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The starry batfish Halieutaea stellata (Vahl) is a small, benthic fish found in Indo-West Pacific Oceans. However, our present knowledge of the helminth parasites of this fish is still fragmentary. In this study, a total of 29 fish collected from the East and South China Sea were examined to determine the prevalence, intensity and species composition of helminth parasites in H. stellata. Using morphological and molecular approaches, four species of nematodes were found parasitic in this fish host, including the adults and fourth-stage larvae of Raphidascaroides nipponensis Yamaguti 1941; adults and third-stage larvae of Raphidascaris lophii (Wu 1949), third- and fourthstage larvae of Hysterothylacium larval type IV-A of Shamsi, Gasser & Beveridge 2013 and thirdstage larvae of Hysterothylacium amoyense (Hsu 1933). Halieutaea stellata represents a new host record for the three last-named nematodes. Raphidascaroides nipponensis with the highest prevalence (82.5%) and intensity (mean = 13.5) of infection was considered as the dominant parasite species in H. stellata. The detailed morphology of the different developmental stages of the four nematode species was studied using light and scanning electron microscopy. All nematode species were also genetically characterized by sequencing and analysing the internal transcribed spacer (ITS) of the ribosomal DNA. This study provides further data on the occurrence of nematode parasites in H. stellata and also contributes to facilitate an accurate and rapid diagnosis of the infection by these little-known nematodes. [ABSTRACT FROM AUTHOR]

The central inversion zone in the Xihu Depression, East China Sea, was formed during the Late Miocene. The entire Tertiary succession, nearly 10,000 m thick, has undergone inversion here. The succession is composed mainly of sandstones and mudstones with minor coals and non-marine limestones. Hydrocarbons are present in a series of structural traps which formed as a result of inversion-related deformation. Oil and gas exploration in the Xihu Depressions has demonstrated that at least 90% of the commercial reserves so far found occur in inversion-related structural traps in the central inversion zone, mainly in Eocene (Pinghu Formation) and Oligocene (Huagang Formation) sandstone reservoirs. Previous studies have shown that structural traps are controlled by the intensity and style of inversion tectonics. However, the relationship between the geometry, kinematics and size of the inversion structures and the oil and gas accumulations is not well understood. In this paper, the factors controlling trap formation (and hydrocarbon acumulations) in the study area are considered. Data came from 2D reflection seismic and electic logs from a number of wells. Controlling factors include inversion fault activity rate, inversion rate and the thickness of sediments eroded as a result of inversion-related uplift of the Tertiary succession. The results show that the best exploration targets are located in the southern part of the central inversion zone. This area has a relatively low inversion fault activity rate (average 3.0 m/Ma) and a low inversion rate (average 0.4); a relatively small thickness of sediments was eroded from the Miocene Longjing and Liulang Formations (< 400 m) and the Eocene Pinghu Formation. By contrast, the northern part of the central inversion zone has a relatively high inversion fault activity rate (average 6.8 m/Ma) and a high inversion rate (0.8), and greater thicknesses of sediments were erosively removed (up to 1600 m). This may have resulted in the less favourable preservation of traps and the large-scale leakage of oil and gas. Most oil and gas accumulations occur in the southern part of the central inversion zone, especially in reservoirs in the Longjing, Liulang and Pinghu Formations. [ABSTRACT FROM AUTHOR]