Differentiating Thamnocalamus Munro from Fargesia Franchet emend. Yi (Bambusoideae, Poaceae): novel evidence from morphological and neural-network analyses

Shiliang Liu,Huixing Song,Mingyan Jiang,Tongpei Yi,Qibing Chen,Mingdong Ma,Rongjie Yang,Jun Yang,Durgesh K Tripathi

doi:10.1038/s41598-017-04613-9

Abstract

Fargesia Franchet emend. Yi is closely allied with Thamnocalamus Munro but differs in many major morphological characteristics. Based on traditional morphological characters, it is difficult to differentiate these two genera. The current study measured 19 species in these two genera to determine whether variations in 12 categories of major characters are continuous. In addition, a self-organizing map (SOM) and cluster analysis were used together to reveal whether the known species of Fargesia represent discontinuous sampling of Thamnocalamus. The results show that 46 morphological characteristics exhibited high variation at the generic and species levels. In addition, the cluster analysis showed that 32 morphological characteristics of Thamnocalamus and Fargesia were divided between two species and well separated from the outgroup. Additionally, significant differences (P < 0.01) were observed in the reproductive structures between these two genera. The unrooted dendrogram, which was based on the SOM neural network, shows the same results as the cluster analysis of morphological characteristics. These data indicate that Fargesia is not a result of discontinuous sampling of Thamnocalamus; thus, Fargesia should not be treated as a synonym for Thamnocalamus.

Highlights

Patterns of overall similarities and the estimated evolutionary history of the taxa[10]
The Kruskal–Wallis analysis showed that the values for WOL, IGF, PWOC, PAS, LN, LMH, SUN, and GWOH did not differ among the species studied, which indicates that these characteristics cannot be used to differentiate the species belonging the Thamnocalamus and Fargesia at P < 0.05 (Tables 1 and 2)
Guo et al.[37] and Li et al.[45] clearly discriminated two genera: Thamnocalamus, with inflorescence panicles consisting of racemes, with each subtended by a spathe; and Fargesia, with terminal inflorescences subtended by several enlarged or not enlarged spathes

Summary

Introduction

Patterns of overall similarities and the estimated evolutionary history of the taxa[10]. The Thamnocalamus group has pachymorph rhizomes and appears to have large microhairs and dumbbell-shaped silica bodies, certain species lack fusoid cells[7] This group consists of Thamnocalamus Munro, Fargesia Franchet (including Borinda Stapleton and Sinarundinaria Nakai)[40, 41] and Yushania Keng f. Li39 designated Fargesia (Borinda, Sinarundinaria), Thamnocalamus and Yushania as the Thamnocalamus group and Ampelocalamus, Chimonocalamus, Drepanostachyum (or Himalayacalamus) and Gaoligongshania as its close allies mainly based on their pachymorph rhizomes and features of their leaf anatomy. The establishment of a well-defined and unambiguous classification of bamboos requires the adoption of a novel approach To verify this issue, specimens of Thamnocalamus and Fargesia from a total of 19 species, which essentially cover the total distribution of the two genera, were collected. In this work, we attempted to integrate morphological data with SOM-network data to assess differences in the patterns of variation in the characteristics between Thamnocalamus and Fargesia

Methods

Results

Conclusion