广西下泥盆统南极鱼类(盾皮鱼纲:节甲鱼目)一新属(英文)

依据采自广西平果早泥盆世郁江组中部的化石材料,记述了盾皮鱼纲节甲鱼目南极鱼科的一新属、新种——小眼坡塘鱼(Potangaspis parvoculatusgen.et sp.nov.)。该新属的眶孔很小,且为颅顶甲骨片所完全包围;中点线沟发育,与眶上感觉沟、中心感觉沟和后点线沟一起共同向颈片的骨化中心辏合。系统发育分析表明新属和发现于南极洲中泥盆统的南极鱼属构成姐妹群关系,支持了南极鱼科位于节甲鱼目最基干位置的假说,同时为早埃姆斯期东冈瓦纳大陆与中国南方之间的古地理密切联系提供了新的证据。

A NEW ANTARCTASPID ARTHRODIRE (PLACODERM FISH) FROM THE LOWER DEVONIAN OF GUANGXI, CHINA

Potangaspis parvoculatus, a new genus and species of the Antarctaspidae (Placodermi: Arthrodira ) , is described from the early Emsian (Yukiang Formation, Early Devonian) of Pingguo, Guangxi, China. This new form is characterized by small orbits enclosed by skull roof, and long, narrow nuchal plate on which the central and supraorbital sensory canals, middle and posterior pit-lines converge. Phylogenetic analysis corroborates the basal position of the family Antactaspidae amongst the Arthrodira, and suggests a sister group relationship between the new form and Antarctaspis mcmurdoensis from the Middle Devonian of Antarctic, thus providing additional evidence to support the biogeographic proximity between South China and East Gondwana during the early Emsian.