Two new species of Helochares, with additional faunistic records from China (Coleoptera, Hydrophilidae, Acidocerinae).

Two new species, Helocharesguoi Yang & Jia, sp. nov. and Helocharesdistinctus Jia & Tang, sp. nov., are described. Two species are recorded for the first time from China: Helocharesnegatus Hebauer, 1995 from Yunnan, and Helocharesminusculus d'Orchymont, 1943 from Guangdong. Additional faunistic data from China are provided for the following species: Helochareshainanensis Dong & Bian, 2021, Helocharesnipponicus Hebauer, 1995, Helocharessauteri d'Orchymont, 1943, Helocharesdensus Sharp, 1890, Helochareslentus Sharp, 1890, Helocharesneglectus (Hope, 1854) and Helocharesanchoralis Sharp, 1890. The Chinese fauna of Helochares comprises 16 species, 11 of which are illustrated in this contribution. Helocharescrenatus Régimbart, 1921 is removed from the Chinese fauna.

Ion micro-distribution in varying aged leaves in salt-treated cucumber seedlings.

Na+ distribution is one of the most important strategies for plant resistance to salt stress. The way of Na+ compartmentation in different aged leaves has been controversial, especially at the cell and sub-cellular level. The roles that Na+ and K+/Na+ play the key role in photosynthesis need to be further verified. In this study, using two cucumber cultivars Cucumis sativus L. cv. zhongnong 8 (ZN8, relatively salt tolerant) and Cucumis sativus L.cv. Jinchun 4 (JC4, salt sensitive) as experiment material, we analyzed the mode of ion compartmentation of Na+ in organelles in different aged leaves and determined which factors (the organelles' Na+ or K+/Na+) affect leaf photosynthesis, using high-pressure freezing and freeze-substitution, Ultrathin sectioning technique and X-ray. The main results: 1. The sub-cellular trends of Na+ accumulation was cell wall > vacuole > cytoplasm > chloroplasts; 2. The Na+ accumulation in cytoplasm and chloroplasts was similar in different aged leaves and in seedlings of different salt tolerance cultivars; 3. The K+/Na+ ratio is the main factor that affects the photosynthesis of the same aged leaves in our experiment. A weak capacity for ion compartmentation may be an important reason leading to salt sensitivity.

A faunistic study of genus Chasmogenus Sharp, 1882 of China (Coleoptera, Hydrophilidae).

Chasmogenus Sharp, 1882 is newly reported from the Chinese Mainland. A new species, C. parorbussp. n., is described from China (Yunnan). Chasmogenus orbus Watanabe, 1987 is reported from Hong Kong, the first record outside Japan. Chasmogenus abnormalis (Sharp, 1890) is reported from the Chinese mainland for the first time. The male genitalia of each species are illustrated. A key to the Chinese species of the genus is provided.

Description of three new species of Crenitis Bedel from China, with additional faunistic records for the genus (Coleoptera: Hydrophilidae: Chaetarthriinae).

Three new species of the genus Crenitis Bedel, 1881 are described from China: C. aduncata sp. nov. (Yunnan), C. lianggeqiui sp. nov. (Yunnan and Sichuan) and C. obovata sp. nov. (Guangxi and Guizhou). All three species are assigned to the subgenus Crenitis. New locality records in China are provided for C. apicalis (Reitter, 1896) (from Inner Mongolia) and C. convexa Ji & Komarek, 2003 (from Ningxia, Chongqing). A key to the Chinese species of the subgenus Crenitis is provided.

Effect of root length on epicotyl dormancy release in seeds of Paeonia ludlowii, Tibetan peony.

BACKGROUND AND AIMS: Epicotyl dormancy break in seeds that have deep simple epicotyl morphophysiological dormancy (MPD) requires radicle emergence and even a certain root length in some species. However, the mechanisms by which root length affects epicotyl dormancy break are not clear at present. This study aims to explore the relationship between root length and epicotyl dormancy release in radicle-emerged seeds of Tibetan peony, Paeonia ludlowii, with discussion of the possible mechanisms. METHODS: Radicle-emerged seeds (radicle length 1.5, 3.0, 4.5 and 6.0 cm) were incubated at 5, 10 and 15 °C. During the stratification, some seeds were transferred to 15 °C and monitored for epicotyl-plumule growth. Hormone content was determined by ELISA, and the role of hormones in epicotyl dormancy release was tested by exogenous hormone and embryo culture. KEY RESULTS: Cold stratification did not break the epicotyl dormancy until the root length was ≥6 cm. The indole-3-actic acid (IAA) and GA3 contents of seeds having 6 cm roots were significantly higher than those of seeds with other root lengths, but the abscisic acid (ABA) content was lowest among radicle-emerged seeds. GA3 (400 mg L(-1)) could break epicotyl dormancy of all radicle-emerged seeds, while IAA (200 mg L(-1)) had little or no effect. When grown on MS medium, radicles of naked embryos grew and cotyledons turned green, but epicotyls did not elongate. Naked embryos developed into seedlings on a mixed medium of MS + 100 mg L(-1) GA3. CONCLUSIONS: A root length of ≥6.0 cm is necessary for epicotyl dormancy release by cold stratification. The underlying reason for root length affecting epicotyl dormancy release is a difference in the GA3/ABA ratio in the epicotyl within radicle-emerged seeds, which is mainly as a result of a difference in ABA accumulation before cold stratification.