Doubling the known diversity of a remote island fauna: marine bivalves of the Juan Fernández and Desventuradas oceanic archipelagos (Southeastern Pacific Ocean).

Juan Fernández and Desventuradas are two oceanic archipelagos located in the southeastern Pacific Ocean far off the Chilean coast that received protected status as marine parks in 2016. Remoteness and access difficulty contributed to historically poor biodiversity sampling and limited associated research. This is particularly noticeable for bivalves, with most prior regional publications focused on single taxa or un-illustrated checklists. This study investigates marine bivalves collected between the intertidal and 415 m depth during (1) the 1997 IOC97 expedition aboard the M/V Carlos Porter, with special focus on scuba-collected micro-mollusks of both archipelagos, (2) two expeditions by the R/V Anton Bruun (Cruise 12/1965 and Cruise 17/1966), and (3) Cruise 21 of USNS Eltanin under the United States Antarctic Program, which sampled at Juan Fernández in 1965. Also, relevant historical material of the British H.M.S. Challenger Expedition (1873-1876), the Swedish Pacific Expedition (1916-1917), and by German zoologist Ludwig H. Plate (1893-1895) is critically revised. A total of 48 species are recognized and illustrated, including 19 new species (described herein) and six other potentially new species. The presence of two species mentioned in the literature for the region (Aulacomya atra and Saccella cuneata) could not be confirmed. The genera Verticipronus and Halonympha are reported for the first time from the Eastern Pacific, as are Anadara and Condylocardia from Chilean waters. Lectotypes are designated for Arca (Barbatia) platei and Mytilus algosus. These findings double the number of extant bivalve species known from the Juan Fernández and Desventuradas archipelagos, highlighting the lack of attention these islands groups have received in the past. A high percentage of species endemic to one or both archipelagos are recognized herein, accounting for almost 78% of the total. The newly recognized level of bivalve endemism supports the consideration of Juan Fernández and Desventuradas as two different biogeographic units (Provinces or Ecoregions) of the Eastern Pacific Ocean.

Endoscopic ultrasound-guided pancreatic fluid collection drainage: Where are we?

Pancreatic fluid collections (PFCs) result from injury to the pancreas from acute or chronic pancreatitis, surgery, or trauma. Management of these collections has evolved over the last 2 decades. The choice of interventions includes percutaneous, endoscopic, minimally invasive surgery, or a combined approach. Endoscopic drainage is the drainage of PFCs by creating an artificial communication between the collection and gastrointestinal lumen that is maintained by placing a stent across the fistulous tract. In this editorial, we endeavored to update the current status of endoscopic ultrasound-guided drainage of PFCs.

A novel lumen-apposing metal stent for endoscopic drainage of symptomatic pancreatic fluid collections: a retrospective study.

Background and Objectives: Previous studies showed that lumen-apposing metal stent (LAMS) provides a feasible route to perform direct endoscopic necrosectomy. However, the high risk of bleeding and migration induced by the placement of LAMS attracted attention. The aim of this study was to evaluate the safety and effectiveness of a novel LAMS. Methods: In this retrospective study, we enrolled patients with symptomatic pancreatic fluid collections (PFCs) to perform EUS-guided drainage with a LAMS in our hospital. Evaluation variables included technical success rate, clinical success rate, and adverse events. Results: Thirty-two patients with a mean age of 41.38 ± 10.72 years (53.1% males) were included in our study, and the mean size of PFC was 10.06 ± 3.03 cm. Technical success rate and clinical success rate reached 96.9% and 93.8%, respectively. Stent migration occurred in 1 patient (3.1%), and no stent-induced bleeding occurred. The outcomes of using LAMS in 10 patients with pancreatic pseudocyst and 22 patients with walled-off necrosis were comparable. Compared with pancreatic pseudocyst, walled-off necrosis needed more direct endoscopic necrosectomy times to achieve resolution (P = 0.024). Conclusions: Our study showed that the novel LAMS is effective and safe for endoscopic drainage of PFCs with a relatively low rate of adverse events. Further large-scale multicenter studies are needed to confirm the present findings.

Mini-Craniotomy for Chronic Subdural Hematoma: A Reliable Surgical Option.

Introduction Chronic subdural hematoma (SDH) is one of the most common conditions encountered in the neurosurgical practice. Surgical modalities like twist drill craniostomy, burr hole evacuation, mini-craniotomy, and craniotomy are practiced in the management of chronic SDH. Mini-craniotomy without excision of membranes may help to achieve best results with decreased complication rate. Materials and Methods Patients with chronic SDH operated from September 2013 to September 2022 were included in the study. Mini-craniotomy (40-60 mm) was done and cruciate incision was given over the dura. Dura was left wide open by reflecting and suturing the cut edges of the dural leaflets to the craniotomy edge allowing to evacuate subdural space under vision during surgery and to allow any residual collection to drain out freely in the postoperative period. A drain was placed between the inner membrane and the bone flap. Preoperative and postoperative clinical and radiological parameters were recorded. Complications, recurrence, and residual collections were noted. Results Seventy-seven patients were included in the study. Mean age was 57.32 years. Median Glasgow Coma Scale (GCS) at presentation was 13 while median GCS at discharge was 15. Two patients with preexisting comorbidities expired after surgery due to medical causes. No recurrences were noted. Fourteen patients had residual collections which resolved by 6 weeks. Two patients had wound infection. One of these patients later needed a bone flap removal due to osteomyelitis. Conclusion Mini-craniotomy without membranectomy is a good option for complete evacuation of chronic SDH under vision mainly avoiding the complication of membranectomy. It is not associated with increased complications rate. It needs fewer follow-ups as brain expansion can be established radiologically in a short period.

Association between acute peripancreatic fluid collections and early readmission in acute pancreatitis: A propensity-matched analysis.

BACKGROUND: Patients with acute pancreatitis (AP) frequently experience hospital readmissions, posing a significant burden to healthcare systems. Acute peripancreatic fluid collection (APFC) may negatively impact the clinical course of AP. It could worsen symptoms and potentially lead to additional complications. However, clinical evidence regarding the specific association between APFC and early readmission in AP remains scarce. Understanding the link between APFC and readmission may help improve clinical care for AP patients and reduce healthcare costs. AIM: To evaluate the association between APFC and 30-day readmission in patients with AP. METHODS: This retrospective cohort study is based on the Nationwide Readmission Database for 2016-2019. Patients with a primary diagnosis of AP were identified. Participants were categorized into those with and without APFC. A 1:1 propensity score matching for age, gender, and Elixhauser comorbidities was performed. The primary outcome was early readmission rates. Secondary outcomes included the incidence of inpatient complications and healthcare utilization. Unadjusted analyses used Mann-Whitney U and χ 2 tests, while Cox regression models assessed 30-day readmission risks and reported them as adjusted hazard ratios (aHR). Kaplan-Meier curves and log-rank tests verified readmission risks. RESULTS: A total of 673059 patients with the principal diagnosis of AP were included. Of these, 5.1% had APFC on initial admission. After propensity score matching, each cohort consisted of 33914 patients. Those with APFC showed a higher incidence of inpatient complications, including septic shock (3.1% vs 1.3%, P < 0.001), portal venous thrombosis (4.4% vs 0.8%, P < 0.001), and mechanical ventilation (1.8% vs 0.9%, P < 0.001). The length of stay (LOS) was longer for APFC patients [4 (3-7) vs 3 (2-5) days, P < 0.001], as were hospital charges ($29451 vs $24418, P < 0.001). For 30-day readmissions, APFC patients had a higher rate (15.7% vs 6.5%, P < 0.001) and a longer median readmission LOS (4 vs 3 days, P < 0.001). The APFC group also had higher readmission charges ($28282 vs $22865, P < 0.001). The presence of APFC increased the risk of readmission twofold (aHR 2.52, 95% confidence interval: 2.40-2.65, P < 0.001). The independent risk factors for 30-day readmission included female gender, Elixhauser Comorbidity Index ≥ 3, chronic pulmonary diseases, chronic renal disease, protein-calorie malnutrition, substance use disorder, depression, portal and splenic venous thrombosis, and certain endoscopic procedures. CONCLUSION: Developing APFC during index hospitalization for AP is linked to higher readmission rates, more inpatient complications, longer LOS, and increased healthcare costs. Knowing predictors of readmission can help target high-risk patients, reducing healthcare burdens.

Taxonomic notes on the collection of the tribe Lamiini (Coleoptera, Cerambycidae) housed in the Natural History Museum, London.

In the present paper, the genus Mimomyagrus Breuning, 1970 is synonymized with Combe Thomson, 1864, and Mimomyagruspfanneri Breuning, 1970 is considered a junior synonym of Combebrianus (White, 1858). The female of Arctolamiasinica Bi & Chen, 2022 is described for the first time and this species is reported as new to Myanmar. Type material of Lamiapunctator Fabricius, 1776 [= Anoplophorachinensis (Forster, 1771)], Cerambyxgalloprovincialis Olivier, 1800 [= Monochamusgalloprovincialis (Olivier, 1800)] and Melanaustergranulipennis Breuning, 1938 [= Monochamusguerryi Pic, 1903] are confirmed to be preserved in Natural History Museum, London.

Ten lessons learned from the mass digitisation of a herbarium collection.

Worldwide, herbaria maintain collections of reference specimens representing global plant diversity. These collections are a valuable resource for fundamental botanical research and applied scientific research across various disciplines, and play a significant role in addressing major societal challenges such as biodiversity conservation. The digitisation of herbarium specimens and their online dissemination is one of the most important recent developments in the curation of these collections. Digitisation significantly enhances access to the collections for the research community and facilitates large-scale analysis of biodiversity data. Digitisation also provides a means for preserving the physical specimens, as it reduces the need for handling and transportation. Rapid technological developments have greatly accelerated the rate of databasing and digital imaging of collections. Meise Botanic Garden recently completed a six-year project to mass digitise its herbarium collections of about 3 million specimens mounted on sheets and through this process we have learned valuable lessons. We have captured our experience in 10 recommendations for other collection-holding institutions to take inspiration from as they start planning their own digitisation efforts. We also present case studies where we delve deeper into certain topics as examples.

Ethical futures in biological anthropology: Research, teaching, community engagement, and curation involving deceased individuals.

Although ethical reforms in biological anthropology have gained ground in recent years, there is still a scarcity of ethical standards for work involving historical documented collections (HDCs) at US museums and universities. These collections of deceased individuals were created in the late 19th to mid-20th centuries under anatomy laws that targeted socially marginalized communities and allowed for the dissection of these individuals without their consent. Due to the extensive information associated with the individuals and made available to researchers, these collections have served as foundational resources for theory and methods development in biological anthropology into the 21st century. Recognizing the need for ethical guidelines for research, teaching and training, community engagement, and curation involving HDCs, we held a workshop called "Ethical Futures for Curation, Research, and Teaching in Biological Anthropology" on November 15-17, 2021. Here we summarize the conversations and major points of consensus among the workshop participants on these topics in order to advance these ethical considerations more broadly across the field.

Impact of the Timing of Percutaneous Catheter Drainage following Endoscopic Drainage on Outcomes in Acute Necrotizing Pancreatitis.

Background The role of dual-modality drainage of walled-off necrosis (WON) in patients with acute pancreatitis (AP) is established. However, there are no data on the association of clinical outcomes with the timing of percutaneous catheter drainage (PCD). We investigated the impact of the timing of PCD following endoscopic drainage of WON on clinical outcomes in AP. Materials and Methods This retrospective study comprised consecutive patients with necrotizing AP who underwent endoscopic cystogastrostomy (CG) of WON followed by PCD between September 2018 and March 2023. Based on endoscopic CG to PCD interval, patients were divided into groups (≤ and >3 days, ≤ and >1 week, ≤ and >10 days, and ≤ and >2 weeks). Baseline characteristics and indications of CG and PCD were recorded. Clinical outcomes were compared between the groups, including length of hospitalization, length of intensive care unit stay, need for surgical necrosectomy, and death during hospitalization. Results Thirty patients (mean age ± standard deviation, 35.5 ± 12.7 years) were evaluated. The mean CG to PCD interval was 11.2 ± 7.5 days. There were no significant differences in baseline characteristics and indications of CG and PCD between the groups. The mean pain to CG interval was not significantly different between the groups. Endoscopic necrosectomy was performed in a significantly greater proportion of patients undergoing CG after 10 days ( p = 0.003) and after 2 weeks ( p = 0.032). There were no significant differences in the complications and clinical outcomes between the groups. Conclusion The timing of PCD following endoscopic CG does not affect clinical outcomes.

Comparative Efficacy and Safety of Different Stent Types for Pancreatic Fluid Collections: A Systematic Review and Network Meta-Analysis.

BACKGROUND AND AIMS: Drainage of pancreatic fluid collections (PFCs) is required in select cases including infected or symptomatic collections. In this network meta-analysis, we have compared lumen-apposing metal stents (LAMS), fully covered self-expandable metal stents (FCSEMS), and double-pigtail stents (DPS) to identify the most useful stent type in the management of PFCs. METHODS: We reviewed several databases to identify studies that compared DPS or FCSEMS with LAMS and the ones which compared DPS with FCSEMS for the treatment of PFCs. Our outcomes of interest were clinical success, adverse events, technical success, recurrence of PFCs, and procedure duration. Random effects model and frequentist approach were used for statistical analysis. RESULTS: We included 28 studies with 2974 patients. Rate of clinical success was significantly lower with DPS compared to LAMS, OR (95% CI): 0.43 (0.32, 0.59). Rate of recurrence was higher with DPS compared to LAMS, OR (95% CI): 2.06 (1.19, 3.57). We found no significant difference in rate of adverse events between groups. Rate of technical success was higher for FCSEMS compared to LAMS. Procedure duration was significantly shorter for LAMS compared to DPS and FCSEMS. Based on frequentist approach, LAMS was found to be superior to DPS and FCSEMS in achieving higher clinical success, lower rate of adverse events and recurrence, and shorter procedure time. CONCLUSIONS: This network meta-analysis demonstrates the superiority of LAMS over DPS and FCSEMS in the management of PFCs in achieving a higher clinical success, shorter procedure time, and lower rate of recurrence. Some of the analyses are not adequately powered to make firm conclusions, and future large multicenter RCTs are required to further evaluate this issue.

An annotated catalogue of selected historical type specimens, including genetic data, housed in the Natural History Museum Vienna.

Museum collections are an important source for resolving taxonomic issues and species delimitation. Type specimens as name-bearing specimens, traditionally used in morphology-based taxonomy, are, due to the progress in historical DNA methodology, increasingly used in molecular taxonomic studies. Museum collections are subject to constant deterioration and major disasters. The digitisation of collections offers a partial solution to these problems and makes museum collections more accessible to the wider scientific community. The Extended Specimen Approach (ESA) is a method of digitisation that goes beyond the physical specimen to include the historical information stored in the collection. The collections of the Natural History Museum Vienna represent one of the largest non-university research centres in Europe and, due to their size and numerous type specimens, are frequently used for taxonomic studies by visiting and resident scientists. Recently, a version of ESA was presented in the common catalogue of the Fish and Evertebrata Varia collections and extended to include genetic information on type specimens in a case study of a torpedo ray. Here the case study was extended to a heterogeneous selection of historical type series from different collections with the type locality of Vienna. The goal was to apply the ESA, including genetic data on a selected set of type material: three parasitic worms, three myriapods, two insects, twelve fishes, and one bird species. Five hundred digital items (photographs, X-rays, scans) were produced, and genetic analysis was successful in eleven of the 21 type series. In one case a complete mitochondrial genome was assembled, and in another case ten short fragments (100-230 bp) of the cytochrome oxidase I gene were amplified and sequenced. For five type series, genetic analysis confirmed their taxonomic status as previously recognised synonyms, and for one the analysis supported its status as a distinct species. For two species, genetic information was provided for the first time. This catalogue thus demonstrates the usefulness of ESA in providing digitised data of types that can be easily made available to scientists worldwide for further study.

Divergent ecological selection maintains species boundaries despite gene flow in a rare endemic tree, Quercus acerifolia (maple-leaf oak).

Strong gene flow from outcrossing relatives tends to blur species boundaries, while divergent ecological selection can counteract gene flow. To better understand how these two forces affect the maintenance of species boundaries, we focused on a species complex including a rare species, maple-leaf oak (Quercus acerifolia), which is found in only four disjunct ridges in Arkansas. Its limited range and geographic proximity to co-occurring close relatives create the possibility for genetic swamping. In this study, we gathered genome-wide SNPs using restriction-site associated DNA sequencing (RADseq) from 190 samples of Q. acerifolia and three of its close relatives, Q. shumardii, Q. buckleyi, and Q. rubra. We found that Q. shumardii and Q. acerifolia are reciprocally monophyletic with low support, suggesting incomplete lineage sorting, introgression between Q. shumardii and Q. acerifolia, or both. Analyses that model allele distributions demonstrate that admixture contributes strongly to this pattern. Populations of Q. acerifolia experience gene flow from Q. shumardii and Q. rubra, but we found evidence that divergent selection is likely maintaining species boundaries: 1) ex situ collections of Q. acerifolia have a higher proportion of hybrids compared to the mature trees of the wild populations, suggesting ecological selection against hybrids at the seed/seedling stage; 2) ecological traits co-vary with genomic composition; and 3) Q. acerifolia shows genetic differentiation at loci hypothesized to influence tolerance of radiation, drought, and high temperature. Our findings strongly suggest that in maple-leaf oak, selection results in higher divergence at regions of the genome despite gene flow from close relatives.

WiPFIM: A digital platform for interlinking biocollections of wild plants, fruits, associated insects, and their molecular barcodes.

The current knowledge on insects feeding on fruits is limited, and some of the scarce existing data on the fruit-associated insects are secluded within the host institutions. Consequently, their value is not fully realized. Moreover, in countries like Kenya, the integration of biocollections data within a digital framework has not been fully exploited. To address these gaps, this article presents a description of the development of a web-based platform for data sharing and integrating biodiversity historical data of wild plants, fruits, associated insects, and their molecular barcodes (WiPFIM) while leveraging data science technologies. The barcodes corresponding to the biocollections data were retrieved from BOLD database. The platform is an online resource about fruit-insect interactions that can be of interest to a worldwide community of users and can be useful in building innovative tools. The platform is accessible online at https://test-dmmg.icipe.org/wpfhi.

Geometric morphometry of the Rhodniusprolixus complex (Hemiptera, Triatominae): patterns of intraspecific and interspecific allometry and their taxonomic implications.

In the subfamily Triatominae, the genus Rhodnius is one of the most studied, not only because of its epidemiological importance, but also because of the difficulty in differentiating its species. Currently, one of the strategies to control Chagas disease, besides other initiatives such as the analysis of donated blood, is focused on fighting the vector. Correctly identifying triatomines is essential for the entomoepidemiological surveillance of Chagas disease. The objective of the present work was to compare the species of the R.prolixus complex using geometric morphometry of hemelytra and heads to evaluate the patterns of intraspecific and interspecific allometry and their taxonomic implications. This method can help in the diagnosis of close species, whose morphological characteristics are insufficient for correct identification. Specimens from five different collections were used, covering the species included in the R.prolixus complex (R.barretti, R.dalessandroi, R.domesticus, R.marabaensis, R.milesi, R.montenegrensis, R.nasutus, R.neglectus, R.neivai, R.prolixus and R.robustus). Morphometric analyses indicated that the hemelytra are not structures with good resolution for separating species and, for this reason, the use of the heads proved to be more adequate for this group (thus allowing differentiation of all species of the R.prolixus complex). The results suggest that R.milesi is a variant of R.neglectus and confirms that R.prolixus and R.robustus are distinct species. Furthermore, we propose the creation of the R.neivai complex comprising R.domesticus and R.neivai.

Systematic review of literature to evaluate global distribution of species of the Sporothrix genus stored in culture collections.

Introduction: Sporotrichosis is a subcutaneous mycosis caused by fungi of the genus Sporothrix sp. Phenotypic and genotypic differences have been associated with their geographic distribution, virulence, or clinical manifestation of sporotrichosis. In the past decade, the interest in identifying species of the Sporothrix sp. has been increasing, due to its epidemiological importance and, in consequence, is important to know how to preserve them for future studies, in culture collection. Aims: The purposes of this study were to analyze the global distribution of environmental isolates and/or causal agents of sporotrichosis identified by polyphasic taxonomy, with mandatory use of molecular identification, and to evaluate the percentages and distribution of isolates stored in culture collections. Methods: A systematic review of articles on animal and human sporotrichosis and/or environmental isolation of the fungus, from 2007 to 2023, was done. Results: Our results demonstrated that, S. globosa, S. schenckii, and S. brasiliensis were the most identified species. With respect to the deposit and maintenance of species, we observed that only 17% of the strains of Sporothrix sp. isolated in the world are preserved in a culture collection. Conclusions: This systematic review confirmed a difficulty in obtaining the frequency of Sporothrix species stored in culture collection and insufficient data on the molecular identification mainly of animal sporotrichosis and isolation of Sporothrix sp. in environmental samples.

The diversity of social complexity in termites.

Sociality underpins major evolutionary transitions and significantly influences the structure and function of complex ecosystems. Social insects, seen as the pinnacle of sociality, have traits like obligate sterility that are considered 'master traits', used as single phenotypic measures of this complexity. However, evidence is mounting that completely aligning both phenotypic and evolutionary social complexity, and having obligate sterility central to both, is erroneous. We hypothesize that obligate and functional sterility are insufficient in explaining the diversity of phenotypic social complexity in social insects. To test this, we explore the relative importance of these sterility traits in an understudied but diverse taxon: the termites. We compile the largest termite social complexity dataset to date, using specimen and literature data. We find that although functional and obligate sterility explain a significant proportion of variance, neither trait is an adequate singular proxy for the phenotypic social complexity of termites. Further, we show both traits have only a weak association with the other social complexity traits within termites. These findings have ramifications for our general comprehension of the frameworks of phenotypic and evolutionary social complexity, and their relationship with sterility.

Data-centric species distribution modeling: Impacts of modeler decisions in a case study of invasive European frog-bit.

Premise: Species distribution models (SDMs) are widely utilized to guide conservation decisions. The complexity of available data and SDM methodologies necessitates considerations of how data are chosen and processed for modeling to enhance model accuracy and support biological interpretations and ecological applications. Methods: We built SDMs for the invasive aquatic plant European frog-bit using aggregated and field data that span multiple scales, data sources, and data types. We tested how model results were affected by five modeler decision points: the exclusion of (1) missing and (2) correlated data and the (3) scale (large-scale aggregated data or systematic field data), (4) source (specimens or observations), and (5) type (presence-background or presence-absence) of occurrence data. Results: Decisions about the exclusion of missing and correlated data, as well as the scale and type of occurrence data, significantly affected metrics of model performance. The source and type of occurrence data led to differences in the importance of specific explanatory variables as drivers of species distribution and predicted probability of suitable habitat. Discussion: Our findings relative to European frog-bit illustrate how specific data selection and processing decisions can influence the outcomes and interpretation of SDMs. Data-centric protocols that incorporate data exploration into model building can help ensure models are reproducible and can be accurately interpreted in light of biological questions.

Integrated plant conservation through the Global Conservation Consortia.

The 2020 State of the World's Plants and Fungi report revealed that two in five plant species are threatened with extinction. Despite their diverse ecosystem services and myriad human uses, plants receive a fraction of the conservation resources directed at animal taxa. Several existing frameworks-including International Union for Conservation of Nature (IUCN) Specialist Groups, the American Public Gardens Association Plant Collections Network, and the Center for Plant Conservation National Collection of Endangered Plants-have spurred conservation action, but there remains an urgent need to scale up conservation efforts for the world's plants. Here, a new approach to coordinated conservation action for plant taxa is described: the Global Conservation Consortia (GCC). GCC catalyze institutions and experts to collaboratively develop and implement comprehensive strategies to prevent extinction of threatened plant groups. This review focuses on three tree-focused, U.S.-led consortia: cycads, magnolias, and oaks, but the GCC framework is applicable to other taxonomic groups. This review covers consortia design and implementation, provides conservation action case studies, and shares preliminary successes and challenges as this new and exciting approach to conservation is developed.

Endoscopic Drainage of Pancreatic Fluid Collections.

Pancreatic fluid collections (PFCs) are commonly encountered complications of acute and chronic pancreatitis. With the advancement of endoscopic ultrasound (EUS) techniques and devices, EUS-directed transmural drainage of symptomatic or infected PFCs has become the standard of care. Traditionally, plastic stents have been used for drainage, although lumen-apposing metal stents (LAMSs) are now favored by most endoscopists due to ease of use and reduced procedure time. While safety has been repeatedly demonstrated, follow-up care for these patients is critical as delayed adverse events of indwelling drains are known to occur.

A survey of BWT variants for string collections.

MOTIVATION: In recent years, the focus of bioinformatics research has moved from individual sequences to collections of sequences. Given the fundamental role of the Burrows-Wheeler Transform (BWT) in string processing, a number of dedicated tools have been developed for computing the BWT of string collections. While the focus has been on improving efficiency, both in space and time, the exact definition of the BWT employed has not been at the center of attention. As we show in this paper, the different tools in use often compute non-equivalent BWT variants: the resulting transforms can differ from each other significantly, including the number r of runs, a central parameter of the BWT. Moreover, with many tools, the transform depends on the input order of the collection. In other words, on the same dataset, the same tool may output different transforms if the dataset is given in a different order. RESULTS: We studied 18 dedicated tools for computing the BWT of string collections and were able to identify 6 different BWT variants computed by these tools. We review the differences between these BWT variants, both from a theoretical and from a practical point of view, comparing them on 8 real-life biological datasets with different characteristics. We find that the differences can be extensive, depending on the datasets, and are largest on collections of many similar short sequences. The parameter r, the number of runs of the BWT, also shows notable variation between the different BWT variants; on our datasets, it varied by a multiplicative factor of up to 4.2. AVAILABILITY: Source code and scripts to replicate the results and download the data used in the article are available at https://github.com/davidecenzato/BWT-variants-for-string-collections. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.