The complete chloroplast genome sequence of Psittacanthus schiedeanus (Cham. & Schltdl.) G.Don. (Santalales: Loranthaceae), the first plastome of a mistletoe species in the Psittacantheae tribe.

Psittacanthus schiedeanus (Cham. & Schltdl.) G.Don., 1834, is a mistletoe species in the Loranthaceae, characteristic of the canopy in cloud forest edges and widely distributed in northern Mesoamerica. Here, we report the complete chloroplast genome sequence of P. schiedeanus, the first for a species in the Psittacantheae tribe. The circularized quadripartite structure of the P. schiedeanus chloroplast genome was 122,586 bp in length and included a large single-copy region of 72,507 bp and two inverted repeats of 21,283 bp separated by a small single-copy region of 7,513 bp. The genome contained 112 genes, of which 96 are unique, including 65 protein-coding genes, 27 transfer RNA, and four ribosomal RNA. The overall GC content in the plastome of P. schiedeanus is 36.9%. Based on 43 published complete chloroplast genome sequences for species in the families Loranthaceae and Santalaceae (Santalales), the maximum-likelihood phylogenetic tree with high-support bootstrap values indicated that P. schiedeanus in the Psittacantheae tribe is sister to the tribe Lorantheae. The chloroplast genome provided in this study represents a valuable resource for genetic, phylogenetic and conservation studies of Psittacanthus species, and an important advance for unraveling the evolutionary history of these hemiparasitic plants.

A new species of Struthanthus Mart. (Loranthaceae) from Oaxaca, Mexico.

Struthanthusibe-dzisp. nov. is a new species described and illustrated from the cloud and pine-oak forests of the Sierra Madre del Sur in Oaxaca, Mexico. This species shares similarities of leaf shape and inflorescence type with S.deppeanus, S.quercicola, and S.ramiro-cruzii. However, S.ibe-dzi can be recognized by its glaucous branches, leaves and inflorescences; compressed nodes; convoluted distal half of styles in pistillate flowers; and staminate flowers with asymmetrical thecae and an extended connective forming an apiculate horn in both anther series. A distribution map and an identification key are provided to separate S.ibe-dzi from morphologically similar congeners present in the region.

The Argentine Mistletoes Ligaria cuneifolia (Ruiz & Pav.) Tiegh (Loranthaceae) and Phoradendron liga (Gillies ex Hook. & Arn.) Eichler (Santalaceae). Thirty Years of Research.

Ligaria cuneifolia (Ruiz & Pav.) Tiegh (Loranthaceae) and Phoradendron liga (Gillies ex Hook. & Arn.) Eichler (Santalaceae) are regarded as Argentine mistletoes based on their similarities with the European counterpart, Viscum album L. (Santalaceae). These two species are the most used medicinal plants to treat high blood pressure in the Argentinian population. To provide scientific grounds to their traditional use and therapeutic potential, they were selected as herbal drug candidates. The main findings would support the anti-hypertensive action, the anticholesterolemic and antioxidant features of L. cuneifolia, and immunomodulatory properties for both species. Quercetin-O-glycosides, galloyl glycosides, and proanthocyanidins are present in L. cuneifolia while P. liga shows C-glycosyl flavones and 3-deoxyproanthocyanidins. This review summarizes the phytochemical characterization, medicinal properties and reveals promising results warranting future efforts for further investigation.

Differential reproductive responses to contrasting host species and localities in Psittacanthus calyculatus (Loranthaceae) mistletoes.

Host trees are immediate environments for multi-host mistletoes, so parasitizing different hosts implies exposure to varying environmental conditions between mistletoe generations. Therefore, to maximize reproductive fitness in heterogeneous environments (host species) mistletoes should adjust its reproductive responses in relation to circumstances. Here, we ask how reproductive traits of Psittacanthus calyculatus mistletoes vary on two host tree species (Crataegus mexicana, Prunus serotina) at three different localities. We followed individual mistletoes on each host species and at three localities through the flowering season to quantify traits related to reproductive effort and success, e.g. total number of buds, flowers and fruits produced. In buds about to open, we measured two anthers and quantified the number of pollen grains and their viability. Individual flowers were marked to obtain flower longevity data and were followed until fruit formation. At which time we measured and weighed the fruits and the seeds. Mistletoes from one locality produced more buds, flowers and fruits, and the flowers lasted longer, had larger anthers and produced more pollen as compared to the other two localities. However, mistletoes on Prunus serotina produced fewer floral buds, but their fruits were heaviest, longest and widest and ripened fastest across localities. The probability of fruit formation, percentage of fruits formed, and pollen viability were similar among the mistletoes, regardless of host species or locality. We propose that the observed differences in reproductive effort and success associated with host species or locality are plastic or adaptive in this mistletoe in response to varying conditions.

Tracking Host Trees: The Phylogeography of Endemic Psittacanthus sonorae (Loranthaceae) Mistletoe in the Sonoran Desert.

The host dependence of mistletoes suggests that they track the distributions of their hosts. However, the factors that determine the geographic distribution of mistletoes are not well understood. In this study, the phylogeography of Psittacanthus sonorae was reconstructed by sequencing one nuclear (ITS) and two plastid (trnL-F and atpB-rbcL) regions of 148 plants from populations separated by the Sea of Cortez. Divergence time and gene flow were estimated to gain insight into the historical demography and geographic structuring of genetic variation. We also described and mapped the spatial distribution of suitable habitat occupied by P. sonorae and its most common host Bursera microphylla in the Sonoran Desert, along with their responses to Quaternary climate fluctuations using environmental data and ecological niche modeling (ENM). We detected environmental and genetic differentiation between the peninsular and continental P. sonorae populations. Population divergence occurred during the Pleistocene, around the time of the Last Glacial Maximum. No signals of population growth were detected, with net gene flow moving from the continent to the peninsula. ENM models indicate decoupled responses by the mistletoe and its main host to past climate changes. For the Last Interglacial to the present, most models produce only partial areas of overlap on both the peninsula and the continent. Our results support a scenario of Late-Pleistocene isolation and divergence with asymmetrical gene flow between peninsular and continental P. sonorae populations. Continental populations migrated to the peninsula and the spatial isolation probably produced genetic differentiation under different environmental conditions.

A mistletoe tale: postglacial invasion of Psittacanthus schiedeanus (Loranthaceae) to Mesoamerican cloud forests revealed by molecular data and species distribution modeling.

BACKGROUND: Ecological adaptation to host taxa is thought to result in mistletoe speciation via race formation. However, historical and ecological factors could also contribute to explain genetic structuring particularly when mistletoe host races are distributed allopatrically. Using sequence data from nuclear (ITS) and chloroplast (trnL-F) DNA, we investigate the genetic differentiation of 31 Psittacanthus schiedeanus (Loranthaceae) populations across the Mesoamerican species range. We conducted phylogenetic, population and spatial genetic analyses on 274 individuals of P. schiedeanus to gain insight of the evolutionary history of these populations. Species distribution modeling, isolation with migration and Bayesian inference methods were used to infer the evolutionary transition of mistletoe invasion, in which evolutionary scenarios were compared through posterior probabilities. RESULTS: Our analyses revealed shallow levels of population structure with three genetic groups present across the sample area. Nine haplotypes were identified after sequencing the trnL-F intergenic spacer. These haplotypes showed phylogeographic structure, with three groups with restricted gene flow corresponding to the distribution of individuals/populations separated by habitat (cloud forest localities from San Luis Potosí to northwestern Oaxaca and Chiapas, localities with xeric vegetation in central Oaxaca, and localities with tropical deciduous forests in Chiapas), with post-glacial population expansions and potentially corresponding to post-glacial invasion types. Similarly, 44 ITS ribotypes suggest phylogeographic structure, despite the fact that most frequent ribotypes are widespread indicating effective nuclear gene flow via pollen. Gene flow estimates, a significant genetic signal of demographic expansion, and range shifts under past climatic conditions predicted by species distribution modeling suggest post-glacial invasion of P. schiedeanus mistletoes to cloud forests. However, Approximate Bayesian Computation (ABC) analyses strongly supported a scenario of simultaneous divergence among the three groups isolated recently. CONCLUSIONS: Our results provide support for the predominant role of isolation and environmental factors in driving genetic differentiation of Mesoamerican parrot-flower mistletoes. The ABC results are consistent with a scenario of post-glacial mistletoe invasion, independent of host identity, and that habitat types recently isolated P. schiedeanus populations, accumulating slight phenotypic differences among genetic groups due to recent migration across habitats. Under this scenario, climatic fluctuations throughout the Pleistocene would have altered the distribution of suitable habitat for mistletoes throughout Mesoamerica leading to variation in population continuity and isolation. Our findings add to an understanding of the role of recent isolation and colonization in shaping cloud forest communities in the region.

Frugivoria de larvas de Neosilba McAlpine (Diptera, Lonchaeidae) sobre Psittacanthus plagiophyllus Eichler (Santalales, Loranthaceae) no sudoeste de Mato Grosso do Sul, Brasil / Larval frugivory of Neosilba McAlpine (Diptera, Lonchaeidae) on Psittacanthus plagiophyllus Eichler (Santalales, Loranthaceae) in southwestern Mato Grosso do Sul State, Brazil

Loranthaceae são plantas hemiparasitas com distribuição geográfica mundial e representadas no Brasil por seis gêneros. Os mais importantes são Phthirusa, Psittacanthus e Struthanthus, os quais parasitam uma grande diversidade de plantas hospedeiras. Este trabalho avaliou a occurrência e a flutuação sazonal de moscas infestando os frutos de Psittacanthus plagiophyllus nos municípios de Anastácio, Aquidauana e Miranda, Mato Grosso do Sul, Brasil, onde ervas-de-passarinho são disseminadas. As coletas foram realizadas de junho de 1998 a julho de 2000 para obtenção de frutos maduros de P. plagiophyllus, seus insetos associados e catalogação dos seus hospedeiros. Os insetos foram criados para identificação, sendo obtidos 1.522 adultos de Neosilba spp., destes, 612 machos foram identificados a nível específico: Neosilba bifida Strikis & Prado (6 indivíduos), N. certa (Walker) (26 indivíduos), N. pendula (Bezzi) (16 indivíduos), N. zadolicha McAlpine & Steyskal (4 indivíduos) e duas diferentes espécies: morfotipo MSP1 (478 indivíduos) e morfotipo 4 (82 indivíduos). O período de mais alta infestação por Neosilba spp. ocorreu durante agosto de 1998 e de 1999 e, a espécie morfotipo MSP1 foi significativamente mais abundante que todas as outras. A morfotipo 4 foi a segunda mais abundante, diferindo significativamente de Neosilba zadolicha. Neosilba foi o único gênero de moscas frugívoras (Tephritoidea) infestante dos frutos de P. plagiophyllus e comportou-se como um invasor primário neste hospedeiro.

Loranthaceae are hemiparasite plants with worldwide distribuition, represented in Brazil by six genera. The most important are Phthirusa, Psittacanthus and Struthanthus that parasitize a great diversity of host plants. This paper evaluated the occurrence and the seasonal fluctuation of flies infesting the fruits of Psittacanthus plagiophyllus in the municipalities of Anastácio, Aquidauana and Miranda, Mato Grosso do Sul, Brazil, where mistletoes are widespread. The samples were taken from June 1998 to July 2000 to obtain the hosts and its associated insects. All insects were reared until adult stage, and it were obtained 1,522 adults of Neosilba spp., of which 612 males were identified at species level: Neosilba bifida Strikis & Prado (6 specimens), N. certa (Walker) (26 specimens), N. pendula (Bezzi) (16 specimens), N. zadolicha McAlpine & Steyskal (4 specimens) and two different species, morphotype MSP1 (478 specimens) and morphotype 4 (82 specimens). The period of highest infestation by Neosilba spp. occurred during August 1998 and 1999, and morphotype MSP1 was significantly more abundant than all other species. The species morphotype 4 was the second most abundant, differing significantly from Neosilba zadolicha. Neosilba was the only genus of frugivorous fly infesting fruits of P. plagiophyllus and behaves as primary invader in this host.

Gas exchange and water balance of a mistletoe species and its mangrove hosts.

The gas exchange and water relations of the hemiparasite Pthirusa maritima and two its mangrove host species, Conocarpus erectus and Coccoloba uvifera, were studied in an intertidal zone of the Venezuelan coast. Carbon uptake and transpiration, leaf osmotic and total water potential, as well as nutrient content in the xylem sap and leaves of mistletoes and hosts were followed through the dry and wet season. In addition, carbon isotope ratios of leaf tissue were measured to further evaluate water use efficiency. Under similar light and humidity conditions, mistletoes had higher transpiration rates, lower leaf water potentials, and lower water use efficiencies than their hosts. Potassium content was much higher in mistletoes than in host leaves, but mineral nutrient content in the xylem sap of mistletoes was relatively low. The resistance of the liquid pathway from the soil to the leaf surface of mistletoes was larger than the total liquid flow resistance of host plants. Differences in the daily cycles of osmotic potential of the xylem sap also indicate the existence of a high resistance pathway along the vascular connection between the parasite pathway along the vascular connection between the parasite and its host. P. maritima mistletoes adjust to the different physiological characteristics of the host species which it parasitizes, thus ensuring an adequate water and carbon balance.