Two new species of Serjania section Serjania (Sapindaceae)

Two new species ofSerjania sect.Serjania,Serjania neei from Bolivia andS. rhytidococca from Mexico, are described, illustrated, and compared with their closest relatives.

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Resumen  En el presente artículo se describen, se ilustran y se comparan con los parientes mas cercanos las nuevas especiesSerjania neei de Bolivia yS. rhytidococca de México, ambas pertenecientes a la secciónSerjania.

     

Morphological variation in populations of Bletia purpurea (Orchidaceae) and description of the new species B. riparia

Bletia purpurea is the most widespread species in its genus. Morphological variation has been recognized throughout the range of its distribution. In this paper, the morphological variation from 63 populations (583 individuals) ofBletia purpurea is assessed to determine whether more than one species were present. Forty-four quantitative and qualitative characters were examined by univariate analyses and exploratory multivariate analyses. Univariate analyses indicate that quantitative characters such as lateral sepal width, petal. width, lip length, and lip width are significantly different for populations from Acazónica, Mexico. Floral parts in the populations from Acazónica are the smallest among all populations. Qualitative characters such as petals covering the lip midlobe and horizontal lip position are found exclusively in the same populations. We concluded that these populations should be described as a new species,B. riparia. Multivariate analyses indicated that morphological variation among the other populations cannot be ascribed to geographic distribution or ecological factors.     

Two new species of Dioscorea (Dioscoreaceae) from Peru

Two new species ofDioscorea,D. gentryi (subgen.Helmia sect.Monadelpha) andD. andromedusae (subgen.Helmia sect.Centrostemon) from Peru, are described and illustrated.     

Five new species of Heteropterys (Malpighiaceae) from Central and South America

Five-new taxa ofHeteropterys H. B. K. subsect.Aptychia Nied. are described, illustrated, and mapped:H. andina from Peru;H. minutiflora from Costa Rica; andH. bullata, H. capixaba, andH. oberdanii, from the Atlantic coastal forest of Brazil. The affinities and diagnostic characters of each species are discussed.     

Seed germination and dormancy in the medicinal woodland herbs Collinsonia canadensis L. (Lamiaceae) and Dioscorea villosa L. (Dioscoreaceae)

We used a double germination phenology or “move-along” experiment (sensu Baskin and Baskin, 2003) to characterize seed dormancy in two medicinal woodland herbs, Collinsonia canadensis L. (Lamiaceae) and Dioscorea villosa L. (Dioscoreaceae). Imbibed seeds of both species were moved through the following two sequences of simulated thermoperiods: (a) 30/15 °C→20/10 °C→15/6 °C→5 °C→15/6 °C→20/10 °C→30/15 °C, and (b) 5 °C→15/6 °C→20/10 °C→30/15 °C→20/10 °C→15/6 °C→5 °C. In each sequence, seeds of both species germinated to high rates (>85%) at cool temperatures (15/6 and 20/10 °C) only if seeds were previously exposed to cold temperatures (5 °C). Seeds kept at four control thermoperiods (5, 15/6, 20/10, 30/15 °C) for 30 d showed little or no germination. Seeds of both species, therefore, have physiological dormancy that is broken by 12 weeks of cold (5 °C) stratification. Morphological studies indicated that embryos of C. canadensis have “investing” embryos at maturity (morphological dormancy absent), whereas embryos of D. villosa are undeveloped at maturity (morphological dormancy present). Because warm temperatures are required for embryo growth and cold stratification breaks physiological dormancy, D. villosa seeds have non-deep simple morphophysiological dormancy (MPD). Neither species afterripened in a 6-month dry storage treatment. Cold stratification treatments of 4 and 8 weeks alleviated dormancy in both species but C. canadensis seeds germinated at slower speeds and lower rates compared to seeds given 12 weeks of cold stratification. In their natural habitat, both species disperse seeds in mid- to late autumn and germinate in the spring after cold winter temperatures alleviate endogenous dormancy.     

Agave rzedowskiana, a new species in subgenus Littaea (Agavaceae) from western Mexico

Agave rzedowskiana is described and illustrated from the states of Sinaloa and Jalisco, Mexico. This species is a member of subgenusLittaea (Tagliabue) Baker “groupStriatae” of Baker. It is compared withA. petrophila García-Mend. & E. Martínez andA. dasylirioides Jacobi & Bouché.

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Resumen  Se describe e ilustraAgave rzedowskiana de los estados de Sinaloa y Jalisco, México. La especie pertenece al subgéneroLittaea (Tagliabue) Baker “Grupo Striatae” de Baker. Se le compara conA. petrophila García-Mend. & E. Martínez yA. dasylirioides Jacobi & Bouché.

     

4种薯蓣属植物的psbA-trnH片段序列分析

对4种薯蓣属(Dioscorea)植物——小花盾叶薯蓣(D.sinoparviflora C.T.Ting.)、盾叶薯蓣(D.zingiberensis C.H Wright.)、黄独(D.bulbifera L.)和薯蓣(D.polystachya Turczaninow) 共22个植物类群的叶绿体psbA-trnH基因区进行PCR扩增并测序,获得了该区间的完整序列,小花盾叶薯蓣的psbA-trnH片段全长589~593 bp,盾叶薯蓣全长为575~599 bp,黄独全长为372 bp,薯蓣全长为355~368 bp。将所得序列用Bayesian推断其系统发育关系,结果发现psbA-trnH片段不能够完全区分4种薯蓣属植物种间和种内的各个分类群(不同产地),且不能区分盾叶薯蓣与小花盾叶薯蓣;推测薯蓣的演变过程可能与人工驯化有关,黄独与栽培薯蓣的亲缘关系较近,而与野生薯蓣的亲缘关系较远。     

A new name and a new species in MexicanRuellia (Acanthaceae)

Based on pollen and floral morphology,Blechum grandiflorum is transferred toRuellia, and the nameR. mirandana is proposed for this species. A new species,Ruellia tuxtlensis, is described which is distinguishable fromR. mirandana by its longer spike and elliptic bracts. It is presently known only from the lowlands of Veracruz, Mexico.     

Ten new species of Tibouchina (Melastomataceae) from Mexico

Ten new species of Tibouchina (T. almedae, T. congestiflora, T. connata, T. hintonii, T. macvaughii, T. nanifolia, T. patens, T. roseotincta, T. sinaloensis, andT. thulia) are described from western Mexico. Distinguishing characteristics, phenology, distribution, and phylogenetic relationships are discussed. Illustrations of all these new species are provided.     

Three new species of Spigelia (Strychnaceae) from Mexico

During a revisionary study ofSpigelia, three new species from Mexico were discovered. Two of these new species appear to be narrow endemics, one in the state of Chiapas and one in the state of Guerrero, and the third is more widespread in Mexico and Guatemala. These new species are described, illustrated, and distinguished from other North AmericanSpigelias.     

A new species of Malaxis (Orchidaceae) from Morelos, Mexico

A new species from the Mexican state of Morelos, Malaxis lyonnetii, is described and illustrated. It is similar to M. lepanthiflora but is distinguished by its much smaller flowers, distally uncinate basal lip lobes, and entire, rounded apical lip lobe.

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Resumen  Se describe e ilustra a Malaxis lyonnetii, una nueva especie del estado mexicano de Morelos. Esta especie es similar a M. lepanthiflora, de la que se distingue por las flores mucho menores, los lóbulos basales del labelo distalmente uncinados y el lóbulo apical del labelo entero y redondeado.

     

Three new species of Ocotea (Lauraceae) from southern Mexico

Three new species ofOcotea (O. disjuncta, O. iridescens, andO. rovirosae) from southern Mexico are described and illustrated.Ocotea disjuncta is related to theO. effusa group, whileO. iridescens seems to be related to theO. heydeana group. The relationships ofO. rovirosae are not clear.      

Pinus georginae (Pinaceae), a new species from western Jalisco, Mexico

Pinus georginae is described and illustrated as a new endemic species from the valleys in the southern basin of Río Ameca, Jalisco, western Mexico. It is closely related to Pinus praetermissa; however, after studying the cones and anatomy of the leaves in detail, characteristics were revealed that identify P. georginae as a distinct species.

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Resumen  Se describe e ilustra Pinus georginae como una especie nueva, endémica de algunos valles intermontanos al sur del Río Ameca, Jalisco, en el Occidente de México. Los árboles se parecen a Pinus praetermissa; sin embargo, al estudiar con detalle los conos y la anatomía de las acículas lo ubican a Pinus georginae como una entidad biológica con categoría específica independiente.

     

Zapoteca quichoi (Leguminosae, Mimosoideae), a new species from southeastern Mexico

Zapoteca quichoi, a new species endemic to southern Tabasco, Mexico, is described and illustrated. This species exhibits morphological characteristics that place it within subgenus Amazonica, together with Z. amazonica and Z. microcephala, from Peru and Colombia, respectively.

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Resumen  Se describe e ilustra Zapoteca quichoi (Leguminosae, Mimosoideae), una nueva especie de Tabasco, México. Esta especie exhibe características morfológicas que la ubican dentro del subgénero Amazonica, junto con Z. amazonica y Z. microcephala, especies nativas de Perú y Colombia respectivamente.

     

A new species of Sicyos L. (Cucurbitaceae) from Oaxaca, Mexico

Sicyos mcvaughii, a new species from Oaxaca, is described and illustrated. It is similar to Sicyos sertuliferus Cogn., and grows in secondary tropical deciduous forest, between 20 and 630 meters.     

Tigridia amatlanensis (Tigridieae: Iridaceae), a new species from Oaxaca, Mexico

Tigridia amatlanensis is described and illustrated as a new species from Mexico. It is recognized by its nodding flowers and its inner and outer tepals cirrhous and markedly dimorphic in length. It is most closely related toT. hallbergii subsp.hallbergii andT. meleagris. Other morphologically similar species areT. catarinensis andT. molseediana.     

A synopsis of the genus Mandevilla (Apocynaceae) in Mexico and Central America

The 19 species of the genus Mandevilla in Mexico and Central America are treated synoptically. New synonymy is provided and a new species, Mandevilla rigidifolia, is described.