Identification and characterization of a new species of Taxus - Taxus qinlingensis by multiple taxonomic methods.

BACKGROUND: The taxonomy of Taxus Linn. remains controversial due to its continuous phenotypic variation and unstable topology, thus adversely affecting the formulation of scientific conservation strategies for this genus. Recently, a new ecotype, known as Qinling type, is mainly distributed in the Qinling Mountains and belongs to a monophyletic group. Here, we employed multiple methods including leaf phenotype comparison (leaf shapes and microstructure), DNA barcoding identification (ITS + trnL-trnF + rbcL), and niche analysis to ascertain the taxonomic status of the Qinling type. RESULTS: Multiple comparisons revealed significant differences in the morphological characters (length, width, and length/width ratio) among the Qinling type and other Taxus species. Leaf anatomical analysis indicated that only the Qinling type and T. cuspidata had no papilla under the midvein or tannins in the epicuticle. Phylogenetic analysis of Taxus indicated that the Qinling type belonged to a monophyletic group. Moreover, the Qinling type had formed a relatively independent niche, it was mainly distributed around the Qinling Mountains, Ta-pa Mountains, and Taihang Mountains, situated at an elevation below 1500 m. CONCLUSIONS: Four characters, namely leaf curvature, margin taper, papillation on midvein, and edges were put forward as primary indexes for distinguishing Taxus species. The ecotype Qingling type represented an independent evolutionary lineage and formed a unique ecological niche. Therefore, we suggested that the Qingling type should be treated as a novel species and named it Taxus qinlingensis Y. F. Wen & X. T. Wu, sp. nov.

Response of distribution patterns of two closely related species in Taxus genus to climate change since last inter-glacial.

Climate change affects the species spatio-temporal distribution deeply. However, how climate affects the spatio-temporal distribution pattern of related species on the large scale remains largely unclear. Here, we selected two closely related species in Taxus genus Taxus chinensis and Taxus mairei to explore their distribution pattern. Four environmental variables were employed to simulate the distribution patterns using the optimized Maxent model. The results showed that the highly suitable area of T. chinensis and T. mairei in current period was 1.616 × 105 km2 and 3.093 × 105 km2, respectively. The distribution area of T. chinensis was smaller than that of T. mairei in different periods. Comparison of different periods shown that the distribution area of the two species was almost in stasis from LIG to the future periods. Temperature and precipitation were the main climate factors that determined the potential distribution of the two species. The centroids of T. chinensis and T. mairei were in Sichuan and Hunan provinces in current period, respectively. In the future, the centroid migration direction of the two species would shift towards northeast. Our results revealed that the average elevation distribution of T. chinensis was higher than that of T. mairei. This study sheds new insights into the habitat preference and limiting environment factors of the two related species and provides a valuable reference for the conservation of these two threatened species.

Development of chloroplast microsatellite markers for Glyptostrobus pensilis (Cupressaceae).

PREMISE: Glyptostrobus pensilis (Cupressaceae) is a critically endangered conifer native to China, Laos, and Vietnam, with only a few populations remaining in the wild. METHODS AND RESULTS: Using a complete chloroplast genome sequence, we designed 70 cpSSR loci and tested them for amplification success and polymorphism in 16 samples. Ten loci were found to be polymorphic and their genetic diversity was characterized using a total of 83 individuals from three populations in China. A total of 43 haplotypes were present, the effective number of haplotypes varied from 4.55 to 13.36, and the haplotypic richness ranged from 8.04 to 16.00. Gene diversity ranged from 0.81 to 0.97 (average 0.89). The number of alleles per locus and population ranged from one to eight, and the effective number of alleles ranged from 1.00 to 3.90. All polymorphic loci were successfully amplified in the related species Cryptomeria japonica var. sinensis, Taxodium distichum, T. ascendens, and Cunninghamia lanceolata. CONCLUSIONS: These newly developed chloroplast microsatellites will be useful for population genetic and phylogeographic analyses of G. pensilis and related species.