STUDIES ON THE FAUNA OF ACANTHOCEPHALA OF FISHES FROM MIDDLE REACHES OF THE CHANGJIANG(YANGTZE)RIVER

Ten species of Acanthocephala were collected from 766 fishes belonging to 72 species along middle Changjiang River from December 1981 to April 1985. In addition to seven known species, two new species(Neoechinorhynchus saurogobi and Brentisentis yangtzensis)and a new combination(Brentisentis cyprini)are presented herein. The diagnoses of the new findings are given below with the measurements in mm.Neoechinorhynchus saurogobi sp. nov.(Fig. 1)Body long and slender, slightly enlarged anteriorly and curved ventrally. Trunk smooth, with circular lacunar system. Giant hypodermic nuclei 1-6 in dorsal side and single in ventral side. Proboscis very small, globular, with 6 spiral rows of 3 hooks each, hooks of first circle large, second and third circles remarkably small. Proboscis receptacle saccular, singlelayered, with ganglion at its base. Two lemnisci stout, unequal, usually with 1-2 giant nuclei.Male. Usually much smaller than female. Body 2.52-6.79 long, 0.29-0.57 broad. Proboscis 0.099-0.120×0.099—0.105, hooks of first circle 0.043-0.046×0.007; second circle 0.030-0.036×0.005; third circle 0.026-0.030×0.004—0.005. Proboscis receptacle 0.19—0.24×0.074—0.110. Longer lemniscus 1.23-1.62; shorter one 0.92-1.48. Two testes at posterior end of middle trunk, elongate elliptical, disconnected, anterior one 0.19-1.54×0.10—0.41, posterior one 0.18-1.23×0.13-0.45. Cenent gland syncytial, with several elongate elliptical nuclei.Female: Body 4.35-14.06 long, 0.75—1.03 broad. Proboscis 0.082-0.105×0.080-0.115. Hooks of first circle 0.036-0.052×0.008; second one 0.026-0.036×0.003-0.005; third one 0.020-0.036×0.005. Proboscis receptacle 0.18-0.26×0.09-0.14. Longer lemniscus 0.93-2.21; shorter one 0.90-1.85. Uterine bell funnel-shaped, genital pore terminal, length of uterus and uterine bell combined 0.30-0.49. Eggs ovoid, 0.030-0.036×0.016-0.018.Host: Saurogobio dabryi Location: IntestineDistribution: Changjiang River(Huanggang County, Hubei Province).Holotype(♂), allotype ♀, paratypes 2(♂)(♂)and 4♀♀, deposited in the Institute of Hydrobiology, Academia Sinica.N. saurogobi sp. n. is similar to N. agilis Rus, 1819, but its proboscis and hooks are remarkably smaller. The ratio of length to breadth of the eggs of N. saurogobi sp. n. is 2:1 while that of N. agilis is about 4:1. Besides, N. agilis was recorded from marine and brackish- water fishes, instead of freshwater fish. Brentisentis yangtzensis sp. nov.(Fig. 2)Body milky white, cylindrical, somewhat stouter iri anterior third. Proboscis claviform,0.90-1.13 long, 0.19-0.41 broad, with 17 longitudinal rows of 16-19(usually 17-18)looks each, dorsal and ventral hooks usually larger than those in both sides. Subapical hooks being the largest, then gradually decreasing toward the base, basal hooks somewhat slender. First circle of dorso-ventral hooks 0.051-0.053×0.009-0.010; lateral 0.035-0.047×0.007—0.009, second circle of dorso-ventral 0.062-0.066×0.012-0.015; lateral 0.055-0.061×0.009-0.013, basal hooks at dorso-ventral 0.045-0.057×0.008-0.009; lateral 0.035-0.053×0.006-0.008. Neck short, 0.23-0.36×0.16-0.26. Trunk provided with thick spines at its anterior narrow region, forming 6-11 incomplete circles, spines at ventral side usually more than dorsal side, spines 0.020-0.039×0.006-0.013. Proboscis receptacle long saccular, with doublewalls, 1.6-2.3 long and 0.28-0.37 broad, ganglion at its anterior portion. Lacunar system reticular. Lemnisci usually 2,(2-4), longer than proboscis receptacle, equal or unequal in length, occasionally bifurcated at tip.Male: Usually smaller than female. Body 6.07-8.16 long, 0.74--1.03 broad. Testes situated tandem in the middle of trunk, anterior one 0.42-0.65×0.41-0.57; posterior one 0.30-0.70×0.41-0.51. Cement glands 8 in number, well-developed, sausage in shape, slightly enlarged anteriorly, gathered in a sheaf, situated behind the testes. Seminal vesicle and cement glands overlaping. Posterior end with well-developed bursal cap.Female: Body 8.7-13.0 long, 0.8-1.1 broad. Uterus and uterine bell 0.81-0.98 long. Egg elongate with fine transverse striations, with polar prolongations on midde layer of shell, size 0.068-0.078×0.013-0.016.Host: Leiocassis longirostris(type host), L crassilabris, Pseudobagrus fulvidraco,Parasilurus asotus, Leptobotia elongata, etc.Location: Intestine.Distribution: Changjang River(Yidu and Huanggang County, Hubei Province).Holotype(♂), allotype ♀, paratypes 9(♂)(♂)and 9♀♀, deposited in the Institute of Hydrobiology, Academia Sinica.This species resembles Brentisentis uncinus Sandra H. Leotta et al., 1982, but differs from the latter by the proboscis 19-24 longitudinal rows of 16-20 hooks each. Moreover, it differs in size and arrangement of the hooks of B. uncinus.