Surrey W. L. Jacobs

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

Phylogenetic relationships in subtribe Poinae (Poaceae, Poeae) based on nuclear ITS and plastid trnT-trnL-trnF sequences

The worldwide temperate subtribe Poinae comprises the largest grass genus, Poa (500+ species), and multiple additional small genera. We explore generic boundaries and relationships among genera of Poinae using nuclear ribosomal internal transcribed spacer data (ITS) and plastid trnT–trnL–trnF (TLF) sequence data. ITS and TLF analyses are mostly congruent with regards to circumscription of genera, and with respect to relationships among Poinae genera, but tree structure is generally better supported among genera in the ITS strict consensus tree. ITS and TLF both support two main Poinae lineages: (i) Poa and (ii) a clade comprising all other sampled Poinae. Nine small genera were nested within the large Poa clade, including Aphanelytrum, Dissanthelium, and Tovarochloa, supporting inclusion of these as sections within Poa. In the second clade, three subclades support close relationships among Nicoraepoa, Hookerochloa, and Arctagrostis; Arctophila and Dupontia; and Apera, Bellardiochloa, and Ventenata. Genera...

Systematics of Vallisneria (Hydrocharitaceae)

Abstract Morphology, species delimitation, and interspecific relationships were evaluated in a phylogenetic context in the aquatic monocotyledon genus Vallisneria using a combination of morphological and molecular (nrITS, rbcL, trnK 5′ intron) data. Contrary to previous studies that recognized few species worldwide, we distinguished 12 species by molecular data, and an additional 2–3 species by morphological differences within groups that were invariant at the molecular level. Two new Vallisneria species ( V. australis , V. erecta ) are formally described. Other potentially novel species were detected from the cultivated material examined but require further study to elucidate their taxonomic status. Phylogenetic analyses indicated that vittate (caulescent) species (including Maidenia rubra) are not basal, but nested between two groups of rosulate (rosette) species. To preserve Vallisneria as monophyletic, a new combination is made ( V. rubra ) that accommodates the transfer of M. rubra to Vallisneria. Several taxonomic characters associated with the stigma morphology of pistillate flowers were found to represent suites of features related to pollination. In most cases, these character suites corresponded to a particular arrangement of filaments in the staminate flowers. The precise geographical origin of Vallisneria remains difficult to determine. However, we conclusively documented the presence of the Old World V. spiralis in Texas (United States), which constitutes the first authentic record of this nonindigenous species in North America.

Congruence, Conflict, and Polyploidization Shown by Nuclear and Chloroplast Markers in the Monophyletic “Bristle Clade” (Paniceae, Panicoideae, Poaceae)

Abstract Molecular phylogenetic analyses using the chloroplast marker ndhF and a single copy nuclear marker, knotted1, show that the panicoid grasses bearing sterile branches (bristles) in their inflorescences form a monophyletic group. The genus Cenchrus is monophyletic, and monophyly of Pennisetum cannot be ruled out. Setaria is not monophyletic, either as a whole, excluding the palm-leaved species from section Ptychophyllum, or excluding various uncertainly placed species such as S. grisebachii. There is also no evidence that Setaria and Paspalidium form a monophyletic group. The Australian genera Zygochloa, Spinifex, and Pseudoraphis are placed in the ‘bristle clade’, confirming that inflorescences of these grasses are homologous with the inflorescences composed of spikelets and sterile branchlets (bristles). Comparison of the nuclear and chloroplast gene trees identifies several taxa as tetra- or higher polyploids; these are confirmed by southern hybridization. In particular, the Australian species of Paspalidium are allopolyploid, a novel and unexpected result. Zuloagaea bulbosa, a species that lacks the synapomorphic bristles in its inflorescence, is confirmed as a morphologically anomalous member of the clade, and is clearly allopolyploid. This study demonstrates the utility of knotted1 as a phylogenetic marker; we show that it is single copy in diploid taxa and that it exhibits adequate variation to distinguish closely related species. Interestingly, inflorescence morphology correlates only partially with relationships suggested by either nuclear or chloroplast trees, suggesting that inflorescence form is easily changed over evolutionary time.

Phylogenetic relationships of Australian Poa (Poaceae: Poinae), including molecular evidence for two new genera, Saxipoa and Sylvipoa

Phylogenetic relationships among Australian species of Poa and other subtribe Poinae genera were studied on the basis of plastid trnT–trnL–trnF and nuclear ribosomal ITS and ETS DNA sequence data. Molecular evidence is provided for two new monotypic endemic Australian genera, Sylvipoa and Saxipoa, on the basis of two species formerly included in Poa, P. queenslandica and P. saxicola, respectively. Both new genera resolved in a clade with three subtribe Poinae genera, the Australian genus Hookerochloa, the South American genus Nicoraepoa, and the arctic genus Arctagrostis. Sylvipoa and Nicoraepoa are sister taxa. Saxipoa resolved as sister to these plus Arctagrostis, but also shares DNA sequence characters with Hookerochloa, suggesting a possible hybrid origin. All other Australian Poa species studied resolved in a subclade within the P. subgenus Poa supersection Homalopoa clade, supporting their classification together in an expanded P. section Brizoides. Five New Zealand and one New Guinea species also resolved in this subclade, supporting their membership in this section. We postulate a minimum of two dispersal events into Australia, one for Poa and one for other Poinae genera, and a minimum of three into New Zealand and two into New Guinea for Poa.

Molecules and Morphology in South American Stipeae (Poaceae)

Abstract We conducted phylogenetic analyses of molecular data (ITS, trnH–psbA, trnC–trnL, and trnK–rps16) for 71 species of stipoid grasses. Of these species, 30 are native to South America, seven are native to Mexico and/or the southwestern United States, 15 to other parts of North America, 12 to Eurasia and/or the Mediterranean region, and seven to Australia. The outgroup was Glyceria declinata, a member of the Meliceae, a tribe that is in the same clade as and possibly sister to, the Stipeae. The purpose of the study was to evaluate alternative generic treatments of the South American Stipeae, all of which are based on morphological and anatomical information. Questions of particular interest were the merits of recognizing Amelichloa and of including Stipa subgg. Pappostipa and Ptilostipa in Jarava. Trees obtained from separate analyses of the ITS and cpDNA data were poorly resolved. The majority rule consensus tree obtained from the combined data provided strong support for the monophyly of only two currently recognized genera, Piptochaetium and Hesperostipa. There was strong support for a lineage comprising Amelichloa, Jarava s. str., most North American species of Achnatherum, and most samples of Nassella. Amelichloa was included within a poorly resolved Nassella clade that was sister to the Jarava clade. Austrostipa, with the exception of one sample, was monophyletic and sister to the poorly supported Achnatherum-Amelichloa-Nassella-Jarava clade. Stipa subg. Pappostipa formed a separate strongly supported clade if the North American samples of S. speciosa were excluded from consideration. None of the trees support including S. subg. Pappostipa in Jarava. For S. subg. Ptilostipa we obtained no ITS data and cpDNA data for only one species. The cpDNA data placed the species in a clade with two Nassella species.

Generic Circumscription in Menyanthaceae: A Phylogenetic Evaluation

Abstract Menyanthaceae consist of five genera of aquatic and wetland plants distributed worldwide. The three monotypic genera (Liparophyllum, Menyanthes, and Nephrophyllidium) are clearly differentiated morphologically, but the two larger genera (Nymphoides and Villarsia) contain several taxa of uncertain affinity. We undertook a phylogenetic analysis, using a combination of morphological and molecular data, to resolve relationships among species and to evaluate the current circumscription of genera. DNA sequence data for nuclear (ITS) and chloroplast (rbcL and trnK/matK) gene regions were largely congruent (by partition-homogeneity test), and a combined data phylogeny revealed several strongly supported relationships. Analyses using asterid outgroup taxa supported the monophyly of Menyanthaceae. Menyanthes trifoliata and Nephrophyllidium crista-galli comprised a clade sister to the remainder of the family. Species of Nymphoides, except N. exigua, resolved to a single, deeply-nested clade, indicating that the floating-leaved habit is derived evolutionarily within the family. The genus Villarsia comprised a paraphyletic grade toward Nymphoides, wherein the species resolved to three assemblages: (1) a shallowly nested clade containing V. albiflora, V. calthifolia, V. marchantii, V. parnassifolia, V. reniformis, and V. umbricola; (2) an isolated South African clade including V. manningiana and the type species, V. capensis; and (3) a heterogeneous clade of taxa from three genera, including V. exaltata, V. lasiosperma, and V. latifolia, plus the anomalous species V. capitata, V. congestiflora, Liparophyllum gunnii, and Nymphoides exigua. Our results indicate that the genera Menyanthes, Nephrophyllidium, and Nymphoides should be retained as circumscribed, with the exception that Nymphoides exigua should be restored to Villarsia. The genus Villarsia, however, eventually should be subdivided among monophyletic lineages, whereby in the strict sense Villarsia would contain only South African taxa.

Phylogeny and Systematics of Aponogeton (Aponogetonaceae): The Australian Species

Abstract Aponogeton is an important genus whose species are cultivated widely as ornamental aquatic plants. Although a fairly recent monograph has been published, the genus remains poorly studied systematically. We conducted a phylogenetic survey of Aponogeton that focused on relationships among the nine native Australian species as well as their relationship to other members of the genus. Our analyses included a phylogenetic assessment of morphological characters and molecular data obtained both from chloroplast (trnK 5′ intron, matK) and nuclear DNA (nrITS) loci. Molecular data provided evidence of hybridization and polyploidy as well as an informative overview of interspecific relationships in the genus. Two potentially new Australian species also were identified by the molecular data. Combined molecular data produced a well-resolved cladogram that enabled us to evaluate previous phylogenetic hypotheses based on non-explicit methods as well as the soundness of the existing classification of the genus. We conclude that Aponogetonaceae originated in Australia and subsequently radiated into Africa, Madagascar, and Asia, from which a secondary Australian diversification occurred resulting in a biphyletic origin of the native Australian species. A pattern of morphological distinctiveness coupled with low molecular divergence indicates relatively recent and rapid speciation of Aponogeton in Australia. Our results also demonstrate that in this group, morphological data are extremely unreliable taxonomically due to their extensive homoplasy. The phylogenetic relationships elucidated by this study provide evidence to support the establishment of two additional sections, Flavida and Viridis, which are described.

Revision of the genus Sporobolus (Poaceae, Chloridoideae) in Australia

Twenty-six species of Sporobolus from Australia (including two closely related, weedy species that may occur in the future) are revised taxonomically in this paper. Two new species, S. latzii and S. sessilis, are recognised and described. The DELTA system has been used to generate descriptions of all taxa and a complete list of all characters used is given. Brief discussion is given on classification, ecology, economic value and weed potential, anatomy, rare or threatened status of species, distribution, seed proteins, RAPD analysis and diseases. A key is provided to all species and infra-specific taxa. Illustrations, photographs or reference to illustrations are included as well as distribution maps of all Australian entities. Lists containing information on approximately 3200 exsiccatae examined have been incorporated into an accessory publication*.

Nuclear and plastid DNA sequences reveal complex reticulate patterns in Australian water-lilies (Nymphaea subgenus Anecphya, Nymphaeaceae)

Thisstudyrepresentsthe firstcomprehensiveanalysisofphylogeneticrelationshipswithintheAustralianwater- lilies,Nymphaeasubg.Anecphya.Our51-accessiondatasetcoversall10speciesofthesubgenus,exceptthenewlydescribed N. alexii, and includes information from the nuclear ITS as well as from thechloroplasttrnTtrnFregion. The results show that molecular data are consistent with morphology, because the subdivision of subg. Anecphya into two major clades, a large-seeded and a small-seeded group, could be confirmed. Within the large-seeded group, Nymphaea atrans and N.immutabilisseemtoformoneclade,whereassamplesofN.gigantea,N.georginae,N.macrospermaandN.carpentariae form another. Relationships within the small-seeded group, containing all samples of N. violacea, N. elleniae and N. hastifolia, are less clear, since the trees obtained from the chloroplast and the nuclear marker are incongruent. The samplesofN.violaceadonotformamonophyleticgroupineachofthetrees,but—atleastintheITStree—groupwitheither N. elleniae or N. hastifolia/Ondinea, respectively. Polymorphisms among ITS paralogues, i.e. substitutions at single nucleotidepositionsandlengthpolymorphisms,havebeenobservedinsomesamplesofN.violacea.Thisfactaswellasthe incongruent phylogenetic signal obtained from the chloroplast and the nuclear genomes point to recent hybridisation or introgression in this group. Remarkably, Ondinea purpureais resolved within the small-seeded group by both markers and seems to have a close relationship to N. hastifolia. Although incomplete lineage sorting cannot be fully excluded to explain high variability in N. violacea, molecular data potentially hint to a case of still imperfect taxonomy.