云南曲靖下泥盆统“曲靖东方鱼”的分类学厘定

A taxonomical revision of‘Dongfangaspis qujingensis’from the Lower Devonian of Qujing,Yunnan Province

“曲靖东方鱼”(‘Dongfangaspis qujingensis’)的归属长期以来存在争议,其最初被归入东方鱼属(Dongfangaspis),之后被归入宽甲鱼属(Laxaspis)。然而,由于宽甲鱼属模式种为曲靖宽甲鱼(Laxaspis qujingensis),这一分类学厘定又引起异物同名的问题。描述了来自云南曲靖早泥盆世洛赫考夫期西山村组的“曲靖东方鱼”和变异坝鱼(Damaspis vartus)的新材料。“曲靖东方鱼”在头甲长略大于宽,侧横管末端呈二分叉,V字型后眶上管不汇合,以及至少7条侧横管从侧背管发出等方面与变异坝鱼高度相似。这些相似之处表明,相较于宽甲鱼属和东方鱼属,“曲靖东方鱼”更接近坝鱼属。因此提出将“曲靖东方鱼”从宽甲鱼属中移除,归入坝鱼属。新标本表明变异坝鱼多出来第5对长的侧横管是该种的一个鉴别特征,而正型标本所呈现的非对称感觉管系统应为种内变异所造成。

The affinity of‘Dongfangaspis qujingensis’,initially assigned to Dongfangaspis but later to Laxaspis,has long been controversial.However,the taxonomical revision raises a new problem of junior homonym since the type species of Laxaspis is L.qujingensis.Here,we describe some new materials of‘Dongfangaspis qujingensis’and Damaspis vartus from the Xishancun Formation(early Lochkovian,Early Devonian)in Qujing,Yunnan Province.‘Dongfangaspis qujingensis’strikingly resembles Damaspis vartus in the slightly longer headshield,bifurcated ends of the lateral transverse canals,unconnected V-shaped posterior supraorbital canals,and at least seven pairs of lateral transverse canals issuing from the lateral dorsal canal.These similarities indicate that‘D.qujingensis’is more suggestive of Damaspis than Dongfangaspis and Laxaspis.Therefore,we propose to remove‘Dongfangaspis qujingensis’from Laxaspis to Damaspis.The new specimens of Damaspis vartus reveal five long lateral transverse canals on the right side,corroborating that the asymmetric sensory canal system in the holotype is the intraspecific variation.