Gretchen M. Ionta

PHYLOGENETIC RELATIONSHIPS IN PERIPLOCOIDEAE (APOCYNACEAE S.L.) AND INSIGHTS INTO THE ORIGIN OF POLLINIA1

Abstract Phylogenetic relationships within Periplocoideae (Apocynaceae s.l.) were investigated using sequence data from nuclear ribosomal DNA and two plastid regions: trnD-trnT and trnT-trnF. We included 43 ingroup taxa, representing all but three of 32 currently recognized genera. In the ITS and total evidence analyses, Phyllanthera grayi (P. I. Forst.) Venter is supported as sister to the rest of the subfamily. We identified several well-supported clades, and three of six genera represented here by more than one species (Cryptolepis R. Br., Pentopetia Decne., and Periploca L.) are supported as monophyletic. Pollinial species appear in four distinct, well-defined clades, suggesting either three or four independent origins of pollinia within the subfamily. It is most parsimonious, therefore, to view pollinia in Periplocoideae as non-homologous with those of Secamonoideae and Asclepiadoideae, a hypothesis that is supported by their structural differences.

Two new species of Miconia sect. Sagraea (Melastomataceae) from the Macaya Biosphere Reserve, Haiti, and twelve relevant new species combinations

The Sagraea clade (Melastomataceae, tribe Miconieae) is briefly characterized, typified, and formally treated as a section within Miconia. In addition, two new species of Miconia sect. Sagraea, endemic to the floristically diverse Massif de la Hotte of southwestern Haiti and discovered during the course of a systematic revision of the Caribbean species of this section, are here described and illustrated. Miconia hottensis and M. navifolia, morphologically similar and possible sister species, are compared to each other and to the widespread Caribbean species M. capillaris and the southwestern Dominican Republic endemic M. tetraptera; these four species share rectangular stems with four low ridges or wings and minute, short-stalked, peltate or pseudopeltate hairs and likely form a clade.

Tolmiea diplomenziesii: A new species from the Pacific Northwest and the diploid sister taxon of the autotetraploid T. menziesii (Saxifragaceae)

Tolmiea diplomenziesii, the diploid entity traditionally treated within a broadly circumscribed Tolmiea menziesii, is here formally described. Evidence is provided that this new species represents the diploid sister lineage to T., menziesii, which is re-circumscribed to include only autotetraploid plants. The diploid and autotetraploid entities are compared, and serve as an example of the level of taxonomic evidence for specific status that we consider appropriate for recognition of a cytological entity as a distinct species.

Taxonomic studies in the Miconieae (Melastomataceae). X. Revision of the species of the Miconia crotonifolia complex

The systematics of Miconia angustilamina, M. crotonifolia, M. macrocarpa and M. umbellata, species traditionally considered within either Clidemia and Heterotrichum (M. angustilamina, M. umbellata) or Tetrazygia and Tetrazygiopsis (M. crotonifolia, M. macrocarpa) are investigated. These species, which are considered to be closely related and constitute the M. crotonifolia complex, are taxonomically revised. The circumscription of M. umbellata is expanded to include Heterotrichum cymosum (often considered a Puerto Rican endemic) and that of M. macrocarpa is expanded to include Tetrazygia tuerckheimii, which is recognized as an ecologically differentiated subspecies. The species of the M. crotonifolia complex are restricted to the Greater Antilles and are the most diverse on Hispaniola.ResumenLa relaciones sistemáticas entre Miconia angustilamina, M. crotonifolia, M. macrocarpa y M. umbellata, especies tradicionalmente consideradas dentro de Clidemia y Heterotrichum (M. angustilamina, M. umbellata) o Tetrazygia y Tetrazygiopsis (M. crotonifolia, M. macrocarpa) fueron investigadas. Estas especies, las cuales se consideran como cercanamente relacionadas y que constituyen el complejo de M. crotonifolia son objeto de una revisión taxonómica. El concepto de M. umbellata se expande, incluyendo ahora Heterotrichum cymosum (generalmente considerada endémica a Puerto Rico) y se expande M. macrocarpa con la inclusión de Tetrazygia tuerckheimii, la cual es considerada como una subespecie ecológicamente diferenciada. Las especies del complejo de M. crotonifolia están restringidas a las Antillas Mayores y presentan su mayor diversidad en La Española.

Phylogenetic Relationships in Rhexia (Melastomataceae): Evidence from DNA Sequence Data and Morphology

In the large, pantropical family Melastomataceae, Rhexia is unique in having a temperate distribution. The species of Rhexia, the “meadow beauties,” are a common sight along roadsides and in open habitats in eastern North America, ranging from Nova Scotia to Florida and the West Indies and west to eastern Texas. In order to elucidate interspecific phylogenetic relationships in Rhexia, we analyzed four independently evolving data sets: the internal transcribed spacer (ITS) regions of ribosomal nuclear DNA, the chloroplast region trnC‐D, the nuclear gene that encodes chloroplast‐expressed glutamine synthetase (ncpGS), and 37 morphological characters. The ITS and chloroplast topologies differed in the phylogenetic positions of several taxa (R. lutea, R. nashii, and R. salicifolia), and for R. cubensis, R. lutea, R. nashii, R. parviflora, and R. salicifolia, we recovered multiple alleles of ncpGS, which is single copy in most species of Rhexia, indicating that these individuals may be of hybrid origin. Among the remaining taxa, we identified three major clades: R. petiolata, R. mariana, and R. virginica. We show evidence of a hybrid origin of R. nashii, with parentage from the R. mariana and R. virginica lineages.

Miconia cineana (Melastomataceae: Miconieae), a New Species from the Massif de la Hotte, Haiti, Based on Morphological and Molecular Evidence

Abstract We describe a new species, Miconia cineana (Melastomataceae: Miconieae), from the Massif de la Hotte, Haiti. Although this species has been known from sterile collections since the early 1980s, its phylogenetic position was unknown, although it was presumed to be closely related to species of Pachyanthus s. l. The phylogenetic reconstruction presented here, based on a recent collection of the species, clearly places M. cineana in a clade comprised of Cuban species of the polyphyletic genera Tetrazygia s. l. and Pachyanthus s. l. Thus, M. cineana represents the sole Hispaniolan member of an otherwise Cuban clade, and an uncommon biogeographic pattern in melastomes. Miconia cineana, although described here from sterile specimens, is easily distinguished from the other species of this clade using vegetative morphology, as well as phylogenetic placement. This study highlights the utility of molecular data when coupled with morphology, allowing for the discovery of an unrecognized species in a region of high diversity and endemism, i.e. the Massif de la Hotte.

Floral elaiophores in Lockhartia Hook. (Orchidaceae: Oncidiinae): their distribution, diversity and anatomy.

BACKGROUND AND AIMS A significant proportion of orchid species assigned to subtribe Oncidiinae produce floral oil as a food reward that attracts specialized bee pollinators. This oil is produced either by glabrous glands (epithelial elaiophores) or by tufts of secretory hairs (trichomal elaiophores). Although the structure of epithelial elaiophores in the Oncidiinae has been well documented, trichomal elaiophores are less common and have not received as much attention. Only trichomal elaiophores occur in the genus Lockhartia, and their distribution and structure are surveyed here for the first time. METHODS Flowers of 16 species of Lockhartia were studied. The location of floral elaiophores was determined histochemically and their anatomical organization and mode of oil secretion was investigated by means of light microscopy, scanning electron microscopy and transmission electron microscopy. KEY RESULTS AND CONCLUSIONS All species of Lockhartia investigated have trichomal elaiophores on the adaxial surface of the labellum. Histochemical tests revealed the presence of lipoidal substances within the labellar trichomes. However, the degree of oil production and the distribution of trichomes differed between the three major groups of species found within the genus. All trichomes were unicellular and, in some species, of two distinct sizes, the larger being either capitate or apically branched. The trichomal cuticle was lamellate, and often appeared distended due to the subcuticular accumulation of oil. The labellar trichomes of the three species examined using transmission electron microscopy contained dense, intensely staining cytoplasm with apically located vacuoles. Oil-laden secretory vesicles fused with the plasmalemma and discharged their contents. Oil eventually accumulated between the cell wall and cuticle of the trichome and contained electron-transparent profiles or droplets. This condition is considered unique to Lockhartia among those species of elaiophore-bearing Oncidiinae studied to date.

Using Population Genetic Data as a Tool to Identify New Species: Conradina cygniflora (Lamiaceae), a New, Endangered Species from Florida

Abstract Understanding species limits in recent radiations is often difficult because sufficient time may not have elapsed since speciation to allow for the accumulation of unique species-specific traits. However, because population genetic markers evolve rapidly, patterns of genetic structure based on these markers can often discern genetically isolated population groups, even when other markers, such as DNA sequences, can not. In this study, we analyzed patterns of genetic structure based on microsatellites in Conradina and identified a group of plants in Dunns Creek State Park (Putnam County, Florida) that are genetically divergent from all other described Conradina species. We then carried out a morphological study that revealed several unique characters in these populations, most notably thin-walled unicellular hairs, epidermis features, and larger calyces. Because these populations are genetically and morphologically diagnosable from all other Conradina species, we thus consider them to be specifically distinct, and name this taxon Conradina cygniflora. Conradina cygniflora is endemic to Dunns Creek State Park in south-central Putnam County, Florida, where it occupies nine tightly-clustered sites that probably form around two to four self-sustaining populations. Due to its extremely limited geographic distribution and few individuals, we recommend that Conradina cygniflora be listed as federally endangered.

Taxonomic studies in the Miconieae (Melastomataceae). IX. Calycogonium formonense, a new species from the Massif de la Hotte, Haiti

Calycogonium formonense, a new species, is here described from the floristically diverse Massif de la Hotte of southern Haiti. It is compared to C. hispidulum, to which it is likely related. Although the genus Calycogonium is not monophyletic, C. formonense and C. hispidulum are probably related to other species, e.g., C. calycopteris, C. heterophyllum, and C. reticulatum, that exhibit reduced inflorescences and 4-merous flowers having hypanthia with four conspicuous lobes separated by longitudinal grooves and external calyx lobes that are flattened parallel to the floral radii. These distinctive species may form a clade. Calycogonium formonense is distinguished from C. hispidulum by its smaller leaves with the tertiary veins not raised on the abaxial surface, with entire margins (i.e., margin without elongate multicellular hairs), and usually solitary flowers.

Recognition of Miconia sect. Sagraeoides (Melastomataceae: Miconieae) and associated nomenclatural changes

Recent phylogenetic studies incorporating DNA sequence data have corroborated the suspected non-monophyly of many currently recognized genera of tribe Miconieae (Melastomataceae), which includes about 1800 species restricted to the Neotropics. The genus Mecranium, comprising 24 species endemic to the Greater Antilles and their satellite islands, appears to be a monophyletic exception within the tribe. However, the continued recognition of Mecranium as a genus, at best, would render Miconia paraphyletic. The most practical solution to the problem of non-monophyletic circumscription of genera in the Miconieae is the recognition of a broadly defined Miconia, with the taxonomic recognition of its subclades as subgenera and sections. Here the Mecranium clade is recognized as a section within a broadly circumscribed Miconia, all recognized species are listed, and 26 new names and nomenclatural combinations are published. In addition, the section is described, and the phylogenetic relationships of its species are discussed briefly based on molecular and morphological phylogenetic analyses.