Abstract: During April-June and October-December,1988, 929 fish belonging to 59 specieswere examined in Wuling Mountain Region,and 24 species of nematodes were collected andidentified.There are six species belonging to the genus Rhabdochona Railliet,1916,and twoof them are new to science. The new species are Rhabdochona onychostomi sp.nov;andR. brevichona sp.nov. Descriptions(measurements in millimeter)are given as follows:1.Rhabdochona onychostomi sp.nov.Host:Varicorhinus(Onychostoma)simus(Sauvage et Dabry)Location:Intestine.Locality:Yinjiang County,Guizhou Province; Qianjiang County,Sichuan Province.Specimens:Holotype(1♂),allatype(1♀)and paratype(4♂4♀)are deposited in theLaboratory of Fish Diseases,Institute of Hydrobiology, The Chinese Academy of Sciences.Description:Medium-sized nematode. Buccal capsule cup-shaped, with 4 basal teeth;the anterior margin anned with 6 teeth.Nerve ring located near the anterior extremitv ofmuscular oesophagus. Excretory pore located near or anterior to the middle of muscularoesophagus.Cervical papillae bifurcate, and located near the middle of pharynx. Male:(5 specimens)Length of body 5.883-9.368.Maximum width 0.101-0.110.Buccal capsule 0.017-0.020 long and 0.011-0.012 wide. Pharynx 0.105-0.129 longand 0.004 wide. Length of muscular oesophagus 0.290-0.375, and that of glandularoesophagus 2.510-3.216. Nerve ring 0.147-0.185,excretory pore 0.247-0.297 and cervicalpapillae 0.070-0.082 from anterior extremity.Seven pairs of preanal papillae,the fifth lateral,and others subventral,distance between the sixth pair and the seventh pair shorter thanbetween others.Seven pairs of postanal papillae, the second pair lateral,and otherssubventral.Left spicule thin and elongate and 0.777-0.840 in length.Right spicule thickand short,and 0.079-0.080 in length.Length ratio of spicules 9.5:1.Tail curvedventrally,its length 0.241-0.295,with a saw-tooth-like or blunt tip.Felnale:(5 specimens)Length of body 16.541-23.295. Maximum width 0.161-0.241. Buccal capsule 0.021-0.024 long and 0.012-0.013 wide, Pharvnx 0.110-0.121 longand 0.004-0.005 wide. Length of muscular oesophagus 0.401-0.437,and that of glandularoesophagus 4.073-5.478. Nerve ring 0.174-0.182, excretory pore 0.287-0.308 and cervicalpapillae 0.077-0.083 from anterior extremity.Tail provided with processes,0.351-0.413 long. Vulva postequatorial.Distance between the vulva and anterior extremity 8.758-12.114, and that between the vulva and posterior extremity 7.783-11.181; the ratio of thetwo distanees 1.1:1.Size of mature eggs 0.035-0.038×0.021-0.025(n=20). Discussion: This species is different from other nematodes in that its nerve ring is relatively close to the anterior extremity of muscular oesophagus;the tail is long; tail of the female isprovided with processes,the length ratio of spicules in the male is rather high; and there are 7pairs of postanal papillae.R. onychostomi is very similar to R. fujianensis Wang,1986,but the former has longerleft spicule(0.777-0.840)than the latter(0.544-0.560),and bears 7 instead of 6 pairs ofpreanal papillae;the tail of the female in the fonner is provided with processes.2.Rhabdochona brevichona sp.nov. Host:Rectoris luxiensis Wu et Yao Location:Intestine. Locality:Qianjiang County,Sichuan Rrovince. Speimens: Holotype(1♂),allotype(1♀), andparatype(1♂3♀)are deposited in theLaboratory of Fish Diseases, Institute of Hydrobiology, The Chinese Academy of Scienees.Description: Medium-sized nematode, Buccal capsule funnel-shaped,with 2 poorly developed basaI teeth; anterior margin anned with 8 teeth.Pharynx very short, about twice asbuccal capsule. Cervical papillae bifurcate,and located near the base of buccal capsule.Male:(2 specimens)Length of body 6.951-7.202.Maximum width 0.096-0.110.Buccal capsule 0.021-0.024 long and 0.011 wide. Pharynx 0.045-0.046 long and0.003 wide. Length of muscular oesophagus 0.193-0.236, and that of glandular oesophagus1.528-1.554. Nerve ring 0.169-0.174, excretory pore 0.224-0.255 and cervical papillae0.024-0.029 from anterior extremity. 7 pairs of preanal papillae, the seventh very close to anus. Distance between the sixth and seventh pairs more than twice the distance between other pairs. All papillae subventral. 5 pairs of postanal papillae, the first pair lateral, others subventral. Left spicule 0.161-0.174 and right spicule 0.067-0.070 in length. Length ratio of spicules 2.4:1.Tail curved ventrally, 0.126-0.147).147 long, with a truncated tip. Female:(4 specimens)Length of body 10.077-12.167. Maximum width 0.204-0.257. Buccal capsule 0.026-0.027 long and 0.012-0.014 wide. Pharynx 0.046-0.054 long and 0.004 wide. Length of muscular oesophagus 0.249-0.287, and that of glandular oesophagus 1.903-3.055. Nerve ring 0.161-0.188, excretory pore 0.276-0.295 and cervical papillae 0.024-0.029 from anterior extremity. Tail 0.182-0.201 long, with crown-like appendage provided with processes. Vulva postequatorial. Distance between vulva and the antenor extremity 5.581-6.700 and that between vulva and posterior extremity 5.360-5.467;ratio of the two distances 1.16:1. Size of mature eggs 0.038-0.040×0.025-0.027(n=20).Discussion: The new species has a very short pharynx; cervical papillae are located very anteriorly(near the base of buccal capsule);tail of the male has a truncated tip; distance between the sixth and the seventh preanal papillae of male is very long. These characters make the species different from other members of the genus Rhabdochona. At present the genus Rhabdochona includes a total of 84 species. The species which have crown-like appendage provided with processes at the female tail extremity include Rhabdochona coronacauda, R. chodukini, R. sarana and R. barusi etc. Among them,R. sarana was regarded as the synonym of R. chodukini. R. barusi has 4 floats in the egg. R. coronacauda has lateral alae extending approximately from deirids to anal opening. In R. chodukini, the pharynx and the spicules are relatively long, and the tail crown consists of processes arranged in two circles. These characters make them different from the above new species.