A NEW SPECIES OF APHRAXONIA FROM THE UPPER MIDDLE DEVONIAN OF THE SOUTH TIANSHAN AREA, XINJIAGN, CHINA

Aphraxonia , a rare Middle Late Devonian rugosa coral genus with columella structure, was previously only known from two localities: Upper Devonian of Anatolia area, Turkey and the Qiziqiao Formation (Givetian) of Hunan Province, China (U··nsalaner, 1951; Jia et al ., 1977), including two species: Aphraxonia taurensis U··n salaner and Aphraxonia zhuzhouensis (Jia). Aphraxonia zhuzhouensis (Jia) was originally described by Jia (see Jia et al ., 1977) under the genus Hunanaxonia . After comparing the main features of Aphraxonia U··nsalaner, 1951 and Hunanaxonia Jia, 1977, Hill (1981) thought that no basic differences between the two genera and, thus, he put Hunanaxonia under the subjective synonyms of Aphraxonia U··nsalaner, 1951. In this paper, we report a new species of the genus, namely Aphraxonia wuqiaensis sp, nov., collected from the Middle Devonian of the South Tianshan area, Xinjiang. This new species represents an intermediate form between Aphraxonia taurensis U··nsalaner and Aphraxonia zhuzhouensis (Jia) in the internal morphlogical features. It is the first time to confirm the existence of Aphraxonia outside the Anatolia area of Turkey and Hunan Province of China. This discovery demonstrates that Aphraxonia has wide geographical distribution during the Middle to Late Devonian period although it is rare in the fossil record. It also suggests that the South Tianshan area had close biogeographical relationship with both Turkey and Southern China during the Devonian. The new species was collected from the Middle Devonian Tuogemati Formation on a section, located about 12 km northwest to Tuopa town of Wuqia County, exposed along the highway from Tuopa toTuergart between milestones 96 99 km (Text fig.1). On this section, the Tuogemati Formation is about 800 900 m thick and mainly consists of thin bedded marly limestone and bioclastic limestone. It was conformably overlie by a set of Late Devonian flysch accumulation. At its bottom a reversal fault made it directly contacted with Quaternary fluvial sediments. The new species occurs near the top of the Tuogemati Formation. Abundant tabulate corals Alveolites sp. and Striatopora sp., as well as a few rugosa coral Thamnophyllum sp. and brachiopod Athysina? sp. are found to co exist with the new species. Both Zhou and Chen (1991) and Zhou (2001) mentioned the following fossils were found from the upper part of the Tuogemati Formation around this area, including corals Temnophyllum sp., Alveolites sp., Disphyllum sp., Neospongophyllum sp.; brachiopods Spinatrypa sp., Schizophoria sp., Gypidula sp., Desquamata sp., Emanuella sp., Undispirifer sp., Stringocephalus sp., Borhardtina sp. etc. These fossils indicate that the Tuogemati Formation is Giveian in age.