Stunt nematodes (Tylenchorhynchus spp.) are important plant parasitic nematodes that feed on a wide range of economic hosts. A survey of plant parasitic nematodes was performed in corn fields in May 2019, finding corn seedlings with symptoms like yellow leaves, dwarf plants and death plants in the field (N 37°07′36″, E 102°54′08″) of Baiyin City, Gansu Province, China. The rhizosphere soil samples and roots of diseased plants were collected. Each soil sample was about 1 kg consisted of over 20 corers using a soil auger of 20 cm in length and 20 mm diameter. Nematodes were isolated using modified Baermann technique (Hooper, 1990). On average, 5 females and 13 juveniles were obtained from 100 g soil, and 18 males and 2 females were extracted from 50 g of roots. Females bodies were cylindrical, slightly ventrally arcuated after fixation by gentle heat. Cephalic region with annules, and significant curling at the connection with body contour. Stylet with anteriorly flattened knobs, and median esophageal bulbs well developed. The vulva was located in the center of the body, and reproductive system didelphic amphidelphic. Tail conoid, with obtuse smooth terminus and phasmids almost located in the middle of the tails. Males bodies were similar to females but with slightly slender and sharper tail, with paired and relatively strong spicules, and bursa peloderan. The population showed the following morphometrics: Females (n = 20) included L = 493.97 ± 34.36 (458.45-556.38) μm, a = 25.98 ± 2.1 (22.24-28.72), b’ = 4.81 ± 0.35 (4.23-5.5), c = 15.76 ± 1.19 (13.46-17.59), c’ = 2.69 ± 0.29 (2.31-3.23), V = 57.59 ± 4.66 (50.00-66.11), V’ = 63.40 ± 3.91 (57.12-69.45), stylet length 16.02 ± 0.55 (15.36-17.29) μm, tail length 31.13 ± 2.16 (28.48-34.54) μm, M = 0.46 ± 0.03 (0.42-0.51), O = 0.16 ± 0.01 (0.14-0.17), MB = 0.57 ± 0.04 (0.52-0.63). Males (n = 20): L = 483.21 ± 29.78 (445.62-528.02) μm, a = 27.45 ± 2.1 (24.12-30.59), b’ = 4.80 ± 0.36 (4.24-5.34), c = 16.54 ± 0.98 (15.25-18.51), c’ = 2.29 ± 0.11 (2.07-2.51), stylet length 15.94 ± 0.47 (15.32-16.74) μm, tail length 29.42 ± 1.28 (27.37-31.53) μm, spicule length 18.20 ± 1.46 (15.65-21.00) μm, gubernaculum length 7.30 ± 0.68 (6.64-8.66) μm, M = 0.47 ± 0.02 (0.44-0.51), O = 0.16 ± 0.02 (0.13-0.18), MB = 0.61 ± 0.03 (0.54-0.67). The morphology of this population was in agreement with the original population of Tylenchorhynchus zeae identified in India (Sethi and Swarup, 1968). DNA was extracted from a random single nematodes (n = 10) using the Proteinase K method (Kumari and Subbotin, 2012), and the internal transcribed spacer1 (ITS1) region of rDNA and D2/D3 fragments of the 28 S rRNA were amplified with universal primers rDNA2 and rDNA1.58 s (Szalanski et al., 1997), D2A and D3B (Castillo et al., 2003), respectively. PCR products were sequenced by Tsingke Biological Technology (Beijing, China). The ITS1 sequence (MN757910, 721 bp) and D2/D3 sequence (MN757911, 802 bp) were submitted to GenBank and compared with published sequences by means of BLAST search in the database. The ITS1 sequence had a remarkably similarity of 99.00 to 99.05% with the T. zeae from Taiwan Province (EF519711) in China, and from Spain (KJ461597, KJ461598, KJ461599, KJ461600). The D2/D3 sequences exhibited 99.43 to 99.73% similarity with that of T. zeae from Iran (KM068058) and Spain (KJ461563, KJ461564, KJ461565, KJ461566). According with our morphological and molecular studies, this population was identified as T. zeae. The nematode was discovered from Zea mays in India (Sethi and Swarup, 1968), from cabbage, cauliflower and Zea mays in Taiwan Province, southeast China (Chen et al., 2007), from grapevine and olive in Spain (Handoo et al., 2014). To our knowledge, this is the first report of T. zeae in Gansu Province, northwest China, which expands the geographical distribution of the species.
