Meloidogyne chitwoodi
Golden, O'Bannon, Santo and Finley, 1980
Photo Gallery- Symptoms on Potato
Photo Gallery- Specimen Photos
Molecular Diagnosis
(Description Golden et al.)
Females (60):  Length 430-740 um ( mean 591 um, standard deviation [SD[ 60 um); width 344-518 um (422 um SD 42); a = 1.1-1.8 (1.4, SD 0.2); b = 3.8- 5.0 (4.4, SD 0.4); stylet 11.2-12.5 um (11.9 um, SD 0.3); width of stylet of stylet knobs 3.4-4.3 um (3.8 um, SD 0.3); dorsal esophageal gland orifice (DSO) 3.4-5.5 um (4.2 um, SD 0.6); from base of stylet; center of median bulb 52-80 um (63 um, SD 7) from anterior end; excretory pore 10-27 um (18 um, SD 5) from anterior end; vulva slit length 19-32 um (27 um, SD 3); distance from vulva slit to anus 13-22 um (18 um, SD 2).
Holotype (female):  Length 598 um; width 474 um; a = 1.3; b = 4.3; stylet 12 um; DGO 4.3 um from base of stylet; width of stylet knobs 3.9 um; vulva slit length 29.2 um; distance from vulva slit to anus 18.1 um.
Description. Females:  Body pearly white, globular to pear-shaped, with slight posterior protuberance visible occasionally, and with distinct neck situated anteriorly on a median plane with terminal vulva.  Esophageal and anterior region often appearing as illustrated.  Several small vesicles or vesicle-like structures usually present within the median bulb and are clustered around the lumen anterior to the valve plates of the median bulb.  Head with distinct but weak cephalic frame-work, offset from neck but variable in exact shape, and bearing a labial cap and usually one cephalic annule.  Excretory pore clearly visible and commonly located at a distance equal to about 11/2 stylet lengths from anterior end.  Stylet small but strong, having a dorsal curvature and rounded knobs that slope posteriorly.  Perineal pattern quite distinctive with striae around and above anal area being broken, curved, twisted, or curled as illustrated; overall shape of pattern appearing round to oval, sometimes with inner striae forming an arch of varying degrees.  Punctation not observed.  Vulva sunken in an area variable in shape and devoid of striae.

Males (30): Length 887-1268 um (1068 um, SD 100); a = 28-46 (36, SD 4); b = 6-9 (7.2, SD 1); c = 140-226 (162, SD 20); stylet 18.1-18.5 um (18.3 um, SD 0.2); DGO 2.2-3.4 um (3 um, SD 0.4) from base of stylet; center of median bulb 61-77 um (71 um, SD 5); from anterior end; spicules 26-29 um (27 um, SD 1.2); gubernaculum 6.5-8.2 um (7.7 um, SD 0.6); tail 4.7-9.0 um (6.8 um, SD 0.9).
Allotype (male):  Length 1046 um; a = 39; b = 5.6; c = 174; stylet 18.1 um; DGO 2.6 um; spicules 26 um; gubernaculum 7.3; tail 6 um.
Description.  Males:  Body slender, vermiform, tapering slightly at both extremities.  Head slightly offset, with large labial disc (head cap) and a large post labial annule not divided into annules.  Cuticular annules distinct, becoming more prominent a short distance from either end.  Midbody width 22-37 um (30 um, SD 3.9). Lateral field with four lines, center band smaller than outer two, and with some areolation evident with SEM but difficult to resolve with optical microscopy.  Stylet, knobs, cephalids, hemizonid, excretory pore, and anterior portion commonly appear as illustrated.  Testis one or two.  Spicules arcuate, and under SEM can be seen to have dentate tips ventrally.  Phasmids located at or anterior to cloaca.  Tail short, rounded.

Second-stage larvae (60); Length 336-417 um (390 um, SD 16); a = 24.5-29.8 (27.5, SD 1.2); b = 3.3-3.8 (3.6, SD 0.2); c = 7.9-9.6 (8.9, SD 0.4); stylet 9.0-10.3 um (9.9 um, SD 0.3); DGO 2.6-3.9 um (3.2 um, SD 0.2) from base of stylet; center of median bulb 43-56 um (51 um, SD 3) from anterior end;  head width 4.7-5.2 um (5 um, SD 0.2);  head height 1.7-2.6 um (2.3 um, SD 0.2);  hw/hh ratio 1.8-27 (2.3, SD 0.2);  tail length 39-47 um (43 um, SD 1.8); hyaline tail terminal 8.6-13.8 um (11 um, SD 1); caudal ratio A 1.9-3.9 (2.5, SD 0.3); caudal ratio B 3.0-5.7 (4.2, SD 0.7).
Description.  Larvae:  Body small, vermiform, 12.5-15.5 um (14.2 um, SD 0.6) in width at midbody, tapering at both extremities but more so posteriorly.  Head not offset, with weak cephalic framework, and bearing a labial disc and a large post-labial annule without striations.  Cuticular annulation on most of body very fine, measuing about 1 um.  Lateral field with four lines, not areolated.  Stylet, knobs, hemizonid, excretory pore, and anterior portion generally appearing as illustrated.  Cephalids indistinct and not shown.  Phasmids small, difficult to see, and located in anterior 1/3 of tail.  Rectum not inflated.  Tail commonly appearing as illustrated,  having a short, blunt hyaline portion which remains almost the same diameter for its length and with little or no taper, thus giving relatively high caudal ratios, especially caudal ratio B.  Tail terminus rounded.

Eggs (25):  Length 79-92 um (85 um, SD 3.6); width 40-46 um (42 um, SD 1.8); L-W ratio 1.8-2.3 (2, SD 0.1).  Egg shell hyaline, without visible markings, when observed with optical microscopy.

Type host and locality:  Roots and tubers of potato, Solanum tuberosum, in a field near Quincy, Washington, USA.

Diagnosis:  Meloidogyne chitwoodi is related to M. hapla Chitwood, 1949 in some respects but differs markedly in (i) the perineal pattern, including its overall round to oval shape and especially by the presence of broken, curved, twisted, or curled striae around and above the anal area, and by the sunken vulva in an area without striae; (ii) the presence of vesicles or vesicle-like structures in the median bulb of the females as described above; and (iii) the nature of the larval tail, being short and blunt with the hyaline tail terminal showing little or no taper to its rounded terminus.  Although M. querciana Golden, 1979 has a sunken vulva in an area devoid of striae, other characteristics of this species, including the nature of the perineal striae and length of the female stylet (average 17.5 um), readily distinguish it from M. chitwoodi.

DNA Sequences Obtained
Specimen: Collected:
SLV 1402 San Luis Valley, CO
NM-03 CD
NM-03 CE
CSS TX-04 Texas
CSs TX-07 Texas
BP-01 Nebraska supermarket 
BP-02 Nebraska supermarket 
McAZ Potato1 Arizona