Taxonomic studies in the Miconieae (Melastomataceae). VII. Miconia howardiana,a new speices from Hispaniola

Miconia howardiana, which is known only from a diverse moist montane forest in the vicinity of Loma Trocha de Pey (or “Monteada Nueva”), the easternmost peak of the Sierra de Baoruco, is described and illustrated. It is compared to phenetically similar (and probably phylogenetically related) species of theMiconia favosa complex, i.e.,M. favosa, M. xenotricha, M. campanensis M. Sintenisii, M. foveolata, andM. pycnoneura. The species of this complex are characterized by bullate leaves with frequently cordate bases and often six secondary veins. Most species also have large berries and flowers, 5-locular ovaries, large inflorescence bracts and bracteoles, and more or less dendritic multicellular hairs.     

Taxonomic studies in the Miconieae (Melastomataceae). I. Variation in inflorescence position

In the Miconieae (Melastomataceae) the inflorescences may be either lateral (with shoots pleonanthic and plants showing Rauh's architectural model) or the terminal (with shoots hapaxanthic and plants illustrating Leeuwenberg's, or less commonly Scarrone's or Stone's, architectural models). Inflorescence position is a valuable taxonomic character in the tribe and is usually uniform within genera or speciesgroups. An analysis of variation of this character elucidates the complex and difficult generic delimitations within the tribe.Ossaea DC. andClidemia D. Don, as presently delimited, contain both terminal-and axillary-flowered species and are undoubtedly polyphyletic assemblages. Some groups, e.g.,Clidemia sect.Clidemia, Leandra Raddi sect.Chaetodon Cogn.,Ossaea sect.Octopleura (Griseb.) Cogn., andMyrmidone Mart. have species that develop pseudolateral inflorescences, i.e., the terminal nature of the inflorescence is obscured by the early development of an axillary bud which continues growth of the branch. Pseudolateral inflorescences seem to have evolved several times within the tribe, andClidemia sect.Clidemia likely evolved from the obviously terminal-floweredHeterotrichum DC. andMiconia Ruíz & Pavón sect.Octomeris Hook. f. (p. p.);Myrmidone andMicrophysca Naud. are closely related toTococa Aublet; andLeandra sect.Chaetodon (and probably alsoOssea sect.Octopleura) show affinity with the remaining sections ofLeandra.     

Miconia zanonii (Melastomataceae: Miconieae), a new species from Hispaniola

Miconia zanonii, which occurs in broad-leaved cloud forests at four localities in the Cordillera Central of the Dominican Republic, is described and illustrated. It is compared withM. krugii andM. samanensis, two probably close relatives withinMiconia sect.Chaenopleura.     

A new species of Miconia (Melastomataceae, Miconieae) from northeastern Brazil

Miconia caiuia occurs only in the highly endangered submontane moist forests in the states of Alagoas, Pernambuco, and northern Bahia, Brazil. It belongs to Miconia section Miconia subsection Secundiflorae. This new species can be distinguished from other species in this subsection by the lepidote-stellate trichomes on young branches, petioles, inflorescences and hypanthia, leaves with suprabasal nerves and wrinkled/auriculate bases, abaxial leaf surfaces with only sparse trichomes, a 5-locular ovary, and large mature fruits (10–13?×?12–15 mm) with up to 15 seeds, which are 2.5–3.5 mm long.     

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.     

Taxonomic placement of Calycogonium squamulosum (Melastomataceae: Miconieae)

Calycogonium squamulosum Cogn., a Puerto Rican endemic, is shown properly to be placed inHenriettea DC, (includingHenriettella Naud.), and this transfer is made. The species is allied to several other lepidote taxa ofHenriettea, e.g.,H. squamata (Alain) Alain andH. acunae (Alain) Alain (all endemic to the Oriente region of Cuba).Calycogonium squamulosum is also compared to the Hispaniolan endemic,Henriettea barkeri (Urban & Ekman) Alain [syn.H. elliptica (Urban) Alain], a species with stellate to stellate-strigose hairs.     

Two new species of Charianthus (Melastomataceae: Miconieae) from the Lesser Antilles

In the course of a phylogenetic analysis and systematic revision ofCharianthus, it was discovered thatC. purpureus, as traditionally circumscribed, is polyphyletic, consisting of three morphologically diagnosable entities. Thus two new species,Charianthus dominicensis andC. grenadensis, are described and illustrated. Each is endemic to the Lesser Antillean island for which it is named—Dominica and Grenada, respectively.Charianthus, the only vascular plant genus endemic to the Lesser Antilles, comprises six species of nectariferous, hummingbird-pollinated shrubs and small trees.     

Diplospory and obligate apomixis in Miconia albicans (Miconieae, Melastomataceae) and an embryological comparison with its sexual congener M. chamissois

Apomixis, or asexual reproduction through seeds, has been reported for species of the tribe Miconieae, Melastomataceae, but details of the process have yet to be described. We analyzed and compared sporogenesis and gametogenesis in the apomictic Miconia albicans and the sexual M. chamissois. The results point to some differences between species, which were related to the apomictic process. In M. albicans microsporogenesis, problems during meiosis and degeneration of its products led to total pollen sterility, while M. chamissois presented normal bicellular pollen grains in the mature anther. The absence or abnormality of meiosis in M. albicans megasporogenesis led to the formation of an unreduced embryo sac and also to egg cell parthenogenesis, which gave rise to the apomictic embryo. Embryo and endosperm development were autonomous, resulting in seeds and fruits independent of pollination and fertilization. Thus, in this species, apomixis can be classified as diplosporic and obligate. In contrast, meiosis was as expected in the sexual M. chamissois, and led to the development of a reduced embryo sac. Despite the divergent pathways, many embryological characteristics were similar between the studied species and other Melastomataceae and they seem to be conservative character states for the family.     

<Emphasis Type="Italic">Miconia walterjuddii</Emphasis> (Miconieae: Melastomataceae), a new species from Cuba

Miconia walterjuddii, a new species of Melastomataceae from the mountains in northeast Cuba, is described. This species can be easily assigned to Miconia section Chaenopleura due to its short anthers that open by two longitudinal slits. Sequence data from nrITS confirm this placement. This new species is characterized by its inconspicuous lepidote indumentum of minute adpressed scales ca. 0.05 mm long; small flowers in dichasia, forming a compact, many-flowered, rounded to subcorymbose cymes, with purple to fuchsia colored petals.     

Miconia becqueri,a new species of Miconia (Melastomataceae) with strongly four-lobed ovaries from the Sierra Maestra,Cuba

A new species of Miconia belonging to a clade diagnosed by strongly four-lobed ovaries/hypanthia and elongated calyx teeth flattened parallel to the floral radii, i.e., the Calycogonium hispidulum complex, endemic to the Sierra Maestra of eastern Cuba, is described, illustrated, and compared with related Cuban species. The discovery of Miconia becqueri brings to 15 the number of recognized species of this complex, seven of which occur in Cuba (if Clidemia barbeyana is conspecific with C. wrightii).     

Miconia atlantica, a new species of Melastomataceae from the eastern mountains of Brazil

A new species of Miconia from the mountains in the Atlantic Forest of eastern Brazil is presented here. Miconia atlantica has been collected in the states of São Paulo and Espírito Santo. It belongs to section Glossocentrum and can be recognized among others species in this section by the leaves with acute bases, an indumentum consisting of stellate trichomes moderately covering the abaxial surface of mature leaves, glomerulate inflorescences, and stamens with unappendaged connectives. Marsupiform domatia were found in São Paulo populations.     

Two thrush species as dispersers of Miconia prasina (Sw.) DC. (Melastomataceae): an experimental approach.

We carried out a seed germination experiment using two thrush species in captivity. We compared the number of germinated seeds and germination time of control seeds (manually removed from fruits) and ingested seeds of Miconia prasina by two bird species, Turdus albicollis and T. amaurochalinus, and also compared retention times of seeds by both thrush species. Control seeds germinated more frequently than those ingested for one species, T. albicollis. The germination time of ingested seeds by T. amaurochalinus was similar to the control seeds but seeds ingested by T. albicollis took longer to germinate than the controls. Both thrush species had a similar seed defecation pattern. The cumulative number of defecated seeds increased by 2 hours after fruit ingestion. At the end of the first 30 minutes both species had already defecated approximately 50% of the seeds ingested Our results suggest that both species could act as disperser agents of M. prasina.     

Taxonomic revision of Driessenia (Melastomataceae)

The genus Driessenia Korth. comprises fourteen species and two varieties. Eleven species are endemic to Borneo, the remaining three species occur on Sumatra, Java or Sulawesi. Five species ( D. sessiliflora, D. planopetiolata, D. attenuata, D. grandithyrsa and D. aequiappendiculata ), one variety ( D. microthrix Stapf var. pteroclada ) and one combination ( D. dispar (Cogn.)) are new. The genus Triuranthera Back. is made a synonym of Driessenia . The revision includes a key to the species, illustrations of various floral parts and maps of distribution.     

Tahiti's native flora endangered by the invasion of Miconia calvescens DC. (Melastomataceae)

Abstract. The native flora of tropical oceanic islands is known to be particularly susceptible both to displacement and extinction, following the invasion of alien organisms. Miconia calvescens DC. (Melastomataceae), first introduced to Tahiti (French Polynesia, South Pacific Ocean) in 1937 as an ornamental plant, now covers over two-thirds of the Island. As it forms dense monotypic stands which have progressively overwhelmed the native forests, this plant pest is a direct threat to the rich Tahitian indigenous flora. Between 40 and 50 species of the 107 species endemic to Tahiti are thought to be on the verge of extinction. M. calvescens was finally declared a'noxious species in French Polynesia'in 1990. Without efficient control efforts and effective endangered plant conservation and protection legislation, M. calvescens could cause Tahiti and all the high islands of French Polynesia to become ecological deserts.     

Observations on the big bang flowering of Miconia minutiflora (Melastomataceae)

Trees ofMiconia minutiflora produced abundant flowers for only one to three days during mid-April 1983 in the vicinity of Saül, French Guiana. They attracted large numbers of at least 14 species of bees that collected nectar or pollen or both. Nectar production is uncommon in the Melastomataceae and not previously reported forMiconia. Peak bee activity at the trees was in the morning and by afternoon most visits were limited to those bees in search of remnant pollen, especially species ofTrigona. As has been shown for other neotropical plants, heavy rains may trigger flowering in this species. It is suggested that the flowering system ofM. minutiflora promotes outcrossing because of interactions among the numerous species of bees visiting the trees and because of inter-individual variation in nectar and pollen availability. Therefore, bees may fly to other trees instead of becoming satiated with nectar or pollen from a single tree.     

Mecranium juddii (Melastomataceae: Miconieae), a new species from the Massif de la Hotte, Haiti

Mecranium juddii is described and illustrated. It is known only from 1650–1700 m elevation in the Ravine du Sud on the northern slopes of Morne Formon in Macaya National Park, Haiti.Mecranium juddii is a member of theM. multiflorum complex and is phenetically most similar toM. revolutum andM. alpestre, which differ fromM. juddii in stem indumentum or leaf size and shape.