赤水河四川华吸鳅的早期发育

Early Development of Sinogastromyzon szechuanensis in the Chishui River

四川华吸鳅Sinogastromyzon szechuanensis为长江上游特有鱼类。为了积累其生物学资料,为相关的保护措施提供参考,于2009年通过人工授精获得四川华吸鳅受精卵,对其胚胎和仔鱼的发育过程进行了观察和描述。四川华吸鳅的受精卵呈浅黄色,卵膜径较小（1.85 mm±0.23 mm）,具粘性。在水温26.3~27.8℃下,胚体经历22 h34 min发育成仔鱼出膜;初孵仔鱼全长4.39 mm±0.21 mm,肌节37对;日龄4 d时,卵黄囊吸收完毕,进入外营养期;日龄65 d时,鳞片长齐,进入幼鱼期。整个早期发育过程历时65 d 22 h 34 min。

Sinogastromyzon szechuanensis,which belonged to the cyprinoid family Homalopteridae,is endemic to the upper of the Yangtze River.Understanding its biological information was an important consideration for conservation.From June to August 2009,we continuously observed early development process of S.szechuanensis with artificial fertilized eggs.A total of 45 development stages,30 embryonic and 15 postembryonic ones,had been described and photographed.The buff-colored eggs were in oval shape with membrane-viscous.The average diameter of egg membrane was 1.85 mm±0.23 mm.Under the temperature of 26.3~27.8℃,the first cleavage occurred 40 min after fertilization,the gastrula and muscular contraction stages began at 5 h 23 min and 13 h 39 min,respectively,hatching stage was observed at 22 h 34 min after fertilization.Newly hatched larvae were 4.39 mm±0.21 mm in average total length with 27 pairs of myomeres.Yolk exhaustion and fins differentiation stages completed at 4 d and 16 d after hatching,respectively.65 d after hatching,the scales emerged all over the body surface and juvenile stage started.As a whole,the early development process of S.szechuanensis lasted 65 d 22 h 34 min.