Critical Notes on the Genus Fritillaria L. (Liliaceae) of Xinjiang,China

More than thirty species and varieties of Fritillaria have been reported from Xinjiang,incluing many new taxa recently published． A revision of these was made based on mainly herbarium material and literature．As a result,seven species were recognized,including newly recorded F. stenanthera(Regel)Regel,and nine species and twenty-one varieties were reduced to synonyms．     

Quantifying the effects of nutrient addition on the taxonomic distinctness of serpentine vegetation

Traditional diversity indices summarize the information about the relative abundances of species within a community without regard to differences between species. However, intuitively, a community composed of dissimilar taxa is more diverse than a community composed of more similar taxa. Therefore, useful indices of diversity should account for taxonomic relations among species. In this paper, a new parametric diversity index that combines species relative abundances and their taxonomic distinctiveness is used to quantify the way in which soil fertilization affects the diversity of a garigue community on ultramafic soils of Tuscany (central Italy). Results show that, while ultramafic soils generally host plant communities of limited taxonomic diversity with respect to similar communities on other substrates, fertilization significantly enhances the biomass production of species that are not exclusive to ultramafic soils. As a consequence, if diversity is measured combining species relative abundances with their taxonomic distinctiveness, nutrient addition tends to increase the diversity of ultramafic communities.     

Biodiversity of marine nematodes in Australian sandy beaches from tropical and temperate regions

The universal occurrence and abundance of nematodes provides opportunities to investigate ecological factors that may influence biodiversity. Clarke and Warwick (2001) have proposed diversity indices average taxonomic distance(AvTD), variation in taxonomic distinctness (VarTD) for computing marine nematode biodiversity based on classification trees. Faith [Biological Conservation 61 (1992) 1] had previously proposed a diversity index based on phylogenetic trees, though not applied to nematodes. Clarke and Warwick (2001) also considered an index AvPD analogous to AvTD. These indices have been applied to five very large collections of free-living nematodes from three exposed sandy beaches in Australia. Two were from a beach close to Darwin in northern Australia, two from the temperate southeast coast of Australia and one from the south of the Australian mainland. The collections extend over a considerable range of latitude, from 12°26S to 38°33S and the controversial hypothesis that latitudinal gradients per se influence the biodiversity of marine nematode assemblages is examined. AvTD did not vary among collections and its value for any collection was indistinguishable from that of random samples of the same size drawn from the total species pool. VarTD showed no variation for three of the collections, but was slightly higher than expected for the mid-latitude beach, attributed to unevenness in the classification trees. AvTD and VarTD were not greatly affected by differences in sampling intensity. PD varied directly with the number of species found but observed PD did not differ from the PD of random samples of the same number of species taken from the total species pool. Thus, the observed variation in PD is wholly accounted for by variations in species richness. The number of species found increased with decreasing latitude. It appears that species richness by itself is an adequate index of biodiversity for the free-living nematodes of these sandy beaches, and more complex indices such as AvTD, VarTD and PD are unnecessary.     

Two new species of <Emphasis Type="Italic">Kyphosus</Emphasis> (Kyphosidae) and a taxonomic review of <Emphasis Type="Italic">Kyphosus bigibbus</Emphasis> Lacepède from the Indo-Pacific

Two new species of Kyphosus, K. pacificus and K. hawaiiensis, are described and the taxonomy reviewed of K. bigibbus Lacepède, 1801, closely related to the former. These three species are clearly distinguished from other species of Kyphosus in having 12 dorsal-fin soft rays, the anterior part of the dorsal-fin soft-rayed portion not elevated, 11 anal-fin soft rays, and 58–72 (usually more than 59) scales in longitudinal row along the middle body. Kyphosus pacificus is distributed in the Western-Central Pacific, being characterized by a pointed snout and 26–29 gill rakers (mode 27). Kyphosus hawaiiensis is distributed only in the Central Pacific and is characterized by a blunt snout, 23–25 gill rakers (mode 24), 18 pectoral fin soft rays, and the anterior part of the anal-fin soft-rayed portion well elevated. Kyphosus bigibbus is distributed antitropically in the Indo-West Pacific and is characterized by a blunt snout, 21–24 gill rakers (mode 22), 19 pectoral fin soft rays, and the anterior part of the anal-fin soft-rayed portion not elevated. In addition, Pimelepterus fallax Klunzinger, 1884 was found to be a junior synonym of K. bigibbus Lacepède. A lectotype and paralectotypes are designated for the former because the original type series included an example of a second species.     

关于中国香鱼分类地位的线粒体DNA基因序列分析

测定了辽宁和广东香鱼的Cytb基因序列,与GenBank中日本和韩国香鱼分子数据合并比较。结果表明11尾香鱼402个碱基序列中变异位点8个,信息简约位点有2个,A+T与G+C含量分别为51.4%和48.6%,转换/颠换比为4.9。运用Kimura-2parameter模型,采用邻接法构建的分子系统树,发现中国香鱼与日本和韩国香鱼聚类在一起,不同地理种群的香鱼均未单独分群,表明中国和日、韩香鱼亲缘关系相当近。根据日、韩香鱼的地理分布,推测所分析的辽宁和广东种群可能亦为香鱼指名亚种,但该推论尚需与琉球香鱼亚种的序列进行比较后才能确定。研究虽未发现辽宁香鱼和广东香鱼间存在明显的种群结构差异,但由于中国海域辽阔,生境多样,中国沿海是否会有其它种下群体发生,则需要采用进化速度适中的线粒体和核基因标记,对中国香鱼不同的地理种群进行广泛的大样本分析来确定。     

矮生栒子的分类学研究

在有关模式和产地标本研究基础上,结合叶表皮微形态和细胞学资料,对矮生Ｘｕｎ子（Ｃｏｔｏｎｅａｓｔｅｒ ｄａｍｍｅｒｉ Ｓｃｈｎｅｉｄ．）进行了分类学修订,结果将Ｃ．ｄａｍｍｅｒｉ Ｓｃｈｎｅｉｄ．ｖａｒ．ｒａｄｉｃａｎｓ Ｓｃｈｎｅｉｄ．（即Ｃ．ｒａｄｉｃａｎｓ（Ｓｃｈｎｅｉｄｅｒ）Ｋｌｏｔｚ）归并作该种的同物异名;并描述了矮生Ｘｕｎ子的１个新亚种,Ｃ．ｄａｍｍｅｒｉ ｓｓｐ．ｓｏｎｇｍｉｎｇｅｎ     

宽叶金粟兰及其近缘类群的修订

在标本室研究和野外考察的基础上,对宽叶金粟兰Chloranthus henryi及其近缘种进行了分类学修 订。确认了宽叶金粟兰、及己C．serratus、华南金粟兰C．sessilifolius和台湾金粟兰C．oldhami,将单穗金 粟兰C．monostachys、湖北金粟兰C．hupehensis 、C. philippinensis、C．verticillatus和台湾及己C．serratus var．taiwanensis处理为新异名。通过研究合模式及有关照片,指定了宽叶金粟兰、多穗金粟兰C.multis-tachys和湖北金粟兰的后选模式。     

Benchmarking of 16S rRNA gene databases using known strain sequences

16S rRNA gene analysis is the most convenient and robust method for microbiome studies. Inaccurate taxonomic assignment of bacterial strains could have deleterious effects as all downstream analyses rely heavily on the accurate assessment of microbial taxonomy. The use of mock communities to check the reliability of the results has been suggested. However, often the mock communities used in most of the studies represent only a small fraction of taxa and are used mostly as validation of sequencing run to estimate sequencing artifacts. Moreover, a large number of databases and tools available for classification and taxonomic assignment of the 16S rRNA gene make it challenging to select the best-suited method for a particular dataset. In the present study, we used authentic and validly published 16S rRNA gene type strain sequences (full length, V3-V4 region) and analyzed them using a widely used QIIME pipeline along with different parameters of OTU clustering and QIIME compatible databases. Data Analysis Measures (DAM) revealed a high discrepancy in ratifying the taxonomy at different taxonomic hierarchies. Beta diversity analysis showed clear segregation of different DAMs. Limited differences were observed in reference data set analysis using partial (V3-V4) and full-length 16S rRNA gene sequences, which signify the reliability of partial 16S rRNA gene sequences in microbiome studies. Our analysis also highlights common discrepancies observed at various taxonomic levels using various methods and databases.     

Taxonomic surrogacy in biodiversity assessments,and the meaning of Linnaean ranks

The majority of biodiversity assessments use species as the base unit. Recently, a series of studies have suggested replacing numbers of species with higher ranked taxa (genera, families, etc.); a method known as taxonomic surrogacy that has an important potential to save time and resources in assesments of biological diversity. We examine the relationships between taxa and ranks, and suggest that species/higher taxon exchanges are founded on misconceptions about the properties of Linnaean classification. Rank allocations in current classifications constitute a heterogeneous mixture of various historical and contemporary views. Even if all taxa were monophyletic, those referred to the same rank would simply denote separate clades without further equivalence. We conclude that they are no more comparable than any other, non‐nested taxa, such as, for example, the genus Rattus and the phylum Arthropoda, and that taxonomic surrogacy lacks justification. These problems are also illustrated with data of polychaetous annelid worms from a broad‐scale study of benthic biodiversity and species distributions in the Irish Sea. A recent consensus phylogeny for polychaetes is used to provide three different family‐level classifications of polychaetes. We use families as a surrogate for species, and present Shannon‐Wiener diversity indices for the different sites and the three different classifications, showing how the diversity measures rely on subjective rank allocations.