Randall J. Bayer

Molecular phylogenetics of Acacia (Fabaceae: Mimosoideae) based on the chloroplast MATK coding sequence and flanking TRNK intron spacer regions

The tribe Acacieae (Fabaceae: Mimosoideae) contains two genera, the monotypic African Faidherbia and the pantropical Acacia, which comprise about 1200 species with over 950 confined to Australia. As currently recognized, the genus Acacia is subdivided into three subgenera: subg. Acacia, subg. Aculeiferum, and the predominantly Australian subg. Phyllodineae. Morphological studies have suggested the tribe Acacieae and genus Acacia are artificial and have a close affinity to the tribe Ingeae. Based on available data there is no consensus on whether Acacia should be subdivided. Sequence analysis of the chloroplast trnK intron, including the matK coding region and flanking noncoding regions, indicate that neither the tribe Acacieae nor the genus Acacia are monophyletic. Two subgenera are monophyletic; section Filicinae of subgenus Aculeiferum does not group with taxa of the subgenus. Section Filicinae, eight Ingeae genera, and Faidherbia form a weakly supported paraphyletic grade with respect to subg. Phyllodineae. Acacia subg. Aculeiferum (s. s.) is sister to the grade. These data suggest that characters currently used to differentiate taxa at the tribal, generic, and subgeneric levels are polymorphic and homoplasious in cladistic analyses.

Systematics of Seagrasses (Zosteraceae) in Australia and New Zealand

Abstract Previous taxonomic treatments of the family Zosteraceae in Australia/New Zealand have recognized Heterozostera tasmanica (monotypic) and four Zostera species all belonging to subgenus Zosterella: Z. capricorni, Z. muelleri, Z. mucronata, Z. novazelandica. Zostera has always been taxonomically problematic in Australia, where researchers have expressed difficulty with species recognition due to vague or inconsistent morphological characters. There also has been a lack of agreement on generic (notably the distinctness of Heterozostera) and subgeneric delimitation. Recent anatomical, developmental, and molecular studies urge a reevaluation of relationships in the family. To clarify the taxonomy of Zosteraceae, we investigated interspecific phylogenetic relationships focusing on Australian species of subgenus Zosterella. We examined material comprising all genera of Zosteraceae (Heterozostera, Nanozostera, Phyllospadix, Zostera), six/seven species of Zostera subgenus Zosterella (including all Australian/New Zealand species), and one of four species of Zostera subgenus Zostera. We conducted phylogenetic analyses of morphological data and DNA sequences from nuclear (ITS) and plastid (trnK intron, rbcL) genomes. Our results indicate two major clades (highly divergent at both morphological and molecular levels) and two subclades (with low morphological and molecular divergence) within Zosteraceae. Little morphological and molecular variation was observed among representatives within the clade of Australian/New Zealand members of subgenus Zosterella, and none provided cladistic support for taxa recognized formerly as separate species. We recommend that Zosteraceae comprise two genera (Phyllospadix, Zostera) with the latter subdivided into three subgenera (Zostera, Zosterella, Heterozostera). Furthermore, Australian/New Zealand representatives of Zostera subgenus Zosterella should be merged within a single species (Z. capricorni) to reflect the inability of morphological or molecular data to effectively delimit additional species in this group. Communicating Editor: Jeff H. Rettig

A molecular phylogeny of the endemic Australian genus Gastrolobium (Fabaceae: Mirbelieae) and allied genera using chloroplast and nuclear markers

Gastrolobium (Fabaceae: Mirbelieae) is an endemic Australian genus that produces toxic sodium monofluoroacetate. A phylogenetic reconstruction of Gastrolobium and the related genera Brachysema, Callistachys, Jansonia, Nemcia, Oxylobium, and Podolobium is presented, using sequence data from three regions-the psbA-trnH intergenic spacer and the trnK 5 intron from chloroplast DNA and the 3 end of the external transcribed spacer (ETS) from nuclear ribosomal DNA. Gastrolobium is shown to be paraphyletic, with Brachysema, Jansonia, Nemcia, and Oxylobium lineare nesting within it, and Nemcia is shown to be polyphyletic within Gastrolobium. Past key morphological characters, such as fluoroacetate content and characters associated with pollination syndrome, are shown to be homoplastic, with fluoroacetate possibly a plesiomorphic condition lost in more derived species. Podolobium is also shown to be polyphyletic, with the P. ilicifolium group sister to Gastrolobium and the P. alpestre group sister to Callistachys, a member of the Oxylobium group. It is recommended that Gastrolobium be expanded to include Brachysema, Jansonia, Nemcia, and Oxylobium lineare, while further work is required to test the sister-group relationship between Podolobium s.s. (sensu stricto) and Gastrolobium.

Genetic, cytogenetic and morphological patterns in a mixed mulga population: evidence for apomixis

The mulga complex (Acacia aneura and closely related taxa) is a widespread group that is dominant in much of arid Australia. The group is taxonomically difficult, due to a complex interaction of sympatry and putative hybridisation between the major species, geographic variation within species and sympatric variation within A. aneura. Mulga is highly variable in a wide range of vegetative and reproductive characters and it is not unusual to find five or six distinct forms growing side by side. The aim of this project was to gain a better understanding of the relationships among mulga species and A. aneura varieties, as well as the maintenance of this variation. A single site in the Northern Territory, containing A. ayersiana, A. minyura and two varieties of A. aneura, was sampled intensively. Six morphotypes were observed in the field and five were strongly supported by morphometric analysis. Although the mulga complex is generally tetraploid (2n = 52), triploid (2n = 39) and pentaploid (2n = 65) seedlings were produced in the study population. Microsatellite primers developed for A. mangium (sect. Juliflorae) were amplified in individuals of each morphotype, resulting in genetic marker patterns consistent with polyploidy. Genetic and morphometric distances were correlated and differences between morphotypes account for 63% of the total genetic variation (φPT = 0.63, P < 0.001). Allele sequences confirmed the presence of genuine heterozygosity and clonality was suggested by the low genotypic diversity and the lack of allele segregation. Seedlings had identical genotypes to the maternal plants and polyembryony was observed in each taxon, consistent with apomictic reproduction. Both apomixis and ploidy level variation may restrict gene flow among morphotypes, playing a role in the maintenance of morphological diversity at the study site. The success of the group in arid and semi-arid Australia may also be due, in part, to these factors. SB enet or v ul R. L.

The allotetraploid invasive weed Bromus hordeaceus L. (Poaceae): genetic diversity, origin and molecular evolution.

Bromus hordeaceus (sectionBromus, Poaceae), a predominantly self-fertilizing tetraploid (2n=28), is an annual weed native to the Mediterranean Basin, which now has a world-wide distribution. High morphological variation led to the recognition of four subspecies, three of which correlated with habitat-type. We examined genetic diversity at enzyme loci in 15 populations from the Mediterranean and the Atlantic region. Although sampled over a larger range of ecological and geographical conditions, the North-African populations appeared less genetically differentiated than populations from Brittany, suggesting higher levels of gene flow among the first ones (Nm=3.756 and 1.066 respectively). No genetic differentiation was encountered among the four subspecies. The populations were homozygous at homologous loci, suggesting high rates of selfing, but they frequently exhibited fixed intergenomic heterozygosity. The meiotic chromosome behaviour and disomic inheritance encountered are in accordance with the previously proposed allopolyploid origin of the species. The diploidsB. arvensis andB. scoparius have been previously implicated in the parentage ofB. hordeaceus on the basis of morphology and serology. We comparedB. hordeaceus with related diploid species belonging to the same section (sectionBromus) using different sources of data (flow cytometry, karyotypes, RAPD and DNA sequences). Molecular phylogeny based on internal transcribed spacer sequences of nuclear ribosomal genes provided the first clear scheme of relationships among monogenomic species of the section. A new hypothesis is proposed concerning the origin ofB. hordeaceus: We found that it diverged earlier than all other species of sectionBromus excluding the diploidB. caroli-henrici which is basal in this group. The 13 autapomorphies accumulated byB. hordeaceus, and the absence of intra-individual sequence heterogeneity are also consistent with the relatively ancient origin of the species within the section.

Monograph of Gastrolobium (Fabaceae: Mirbelieae)

A taxonomic revision with full descriptions and key are presented for the 109 known species of Gastrolobium, including 29 new species described here for the first time. Brachysema, Jansonia and Nemcia are formally placed into Gastrolobium and new combinations have been made where necessary. Included in the revision are full taxonomic descriptions for all species, full synonymies, literature references for original publications, typification, including selection of lectotypes where necessary, distributions complete with maps, and taxonomic and nomenclatural notes. New taxa described herein are G. acrocaroli, G. aculeatum, G. alternifolium, G.xa0congestum, G. crispatum, G. cruciatum, G. cyanophyllum, G. diabolophyllum, G. discolor, G. elegans, G.xa0euryphyllum, G. ferrugineum, G. glabratum, G. hians, G. humile, G. involutum, G. melanopetalum, G.xa0mondurup, G. musaceum, G. nudum, G. nutans, G. reflexum, G. rhombifolium, G. semiteres, G. tenue, G.xa0tergiversum, G. venulosum, G. whicherensis and G. wonganensis.

A reassessment of tribal affinities of the enigmatic genera Printzia and Isoetopsis (Asteraceae), based on three chloroplast sequences

The tribal affinities of two dubiously placed genera of the Asteraceae, Printzia and Isoetopsis, were assessed by using three chloroplast DNA sequences, the trnL/F spacer, the trnL intron and the matK coding region. The outgroup was represented by two species of the tribe Barnadesieae, whereas one to six genera (43 species including Printzia and Isoetopsis) of the tribes of the Asteroideae [Anthemideae (six genera), Astereae (five) Calenduleae (two), Gnaphalieae (six), Heliantheae s.l. (five), Inuleae s.str. (three), Plucheeae (two), Senecioneae (four)] and Cichorioideae [Arctotideae (one), Cardueae (two), Lactuceae (two), Liabeae (one), Mutisieae (one), Vernonieae (one)] were chosen as the ingroup. Phylogenetic analysis indicates that both Printzia and Isoetopsis have a strong affinity with members of the tribe Astereae. At some point in their taxonomic history, both genera had been placed in this tribe and there are good morphological and chemical characters that justify this placement.

Genetic evidence supports the new Anatolian lupine accession, Lupinus anatolicus, as an Old World "rough-seeded" lupine (section Scabrispermae) related to L. pilosus.

A noteworthy wild lupine accession was recently discovered in southwestern Turkey and was proposed as a new separate Old World “smooth-seeded” species close toL. micranthus and namedL. anatolicus. Its species status was controversial with respect to cytological and crossability data. In order to examine the position and the evolutionary relationships of this Anatolian accession relative to the Old World lupines, we investigated new data from seed coat micromorphology, and from internal transcribed spacer (ITS) nucleotide sequences of the nuclear ribosomal DNA repeat. The micromorphological seed coat pattern ofL. anatolicus, as revealed by scanning electron microscopy, is characterized by pluricellular tubercles, which represent the typical and unique pattern of the Old World “rough-seeded” lupines (sect.Scabrispermae). In accordance with the micromorphological results, the genetic distances and phylogenetic relationships among the Old World lupines, estimated from ITS data, unambiguously support the new Anatolian lupine accession as part of theL. pilosus-L. palaestinus lineage within the strongly monophyletic group containing all theScabrispermae. The results provided in this study, together with other lines of data available from the literature, are thus hardly compatible with the hypothesis that this new Anatolian lupine accession could be related to Old World “smooth-seeded” lupines (includingL. micranthus); instead, it appears closely related toL. pilosus.