Abstract: A new eubrachythoracid arthrodire, Phymosteus liui gen. et sp. nov., is described from the Upper Devonian (Early Famennian) Xiejingshi Formation of Shimen County, Hunan, central China. The specimen under study, a nearly complete nuchal plate, was collected from the upper part of the formation in association with plant fossils , such as Leptophloeum guanzhuangense and Cyclostigma hunanense, by Dr. Gen Baoyin of Institute of Botany, Chinese Academy of Sciences in 1990s. The new form is at the pachyosteomorph level of organization having a large nuchal gap and possibly referred to the Selenosteidae of aspinothoracid arthrodires. It is the first record of the aspinothroacid arthrodires from China , but whether it widens the distribution of the Selenosteidae from Europe and North America to Asia needs further fossil materials.

摘要： 本文报道的鱼类化石产自湖南石门大京州的上泥盆统写经寺组。在中国泥盆纪地层分区上 ,化石产地属于华南区的湘、鄂、川交界分区(侯鸿飞等 ,1988) 。该分区泥盆系为一套厚度不超过 500 m 的近岸海相碎屑岩沉积 ,仅发育中泥盆统上部至上泥盆统(图 1) ,并普遍超覆在志留系温洛克统之上 ,以角度不整合伏于石炭系或二叠系之下。上泥盆统分两个组 ,从下而上分别为黄家磴组和写经寺组。黄家磴组系杨敬之、穆恩之(1953) 创立 ,标准地点在湖北长阳马鞍山东端的黄家磴。岩性为砂岩夹少量页岩 ,植物化石丰富 ,并含有