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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. 

Community science-generated biodiversity data can provide essential information for understanding species distributions, behaviors and conservation statuses. However, their utility can be limited due to high uncertainty and variability in quality, especially for small taxonomically difficult organisms like fungi and insects. One important set of community-generated data that are increasingly used by scientists are Research Grade (RG) iNaturalist observations. These observations are aggregated into the Global Biodiversity Information Facility database. Here we assessed the accuracy of RG lichen observations in iNaturalist. Lichens are mutualistic symbioses formed between fungi and a photosynthetic partner, either algae or cyanobacteria that occur in every terrestrial ecosystem on the planet (Brodo et al. 2001). They are sensitive indicators of environmental health, especially air quality, and provide essental food and nesting material for animals, along with performing many other ecosystem services (Allen and Lendemer 2021, Brodo et al. 2001, Nimis et al. 2002). We examined hundreds of observations and determined if the identification was correct, if it was not possible to identify the observation given the data provided, or if the identification was incorrect. Identification accuracy of selected species varied widely, from zero observations with enough information for correct identification (e.g., Rhizocarpon geographicum and Cladonia chlorophaea ) to 100% correct identifications (e.g., Cetradonia linearis and Physconia subpallida , McMullin and Allen 2022). Most frequently, species that require microscopic examination or chemical tests for accurate identification were unable to be verified versus those that require only macromorphology. We provide a series of suggestions for best practices to improve the quality of RG observations and thus the utility of community-generated observation data for taxonomically difficult organisms. 

We assess the identification accuracy of ‘research grade’ observations of lichens posted on the online platform iNaturalist. Our results show that these observations are frequently misidentified or lack the necessary chemical and (or) microscopic information for accurate identification. Lichens are a taxonomically difficult group, but they are ubiquitous and eye-catching and are regularly the subject of observations posted on iNaturalist. Therefore, we provide best practice recommendations for posting lichen observations and commenting on observations. Data from iNaturalist are a valuable tool for understanding and managing biodiversity, particularly at this crucial time when large scale biodiversity decline is occurring globally. However, the data must be accurate for them to effectively support biodiversity conservation efforts. Our recommendations are also applicable to other taxonomically difficult taxa. 

ABSTRACT The draft genome sequence of Bacidia gigantensis , a lichenized fungus in the order Lecanorales, was sequenced directly from a herbarium specimen collected from the type locality at Sleeping Giant Provincial Park in Ontario, Canada. Using long-read sequencing on the Oxford Nanopore PromethION platform, we assembled a nearly complete genome sequence. 

Abstract Three species of lichenized basidiomycetes in the Dictyonema clade from southeastern North America are described as new to science: Cyphellostereum georgianum , C. jamesianum and Dictyonema lawreyi , all with a crustose-filamentous growth form. Based on ITS sequences, the species form well-supported monophyletic clades in a phylogeny and are represented by at least two specimens each. They are also distinguishable by morphological and anatomical characters. These new findings emphasize the importance of lichenological studies in North America, especially in historically understudied taxonomic groups, such as basidiolichens. This study is dedicated to James D. Lawrey on the occasion of his 70 th birthday.