Systematics of Thomandersia Baill

This thesis addresses three aspects of the systematics of Thomandersia. Firstly, a taxonomic account of Thomandersia is provided. Secondly, the anatomy of Thomandersia is described. Finally, the phylogenetic position of Thomandersia in Lamiales is investigated and the potential of morphological and molecular datasets to resolve relationships in Lamiales is assessed. Six species of Thomandersia are recognised, based upon previous taxonomic treatments, an assessment of variability within the genus, and a rationale for describing infrageneric taxa. An improved key to species, species descriptions, distribution maps and illustrations are presented. A preliminary analysis of molecular sequence data suggests that previous, morphology-based classifications of Thomandersia in Acanthaceae do not reflect phylogenetic relationships. The floral and wood anatomy of Thomandersia are reexamined in this light and discussed in the context of Lamiales. Unique characters of Thomandersia include a particularly large calycine nectary, expanded placentas, irregular corolla aestivation, and spherical, scaly seeds. Thomandersia is found to share anatomical features with all other Lamiales investigated. Detailed anatomical studies of retinacula, a character shared with Acanthaceae, and extrafloral nectaries, which may be homologous to nectaries in other Lamiales, are presented. The majority of anatomical characters are homoplastically-distributed in Lamiales and therefore of little use for diagnosing monophyletic groups. Morphological and molecular phylogenetic investigations support the resurrection of Thomandersiaceae, a family of isolated phylogenetic position with a large number of molecular and morphological autapomorphies. At the same time, the investigations highlight problems in resolving interfamilial relationships in Lamiales. The ultimate aim of phylogenetic analysis in Lamiales is an accurately-resolved tree with stronglysupported relationships between all taxa. Morphological characters are of limited use in achieving this goal: when a large morphological matrix is combined with molecular data only small, poorly-supported increases in resolution are achieved. The increasing availability of molecular sequence data is expected to make it possible, in the near future, to resolve an accurate, supported phylogeny of Lamiales and elucidate the sister group relationships of isolated taxa such as Thomandersiaceae.</p

Systematics of Thomandersia Baill

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Data from: Monograph of Aframomum (Zingiberaceae)

Aframomum (Zingiberaceae, subfamily Alpinioideae) is a genus of 61 species of herbs, occurring naturally in Africa and Madagascar. Historically the seeds have been an important item in international trade under the names “grains of paradise” or “melegueta.” The important characters in identification of the species are discussed, and special instructions on collecting specimens of the genus are provided. Keys to fruiting and flowering specimens are presented. Each species account includes nomenclature, description, distribution, and specimen citations. Preliminary IUCN conservation assessments are made based on herbarium records for each species. Twelve new species, Aframomum dhetchuvii, A. fragrans, A. hirsutum, A. kamerunicum, A. kodmin, A. lutarium, A. parvulum, A. plicatum, A. rotundum, A. scalare, A. submontanum, and A. tchoutoui, are described

A molecular systematic approach to explore diversity within the sellaphora pupula species complex (bacillariophyta)

The common and cosmopolitan freshwater benthic diatom Sellaphora pupula (Kutz.) Mereschk. is a model system for studying the nature of species in microalgae; the biological significance of morphological variation in this species complex has been widely demonstrated. The aim of this study was to establish a two-gene phylogeny (18S rDNA and rbcL) for 23 Sellaphora taxa, including 19 S. pupula aggregate (agg.) demes or species, S. bacillum (Ehrenb.) D. G. Mann, and S. laevissima (Kutz.) D. G. Mann. A range of analyses on separate and combined data sets indicated that Sellaphora is a monophyletic group containing four major clades. Of the traditionally recognized species, S. bacillum and S. laevissima are natural groups, but S. pupula is paraphyletic or polyphyletic because S. bacillum groups with S. pupula "small lanceolate" and S. lanceolata. Thickened bars at the poles of valves within the core "pupula-bacillum" group may be a morphological synapomorphy; the fossil record suggests that this group is at least 12 million years old. Otherwise, there was no clear pattern in the distribution of different morphologies among the major clades; each clade was also heterogeneous with respect to mating system. More intensive and extensive sampling will doubtless uncover even greater diversity; the challenge lies in its interpretation. Our results demonstrate the limitations of paleoecological, ecological, and biogeographical research based on morphospecies

Data from: Evolution of angiosperm pollen. 6. the Celastrales, Oxalidales, and Malpighiales (COM) clade and Zygophyllales

Analyzing pollen morphological data on a contemporary phylogenetic framework can enhance our understanding of the distribution, diversity, and evolution of palynological characters. In this paper, the sixth in a series detailing pollen morphological characters across angiosperms, we focus on the Celastrales, Oxalidales, and Malpighiales (COM) clade and Zygophyllales, together comprising ca. 20,000 species in 47 families within fabids. We first examined pollen grains from 21 species with light, scanning electron, and transmission electron microscopy, to illustrate pollen diversity within the COM clade and Zygophyllales. Second, based on a reexamination of previously published pollen data and our new observations, we optimized 21 pollen characters on a maximum likelihood (ML) tree of 169 genera in 45 families representing all four orders, using Fitch parsimony, ML, and hierarchical Bayesian inference. The pollen morphology of this group displays great diversity, particularly in size, aperture number, supratectal element shape, and tectum sculpture. Plesiomorphic states for 18 characters were inferred unambiguously under all methods for the COM clade, and over 300 character state changes were hypothesized by each analysis on lineages at different levels within the group. Changes of state were found to occur most frequently in the characters outline in polar view, pollen size, and tectum sculpture; changes of state occurred least frequently in the characters dispersal unit, symmetry, and tectum presence/absence. We identified diagnostic character states for several monophyletic clades and explored palynological evidence to shed light on some unresolved relationships. For example, the previously poorly resolved Malpighiales were found to be distinguished by a single pollen character state change (from annulus absent to present). Patterns of evolutionary change in several notable pollen characters, such as the number of pollen apertures (from three to other states) and tectum sculpture (from perforate to reticulate), were further confirmed, and their possible adaptive functions are proposed. Reflecting current interest in the relationship between pollen morphology and pollination syndrome, we conducted tests of correlated evolution between pollen morphology and pollination syndrome, with results demonstrating significant correlations between a thin exine and anemophily and, unexpectedly, between presence of supratectal elements and anemophily. Evidence for previously postulated evolutionary trends in aperture number (increasing), tectum sculpture (from perforate to reticulate), and infratectum structure (from columellate to granulate) is discussed. The relatively high frequency of state changes in presence or absence of supratectal elements may be linked to switches in pollination syndrome within this group