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Using the genus Casearia, we assessed the status of nested singletons: individual specimens corresponding to accepted species but in molecular trees appearing nested within clades of closely related species. Normally, such cases would be left undecided, while on the other hand, timely taxonomic decisions are required. We argue that morphological, chorological, and ecological data can be informative to illuminate patterns of speciation. Their use can provide a first step in testing taxon concepts at species level. We focused on five cases of nested singletons in trees of the genus Casearia. We employed PCA and cluster analysis to assess phenotypic differentiation. Using geocoordinates, we calculated niche space differentiation based on 19 bioclim variables, by means of PCA and niche equivalency and similarity tests and generated dot maps. We found that the singletons were morphologically distinctive in two of the five cases (Casearia selloana and C. manausensis), relatively distinctive in two other cases (C. zizyphoides and C. mariquitensis), and partially overlapping in the last case (C. grandiflora). For two cases (C. mariquitensis and C. selloana), ecological niche space was broadly overlapping, in two cases it was found broadly nested (C. grandiflora and C. zizyphoides), and in one case narrowly nested (C. manausensis), but in no case niche differentiation was observed. Niche overlap, similarity and equivalency showed corresponding patterns. Given these data, one would interpret C. selloana and C. manausensis as presumably well‐distinguished taxa, their narrow distribution ranges suggesting recently emerging lineages. The other three cases are not clearcut. Morphological data would suggest particularly C. grandiflora conspecific with C. arborea, but differences in the distribution are intriguing. Our approach would reject the notion of potential synonymy based on nested phylogenetic placement for at least two of the five cases. The other case also shows no complete lack of differentiation which would support synonymy. [ABSTRACT FROM AUTHOR]

We analyzed the structure of foliicolous lichen communities in the northernmost lowland forest of the Neotropics, Los Tuxtlas Tropical Biology Station in Veracruz, Mexico, and its dependence on phorophyte and microclimate. Along a 420‐m long transect with 15 equidistant sampling points, within a 10 m radius of each point, we sampled a total 137 phorophytes and 411 leaves. The phorophytes represented 13 species, with diverse leaf traits regarding size, texture, presence of hairs and/or glands, and longevity, including: Astrocaryum mexicanum (Arecaceae), Chamaedorea ernesti‐augustii (Arecaceae), Costus scaber (Costaceae), Guarea glabra (Meliaceae), Heliconia latispatha (Heliconiaceae), Monstera acuminata (Araceae), Myriocarpa longipes (Urticaceae), Piper hispidum (Piperaceae), Poulsenia armata (Moraceae), Pseudolmedia oxyphyllaria (Moraceae), Salacia megistophylla (Celastraceae), Siparuna thecaphora (Siparunaceae) and Syngonium podophyllum (Araceae). NDMS ordination and cluster analysis grouped the phorophytes into hierarchically structured clusters variously correlated with microsite, phorophyte species and foliicolous lichen species richness. Indicator species analysis revealed statistically significant foliicolous lichen species characteristic for terminal clusters and for phorophyte species. We conclude that the principle of "diversity begets diversity" may apply, in that phorophyte diversity influences the diversity of foliicolous lichen communities through the manifestation of subtle phorophyte preferences, best seen in well‐developed communities on leaves with higher longevity. Thus, well‐preserved forest ecosystems, with a higher diversity of suitable phorophytes, will support a higher diversity of foliicolous lichens, a phenomenon that extents to epiphytes in general. [ABSTRACT FROM AUTHOR]

The early‐successional status of lichens in modern terrestrial ecosystems, together with the role lichen‐mediated weathering plays in the carbon cycle, have contributed to the long and widely held assumption that lichens occupied early terrestrial ecosystems prior to the evolution of vascular plants and drove global change during this time. Their poor preservation potential and the classification of ambiguous fossils as lichens or other fungal–algal associations have further reinforced this view. As unambiguous fossil data are lacking to demonstrate the presence of lichens prior to vascular plants, we utilize an alternate approach to assess their historic presence in early terrestrial ecosystems. Here, we analyze new time‐calibrated phylogenies of ascomycete fungi and chlorophytan algae, that intensively sample lineages with lichen symbionts. Age estimates for several interacting clades show broad congruence and demonstrate that fungal origins of lichenization postdate the earliest tracheophytes. Coupled with the absence of unambiguous fossil data, our work finds no support for lichens having mediated global change during the Neoproterozoic‐early Paleozoic prior to vascular plants. We conclude by discussing our findings in the context of Neoproterozoic‐Paleozoic terrestrial ecosystem evolution and the paleoecological context in which vascular plants evolved. [ABSTRACT FROM AUTHOR]

Premise of the study: This study elucidates the phylogenetic position of a unique taxon of Graphidaceae occurring on rock in coastal desert areas, assessing its importance for our understanding of the evolution of the largest family of tropical lichenized fungi. Methods: We used maximum likelihood and Bayesian approaches to reconstruct a three-gene phylogeny of Graphidaceae and a Bayesian molecular clock approach to estimate divergence dates for major clades, as well as Bayesian ancestral ecogeography state analysis. Key results: The new genus Redonographa represents a new subfamily, Redonographoideae, sister to subfamily Graphidoideae. Redonographa is exclusively saxicolous and restricted to the American Pacific coast from California to central Chile, including Galapagos. It contains four species: Redonographa chilensis comb. nov., R. saxiseda comb. nov., R. saxorum comb. nov., an R. galapagoensis sp. nov. The genus Gymnographopsis, with a similar ecogeography but differing in excipular carbonization and chemistry, is also included in Redonographoideae, with the species G. chilena from Chile and G. latispora from So Africa. Molecular clock analysis indicates that Redonographoideae diverged from Graphidoideae about 132 million years ago (Ma) in the Early Cretaceous. Conclusions: The divergence date for subfamilies Redonographoideae and Graphidoideae coincides with the early breakup of Gondwana and ancient origin of the Atacama Desert. However, the common ancestor of Redonographoideae plus Graphidoideae was reconstructed to be tropical-epiphytic. Thus, even if Redonographoideae is subtropical-saxicolous, the hypothesis that Graphidoideae evolved from a subtropical-saxicolous ancestor is not supported. [ABSTRACT FROM AUTHOR]

Phylogenetic diversity of lichen photobionts is low compared to that of fungal counterparts. Most lichen fungi are thought to be associated with just four photobiont genera, among them the cyanobacteria Nosioc and Scytoneina, two of the most important nitrogen fixers in humid ecosystems. Although many Nostoc photobionts have been identified using isolated cultures and sequences, the identity of Scytoneina photobionts has never been confirmed by culturing or sequencing. We investigated the phylogenetic placement of presumed Scytonema photobionts and unicellular morphotypes previously assigned to Chroococcus, from tropical Dictyonerna, Acantholichen, Coccocarpia, and Stereocaulon lichens. While we confirm that filamentous and unicellular photobiont morphotypes belong to a single dade, this dade does not cluster with Scytonema but represents a novel, previously unrecognized, highly diverse, exclusively lichenized lineage, for which the name Rhizonerna is available. The phylogenetic structure observed in this novel lineage suggests absence of coevolution with associated mycobionts at the species or dade level. Instead, highly efficient photobiont strains appear to have evolved through photobiont sharing between unrelated, but ecologically similar, coexisting lineages of lichenized fungi ("lichen guilds"), via the selection of particular photobiont strains through and subsequent horizontal transfer among unrelated mycobionts, a phenomenon not unlike crop domestication. [ABSTRACT FROM AUTHOR]

Aim To analyse the historical biogeography of the lichen genus Chroodiscus using a phenotype-based phylogeny in the context of continental drift and evolution of tropical rain forest vegetation. Location All tropical regions (Central and South America, Africa, India, Southeast Asia, north-east Australia). Methods We performed a phenotype-based phylogenetic analysis and ancestral character state reconstruction of 14 species of the lichen genus Chroodiscus, usingpaup* andmesquite; dispersal–vicariance analysis (DIVA) and dispersal–extinction–cladogenesis (DEC) modelling to trace the geographical origin of individual clades; and ordination and clustering by means ofpc-ord, based on a novel similarity index, to visualize the biogeographical relationships of floristic regions in which Chroodiscus occurs. Results The 14 species of Chroodiscus show distinctive distribution patterns, with one pantropical and one amphi-Pacific taxon and 12 species each restricted to a single continent. The genus comprises four clades. DIVA and DEC modelling suggest a South American origin of Chroodiscus in the mid to late Cretaceous (120–100 Ma), with subsequent expansion through a South American–African–Indian–Southeast Asian–Australian dispersal route and late diversification of the argillaceus clade in Southeast Asia. Based on the abundance of extant taxa, the probability of speciation events in Chroodiscus is shown to be extremely low. Slow dispersal of foliicolous rain forest understorey lichens is consistent with estimated phylogenetic ages of individual species and with average lengths of biological species intervals in fungi (10–20 Myr). Main conclusions The present-day distribution of Chroodiscus can be explained by vicariance and mid-distance dispersal through the interconnection or proximity of continental shelves, without the need for recent, trans-oceanic long-distance dispersal. Phylogenetic reconstruction and age estimation for Chroodiscus are consistent with the ‘biotic ferry’ hypothesis: a South American origin and subsequent eastward expansion through Africa towards Southeast Asia and north-eastern Australia via the Indian subcontinent. The present-day pantropical distributions of many clades and species of foliicolous lichens might thus be explained by eastward expansion through continental drift, along with the evolution of modern rain forests starting 120 Ma, rather than by the existence of a hypothetical continuous area of pre-modern rain forest spanning South America, Africa and Southeast Asia during the mid and late Cretaceous. [ABSTRACT FROM AUTHOR]

The new basidiolichen Multiclavula ichthyiformis Nelsen, Lücking, Umaña, Trest & Will-Wolf is described from Costa Rica. The new species differs from other species of Multiclavula in having a basidiocarp with tomentose stipe and flattened lamina with nonamphigenous hymenium. Molecular sequence data (ITS) confirmed its placement within Multiclavula in the Clavulinaceae (Cantharellales, Agaricomycetes). The new lichen was discovered in a Central American paramo remnant, illustrating the importance of biotic inventories of fungi and lichens to increase our knowledge of the diversity of these groups in endangered tropical ecosystems. The new species was found as part of the TICOLICHEN project in Costa Rica. [ABSTRACT FROM AUTHOR]

Summary • Suppositions about lichen reproductive strategies were investigated and elusive early stages of lichen ontogeny documented in a foliicolous lichen community. • Plastic coverslips attached to supportive netting were placed among foliicolous lichen communities within a neotropical lowland forest. The germination and development of diverse lichen propagules colonizing the coverslips were studied with light microscopy. • Foliicolous lichens were observed to begin development from lichenized vegetative propagules, aposymbiotic fungal spores, fungal spores dispersed together with attached phycobionts, and diahyphae. Aposymbiotically dispersed spores and diahyphae were capable of associating with compatible phycobionts encountered upon the substratum, following germination. • Many developing thalli produced characteristic structures (discoid isidia, thalline setae, pycnidia, etc.) which permitted their recognition as typical members of the foliicolous lichen community. Thalline setae in Tricharia were produced upon the prothallus, and subsequently incorporated into the thallus proper by advance of the lichenized thallus margin. Tricharia and other members of the Gomphillaceae showed a distinctive organization of symbionts in thallus growth, whereby the unicellular green phycobiont cells were positioned at the tips of advancing fascicles of mycobiont hyphae. In Coenogonium sp., branching filaments of the phycobiont Trentepohlia grew along prothallic paths initiated by the mycobiont. [ABSTRACT FROM AUTHOR]

Foliicolous lichenized fungi (FLF) are widely distributed in tropical forests. The Brazilian Atlantic rainforest, one of the most diverse rainforest biomes, has multiple phyto‐physiognomies. Montane forest fragments or forest refuges, so‐called "Brejos," are located within the semiarid Caatinga in Northeast Brazil. Our objective was to determine the FLF diversity within five Brejos and to analyze their biogeographic affinities within the Neotropics. The FLF biota of the Brejos was compared with that of 21 sites belonging to seven other rainforest biomes, ranging from the Atlantic rainforest in Argentina, to montane rainforests in Ecuador, to the Amazonia basin, and rainforests in Central America. One hundred and fifty‐six species were identified in the Brejos. This biota is most similar to that of the Atlantic rainforest and eastern Amazonia, while that of western Amazonia is more similar to that of the Andes and rainforests in Central America (Chocó). Multiple species identified in the Brejos have a wide distribution in tropical America, and only 11 are potentially endemic. Few other species have also a restricted distribution. The FLF biota of the Chocó and western Amazon is substantially richer than that of eastern Amazon, the Atlantic rainforest and the Brejos. This suggests that the biota of the latter areas is largely a depauperate subset of the Chocó and the western Amazon region. We argue that the major differences between the two large regions are related to the Pleistocene and Pliocene, when paleoclimatic and geological changes caused the isolation of the Brejos and the temporary fragmentation particularly of eastern Amazonia. [ABSTRACT FROM AUTHOR]

Amazon, Atlantic forest, Brejos de Altitude, Caatinga, Carrasco, Cerradão and Restinga are major vegetation units in North and Northeast Brazil. Little is known about lichen metacommunity structure in these habitats. While species richness and composition generally depend on climatic factors, in azonal vegetation edaphic factors may have a filtering effect on tree bark structure and hence the composition of epiphytic lichen communities. We hypothesized that climatic stress and a tree bark filtering effect would result in reduced richness and phylogenetic clustering in Caatinga, Carrasco, Cerradão and Restinga, whereas high richness and phylogenetic overdispersion were predicted for Amazon and Atlantic Forest. To test this, we analyzed 2,090 lichenized species in the study area, with a supertree to assess phylogenetic metacommunity structure. Amazon and Atlantic forest exhibited high richness and phylogenetic diversity, with phylogenetic overdispersion only in the Amazon. The zonal Caatinga with drought stress and the extrazonal Brejos both exhibited phylogenetic clustering. Among the azonal, edaphic vegetation units, Cerradão exhibited phylogenetic overdispersion, whereas Restinga showed phylogenetic clustering. Nearest taxon phylogenetic distance indicated a close relationship between Amazon and Atlantic forest, Atlantic forest and Brejos and Atlantic forest and Caatinga. Carrasco was mostly closely related to Cerradão, and Restinga was distantly related to any other unit. These findings indicate more complex patterns in the phylogenetic structure of lichen metacommunities, partly reflecting those of plant metacommunities, as a result of concurrent macroecological evolutionary histories. Our data supported floristic evidence that Carrasco is part of the Cerrado complex and not related to Caatinga. [ABSTRACT FROM AUTHOR]

Recent studies have uncovered remarkable diversity in Dictyonema s.lat. basidiolichens, here recognized as subtribe Dictyonemateae. This group includes five genera and 148 species, but hundreds more await description. The photobionts of these lichens belong to Rhizonema, a recently resurrected cyanobacterial genus known by a single species. To further investigate photobiont diversity within Dictyonemateae, we generated 765 new cyanobacterial sequences from 635 specimens collected from 18 countries. The ITS barcoding locus supported the recognition of 200 mycobiont (fungal) species among these samples, but the photobiont diversity was comparatively low. Our analyses revealed three main divisions of Rhizonema, with two repeatedly recovered as monophyletic (proposed as new species), and the third mostly paraphyletic. The paraphyletic lineage corresponds to R. interruptum and partnered with mycobionts from all five genera in Dictyonemateae. There was no evidence of photobiont‐mycobiont co‐speciation, but one of the monophyletic lineages of Rhizonema appears to partner predominantly with one of the two major clades of Cora (mycobiont) with samples collected largely from the northern Andes. Molecular clock estimations indicate the Rhizonema species are much older than the fungal species in the Dictyonemateae, suggesting that these basidiolichens obtained their photobionts from older ascolichen lineages and the photobiont variation in extant lineages of Dictyonemateae is the result of multiple photobiont switches. These results support the hypothesis of lichens representing "fungal farmers," in which diverse mycobiont lineages associate with a substantially lower diversity of photobionts by sharing those photobionts best suited for the lichen symbiosis among multiple and often unrelated mycobiont lineages. see also the Perspective by Matthew P. Nelsen. [ABSTRACT FROM AUTHOR]

High Andean forests harbor a remarkably high biodiversity and play a key role in providing vital ecosystem services for neighboring cities and settlements. However, they are among the most fragmented and threatened ecosystems in the neotropics. To preserve their unique biodiversity, a deeper understanding of the effects of anthropogenic perturbations on them is urgently needed. Here, we characterized the plant communities of high Andean forest remnants in the hinterland of Bogotá in 32 0.04 ha plots. We assessed the woody vegetation and sampled the understory and epiphytic cover. We gathered data on compositional and structural parameters and compiled a broad array of variables related to anthropogenic disturbance, ranging from local to landscape‐wide metrics. We also assessed phylogenetic diversity and functional diversity. We employed nonmetric multidimensional scaling (NMDS) to select meaningful variables in a first step of the analysis. Then, we performed partial redundancy analysis (pRDA) and generalized linear models (GLMs) in order to test how selected environmental and anthropogenic variables are affecting the composition, diversity, and aboveground biomass of these forests. Identified woody vegetation and understory layer communities were characterized by differences in elevation, temperature, and relative humidity, but were also related to different levels of human influence. We found that the increase of human‐related disturbance resulted in less phylogenetic diversity and in the phylogenetic clustering of the woody vegetation and in lower aboveground biomass (AGB) values. As to the understory, disturbance was associated with a higher diversity, jointly with a higher phylogenetic dispersion. The most relevant disturbance predictors identified here were as follows: edge effect, proximity of cattle, minimum fragment age, and median patch size. Interestingly, AGB was efficiently predicted by the proportion of late successional species. We therefore recommend the use of AGB and abundance of late successional species as indicators of human disturbance on high Andean forests. [ABSTRACT FROM AUTHOR]

Aim: Phylogenetic diversification is a precursor to speciation, but the underlying patterns and processes are not well‐studied in lichens. Here we investigate what factors drive diversification in two tropical, morphologically similar macrolichens that occupy a similar range but differ in altitudinal and habitat preferences, testing for isolation by distance (IBD), environment (IBE), and fragmentation (IBF). Location: Neotropics, Hawaii, Macaronesia. Taxon: Sticta andina, S. scabrosa (Peltigeraceae). Methods: We analysed 395 specimens from 135 localities, using the fungal ITS barcoding marker to assess phylogenetic diversification, through maximum likelihood tree reconstruction, TCS haplotype networks, and Tajima's D. Mantel tests were employed to detect structure in genetic vs. geographic, environmental, and fragmentation distances. Habitat preferences were quantitatively assessed by statistical analysis of locality‐based BIOclim variables. Results: Sticta andina exhibited high phenotypic variation and reticulate phylogenetic diversity across its range, whereas the phenotypically uniform S. scabrosa contained two main haplotypes, one unique to Hawaii. Sticta andina is restricted to well‐preserved andine forests and paramos, naturally fragmented habitats due to disruptive topology, whereas S. scabrosa thrives in lowland to lower montane zones in exposed or disturbed microsites, representing a continuous habitat. Sticta scabrosa showed IBD only across its full range (separating the Hawaiian population) but not within continental Central and South America, there exhibiting a negative Tajima's D. Sticta andina did not exhibit IBD but IBE at continental level and IBF in the northern Andes. Main conclusions: Autecology, particularly preference for either low or high altitudes, indirectly drives phylogenetic diversification. Low diversification in the low altitude species, S. scabrosa, can be attributed to rapid expansion and effective gene flow across a more or less continuous niche due to disturbance tolerance. In contract, high diversification in the high altitude species, S. andina, can be explained by niche differentiation (IBE) and fragmentation (IBF) caused by the Andean uplift. [ABSTRACT FROM AUTHOR]

Nearly one-fourth of the lichen-forming fungi associate with trentepohlialean algae, yet their genetic diversity remains unknown. Recent work focusing on free-living trentepohlialean algae has provided a phylogenetic context within which questions regarding the lichenization of these algae can be asked. Here, we concentrated our sampling on trentepohlialean algae from lichens producing a diversity of growth forms (fruticose and crustose) over a broad geographic substratum, ecological, and phylogenetic range. We have demonstrated that there is no evidence for a single clade of strictly lichenized algae; rather, a wide range demonstrated the ability to associate with lichenized fungi. Variation was also observed among trentepohlialean algae in lichens from a single geographic area and tree, suggesting that fungi in close proximity can associate with different trentepohlialean algae, consistent with the findings of trebouxiophycean algae and cyanobacteria. [ABSTRACT FROM AUTHOR]

Foliicolous lichens are formed by diverse, highly specialized fungi that establish themselves and complete their life cycle within the brief duration of their leaf substratum. Over half of these lichen-forming fungi are members of either the Gomphillaceae or Pilocarpaceae, and associate with Trebouxia-like green algae whose identities have never been positively determined. We investigated the phylogenetic affinities of these photobionts to better understand their role in lichen establishment on an ephemeral surface. Thallus samples of Gomphillaceae and Pilocarpaceae were collected from foliicolous communities in southwest Florida and processed for sequencing of photobiont marker genes, algal cultivation and/or TEM. Additional specimens from these families and also from Aspidothelium (Thelenellaceae) were collected from a variety of substrates globally. Sequences from rbcL and nu SSU regions were obtained and subjected to Maximum Likelihood and Bayesian analyses. Analysis of 37 rbcL and 7 nu SSU algal sequences placed all photobionts studied within the provisional trebouxiophycean assemblage known as the Watanabea clade. All but three of the sequences showed affinities within Heveochlorella, a genus recently described from tree trunks in East Asia. The photobiont chloroplast showed multiple thylakoid stacks penetrating the pyrenoid centripetally as tubules lined with pyrenoglobuli, similar to the two described species of Heveochlorella. We conclude that Heveochlorella includes algae of potentially major importance as lichen photobionts, particularly within (but not limited to) foliicolous communities in tropical and subtropical regions worldwide. The ease with which they may be cultivated on minimal media suggests their potential to thrive free-living as well as in lichen symbiosis. [ABSTRACT FROM AUTHOR]