STUDY ON A NEW CAPILLARIID GENUS NEOCAPILLARIA gen.nov.WITH A NEW SPECIES(N. PHOXINI)FROM FRESHWATER FISH

Neocapillaria gen. nov. Generic diagnosis:Capillaridae. Body capillary,Males much smaller than females.Head end tapered,gradually expanded posteriorly.Oesophagus shorter than or almost equal to the posterior portion of body.Stichocytes clearly visible, about 35 in number.Male:Spicule slightly sclerotized,hose-like,its end spike-like;spicular sheath saccular,nonspiny.Tail expanded,with two small papillae.Cloacal aperture located at tailtip.Female:Tail blunt and round.Vulva situated slightly posterior to level of junction ofoesophogus and intestine.Eggs ellipitical, comparatively long,with plugs at two poles,Parasites of freshwater fishes.Gentype:N. phoxini sp.nov.Host:Phoxinus lagowskii variegatus Cünthcr Location:intestine.Locality:Qingjiang River(Lichuan County,Hubei Province).Diagnosis:see “generic diagnosis”.Measurements(in mm):Male(7 specimens):Length of body 3.614-4.807,maximumwidth 0.041-0.051.Length of oesophagus 1.757-2.121,length ratio of oesophagus to pos-terior part of body after oesophagus 1:1.1.stichocytes 30-35 in number.Width of ex-panded tail 0.034-0.040,of the neck above it 0.025-0.030.Spicules 0.073-0.100 in length.Female(6 specimens):Length of body 8.726-1.3.181,maximum width 0.071-0.08 1. Length of oesophagus 2.707-3.959, representing one-third of body length;stichocytes 30- 37 in number.Vulva 2.798-4.091 from anterior end,5.929-9.090 fromposterior end ,length ratio of them approximately 1:2.Eggs 0.055-0.062×0.025-0.029 insize(n=20).Discussion: Moravec(1982)clasified capillariids into 16 genera and proposed a hypoth-esis on the evolution of capillariids on the basis of the structure of their male caudal end andspicule sheath.According to the hypothesis, the evolutionary position of the new genusNeocapillaria should be between genus Pseudocapillaria and genus Freitascapillaria.The evo-lutionary route of these nematodes may be regarded as follows: from Pseudocapillaria,whosemale tail with two large subventral lobes and two papillae,spicule well sclerotized;through Neocapillaria gen.nov.,whosel male tail expanded, with two small papillae,without dividedsubventral lobes,but ventral side with a concavity,spicule present,but slightly sclerotized;to Freitascapillaria,whose male tail rounded,distinctly laterally expanded without dividedsubventral lobes and papilla,spicule absent.