宁夏中卫纳缪尔期古鳕类化石一新属

记述了产于宁夏中卫县石炭纪纳缪尔期地层的古鳕类化石一新属新种——潘氏黄河鳕(huanghelepis pani gen.et sp.nov.)。新属种的个体中等大小,体形狭长,头长约为体长的1/6左右。颌悬挂很倾斜,具有长而窄的梯形鳃盖骨、相对较大的下鳃盖骨。全身覆鳞,体侧各有一列高度远大于宽度的长方形侧线鳞。这是在中国石炭纪地层中古鳕类化石的首次描述。

A NEW NAMURIAN PALAEONISCOID FISH FROM ZHONGWEI, NINGXIA

Order Palaeonisciformes Berg, 1940 Family incertae sedis Huanghelepis gen. nov.Type species Huanghelepis pani gen . et sp .nov .Etymology Huanghe, Chinese pronunciation (pinyin) for Yellow River along which the fossil localities are situated; -lepis, scale, a suffix for the Latin name of fossil fish.Diagnosis Palaeonisciformes of moderate size, total length reaching 30cm. Body slender, head length about 1/6 of body length. Operculum long, narrow and narrowest in its anterior edge. Subopercular large, nearly square-shaped. Jaw suspensorium quite oblique. Teeth present both in upper and lower jaws. Pectoral fin rays not segmented proximally. Caudal fin heterocercal but nearly symmetrical in outline. Lateral line scales extremely deep in the anterior 4/5 part of body, and its depth more than three times of its breadth anteriorly.Comparison Huanghelepis shares many similarities with the early palaeoniscoid fishes, such as Howequalepis and Mansfieldiscus (Long, 1988), in following aspects: 1) the jaw suspensorium is deeply oblique forward; 2) the preopercular bone is closely contacted to the upper jaw; 3) the presence of peg-socket articulated ganoid scales; 4) the caudal fin is heterocercal. According to those, the new fish is assigned to Palaeonisciformes here.However, the new genus can be clearly distinguished from the other palaeoniscoid fishes in the following features: 1) the body is slender and the head is only about 1/6 of the total length; 2) the opercular is long and narrow, with a length more than 3 times of its breadth; 3) the breadth of the subopercular is larger than that of the opercular; 4) the lateral line scale is extremely deep.As discussed by many researchers, Palaeonisciformes or many families in this order may actually be paraphyletic (Gardiner, 1984; Long, 1988; Gardiner and Schaeffer, 1989), which means the family groupings in this order is not very convincing at present. Here the Huanghelepis is tentatively placed in Palaeonisciformes incertae sedis until more data are obtained .Huanghelepis pani gen. et sp. nov. (Figs. 2-4)Etymology After Professor Pan Jiang, the writer's supervisor.Holotype A nearly complete fish specimen and its counterpart, GMV2026 - 1 a-d.Locality and horizon Shangheyan and Xiaheyan villages, Zhongwei County, Ningxia. The upper part of Tupo Formation, late Namurian of Carboniferous in age.Diagnosis The lateral line scales have striated ornament, and are about 50 - 55 in number.