Murray I. Dawson

Index of chromosome numbers of indigenous New Zealand spermatophytes

Abstract An index of chromosome numbers for spermatophytes indigenous to the New Zealand Botanical Region is presented, along with full references to the original reports. Chromosome numbers are listed for 1212 species out of a total estimated indigenous spermatophyte flora of 1883 described species. This represents 64.4% of the total with chromosome counts (100% for gymno‐sperms, 74.3% for dicotyledons, and 39.8% for monocotyledons).

Contributions to a chromosome atlas of the New Zealand flora - 36. Miscellaneous families

Abstract Chromosome numbers are documented for 122 taxa in 44 genera from 22 angiosperm families in the New Zealand region. Counts for comparison are also reported for 3 species indigenous to Australia.

Contributions to a chromosome atlas of the New Zealand flora — 33. Miscellaneous species

Abstract Somatic chromosome numbers are documented for 59 taxa, including three ornamental cultivars, in 20 genera and 15 families from the New Zealand region. Chromosome counts are also provided for Australian and Norfolk Island representatives of Coprosma (two species) and Melicytus/Hymenanthera (four taxa).

Diversity of brassica (brassicaceae) species naturalised in Canterbury, New Zealand

Abstract Field surveys were undertaken of Brassica naturalised in Canterbury, investigating taxonom‐ic diversity, morphological variation, distribution, and abundance of naturalised taxa, crop escapes, and crop‐weed hybrids. As a result, six species, nine varieties, and two natural hybrids were recognised as naturalised in Canterbury. B. rapa var. oleifera was the most common taxon, while B. rapa var. chinensis, B. rapa var. glabra, B. rapa var. rapa, B. napus var. oleifera, and B. oleracea var. acephala were less abundant and generally occured in small populations of only a few individuals in rural areas. Single plants of B. oleracea var. gongylodes (kohl rabi) and B. napus var. napobrassica (swede) were collected. An additional species, B.juncea, is recorded as a new naturalised plant in Canterbury. Most of the Brassica populations sampled were small, with 64% of the 107 populations observed comprising fewer than 10 plants. Flow cytometry profiles were obtained for 168 samples of B. juncea, B. napus, B. oleracea, and B. rapa, and these usually confirmed morphological identifications to a particular species. However, there were some identification uncertainties with B. napus, as some plants had a flow cytometry profile of that species but the morphology of either B. rapa var. oleifera or B. oleracea var. acephala. Tetra‐ploid plants of B. rapa (var. chinensis, var. oleifera, and var. rapa), and B. oleracea var. acephala were recorded. We also identified two instances of hybridisation. One plant has a flow cytometry profile and a high percentage of malformed pollen that are consistent with being the putative interspecific F1 hybrid B. napus × B. rapa. Another population included plants of the putative intraspecific hybrid B. rapa var. oleifera × B. rapa var. chinensis growing with the two parental species.

TWO SNOW SPECIES OF THE QUADRIFLAGELLATE GREEN ALGA CHLAINOMONAS (CHLOROPHYTA, VOLVOCALES): ULTRASTRUCTURE AND PHYLOGENETIC POSITION WITHIN THE CHLOROMONAS CLADE1

The quadriflagellate snow alga Chlainomonas Christen, distributed in New Zealand and North America, has several unusual structural attributes. A process assumed to be cytokinesis involves extrusion of protoplasm from the parent through a narrow canal, C. kolii (J. T. Hardy et Curl) Hoham produces a net‐like outer envelope rather than a cell wall, and the flagellar basal apparatus of Chlainomonas consists of two semi‐independent pairs of basal bodies. Structural connections between basal body pairs appear minimal, but a connecting system different from that observed in other genera exists within each pair. Phylogenetic analysis using rbcL sequences places Chlainomonas in the Chloromonas clade, other known members of which are all biflagellate. Chlainomonas is split into two robust lineages, with New Zealand collections sharing an origin with northern North American collections. Although the quadriflagellate condition is regarded as ancestral in the Chlorophyceae, we speculate—based on ultrastructural and molecular data presented here—that Chlainomonas represents a derived form that has arisen from fusion of two ancestral biflagellate cells. Other explanations (for example, that Chlainomonas represents a diploid form of a biflagellate species) are remotely possible but are presently at odds with extensive observations of field material. Improvements in techniques for experimental manipulation of these sensitive cryophiles will be required to fully characterize their structure and progress our understanding of their biology.

Chromosome number variation in two antipodean floras

Italy and New Zealand are very similar in shape, extension, altitudinal and latitudinal range but located in opposite hemispheres. This paper compares variation in chromosome number in these two hotspot regions. The results challenge previous ideas concerning links between geography and patterns of chromosome number variation.

Evidence for apomictic seed formation in Coprosma waima (Rubiaceae)

Abstract Facultative autonomous apomictic seed formation has been identified in Coprosma waima by progeny tests, flow cytometry, and DNA Amplified Fragment Length Polymorphism profiles. An isolated, cultivated, female plant of C. waima produced seeds, from which were raised female C. waima plants. Flow cytometry of seeds collected from these female plants had an embryo to endosperm ploidy ratio of 2:4. This is consistent with parthenogenetic embryo development from a single unreduced egg nucleus, and autonomous endosperm development from two unreduced polar nuclei. DNA Amplified Fragment Length Polymorphism profiles of the maternal plant and three female progeny were identical, indicating they were genetically homologous. Seeds from wild plants of C. waima have an embryo to endosperm ploidy ratio of 2:3, consistent with sexual reproduction. We also present evidence of apomictic seed formation in C. parviflora, C. robusta, and C. serrulata.

Contributions to a chromosome atlas of the New Zealand flora—39. Orchidaceae

Abstract Somatic chromosome numbers are documented for the majority of the New Zealand indigenous Orchidaceae, with counts for 80 species, 23 taxonomically indeterminate taxa, and 3 hybrids in 34 genera. Related chromosome counts are provided from elsewhere for comparison: 43 species, 12 taxonomically indeterminate taxa, and 4 hybrids in 17 genera from Australia; 1 species from Lord Howe Island; and 4 species in 3 genera from New Caledonia. A wide diversity of chromosome morphology and primary and secondary basic numbers among genera is reported (e.g., x/x2= 11, 12, 13, 14, 15, 17, 18, 19, 20, 21, 22, 25, 26, 27). Relatively limited polyploidy was uncovered, confirmed for New Zealand representatives to the tetraploid level (e.g., for the Nematoceras trilobum agg., 2n = 2x2 = 36 → 2n = 4x2 = 72; Drymoanthus, 2n = 2x = 38 → 2n = 4x = 76; and Microtis, 2n = 2x/2x2 = 44 → 2n = 4x/4x 2= 88; in these examples diploid taxa also occur). Amphidiploidy (allopolyploidy) is reported within one genus only, Thelymitra, where it is extensive. Reticulate cytoevolution in Thelymitra is discussed, and the highest chromosome number obtained in this study is 2n = 93 for T. luteocilium from Australia. Extensive aneuploidy appears to be a feature of the Australasian Orchidaceae. Aneuploidy occurs at several levels: within a species (Stegostyla lyallii, 2n = 47, 48; Pterostylis aff. montana agg., 2n = 43, 44; Earina mucronata, 2n = 40, 41, 42; Petalochilus chlorostylus, 2n = 39, 40, 41); between species in the same genus (Hymenochilus, x/x2 of 27→26(→24?); Prasophyllum, x/x2 of 22→21; Adelopetalum, x/x2 of 19→18; Thelymitra, x/x2 of 14→13; Calochilus, x/ x2 of 12→11); between subgenera (Pterostylis subg. Pterostylis, x2 = 2n, derived from x/x2 = 22 found in the other two subgenera); and between related genera (e.g., Molloybas and Singularybas, x2 = 17, from x = 18 elsewhere in the Corybas alliance; Calochilus, x2 = 12, derived from x2 = 13 as found in Thelymitra). The diversity of chromosome morphology and numbers documented here provide independent and informative characters to test the integrity of the recent and extensive generic recircumscriptions of the Australasian Orchidaceae, based on plant macro‐morphology and molecular sequence data. In many cases, the chromosome evidence strongly supports recognition of segregate genera (e.g., for some of the segregate genera of Caladenia, Corybas, Prasophyllum, and Pterostylis) and their subtribal and phylogenetic placements. In other circumstances, the chromosome evidence is uninformative (e.g., for the segregate genera Adelopetalum,Ichthyostomum, and Winika), or else there are indications that certain genera and subtribes remain cytologically heterogeneous and may not be monophyletic (e.g., within Prasophyllum as currently circumscribed).

A new species of Leucopogon (Ericaceae) from the Surville Cliffs, North Cape, New Zealand

Abstract A new ultramafic endemic Leucopogon xerampelinus is named from the Surville Cliffs, North Cape, New Zealand. The Surville Cliffs population has previously been referred to Leucopogon parviflorus, from which it differs by its prostrate, trailing habit, reddish leaf colour, smaller flowers, and restriction to ultramafic rocks. However, we consider that the floral and vegetative morphology indicates that it may be more closely related to L. fasciculatus. Leucopogon xerampelinus is a common shrub of the plateau, gully heads, and cliff faces of its ultramafic habitat. Although the new species is entirely restricted to the 120 ha exposure of ultramafic rocks at North Cape, within this area it is very common. Possible long‐term threats include the spread of weeds, and damage from some browsing mammals. As such the conservation status is assessed as “At Risk/Range Restricted”.

Chromosome numbers of Phragmites australis (Arundineae: Gramineae) in New Zealand

Abstract Somatic chromosome numbers for New Zealand provenances of Phragmites australis are reported. A wide range of cytological variation was encountered—one plant was tetraploid (2n = 4x2 = 48), two were octoploid (2n = 8x2 = 96), and two were mixoploid (2n = 48, 53, 54; and 2n = 96, c. 264). One Australian provenance was octoploid. Possible regions of origin for the New Zealand populations are suggested, and multiple introductions postulated, although it is conceivable that some octoploids could be indigenous in a cytodeme shared with Australia.