臂轮凹口虫新种及其生活史的研究

OPHRYOGLENA BRACHIONI SP. NOV. (CILIOPHORA, OPHRYOGLENIDAE) AND ITS LIFE CYCLE

于1979年7月在武昌中国科学院水生生物研究所湖汊采集水草,经研究发现须根上栖息的轮虫体内有一种专门攻击萼花臂尾轮虫和双棘臂尾轮虫的凹口虫,经鉴定系一新种,其主要特征为,传布子长椭圆形,两端较尖小,中间稍微凹;体前方有锥形的钻孔器,后端有3—5根长尾毛;大核香肠状,小核一个,椭圆形,伸缩泡一个,居中偏后。营养子圆球形,直径78—141μm,大核肾形,小核和伸缩泡各一个,亦具尾毛;裂子数为2—32个。寄生。致死轮虫,并在轮虫躯壳内完成其生活史。能形成次级包囊和抵抗性包囊。

A new ciliate of Ophryoglena was found in Jnly 1979 within the cavities of two species of rotifers, Brachionus calyflorus and Brachionus bidentata which stay on the root of some hydrophytes in the fish pond of The Institute of Hydrobiology. The characteristics of this ciliate is as follows: theront elongated ellipsoid, pointed both ends, body concave in median, with a small cone at anterior end and 3-5 caudal bristles at posterior end, macronucleus sausage-like, micronucleus ellipsoid, a contractile vacuole in medial part of body; trophont spheroid shaped, 78-141 μm in diameter; macronucleus kidney shaped, a micronucleus and contractile vacuole and having caudal bristles like those of theront; parasitic, can kill rotifer and complete its life cycle within body of rotifer including five stages, forms secondary cyst in the water and resistant cyst in the shell of rotifer.Infection test shows that: 1) 2, 4, 8 cells of tomont can become theront to infect the host success fuly; 2) 16, 32 cells of tomont can not attack the host successfuly; 3) Only the species of Brachionus can be infected. The other genera are not affected.The state of the division of this new ciliate shows two theronts can be produced in the first and second generation, four in the third, and varied numbers in the fourth.The type specimens are deposited in the Laboratory of Fish Diseases, Institute of Hydrobiology, Academia Sinica.