PLANT PARASITIC NEMATODES OF NORTH-WESTERN I. THE GENUS TYLENCHORHYNCHUS

BY

C. L. SETHI AND GOPAL SWARUP Division of Mycologyand Plant Pathology, Indian Agricultural Research Institute, New A survey of four States of north- revealed a preponderance of species of Tylen- chorhynchus in soil samples. Eleven known species, three of which are recorded for the first time from India, and four new species, T. chorzai,T. zeae, T. phaseoli and T. berberidis, were identified in these collections. The new species are described and illustrated and the geographical distribution and associated plants of the other species are given.

Four States of north-western India, Delhi, , Himachal Pradesh and , were surveyed for plant parasitic nematodes. A total of 477 soil samples (106 from Delhi, 198 from Punjab, 95 from Himachal Pradesh and 78 from Rajasthan) from the root zones of field crops, bushes, trees and ornamentals were collected and analysed. The results showed a preponderance of the genus Tylenchorhynchus in the samples: eleven known species and four new ones were identified. T. acutus Allen, 1955, T. martini Fielding, 1956 and T. ewingi Hop- per, 1959 are recorded for the first time from India. The descriptions of the new species are given.

TYLENCHORHYNCHUSCHONAI *) N. SP. Fig. 1, A-C Measurements: 12 Females: L = 0.56-0.66 mm; a = 28-32; b = 4.3-5.8; = = c 15-17; V = 57-62 ; spear 25-28 f.1o. 6 Males: L = 0.57-0.67 mm; a = 28-34; b = 5.0-5.5; c = 15-16; T = 38-42; = spear 25-29 f.1o. = = Female (holotype) : L 0.56; a = 28; b = 4.3; c = 17; V = 59 ; spear Body cylindrical, tapering at both ends, slightly ventrally arcuate when relaxed by gentle heat. Body coarsely annulated with transverse striae averaging about 2-3 tt apart at mid-body. Lateral field with three incisures with the outer margins slightly crenate and ending behind spear base. Phasmids located four annules behind anal opening. Lip region rounded with three labial annules; continuous with body contour; sclerotisation inconspicuous. Spear with prominent knobs. Excretory pore opening slightly anterior to base of posterior bulb. Hemizonid prominent and located immediately behind excretory pore.

*) Named after Dr. B. L. Chona, former Head, Division of Mycology& Plant Pathology. 78

Gonads paired, opposed, outstretched with rounded spermathecae containing tail unstriated. Ratio sperms. Tail bluntly conoid, bearing fourteen annules; tip of tail length to anal body-width 2.5. = T = Male (allotype): L == 0.67 mm; a = 32; b = 5.0; c 16; 42; = spear 29 /A. to Body slightly arcuate when relaxed. Lip region and anterior portion similar that of female. Lateral field with three incisures and phasmids located midway on tail. Bursa with crenate margin arising about fourteen annules anterior to anterior cloaca, completely enveloping tail. Gubernaculum curved with rounded median portion, 14 It long. Spicules long when measured along the curved line. Holotype: collected December 7, 1964; vial no. D 22; slide no. D 22e; deposited with the Division of Nematology, Indian Agricultural Research Institute, New Delhi. Allotype: data same as for holotype. Paratype.r: Eleven females and five males on slides nos. D 22a, b, c, d; other data same as for holotype. Type habitat: collected around roots of Syzygium cumini.r Skeel. Type locality: Indian Agricultural Research Institute Campus, New Delhi. Diagno.ri.r: Tylenchorhynchu.r with above general description and measurements. T. chonai n. sp. differs from the closely similar T. triglyphus Seinhorst, 1963 (= T. trilineatus Timm, 1963) in head shape and in its longer stylet (20-23 /-t in T. Also isolated from around roots of Bougainvillea sp. and Hibiscus ro.ra-.rinen.ri.r L.

TYLENCHORHYNCHUSPHASEOLI N. SP. Fig. 1, D-G Measurements: 6 Females: L = 0.61-0.77 mm; a == 28-35; b = 4.0-5.4; = = c 17-20; V = 54-58; spear 19-26 [t. 5 Males: L = 0.62-0.67 mm; a = 30-37; b = 5.0-5.3; c = 14-15; T = 17-25; = spear 20-22 li. = = = = Female (holotype): L 0.74 mm; a 33; b 5.4; c = 17; V 2s 58 22; = spear 20 Body cylindrical, tapering at both ends, ventrally arcuate when killed by gentle heat; body annules moderately coarse, striae 1.2 ¡t apart at mid body. Lateral field with four incisures. Lip region bearing six annules and set off from body by deep constriction; labial sclerotisation light. Stylet with posteriorly directed knobs. Dorsal oesophageal gland opening 2 tt behind stylet base. Median bulb well developed followed by a long isthmus. Nerve ring located approximately at centre of isthmus. Excretory pore about four annules in front of anterior end of basal bulb; hemizonid prominent, immediately in front of excretory pore and two annules in length.