Spores of ferns and allied plants, and micro-algae frequently occur in abundance in Quaternary deposits, but their palaeoenvironmental significance is seldom evaluated. This paper presents morphological descriptions of spores of Selaginella sinensis (Desv.) Spring, 1843 (Selaginellaceae) and Ceratopteris cf. thalictroides (L.) Brongniart, 1821 (Parkeriaceae) and the algae Pediastrum boryanum (Turpin) Meneghini, 1840, P. simplex Meyen, 1829, P. integrum N geli, 1849 (all Hydrodictyaceae), Spiniferites Mantell, 1850, emend. Sarjeant, 1970 (Spiniferitaceae) and Concentricystes Rossignal, 1962, emend. Jiabo, 1978 (systematic position unclear), and discusses their occurrence in mostly Quaternary sedimentary successions. All are closely associated with aquatic habitats. Extant Selaginella sinensis often colonizes fairly wet hillsides and gaps between rocks, and shady sides of ravines and slopes; it is also found within thickets of trees and shrubs (boscages) and in forests with calcareous soils. Ceratopteris thalictroides, Pediastrum and Concentricystes inhabit freshwater lakes and both natural and artificial wetlands, such as paddy fields and ditches. Spiniferites is a salt-water genus and usually associated with the marine realm. Fossil and subfossil representatives of all of these taxa can be useful proxies of biodiversity and, therefore, also important for determining environmental conditions during the Quaternary period.
TANG LingYuMAO LiMiLü XinMiaoMA QingFengZHOU ZhongZeYANG ChunLeiKONG ZhaoChenBATTEN David J
The Hengduan Mountains(henceforth H-D Mountains) on the Tibet Plateau are a distribution and diversity center for many alpine genera. We examine patterns of genetic variation in an arctic-alpine plant to evaluate the possibility that the H-D Mountains constitute the area of origin of the species as well as to uncover postglacial migration routes. 220 individuals of the arctic-alpine plant Koenigia islandica were sampled from 26 populations distributed in western China and northern Finland. DNA haplotypes were identified using restriction site analysis of two chloroplast DNA intergene spacer regions, atpB-rbcL and trnL-trnF. We examined the geographical distribution of haplotype diversity in relation to latitude, and also compared various indices of diversity in putatively glaciated and unglaciated regions. Patterns of migration were inferred using nested clade analysis. A total of 25 haplotypes were detected. High haplotype diversity was found in the H-D Mountains. H3 and its radiated haplotypes were distributed in the Himalayas. Two haplotypes were fixed concurrently in the H-D Mountains and northern Finland. High genetic diversity of K. islandica and high species diversity of K. islandica are expected in the origin area. Our observations suggest that the H-D Mountains are not only the place of origin of K. islandica, but also the refugia for K. islandica on the Tibet Plateau. What is more, the migration route for the arctic-alpine plant K. islandica must have originated in the region defined by the H-D Mountains in western China extending northward to the Arctic circumpolar, and moved westward along the Himalayas, then northward across the Altay Mountains and the Central Siberian Plateau at different time periods.
LONG CongMIN YunJiangZHAO XiuXiaYANY ChunLeiSUN HangLü HouYuanTANG LingYuZHOU ZhongZe
