Kengiochloa, a new bamboo genus to accommodate the morphologically unique species, Pseudosasa pubiflora (Poaceae)

Abstract

Pseudosasa was confirmed as polyphyletic by recent phylogenetic analyses, with Chinese species of Pseudosasa distantly related to those from Japan. Among the Chinese species of Pseudosasa, Pseudosasa pubiflora is a morphologically unique as well as taxonomically problematic species endemic to South China, of which the generic designation is still uncertain. Molecular analyses based on both plastid and nuclear genomic data demonstrated that this species is closest to the recently published genus Sinosasa. Morphologically, the two are somewhat similar to each other in flowering branches developing at the nodes of every order of branches, raceme-like units of inflorescence with 3–5 short spikelets, each spikelet with few florets including a rudimentary one at the apex, and each floret with 3 stamens and 2 stigmas. However, P. pubiflora is very different from Sinosasa species in many reproductive and vegetative characters, such as the morphology of paracladia (lateral spikelet “pedicels”), the absence or existence of pulvinus at the base of paracladia, the relative length of the upper glume and the lowest lemma, the shape of lodicules and primary culm buds, the branch complement, the morphology of nodes, culm leaves and dried foliage leaf blades, and the number of foliage leaves per ultimate branchlet. The morphological and molecular evidence warrants recognition of a new genus to accommodate this unique species, which is here named Kengiochloa. After consulting related literature and examination of herbarium specimens or specimen photos, a taxonomic revision of K. pubiflora and its synonyms was made, and it was confirmed that four names, viz. P. gracilis, Yushania lanshanensis, Arundinaria tenuivagina and P. parilis, should be merged with K. pubiflora, while Indocalamus pallidiflorus and Acidosasa paucifolia are distinct species.