A Taxonomic Study Of The Genus Gelidocalamus Wen (Bambusoideae)

Gelidocalamus Wen(Bambusoideae),endemically distributed in the subtropical regions of China,is a genus of the trib.Arundinarieae with monopodial culm.However,there are still controversies,such as the systematic position of this genus,its infrageneric classification and its relationship with allied genera.In this study,we have queried species names and specimen collection information within this genus from the database at home and abroad,investigated most of species and their population during our botanical expedition,and analyzed the pattern of its species diversity distribution.Based on various data from cladistic systematics,morphology,and SEM observation of abaxial leaf epidermis,the confusion of classification and nomenclature has been clarified and the genus Gelidocalamus has been preliminarily revised.Results are as follows:1)Based on the collection and analysis of holding specimens from the database at home and abroad,specimens are far from abundant with limited amounts and also unbalanced that a few species are sufficient while most are very few;After the investigation of 34 regions in the eight provinces of the southern China(43 populations,537 specimens),the genus may be mainly distributed in the humid evergreen broad-leaf forest of the Eastern China,of which the Nanling Mountain may be the diversity center.2)Results from the Scanning Electron Microscope(SEM)indicate that the leaf epidermis of Gelidocalamus is complex with various traits and the distributional patterns of the papillae on the stomatal apparatus are of taxonomic significance.Some taxa(e.g.G.subsolidus and G.longiinternodus)have identical characters of abaxial leaf epidermis with its allied genus Indocalamus,whilst the leaf epidermis traits of other taxa are similar with the explored stomatal apparatus covered slice-shaped wax and the short papillae irregularly distributed on the abaxial leaf epidermis,such as G.stellatus,G.tessellatus,G.multifolius,G.annulatus,G.latifolius and G.xunwuensis.3)Cluster analysis of 34 morphological characters indicates that the genus may be not monophyletic and some taxa maybe belong to another genus.9 taxa(e.g.G.stellatus and G.tessellatus)are grouped together while other taxa(e.g.G.rutilans,G.solidus,G.subsolidus and G.kunishii are clustered with the outgroup.Especially,G.longiinternodus is divided into the cluster of the genus Indocalamus,indicated the taxon need to be renewedly revised.Finally,based on above results and wild observation,we clarified some chaos of some taxa in Gelidocalamus,reported 1 new taxa(Gelidocalamus xunwuensis),1 new variety(G.stellatus var.mangshanensis)and 1 new combination(G.stellatus var.wugongshanensis),added 2 omit species(G.dongdingensis and G.monophyllus)and corrected some impertinent descriptions of 9 Gelidocalamus taxa.