Search

Large-scale efforts to aggregate and promote the re-use of biodiversity data are leading to novel insights into biogeography and macroecology. However, secondary analyses must account for the tradeoffs and limitations of the original studies. Studies of speciose and taxonomically complex groups often utilize morphospecies or functional subsets as proxies, potentially complicating data re-use. We evaluated whether lichen biodiversity patterns are robust to differences in sampling methodology, utilizing parallel analyses to compare species richness, regional species pool variation, species probabilities of occurrence, and correlation of those three with environmental variables in data sets that cover the same geographic region. Our analyses revealed that, although individual species distributions sometimes differed in idiosyncratic ways, inference based on the aggregated response of multiple species was generally robust across the two datasets, despite differences in observer expertise and functional and taxonomic scope. This suggests that biodiversity data assembled from disparate sources could be used to evaluate biogeographical and macroecological hypotheses in understudied groups such as lichens, particularly at larger spatial scales. Key words: biodiversity data, biodiversity proxies, diversity-environment relationships, lichens, macrolichens, Pennsylvania, temperate forest. Les efforts déployés à grande échelle pour regrouper et promouvoir la réutilisation des données sur la biodiversité permettent d'obtenir de nouvelles informations sur la biogéographie et la macroécologie. Toutefois, les analyses secondaires doivent tenir compte des compromis et des limites des études originales. Les études de groupes riches en espèces et complexes d'un point de vue taxonomique utilisent souvent des morpho-espèces ou des sous-ensembles fonctionnels comme indicateurs, ce qui peut compliquer la réutilisation des données. Les auteurs ont évalué si les modèles de biodiversité des lichens sont robustes aux différences quant à laméthodologie d'échantillonnage, en utilisant des analyses parallèles pour comparer la richesse en espèces, la variation des pools régionaux d'espèces, les probabilités d'occurrence des espèces, et la corrélation de ces trois éléments avec les variables environnementales dans des ensembles de données qui couvrent la même région géographique. Les analyses ont révélé que, bien que les distributions des espèces individuelles diffèrent parfois de manière idiosyncrasique, l'inférence basée sur la réponse agrégée de plusieurs espèces était généralement robuste dans les deux ensembles de données, malgré les différences d'expertise des observateurs et de portée fonctionnelle et taxonomique. Cela suggère que les données sur la biodiversité rassemblées à partir de sources disparates pourraient être utilisées pour évaluer des hypothèses biogéographiques et macroécologiques dans des groupes peu étudiés tels que les lichens, en particulier à des échelles spatiales plus grandes. [Traduit par la Rédaction] Mots-clés : données sur la biodiversité, indicateurs de biodiversité, relations entre la diversité et l'environnement, lichens, macrolichens, Pennsylvanie, forêt tempérée., Introduction Biodiversity data serve a fundamental role in advancing knowledge of species (Bebber et al. 2010), their interactions (Meineke and Davies 2018) and conservation needs (Paton 2009; Ballard et al. [...]

Lecidea varians is among the most common and abundant bark-dwelling crustose lichens in temperate eastern North America. As presently delimited, it is highly variable, including chemical and morphological diversity well beyond that currently accepted for most lichen species. The generic placement of L. varians has also been questioned for decades. It has long been recognized as aberrant in Lecidea and Pyrrhospora, excluded from Lecidella, and more recently transferred to Traponora. Drawing from the results of extensive chemical, molecular phylogenetic and morphological studies, we show that L. varians and its relatives represent a previously unrecognized lineage within the speciose lichen family Lecanoraceae. The lineage appears to occupy an isolated position, distinct from the aforementioned genera, and is newly described as the genus Xanthosyne (typified by L. varians). The chemical and morphological variation within L. varians is mirrored by, but not entirely correlated with, considerable molecular diversity. A new taxonomy is proposed for L. varians and its relatives to serve as a framework for future studies. Three species are recognized: X. varians (≡ Lecidea varians), common and widespread in parts of North America; X. granularis, a new species from the Atlantic Coast of eastern North America that differs morphologically from X. varians in having a leprose thallus; and X. sharnoffiorum, a new species also found mainly along the Atlantic Coast of eastern North America, which has a coarsely granular, non-leprose thallus and produces a unique, unidentified xanthone. Multiple well-supported lineages were recovered within X. varians that correlate to varying degrees with chemical and morphological variability, as well as geographic distribution. Eight subspecies are recognized to accommodate the variation within X. varians: X. varians subsp. exigua comb. nov. (≡ Lecidea exigua) characterized by the presence of atranorin and a consistent set of three xanthones, is widespread in southern Europe and western North America (coastal California); X. varians subsp. varians (≡ Lecidea varians) is distributed mainly in northeastern North America and produces thuringione and arthothelin; X. varians subsp. morsei subsp. nov. is morphologically and chemically variable, with one chemotype (thiophanic acid) with a northeastern distribution, and the other with a unique and unidentified xanthone, found mainly in the interior U.S.A.; X. varians subsp. obscura subsp. nov. occurs mainly in the central U.S.A. and North Temperate regions, produces a unique, unidentified xanthone and generally has black apothecia with green epihymenial pigments; X. varians subsp. pseudomorsei subsp. nov. and X. varians subsp. submorsei subsp. nov. resemble X. varians subsp. morsei but differ in molecular sequence characters; X. varians subsp. subtilis comb. nov. (≡ Lecidea subtilis) and X. varians subsp. subexigua subsp. nov. occur in the Appalachian Mountains, the former producing atranorin and the latter lacking atranorin, both with thiophanic acid with or without other xanthones. In an addendum, Lecidella subviridis is discussed with respect to the genus Xanthosyne. An identification key is provided for all species and their subspecies within Xanthosyne. [ABSTRACT FROM AUTHOR]

A lectotype is designated for the name of the iconic and well‐known macrolichen Ramalina menziesii Taylor from among a suite of largely overlooked syntypes deposited in the Thomas Taylor Herbarium at the Farlow Herbarium, Harvard University. Lectotypes are also selected for the synonyms of R. menziesii: Chlorodictyon foliosum, Ramalina reticulata (≡ Lichen reticulatus Noehd., nom. illeg.) and R. retiformis. The place of publication of L. reticulatus Noehd. is discussed in detail. The case highlights the surprising degree to which the application of names for taxa that have been extensively studied and are widely known outside a narrow specialist field, can remain unresolved. [ABSTRACT FROM AUTHOR]