Body straight, or slightly curved, with body behind vulva slightly bent ventrally when killed by gentle heat. Body tapers slightly from mid body to head, narrows slightly behind vulva, thereafter almost cylindrical to broadly rounded tail tip. Tail 19-25 annules long. Lateral field originates about level of pear knobs as a single incisures soon becoming two lines, then three about half way down procorpus and four just behind median bulb. Lateral field irregularly areolate along the whole of its length, with fewer lines between the middle two lines than across the outer two bands. A few large specimens had oblique striae instead of areolations for a short length of the lateral field just in front of the vulva. Areolations very fine, not seen in glycerine mounts, only seen in immersion oil mounts. Phasmid approximately mid tail, with two middle lines of lateral field coalescing shortly behind it to become one irregular line at junction of areolations. Outer two lines continue almost to tail tip. Head with three sometimes indistinct annules offset from body by slight constriction. Head skeleton strong, amphid openings and one papilla on lateral lips, one papilla on each subventral and on each subdorsal lip. Spear in two parts with large rounded basal knobs, 16-20 u long, front part slightly shorter than the rear. Excretory pore about 86-99 u from head in glycerine mounted specimens, just behind hemizonid occupying two annules; a hemizonion seen in some specimens about ten annules behind the hemizonid. Nerve ring surrounds isthmus just in front of the posterior glandular portion of the oesophagus. Oesophago-intestinal junction about the level of the excretory pore. Oesophageal glands overlap intestine ventrally as a long narrow lobe more than two body widths long. Gonad anterior to vulva, lying in left ventral quadrant of body. The ovary consists of a single row of oocytes. There is a conspicuous rounded non-functional spermatheca. Vulva about 78-81 %, post vulval sac short, usually about one body width or less in length.
Holotype. Female on slide 57/18/1 in collection of Nematology Department, Rothamsted Experimental Station, Harpenden.
Paratypes. Females on slides 57/18/2-8, Rothamsted Experimental Station; and on slides at Instituut voor Plantenziektenkundig Onderzoek, Wageningen; Laboratorium voor Nematologie, Landbouwhogeschool, Wageningen; Plant Industry Station, Beltsville, Maryland, U.S.A.; University of California Nematode Survey Collection, Davis, California, U.S.A., Zoological Institute of the Academy of Sciences of the U.S.S.R., Leningrad, U.S.S.R. and in the authorís possession.
Type locality: Broadbalk field, Rothamsted Experimental Station.
Type habitat: Wheat roots and soil.
Differential diagnosis: P. pinguicaudatus differs from all but five species of Pratylenchus in having three head annules, a smooth tail tip and no males. It differs from P. thornei in head and tail shape, in the head being set off by a constriction and in the position of the vulva (74-79 % in P. thornei). It differs from P. uralensis, P. zeae and P. delattrei in tail shape and from all these and P. andinus in having the oesophagus overlapping the intestine in a narrow lobe more than two body widths long, and in the position of the vulva (73 % in P. uralensis, 73-80 % in P. delattrei , 68-76 % in P. zeae and 81-85 % in P. andinus).
Biology of P. pinguicaudatus
P. pinguicaudatus was found in wheat plants in the field
and, in addition to invading roots of barley, maize and wheat grown in
agar culture in Petri dishes, entered the stems and leaves of barley.
In these cultures adults, eggs and all larval stages were found in stems
above the first node and were associated with necrosis at the node.
All stages were also found between the ensheathing leaves of the stem base
and within the leaf tissues. Roots were most often entered behind
the tip in the region of root-hair production, and at the junction of lateral
roots with the main root. Occasionally the root tip was also penetrated.
Eggs are usually unsegmented when laid and hatch in about 10 days. The first moult was not seen and presumably occurs in the egg, as free larval stages and adults fall into four length groups, (180-280 u, 290-350 u, 360-440 u and 450-630 u: suggesting that there are only three free larval stages. One fully developed larva measured in the egg was 244 u long.
The nematode was successfully cultured on sterile Lucerne callus tissue on agar.