Abstract

Lippia is the second largest genus in the family Verbenaceae, comprising about 100 species widely distributed in the Neotropics and some representatives in Africa. The genus is considered poorly delimited taxonomically because many species can only be distinguished by minor morphological differences, resulting in a large number of described taxa. This study aimed to examine and describe the pollen characters of Lippia sect. Rhodolippia and identify important pollen attributes for the delimitation of species occurring in Brazil. Multivariate analysis was used to investigate similarities between species and find diagnostic characters for taxonomic identification. Pollen grains of 16 species were acetolyzed, measured, described, illustrated using a light microscope (LM) and submitted to statistical treatments. For a more detailed examination of pollen surfaces and apertures, non-acetolyzed pollen grains were observed and micrographed by scanning electron microscopy (SEM). The results showed that species belonging to the section Rhodolippia have pollen grains that are prolate spheroidal or oblate spheroidal, 3-colporate (3-4-colporate in L. felippei) or 3-colpororate, mesoaperture present or absent, endoaperture lalongate, with ends bifurcated, tapered, rounded, H-shaped or truncated. The exine ornamentation is psilate-perforate in most species. Principal component analysis and hierarchical clustering identified two groups: 3-colporate and 3-colpororate pollen grains. Palynological analysis evidenced the eurypollinic character of the genus and resulted in the first description of mesoaperture and the type of ends of the endoaperture. These findings can provide taxonomic and phylogenetic support for future studies on Lippia.

摘要

Lippia是马鞭草科的第二大属，包括广泛分布于新热带地区的约100种和非洲的一些代表。该属被认为在分类学上划界很差，因为许多物种只能通过微小的形态差异来区分，从而导致大量描述的分类群。本研究旨在研究和描述利皮亚科的花粉性状。红花并确定重要的花粉属性，以划定在巴西发生的物种。多变量分析用于调查物种之间的相似性并找到分类鉴定的诊断特征。使用光学显微镜 (LM) 对 16 种花粉粒进行乙酰水解、测量、描述和说明，并进行统计处理。为了对花粉表面和孔进行更详细的检查，通过扫描电子显微镜 (SEM) 观察和显微照相未乙酰化的花粉粒。结果表明，属于Rhodolippia科的物种的花粉粒为扁长球状或扁球状，3-colporate（3-4-colporate in L. felippei) 或 3-colporate, mesoaperture 存在或不存在,endaperture lalongate, 末端分叉, 锥形, 圆形, H 形或截断。在大多数物种中，外壁装饰是psilate-perforate。主成分分析和层次聚类确定了两组：3-colporate 和 3-colporate 花粉粒。孢粉学分析证明了该属的 eurypollinic 特征，并导致了对中孔和内孔末端类型的首次描述。这些发现可以为未来对Lippia 的研究提供分类学和系统发育支持。