Xiphinema americanum
| American dagger nematode | |
|---|---|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Nematoda |
| Class: | Adenophorea |
| Subclass: | Enoplia |
| Order: | Dorylaimida |
| Superfamily: | Dorylaimoidea |
| Family: | Longidoridae |
| Subfamily: | Xiphineminae |
| Genus: | Xiphinema |
| Species: | X. americanum |
| Binomial name | |
|
Xiphinema americanum Cobb, (1913) |
|
Xiphinema americanum (American dagger nematode) is a plant pathogenic nematode. It is one of many species that belongs to the genus Xiphinema. It was first described by N. A. Cobb in 1913, who found it on both sides of the United States on the roots of grass, corn, and citrus trees. Not only is Xiphinema americanum known to vector plant viruses, but also X. americanum has been referred to as "the most destructive plant parasitic nematode in America", and one of the four major nematode pests in the Southeastern United States.
The length of the adult Xiphinema americanum ranges from 1.3 to 3.0 millimeters. The dagger nematode is characterized by a 100 μm odontostyle which is used for deep penetration of root tips with its spear-like stylet. The odontostyle is connected to the lining of the cheilostome by a folded membrane called the "guiding ring". The guiding ring is attached to a flanged odontophore.
Females: The body is usually in an "open C" conformation. The shape of the body tapers towards the extremities. The two rings of the odontophore are located 3 μm apart. The Xiphinema americanum esophagus is dorylaimoid with an enlarged posterior portion that occupies roughly 1/3 of its total length. The esophagus contains a muscular bulb which is 80 μm long and 20 μm wide. The valve between the esophagus and the intestine is amorphous. The vulva is 46-54% of the total body length, and is located equatorially with a transverse slit shape, with the vagina having a diameter of 1/3 of the body diameter. The ovaries normally occur in pairs, and are amphidelphic and relexed. The prerectum of X. americanum measures 120-140 μm long, with a rectum that is roughly the same length as the body diameter at the anus. The tail contains 2-3 pairs of caudal pores, is conoid, and curves dorsally with a subacute terminus.
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