capsule or helmet and the conspicuous somatic annuli. In some groups anterior and posterior adhesion tubes are utilized in locomotion.
Industry:Science
An order of nematodes in which, generally, the stoma is funnel shaped and lightly cuticularized; however, in some families the stoma is spacious and heavily cuticularized, and is armed with protrusible teeth. The amphids vary from simple spirals to circular forms. Usually the second and third circlets of cephalic sensilla are combined, but in some taxa the third circlet of four distinct setae is separate. The normal pattern of distribution is often disrupted by numerous cervical setae. The near-cylindrical esophagus is sometimes swollen posteriorly. The cuticle may be smooth or may have annuli or ornamentation. When the annuli are distinct, the somatic setae may be long and in four to eight longitudinal rows. The female gonads are outstretched and either single or paired.
Industry:Science
