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Eighty-eight chromosome number counts representing 62 species in nine genera of the Lythraceae are presented based primarily on meiotic figures from pollen mother cells. Included are first reports for 47 species and the first count for the monotypic genus Koehneria. Numbers for 40 species of Cuphea from Brazil and Bolivia are reported, significantly increasing representation of chromosome number data for South American sections of the genus. Comparisons of the new counts are made to previously published numbers for each genus. Basic numbers for 24 of the 31 genera are provided. Eight genera retain the apparent original diploid number of x = 8; 12 are functional diploids of paleopolyploid origin with secondary basic numbers of x = 15, 16, 24, 28, or 32. Polyploid events are hypothesized to have occurred early in the evolution of the family so that the majority of monotypic or ditypic genera, which today constitute 65% of the family, are relictual polyploids. The most chromosomally diverse and actively speciating genera are the herbaceous perennials Ammannia, Nesaea, Cuphea, and Lythrum. In contrast, the woody genera Diplusodon, Ginoria, and Lafoensia, are species-rich but speciation has not involved chromosome number changes. Further understanding of chromosomal evolution in Lythraceae will depend on production of well-supported phylogenies for the family and cytological investigations in the genera where many different chromosome numbers occur.
Plagiochila perdentata sp. nov. (sect. Abietinae Carl) from Papua New Guinea is described and illustrated. Five species names are newly placed in synonymy: Plagiochila curvula Steph., P. incurva Steph., and P. leratii Steph. (conspecific with P. hampeana Gottsche), and P. saveziana Steph. and P. longistipula Steph. (conspecific with P. norfolkiensis Steph.). Plagiochila peradenyensis Schiffn. is transferred from sect. Contiguae Carl to sect. Abietinae. A key to the twelve known species of sect. Abietinae is provided.
The Amblystegiaceae include pleurocarpous mosses typical of moist, wet, or aquatic habitats. Sporophytes are uniform, and genera are distinguished by the habit, arrangement, and anatomy of leaves, leaf cell shape, and costal structure. Generic limits are controversial. Species have been shifted from genus to genus, sometimes in or out of other related families. Nucleotide sequences from the Internal Transcribed Spacer region of nuclear ribosomal DNA repeat from 39 accessions were analyzed to test monophyly of the genera Amblystegium, Campylium, and Drepanocladus. Reconstructions constrained to support monophyly of each genus were significantly less parsimonious and less likely than from unconstrained searches. ITS sequences support previous suggestions based on morphology that Campylophyllum halleri is not closely related to Campylium stellatum or Campyliadelphus chrysophyllus. Our results also support previous treatments that divide Drepanocladus into two or more segregate genera. Leptodictyum riparium appears more closely related to Campylium stellatum and Campyliadelphus chrysophyllus than to Amblystegium species. Some, but not all, populations of A. humile, Hygroamblystegium tenax, H. fluviatile, and H. varium form a strongly supported clade.
We describe and illustrate Metaxya lanosa, the second known species in the genus and the fern family Metaxyaceae (Pteridophyta). It is currently known from four different watersheds in Amazonian Peru and Venezuela. It can be distinguished readily from M. rostrata by the noticeably woolly-hairy stipes and rachises (hairs red-brown or orange-brown and easily abraded), broader, more elliptic pinnae, cartilaginous and whitish pinna margins, more distinct veins abaxially, and longer pinna stalks, especially on the distal pinnae. rbcL data from a very limited sampling are ambiguous but do not reject support for the recognition of at least two species within Metaxya.
The basal subfamily Caesalpinioideae of the Leguminosae generally is subdivided into four or five tribes, but their monophyly remains questionable. Recent cladistic analyses based on morphological characters and chloroplast rbcL sequences suggest conflicting hypotheses of relationships among tribes and subtribal groupings and of the identification of the basal Caesalpinioideae. Our phylogenetic analysis of the chloroplast trnL intron for 223 Caesalpinioideae, representing 112 genera, plus four Papilionoideae, 12 Mimosoideae and three outgroup taxa, provides some well-supported hypotheses of relationships for the subfamily. Our analysis concurs with the rbcL studies in suggesting that a monophyletic Cercideae is sister to the remainder of the Leguminosae. Among the other tribes of Caesalpinioideae, only the broadly circumscribed Detarieae (including Amherstieae or Macrolobieae) is also supported as monophyletic. The Detarieae s.l. occurs as sister to all Leguminosae, excluding Cercideae. Cassieae subtribes Dialiinae and Labicheinae together are sister to the remaining Leguminosae, which includes a monophyletic Papilionoideae, a paraphyletic Mimosoideae, and several monophyletic groups that correspond to previously defined generic groups or subtribes in the Caesalpinioideae. The trnL intron analysis suggests that basal legumes are extremely diverse in their floral morphology, and that presence of simple, actinomorphic flowers may be a derived feature in a number of lineages in the family.
A parsimony analysis was conducted on 319 rbcL sequences, comprising 242 from 194 genera of Leguminosae and 77 from other families. Results support earlier conclusions from rbcL and other molecular data that a monophyletic Leguminosae is part of a Fabales that includes Polygalaceae, Surianaceae, and the anomalous rosid genus Quillaja. Within legumes, results of previous analyses were also supported, such as the paraphyletic nature of Caesalpinioideae and monophyly of Mimosoideae and Papilionoideae. Most new data (74 sequences) were from Papilionoideae, particularly Phaseoleae, Millettieae, and allies. Although the overall topology for Papilionoideae was largely unresolved, several large clades were well-supported. The analysis contained a large sample of Phaseoleae and Millettieae, and not surprisingly showed both tribes to be polyphyletic, though with all taxa except Wisteria and allied Millettieae belonging to a single well supported clade. Within this clade was a strongly supported group that included Phaseoleae subtribes Erythrininae, Glycininae, Phaseolinae, Kennediinae, and Cajaninae, with only the last two being monophyletic. Desmodieae and Psoraleeae were also part of this clade. The monophyletic Phaseoleae subtribes Ophrestiinae and Diocleinae grouped with most Millettieae in a clade that included a group similar to the core Millettieae identified in other studies. All but one of the remaining Millettieae sampled formed an additional clade within the overall millettioid/phaseoloid group.
The Swartzieae, Sophoreae, Dipterygeae, and Dalbergieae are considered the most basal tribes of the subfamily Papilionoideae (Leguminosae). Nucleotide sequences from the chloroplast trnL intron for the majority of genera of these tribes were analyzed cladistically together with placeholder representatives of more derived tribes. Preliminary results indicate radical changes are necessary for papilionoid classification because Swartzieae, Sophoreae, and Dalbergieae are polyphyletic. Their constituent genera are mixed in a series of monophyletic groups, many of which have never been proposed previously, and the relationships amongst which are poorly resolved. Some of these groups, such as the genistoid and dalbergioid clades, are species-rich because they contain major papilionoid radiations. In other cases, putatively basal genera form small clades with no derived taxa included. There is weak evidence that Bobgunnia, Swartzia, Cyathostegia, Bocoa, and Ateleia (all Swartzieae) may be the sister group to all other papilionoids, and that a large clade is congruent with a 50kb inversion in the chloroplast large single copy (LSC) region.
Nuclear DNA sequence data (Internal Transcribed Spacer 1 of the 45S rDNA cistron) and morphological data were used for phylogenetic studies of the tribe Brongniartieae (Fabaceae), a tribe of four Australian and two tropical American genera. Alignment of the ITS-1 region was largely unambiguous and the phylogeny produced using parsimony methods had a high consistency index. Morphological data were mostly congruent with the molecular data and were informative for some nodes where molecular data were lacking. Combining molecular and morphological data resulted in a well-resolved phylogeny. Analyses confirm the monophyly of the tribe and show that the American genus Brongniartia is more closely related to Australian genera than to Harpalyce, the other American genus in the tribe. There is evidence that the Australian genus Plagiocarpus is related to Brongniartia. Templetonia is polyphyletic. Templetonia biloba, T. incana, and Lamprolobium form a monophyletic group. Analyses also support the recognition of three groups within the Australian endemic genus Hovea.
Artificial hybridizations of Schiedea and Alsinidendron (Caryophyllaceae: Alsinoideae), genera endemic to the Hawaiian Islands, were used to study the effects of phylogenetic relationship, genetic divergence, breeding system, and population size on the ability of species to cross and produce fertile F1 hybrids. Using 17 taxa, all crosses attempted produced vigorous F1 hybrids, although pollen fertility of hybrids varied substantially. Fertility of F1 hybrids was positively related to genetic identity measured using allozyme variability. Fertility of hybrids was not predicted by phylogenetic relationships, estimated from morphological and molecular data. Hybrids between species with dimorphic breeding systems had significantly higher pollen fertility than other combinations, although this effect was not significant when population size was controlled in the analysis. The association of dimorphism and ability to produce fertile F1 hybrids is probably indirect: dimorphic species of Schiedea occur in large populations and have high genetic identities. Although artificial hybrids are easily produced in the greenhouse, natural hybridization in Schiedea and Alsinidendron is limited, apparently because instances of sympatry are rare and autogamy is often found in one of the two species occurring sympatrically.
We tested the phylogenetic hypothesis that the circumscription of the genus Ipomoea comprises all members of Hallier's historical taxon, subfamily “Echinoconiae”, including Argyreia, Astripomoea, Lepistemon, Rivea, Stictocardia, and Turbina. Support for the paraphyly of Ipomoea was found based on phylogenetic analysis of 45 taxa using DNA sequences (the ITS region and three exons and two introns of the 3’ end of the nuclear gene waxy) in combination with morphological data. Two major clades within Ipomoea s. l. were resolved in the strict consensus of 16 most parsimonious trees. One clade included most of the smaller segregate genera interspersed with species of Ipomoea, whereas the other was formed by Ipomoea s.s. and Astripomoea. Our results also indicated the genus Turbina is polyphyletic and Rivea is nested within Argyreia. Together, these results suggest new phylogenetic interpretations and point towards a revised view of the nature of morphological evolution among these taxa. We used both our current understanding of morning glory systematics and the distribution of character state variation in seven taxonomically important characters to demonstrate that: 1) the common Ipomoea form is widely distributed, 2) the common form has given rise to specialized forms exhibiting a diversity of character state combinations, and 3) many of the specialized forms have arisen repeatedly. On the basis of these observations, we forward a general model of mosaic evolution that emphasizes extreme evolutionary lability in morphology among morning glory species.
The genus Downingia (Campanulaceae) has been the subject of numerous biosystematic studies, yet little is known of the evolutionary relationships among the 13 currently recognized species. Phylogenetic analyses were undertaken in order to examine the available biosystematic data in a phylogenetic framework. The genus is of particular interest for its extensive chromosomal variation and for its distribution in relatively new, but threatened, vernal pool habitats of western North America. Parsimony analyses of molecular sequence data from the nuclear 18S–26S rDNA internal transcribed spacer region (ITS) and the chloroplast 3’ trnK intron indicate Downingia is monophyletic. Monotypic Porterella is sister to Downingia. Additional close relatives include Legenere and Howellia. Two main clades emerge within Downingia, neither of which have been previously recognized using morphological features. One of the two clades is homogenous in chromosome number (n = 11), and the other heterogenous, with chromosome numbers of n = 6, 8, 9, 10, 11, and 12. Reduced, presumably selfing floral forms appear to have arisen at least twice. “Long anther tube” floral forms appear to have arisen three times from “short anther tube” floral forms. The data suggest that the current circumscriptions of some species, notably D. yina, need further examination.
Previous molecular systematic studies have indicated that the spiny-fruited umbellifers (Apiaceae tribe Caucalideae sensu Heywood) comprise two major lineages, recently delimited as Scandiceae subtribes Daucinae and Torilidinae, with the former including representation of tribe Laserpitieae sensu Drude. These taxa are allied with the monophyletic Scandiceae subtribe Scandicinae whose members lack spiny fruits. The relationship among these three subtribes is equivocal when nuclear ribosomal DNA internal transcribed spacer sequences are compared. Evidence from plastid DNA, however, suggests that Daucinae and Torilidinae are sister taxa. Herein, we provide results of a phylogenetic study of these spiny-fruited umbellifers based on morphology in order to study the evolution of these characters and to ascertain their utility for resolving relationships by comparison to the results of previous molecular analyses. Maximum parsimony analysis of 56 morphological characters resulted in a paraphyletic Torilidinae (Astrodaucus, Caucalis, Glochidotheca, Lisaea, Szovitsia, Torilis, Turgenia, and Yabea) from which a monophyletic Daucinae (Agrocharis, Ammodaucus, Cuminum, Daucus, Laserpitium, Orlaya, Pachyctenium, and Pseudorlaya) are derived. Scandicinae are maintained as monophyletic, sister to Daucinae plus Torilidinae. The genus Artedia, previously attributable to either Daucinae or Torilidinae, shows affinity with the former. The Daucinae plus Torilidinae clade is supported by three fruit synapomorphies—the regular distribution of appendages on both primary and secondary ridges, the presence of primary ridges and hairs on the face of the commissure, and the presence of vittae under the lateral ridges—but each subtribe cannot be circumscribed unambiguously on the basis of morphological data. Characters of the primary appendages exhibit less homoplasy than those of the secondary fruit appendages and support many clades identified in the molecular analyses. Parsimony analysis of combined morphological and ITS data, however, reaffirms the monophyly of subtribe Torilidinae and provides greater resolution of relationships within each of the subtribes than do either of the separate analyses.
DNA sequences for 100 species representing all subfamilies of Orchidaceae and Hypoxis as outgroup were produced for the intron between the b and c exons of subunit 1 of mitochondrial NADH dehydrogenase (nad1). Although the proportion of variable sites is relatively low (slightly greater than rbcL in the same taxa), length variation is common, such that the intron ranges from 905 bp to approximately 2100 bp among the species. The low variability means that the sequences are fairly easily aligned, and provides an opportunity to consider the use of indels where they are a significant proportion of the data set. Critical examination of indel-coding schemes indicates that unordered multistate coding is most useful when nested indels are present. Cladistic analysis of base changes and indels alone, as well as a combined data set, reveals the importance of the indels as characters, since they provide significant additional resolution and branch support beyond that for base changes alone and have higher consistency and retention indices than base changes. The phylogenetic pattern obtained from this locus is consistent with recognition of either four or five subfamilies, and places the vanilloid orchids away from the epidendroids, in agreement with other molecular data.
Mount Kinabalu, (Sabah, Malaysia) is the youngest (ca. 1.5 million yrs old) and highest (4,095 m) mountain between the Himalayas and Irian Jaya, Indonesia. Because of this combination of youth and isolation, considerable mystery surrounds the origins of its high elevation endemics. We chose a group of high-elevation species from Dendrochilum subgen. Platyclinis sect. Eurybrachium to begin an investigation of the origin(s) of endemicity on Mount Kinabalu. We tested biogeographic hypotheses that the Kinabalu endemics arose from ancestors in: 1) the high mountains of Sumatra, 2) the high mountains of Mindanao, Philippines, and 3) lower elevations on Mount Kinabalu or elsewhere in Borneo. Using phylogenetic patterns predicted by the three competing hypotheses, we evaluated which had the highest support in a likelihood framework. Based on analyses of ITS 1 and ITS 2 sequence variation in Dendrochilum, we rejected hypotheses that the Kinabalu high-elevation endemics arose from ancestors in other high mountains of southeast Asia (Sumatra or the Philippines), and tentatively accepted their origin from lower elevation ancestors in Borneo. The origin of high-elevation endemics from lower elevation Bornean ancestors appears to be a general mode of evolution for many species on Mount Kinabalu.
Circumscriptions of Arethuseae have varied since the tribe was first described by John Lindley in 1840, containing over ninety genera among the different authors. The latest system of Arethuseae defined by Dressler, including around thirty genera, is the most commonly accepted today. The goals of this study are to assess whether Arethuseae sensu Dressler and component subtribes are monophyletic and evaluate the position(s) of Arethuseae within Orchidaceae. Sequences of two plastid genes, matK and rbcL, have been obtained for 24 representative genera of Arethuseae in Dressler's latest two taxonomic systems for the tribe, plus 46 other genera throughout Orchidaceae. Both separate and combined analyses of the matK and rbcL data indicate that the tribe may not be monophyletic, which is also true for most subtribes within Arethuseae. Furthermore, matK data suggest that this gene may be non-functional within Orchidaceae.