Mesocriconema xenoplax
(Raski, 1952) Loof & De Grisse, 1989
syn.
 Criconemoides xenoplax Raski, 1952
Macroposthonia xenoplax (Raski, 1952) De Grisse & Loof, 1965
Criconemella xenoplax (Raski, 1952) Luc & Raski, 1981
Criconema pruni Siddiqi, 1961
Criconemoides pruni (Siddiqi, 1961) Raski & Golden, 1966
Macroposthonia pruni (Siddiqi, 1961) De Grisse & Loof, 1965
Mesocriconema pruni (Siddiqi, 1961) Andrássy, 1965
Criconemella pruni (Siddiqi, 1961) Luc & Raski, 1981
Criconemoides nainitalensis Edward & Misra, 1963

Photo Galleries:

George Washington Memorial Parkway
Ichetucknee River, FL
Fairfax County, VA
Great Smoky Mountains
Georgia peach
 South Carolina peach
British Columbia
Plattsmouth, NE
Old Pali Highway, Hawaii
Arkansas pine
UC Davis
FEMALE : 0.404-0.620 mm. ; a = 8.3-13.6; b = 3.1-4.8; c = 23.1-55.6; V = 90.2-95.3%.
MALE : 0.530-0.610 mm. ; a = 22.5-27.7; b =   ?  ; c = 12.4-15.3; T = 27.9-35.1%.
    LARVA (Fig.1, M-N).  Head and tail bluntly rounded as in female.  Sublateral lobes present.  Spear length 59-65 u.  Total annules 96-114, marked on posterior edge by fine longitudinal lines.
    FEMALE (Fig. 1, A-I, O, T).  Oral aperture obscure at surface, internally shows as a narrow slit near base of sclerotization.  Conspicuous, elevated, labial disc surrounding oral opening.  Amphid apertures obscure appearing as narrow, darkened slits on lateral margins of labial disc.  Labial disc expanded near base to include the amphidial pouches.  Sclerotization hexaradiate with internal innervations present in four submedian sectors.  Lateral sectors bearing elongate, indefinite innervations of amphids.  Sublateral lobes conspicuous, placed equidistant about the labial disc and well separated from one another.  The lobes project outward and forward sometimes as far as edge of labial disc.  In ventral view the ventro-sublateral lobes appear connected.  The same is true of the dorso-sublateral lobes but there is no perceptible connection between the sublateral lobes dorso-ventrally.  These connections are obscure in face view.  First annule variable, usually divided into four labial plates which may be simple, notched or indented.  Labial plates may also be reduced in number, rudimentary in size, complicated by anastomosis with second annule or completely lacking.  First two annules not retrorse, smaller and narrower than succeeding body annules but not set off, presenting a bluntly rounded outline.
 Spear length 71-86 u.  Excretory pore on 25-35th annule from anterior end.  Vulva on 6-11th annule from end of body, generally on 7-8th.  Anterior flap of vulva variable but usually presents a bilobed appearance.  Anastomosis with preceding or succeeding annules often complicates vulva pattern.  Ovary extends 40.2-79.0% of body length.  Anus located on 4-8th annule from end of body.  Terminus a simple rounded or lobed button.  Total annules 87-114.
    MALE (Fig. 1, J-L, P-S).  Details of face view exaggerated slightly for purposes of illustration since they are somewhat obscure.  Lip region definitely elevated, no striae present on lips.  Sublateral lobes small, placed equidistant about the large labial disc.  Innervations of amphids appear to be present but amphid apertures obscure.  Hexaradiate sclerotization delicate, extending 4-5 annules posterior to lips, internal innervations present in four submedian sectors.
 Annulation coarse, 1.4-1.5 u wide near head, 2.8-3.1 u wide midway.  Lateral field marked by four incisures beginning as two at about 6-7th annule from lip region.  Faint cross striae present in first part of lateral field.  Esophagus indistinct, spear absent.  Excretory pore 0.132-0.138 mm. from anterior end of body.  Herizonid almost two annules wide, located 6-7 annules anterior to excretory pore.
 Spicules 38-43 u long, slightly curved.  Gubernaculum simple, rod-like, 8-9 u long.  Spicule sheath protrudes conspicuously, bears a short, rod-like process on posterior edge.  Tail constricts posterior to spicules and is coarsely annulated to terminus which is bluntly rounded.  Bursa small, begins slightly anterior to cloacal opening and extends almost to terminus.  Lines of lateral field extend almost to terminus on lateral sides of bursa.
 Males rare, known only from type locality.
    TYPE SPECIMENS.  Holotpe-females, Catalogue #1; allotype-male, Catalogue #2; 87 paratypes in Calif. Coll. #201 in University of California collection, Berkeley.
    TYPE HABITAT.  Soil taken about roots of Thompson seedless grape (Vitis vinifera var. sultanina) gorwn on #1613 (Vitis longii) rootstock.
    TYPE LOCALITY.  About 4 miles east of Fresno, Fresno County, Calif.
    DISTRIBUTION.  This species was also collected from many localities in California in soil about roots of walnut, plum, California laurel (Umbellularia californica) and from a stream bank; soil at roots of pine, Idaho Springs, Colorado; soil taken in woods near Beebe Lake, Ithaca, N.Y. and soil from woods near Peconic, Long Island, N.Y.
    DIAGNOSIS.  Criconemoides xenoplax keys to C. rusticum according to Taylor (1936) but differs from it in spear length and shape of head and tail.  Micoletzky (1917) reported the spear length of C. rusticum as 57.5 u and illustrated the head and tail with blunt ends.  The spear of C. xenoplax is longer (71-86 u) and has the head and tail much more rounded than is illustrated by Micoletzky.  Goodey (1951) reports the spear of C. rusticum as 50 u.  He also pointed out that the spear of C. rusticum illustrated by Taylor (1936) actually measured 50 u.
 Cobb (1918) described C simile with a “head surmounted by a flat lip region composed probably of 6 very flat lips placed in a slightly depressed front surface of the first annule . . . .  No labial papillae have been seen.”  No spear measurement was given but it is probable this species is similar to C. rusticum as illustrated by Micoletzky and is so considered here.  The specimens used by Chitwood (1949) in reerecting C. simile had spear measurements of 70-75 u and therefore were not C. rusticum.  Further examination of material used by Chitwood will be necessary to determine whether it is the same as C. xenoplax.
(Original Description- Raski, 1952)

0.58 mm; a = 22; b = 4.8; c = ?; V = 95
Body cylindroid except extremities.  Annules without anastomosis except in rare instances.  Sublateral labial lobes conspicuous.  Perioral disc rounded.  First cephalic annule indented, not circular, somewhat cupped; second slightly wider, definitely set off by constriction.  Remaining body annules rounded, slightly retrorse, numbering about 112.  Spear massive, 55u long, its muscles somewhat sclerotized in basal third.  Median bulb massive, tapering to a broad isthmus.  A minute cardia present.  Excretory pore and hemizonid not observed.  Vulva usually on 6th or 7th annule from terminus.  Ovary outstretched, oocytes in single file except for a short region of multiplication.  Anus not definitely seen.
Habitat:  Numerous females and young from Medicine Butte, S. Dakota and one female from Fairmont, Nebraska.
(Description- Thorne and Malek, 1968)

This species included in the Criconematid Project

DNA Sequences Obtained
Specimen: Collected:
Fresno 6 from UC Davis
UCD-22 from UC Davis
Platts-02 Plattsmouth, NE
16801 Williams Prairie, Iowa
Konza FS-31 Konza Prairie
PNID-223080 Konza Prairie