Abstract: A new species of Microbrachius, M. chuandongensis sp. nov., is described in this paper. The referred specimens include one complete head-shield articulated with its trunk-armour, one head-shield, two trunk-armours, one proximal segment of the pectoral appendage, and some plates showing the ornamentation. All the material was collected from the Upper Emsian (Lower Devonian) of Chuandong Village, west Qujing, Yunnan Province.

摘要： 记述了胴甲鱼类(antiarchs)小肢鱼一新种，穿洞小肢鱼(Microbrachius chuandongensis sp. nov.)。该化石发现于云南曲靖下泥盆统上部穿洞组，其时代大致与埃姆斯期(Emsian)相当。新种在以下3点与中华小肢鱼(M. sinensis)明显不同:1)个体明显小于中华小肢鱼;2)新种前中背片为五边形，举穴宽;3)新种纹饰在背甲上由纵向排列细而密的嵴组成。新种由于具有较大的中腹片和嵴状纹饰上没有瘤状突起，因而与小肢鱼的属型种M. dicki不同。