Darin S. Penneys

Phylogeny of Miconia (Melastomataceae): Patterns of Stamen Diversification in a Megadiverse Neotropical Genus

Phylogenetic relationships within Miconia and other genera in the Neotropical tribe Miconieae were investigated using a maximum parsimony analysis of nuclear internal transcribed spacer and ndhF nucleotide sequences. Included were all sections in Miconia (212 species, ∼20% of the genus) and 12 of the 15 remaining genera assigned to the tribe (an additional 239 species). Given the tribe’s reputation for problematic generic distinctions, it was not surprising that most traditionally recognized taxonomic groups—both genera and sections—were shown to be polyphyletic or paraphyletic. Nevertheless, Miconia is composed of several distinct monophyletic groups, with a large majority of the species belonging to only four clades. Some of these groups represent parts of sections proposed in the last revision of the genus, but most of the diversification seems to have occurred in geographical areas that are more restricted than would have been predicted by the distribution of these sections. Moreover, parallel evolutionary trends are seen in anther form, i.e., shifts from elongate to shorter anthers and from minute‐pored to large‐pored or slitlike dehiscent anthers. These changes may relate to pollinator shifts, especially from buzz pollination to nonvibrational pollination. Thus, the major evolutionary diversifications within the tribe have been obscured by convergence in stamen morphology, leading to many arbitrary generic and sectional circumscriptions.

A preliminary phylogeny of the tribe Miconieae (Melastomataceae) based on nrITS sequence data and its implications on inflorescence position

Miconieae is the most diverse tribe of Melastomataceae, with 30 genera and over 2200 species. The tribe is characterized by fleshy fruits and partially to totally inferior ovaries. To test monophyly of the tribe and assess phylogenetic relationships within it, sequence data from nrITS were gathered and analyzed for 110 taxa in Miconieae and 32 putative outgroups. The tribe Miconieae is not resolved as monophyletic, but rather composed of two distinct clades: one composed of the cauliflorous genera Henriettea, Henriettella, Loreya and Bellucia, and a second clade with all other taxa in Miconieae, sister to a polytomy that includes representatives from tribes Merianieae and Blakeeae. Terminal inflorescences are optimized as basal within Miconieae, with lateral inflorescences evolving in at least four different instances. Cauliflory does not appear to be derived from truly axillary inflorescences; instead it seems to have evolved independently. The terminal-flowered genera Tococa, Conostegia, Tetrazygia, Anaectocalyx, Charianthus, Calycogonium, and Leandra pro parte seem to be derived from within the large genus Miconia, as is Clidemia, a genus with both axillary inflorescences and terminal inflorescences that are deflexed to a lateral position by an axillary branch. Maieta and Necranium, both with axillary inflorescences, are resolved as derived from within Clidemia.

Multiple Events of Dispersal and Radiation of the Tribe Miconieae (Melastomataceae) in the Caribbean

In the Caribbean region, the Melastomataceae are represented by about 450 species (from 28 genera), close to 400 of them endemic. The majority of these endemic species (approximately 330) belong to the tribe Miconieae, a monophyletic group characterized by flowers with inferior or partly inferior ovaries that develop into baccate fruits, stamens with no or only poorly developed connective appendages, and the absence of megastyloids and imbricate bracts at the base of the flowers. A phylogenetic analysis of 460 accessions from 450 species of the tribe Miconieae, including 139 present in the Antilles (103 of these endemic), was performed based on nuclear (nrITS) and plastid (ndhF) DNA sequence data. This analysis shows that most of the Caribbean endemics are the product of five radiation events: (1) a clade containing the Caribbean endemic (or near-endemic) genera Pachyanthus, Calycogonium, Tetrazygia and Charianthus, as well as a few representatives of Miconia and Leandra. (2) The genus Mecranium. (3) The Caribbean species of Miconia section Chaenopleura (which are probably not the sister group of Andean Chaenopleura). (4) The Greater Antillean species of Clidemia and Ossaea (including Sagraea). (5) The Lesser Antillean representatives of Clidemia. Caribbean endemics that are more closely related to mainland species, rather than other Caribbean species are rare, and these often are segregates of widespread continental species. Because of a lack of resolution at the base of several clades, it is currently not possible to determine which mainland groups are the closest relatives of these Caribbean endemics, thus preventing us from establishing unequivocally the geographical origins of these species.ResumenEn la región del Caribe la familia Melastomataceae está representada por cerca de 450 especies (de 28°géneros), 400 de ellas endémicas. La mayoría de estas especies (approximately 330) pertenecen a la tribu Miconieae, un grupo monofilético caracterizado por flores con ovario parcial o totalmente ínfero que se desarrollan en frutos bayados, estambres con apéndices ausentes o poco desarrollados, ausencia de mega estiloides, y la ausencia de brácteas imbricadas en la base del as flores. Se realizó un análisis filogenético basado en secuencias nucleares (nrITS) de cloroplasto (ndhF) para la tribu Miconieae. El análisis incluyó 460 individuos, representando 450 especies de la tribu, de las cuales 139 están presentes en el Caribe (103 de estas endémicas). El análisis muestra que la mayoría de las especies endémicas del Caribe son producto de cinco eventos de radiación: (1) Un clado que contiene los géneros endémicos (o casi endémicos) Pachyanthus, Calycogonium, Tetrazygia y Charianthus, así como representantes de Miconia y Leandra. (2) El género Mecranium. (3) las especies Antillanas de Miconia sección Chaenopleura. (4) Las especies de las Antillas mayores de Clidemia y Ossaea (incluyendo Sagraea). (5) Las especies de las Antillas menores de Clidemia. Especies endémicas del Caribe que son hermanas o que están cercanamente relacionadas con especies del continente, y no con especies de la región son raras, y generalmente son segregadas de especies de amplia distribución. Debido a la falta de resolución en la base de muchos de estos clados en este estudio, en este momento no es posible determinar con precisión que grupos presentes en el continente son hermanos a los grupos del Caribe, por lo que no es posible establecer los orígenes geográficos de la mayoría de grupos endémicos.

A Systematic Revision and Cladistic Analysis of Charianthus (Melastomataceae) using Morphological and Molecular Characters

Abstract In this paper we present a revision of Charianthus, which represents the first genus in the Miconieae (Melastomataceae) to be the subject of a combined molecular and morphological cladistic analysis. Charianthus is a morphologically well-characterized clade of six species of hummingbird pollinated shrubs and small trees found in the tropical montane rain forests and elfin forests of the Lesser Antilles. Analysis of the internal transcribed spacer (ITS) region, combined with morphological data, resulted in a strongly supported Charianthus clade. Charianthus fadyenii was placed in the Tetrazygia clade where its position as sister to T. bicolor is strongly supported. Inclusion of C. fadyenii in Charianthus renders both Charianthus and Tetrazygia non-monophyletic, therefore, this species has been transferred to Tetrazygia. Charianthus purpureus, as defined by earlier taxonomists, is a polyphyletic species because of the inclusion of morphologically distinctive populations on the islands of Dominica and Grenada; thus, two new species, C. dominicensis and C. grenadensis, have been described, based on the results presented herein. The revised circumscription of Charianthus renders it the only vascular plant genus endemic to the Lesser Antilles.

Henrietteeae (Melastomataceae): A New Neotropical Berry-Fruited Tribe

Abstract With nearly 2,000 species, all restricted to the Neotropics, Miconieae represent the largest radiation within Melastomataceae. Generic limits and relationships within the tribe have long been contested. Our molecular phylogenetic analyses of the tribe, based on sequences of nrITS and ndhF, resulted in consistent support for a clade comprising Bellucia, Loreya, Henriettea, and Henriettella, which is neither nested within nor sister to the Miconieae. Furthermore, and based upon a series of presumably synapomorphic anatomical and morphological characters, e.g. megastyloid crystals, absence of both medullary and cortical vascular bundles, plinerved leaves, axillary or cauliflorous inflorescences, we consider three additional genera, Kirkbridea, Llewelynia, and Myriaspora, to belong to this clade, a newly recognized tribe, Henrietteeae. These seven genera had formerly been assigned to the Miconieae based on their having exappendiculate anthers (except Kirkbridea) and berry fruits. Henriettella and Llewelynia are relegated to synonymy under Henrietten (25 new combinations are made under that genus: Henriettea boliviensis, H. bracteosa, H. caudata, H. duckeana, H. fissanthera,H. glabra,H. cogniauxiana, H. goudotiana,H. heteroneura, H. hondurensis, H. ininiensis, H. lawrancei, H. lundellii, H. maguirei, H. manarae, H. odorata, H. ovata, H. prancei, H. rimosa, H. steyermarkii, H. tachirensis, H. tobagensis, H. tovarensis, H. trachyphylla, H. williamsii), and Loreya and Myriaspora are synonymized under Bellucia (with nine new combinations under that genus: Bellucia egensis, B. gracilis, B. klugii, B. nigricans, B. ovata, B. riparia, B. strigosa, B. subandina, B. wurdackiana). A description of Henrietteeae along with a key to and brief descriptions of its constituent genera are provided, in addition to necessary new combinations.

Comparative Anatomy and Morphology of Nectar-producing Melastomataceae

BACKGROUND AND AIMS Most neotropical Melastomataceae have bee-pollinated flowers with poricidal anthers. However, nectar rewards are known to be produced in about 80 species in eight genera from four different tribes. These nectar-producing species are pollinated by both vertebrates and invertebrates. METHODS The floral morphology and anatomy of 14 species was studied in six genera of nectar-producing Melastomataceae (Blakea, Brachyotum, Charianthus, Huilaea, Meriania and Miconia). Anatomical methods included scanning electron microscopy, and serial sections of paraffin-embedded flowers. KEY RESULTS All vertebrate-pollinated melastome flowers have petals that do not open completely at anthesis, thus forming a pseudo-tubular corolla, while closely related species that are bee pollinated have rotate or reflexed corollas. In most species, nectar secretion is related to stomatal or epidermal nectaries and not filament slits as previously reported. Moreover, the nectar is probably supplied by large vascular bundles near the release area. Blakea and Huilaea have nectary stomata located upon the dorsal anther connective appendages. Brachyotum also has nectary stomata on the anther connectives, but these are distributed lengthwise along most of the connective. Meriania may release nectar through the anther connective, but has additional nectary stomata on the inner walls of the hypanthium. Miconia has nectary stomata on the ovary apex. Charianthus nectaries were not found, but there is circumstantial evidence that nectar release occurs through the epidermis at the apex of the ovary and the lower portions of the inner wall of the hypanthium. CONCLUSIONS Nectar release in Melastomataceae is apparently related to nectary stomata and not filament slits. The presence of nectary stomata on stamens and on ovary apices in different lineages suggests that the acquisition of nectaries is a derived condition. Nectary location also supports a derived condition, because location is strongly consistent within each genus, but differs between genera.

Phylogenetics and Morphology in the Blakeeae (Melastomataceae)

Blakeeae (Melastomataceae) are a Neotropical tribe of mostly hemiepiphytic woody plants that frequently form domatia harboring mites or ants in mutualistic associations. The tribe comprises 10 species in Chalybea and Huilaea and nearly 200 species in Blakea and Topobea. Key characters separating the latter two genera pertain to anther morphology; however, numerous species have been discovered with intermediate anther forms, thus making an already dubious distinction even more doubtful. In order to test the monophyly of Blakea and Topobea, we conducted three phylogenetic analyses using 111 morphological characters, partitioned into qualitative, quantitative, and combined data sets. These analyses resolved the genera as polyphyletic. Blakea has nomenclatural priority; thus, Topobea must be synonymized. Morphological character evolution tracked on the combined cladogram demonstrates the phylogenetic utility of these 111 characters, as many are synapomorphic for particular radiations within Blakea. Noteworthy examples of character evolution, natural history, and clades are discussed.

A Specialized Bird Pollination System with a Bellows Mechanism for Pollen Transfer and Staminal Food Body Rewards

Bird pollination has evolved repeatedly among flowering plants but is almost exclusively characterized by passive transfer of pollen onto the bird and by nectar as primary reward [1, 2]. Food body rewards are exceedingly rare among eudicot flowering plants and are only known to occur on sterile floral organs [3]. In this study, we report an alternative bird pollination mechanism involving bulbous stamen appendages in the Neotropical genus Axinaea (Melastomataceae). We studied the pollination process by combining pollination experiments, video monitoring, and detailed analyses of stamen structure and metabolomic composition. We show that the bulbous stamen appendages, which are consumed by various species of passerines (Thraupidae, Fringillidae), are bifunctional during the pollination process. First, the appendages work as bellows organs in a unique pollen expulsion mechanism activated by the passerines. As the birds seize an appendage with their beaks in order to remove it from the flower for consumption, air contained in the appendages aerenchymatous tissue is pressed into the hollow anther. The resulting air flow causes the expulsion of a pollen jet and the deposition of pollen on the birds head and beak. Second, the stamen appendages provide a hexose-rich, highly nutritious (15,100 J/g) food body reward for the pollinating passerines. This discovery expands our knowledge of flowering plant pollination systems and provides the first report of highly specialized bellows organs for active pollen transfer in flowering plants. In addition, this is the only known case of a food body reward associated with reproductive structures in the eudicot clade of flowering plants.

Combined Molecular and Morphological Phylogenetic Analyses of the Blakeeae (Melastomataceae)

Premise of research. The Blakeeae (Melastomataceae) comprise nearly 200 species in Blakea and Topobea and another 10 species in Chalybea and Huilaea. The former two genera have been separated primarily on the basis of characters pertaining to anther morphology. Combined molecular and morphological phylogenetic analyses were conducted to evaluate generic limits, reconstruct patterns of morphological character evolution, and identify clades within the tribe. Methodology. To test the monophyly of Blakea and Topobea, we analyzed 111 morphological characters, nuclear ribosomal internal transcribed spacer region, the accD-psaI and atpB-rbcL spacer regions, and trnL-trnF nucleotide sequence data, using maximum likelihood and parsimony in individual and variously combined data sets comprising up to 3955 characters and 135 terminals. Pivotal results. Chalybea and Huilaea were recovered as a clade sister to the clade of Blakea and Topobea. Neither of the latter two genera was resolved as being monophyletic in any analysis, nor does anther morphology support their separation. Five infrageneric groupings were discovered, and their synapomorphic morphological characters and natural history are discussed. Conclusions. We present the first phylogenetic analysis of the Blakeeae, using combined molecular and morphological characters. Topobea must be transferred to Blakea. Within Blakea, a single shift from bee to vertebrate pollination has occurred, and this clade is well defined by morphological synapomorphies, including pseudocampanulate corollas and stomatal nectaries on the anther connectives. Floral mimicry is hypothesized to occur in the Solanum flowered clade.

A new species of Henriettea (Melastomataceae) from the Sierra de Baoruco, the Dominican Republic

Henriettea uniflora, which is known only from a diverse moist montane forest in the vicinity of Loma Trocha de Pey (or “Monteada Nueva”), Loma Pie de Palo, and Loma Remigio, the easternmost peaks of the Sierra de Baoruco, is described and illustrated. It is compared to species of the Henriettea squamulosa complex, especially H. squamulosa and H. ciliata. The species of this complex are characterized by an indumentum of ferruginous, stellate-lepidote hairs.