The revision of Metalasia by Karis (1989) made it clear that the rest of the Metalasia group, as defined by Anderberg (1991a), also needed to be investigated. Anderberg (1991a) identified the Relhania and Metalasia groups in the subtribe Relhaniinae of the tribe Gnaphalieae. The Metalasia group consists of 14 genera, of which seven are monotypic and four have recently been described. The monotypic genera Bryomorphe, Dolicothrix and Phaenocoma are well known, whereas the more recently described Atrichantha, Calotesta, Hydroidea and Planea (Hilliard & Burtt, 1981; Karis, 1990) are known from limited collections. In the broader context of the tribe it also became evident that Disparago (Koekemoer, 1993), Stoebe and Elytropappus (Levyns, 1937, 1935b) needed to be re-assessed to establish the rank of their formal and informal groupings. A number of genera in the group: Amphiglossa, Bryomorphe, Lachnospermum, Phaenocoma and Pterothrix, had not been studied since Flora Capensis (Harvey, 1865) and needed attention. The aims of this study were therefore, to clarify the taxonomy and nomenclature, to provide full taxonomic treatments for all the species in the Metalasia group, and to discuss their phylogenetic relationships. The fact that almost all taxa are endemic to southern Africa provided additional motivation to investigate the group. Furthermore the newly described genera and species have not been studied in the context of the whole group and the large number of specimens that are available today add a wealth of new information to the available knowledge. The need for further investigation was also emphasized by comments by Anderberg (1991a) that Elytropappus and Stoebe are probably paraphyletic or polyphyletic and that Amphiglossa is probably paraphyletic if Pterothrix is kept separate. Extensive fieldwork was undertaken to investigate species in their natural habitat. Spirit-preserved and dried specimens were collected and studied in the herbarium. Thorough morphological studies were undertaken, with extensive use of the SEM and light microscopes; photographs were produced to document the characters. Accurate records were kept of all specimens to assist in determining distribution ranges for each taxon as well as species densities for every genus. Anatomy of selected species was investigated. The results revealed that the leaves of Dolicothrix and Dicerothamnus were indeed glandular, that there are two small resin cavities in the leaf bases of some Seriphium species, and for the first time, provided information on leaf and cypsela anatomy for the group. During the course of this study several nomenclatural problems were solved: the correct name for Bryomorphe aretioides; Klenzea lycopodioides is a synonym of Dolicothrix ericoides, rather than of Bryomorphe; and the confusion around the names Elytropappus gnaphaloides and E. glandulosus was cleared. It was also found that Elytropappus hispidus and E. cyathiformis, and Stoebe cyathuloides and S. sphaerocephala are conspecific. On generic level it was found that Amphiglossa and Pterothrix are congeneric; and that Disparago, Elytropappus and Stoebe are paraphyletic. This resulted in Seriphium being re-surrected for a group of Stoebe species, and Disparago being divided into four genera and Elytropappus into three. Taxonomic treatments for 64 species, including nomenclature, synonymy, typification, full descriptions, geographical distribution, and keys to genera and species, are given. Fieldwork resulted in a large number of new distribution records, the discovery of six new species and also the re-collection of two species (Amphiglossa callunoides and A. corrudifolia) that were only known from type specimens and were thought to be extinct. Although attempts were made to investigate the group, both chemically and cytologically, I was not able to do this successfully. Chemical results indicated that the volatile oils and flavonoids are complex and would provide a wealth of information for future studies. Together with DNA investigations in the Gnaphalieae it could possibly assist to unravel existing uncertainties. A summary of the taxonomic implications of this study is given below: Genera New species No of species Taxonomic implications Amphiglossa A. celans, A. grisea A. rudolphii, A. susannae 11 • Pterothrix as synonym with several new combinations • Four new species • P. flaccida and P. spinescens as synonyms Atrichantha 1 Bryomorphe 1 • Nomenclature clarified Calotesta 1 Dicerothamnus 2 • New genus • New combinations Disparago 4 • Reverting to original concept of Gaertner for the genus • Three new genera created Dolicothrix 1 • Klenzea lycopodioides as new synonym Elytropappus E. aridus E. monticola 3 • E. cyathiformis as synonym • Genus split into three Gongyloglossa 1 • New genus • New combination Hydroidea 1 Lachnospermum 3 • Nomenclature clarified Laevicarpa 1 • New genus • New combination Metalasia 52 Monticapra 3 • New genus • New combinations Myrovernix 5 • New genus • New combinations • M. intricata transferred from Stoebe Phaenocoma 1 Planea 1 Seriphium 9 • Resurrect the genus • New combinations • Elytropappus ruscianus, Stoebe burchellii and S. vulgaris as synonyms Stoebe 16 • S. copholepis, S. ensori, S. sphaerocephala, S. humilis, S. salteri and S bruniades as synonyms. Total 117 Characters and character states were evaluated in terms of their taxonomic value and their contributions towards an improved understanding of phylogenetic relationships amongst the genera and species of the Metalasia group. The patterns of character state distributions were explored, using cladistic methods. This resulted in the discovery of several ‘new’ characters, as well as new ways of interpreting some of the ‘old’ characters. Examples include several very interesting observations made by means of SEM studies; e.g. the true identity of Elytropappus cyathuloides, the glands on the leaf surfaces of Dicerothamnus rhinocerotis, D. adpressus and Dolicothrix ericoides as well as resin cavities at the bases of leaves of some Seriphium species. All data gathered from the study were evaluated and analyzed cladistically to determine inter- and infraspecific relationships. New hypotheses regarding the relationships amongst the genera and species of the Metalasia group are presented. / Van Wyk, B.E., Prof.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uj/uj:8279 |
| Date | January 2002 |
| Creators | Koekemoer, Marinda |
| Source Sets | South African National ETD Portal |
| Detected Language | English |
| Type | Thesis |
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