OBJECTIVE: To describe accidents involving brown spider (genus Loxosceles) bites notified by the Pernambuco Poison Information and Care Center (CIATox-PE), Brazil, from January 2018 to December 2022.
METHODS: This was a case series study of brown spider bites notified by the CIATox-PE.
RESULTS: The study included 22 cases with median age of 35 years, the majority being female (13); the cases occurred in rural and urban areas (12 versus 10), at night (10); Petrolina was the municipality with the highest number of notifications (6); spider bites occurred mainly in the lower (11) and upper (9) limbs, almost exclusively inside households (21); specific serum therapy was not indicated for 8 cases because the time for its effectiveness had already elapsed.
CONCLUSIONS: Loxoscelism cases occurred more frequently in females, in both rural and urban areas and mainly at home, with delays in seeking medical care.
RESULTS: The 22 cases described represent an alert for the presence of a venomous species not reported in previous studies in Pernambuco. The severity of cases may be associated with delays in seeking medical care, especially due to the population\'s lack of information.
UNASSIGNED: Identify the presence of brown spiders in households in the region and the potential severity of poisonings. Alert health professionals to recognize the clinical picture with a view to appropriate early treatment.
CONCLUSIONS: Develop research on poisoning by venomous animals and educational actions alerting the population to prevent these accidents and updating health professionals on care.

We describe three new species of Myoplatypus Wood, 1993: from Peru, Myoplatypus petrovi Kirkendall new species; from Honduras, M. quadricornis Kirkendall new species; from Nicaragua (M. nicaraguensis Kirkendall new species). We transfer Platypus biprorus Blandford, 1896 and Platypus sicarius Wood, 1971 into Myoplatypus, and we synonymize Platypus querceus Wood, 1971 with M. biprorus. The net result of these actions is a genus comprising nine tropical and one temperate American species. Males of all species are illustrated by photographs and a key to all species is provided. The collections reported here include the first South American records of Myoplatypus, a genus hitherto known only from North and Central America. Most Myoplatypus species are known from just one or a few collections and none of the tropical species are very widespread; only five tropical species have any known hosts (Quercus [Fagaceae] for three of them). The paucity of specimens could be because of peculiarities of biology that lead to them being under-collected (such as restriction to high elevations), but it also could be that they are narrow endemics, in which case these pinhole borer species deserve conservation attention. Nosotros describimos tres nuevas especies de Myoplatypus Wood, 1993: de Per, Myoplatypus petrovi Kirkendall espcie nueva; de Honduras, M. quadricornis Kirkendall espcie nueva; de Nicaragua, M. nicaraguensis Kirkendall espcie nueva. Platypus biprorus Blandford, 1896 y Platypus sicarius Wood, 1971 se transfieren a Myoplatypus, y Platypus querceus Wood, 1971 se sinonimiza con M. biprorus Blandford. El resultado neto de estas acciones es un gnero que consiste en nueve espcies tropicales y una templada. Los machos de todas las especies estn ilustrados con fotografas y se da una clave para todas las especies. Las colecciones reportadas aqu incluyen los primeros registros sudamericanos de Myoplatypus, un gnero hasta ahora conocido solo en Amrica del Norte y Amrica Central. La mayora de las especies de Myoplatypus se conocen a partir de solo una o unas pocas colecciones y ninguna de las especies tropicales est muy extendida; slo cinco especies tropicales tienen hospedadores conocidos (tres de ellos son robles). La escasez de especmenes podra deberse a algunas peculiaridades de la biologa que los llevan a una recoleccin insuficiente (como la restriccin a grandes alturas), pero tambin podra ser que sean endmicos estrechos, en cuyo caso estas especies de barrenadores merecen atencin de conservacin.

Understanding mechanics of spider silk holds immense importance due to its potential to drive innovation in the development of materials with exceptional mechanical characteristics suited for a wide range of applications. Coarse-grained (CG) molecular simulations plays a particularly valuable role in this endeavor, allowing for the efficient investigation of spider silk\'s mechanical properties. Our research is centered on the examination of spider silk, which comprises major ampullate silk protein (MaSp1). To achieve this, we developed a CG molecular dynamics model. Our investigation began with a focus on MaSp1 chains subjected to uniaxial tensile load, with comparisons made between the CG model results and all-atom simulations. Subsequently, we extended our simulations to encompass more extensive systems, including fully-ordered MaSp1 bundles undergoing uniaxial static stretching. Through comparison with existing literature, we assess how well the CG model reproduces the mechanical properties of spider silk in highly ordered structures. Furthermore, we explored a scenario where MaSp1 bundles were randomly positioned and stretched, providing valuable insights into silk behavior when the initial structure lacks order. Another simulation involved random positioning, but with some degree of orientation in the loading direction, allowing for a closer examination of the initial structure\'s influence.

Miniaturization is an evolutionary trend observed in many animals. Some arachnid groups, such as spiders and mites, demonstrate a strong tendency toward miniaturization. Some of the most miniaturized spiders belong to the family Anapidae. In this study, using light and confocal microscopy and 3D modelling, we provide the first detailed description of the anatomy of a spider of the genus Rayforstia, which is only 900 µm long. In comparison with larger spiders, Rayforstia has no branching of the midgut in the prosoma and an increased relative brain volume. In contrast to many miniature insects and mites, the spider shows no reduction of whole organ systems, no allometry of the digestive and reproductive systems, and also no reduction of the set of muscles. Thus, miniature spider shows a more conserved anatomy than insects of a similar size. These findings expand our knowledge of miniaturization in terrestrial arthropods.

Seasonality considerably impacts on the life of organisms and leads to numerous evolutionary adaptations. Some species face seasonal changes by entering a diapause during different life stages. During adulthood, a diapause in the non-reproductive period can affect male gametogenesis as, for example, it occurs in insects. Spiders are distributed worldwide and show a variety of life cycles. However, data on spiders\' life cycles and seasonal adaptations are limited. Here, we explored the effect of reproductive diapause in a seasonal spider for the first time. We used the South American sand-dwelling spider Allocosa senex as a model as this species is diplochronous, meaning that individuals live two reproductive seasons, with juveniles and adults overwintering in burrows. It has been observed that individuals of this species reduce their metabolism during the non-reproductive season, diminishing prey consumption and locomotion to a minimum. This species is also well-known for exhibiting wandering and courting females and sedentary males. We analyzed spermatogenesis throughout the male\'s life cycle and described the male\'s reproductive system and spermiogenesis using light and transmission electron microscopy. We found that spermatogenesis in A. senex is asynchronous and continuous. However, when males face the non-reproductive season, the late spermatogenic stages and spermatozoa decline, causing an interruption but not a total arrest of this process. This seasonality is also reflected in smaller testes\' size in males from the non-reproductive season than in other periods. The mechanisms and constraints are unknown, but they could be related to the metabolic depression during this life cycle period. Since sex-role reversal apparently sets a low-intensity sperm competition scenario compared with other wolf spiders, surviving two reproductive seasons may balance mating opportunities by distributing them between both periods. Thus, the partial interruption of spermatogenesis during diapause could allow new mating encounters during the second reproductive season.

A direct, positive correlation between biodiversity and the traditional agricultural landscape is evident on the national or regional scale. It is mostly conditioned by higher landscape diversity and less intensive farming. We have carried out research on a detailed scale at plot level (productive plots of arable lands, grasslands, vineyards, orchards, and unproductive agrarian landforms (mostly field margins) such as terraced slopes, terraced steps, heaps, mounds, and unconsolidated walls) in three traditional agricultural landscapes: the mountain village Liptovská Teplička, the vineyard landscape in Svätý Jur, and dispersed settlements in a submontane area in Hriňová. We determined the statistical significance of the impact of the selected landscape ecological factors (a set of factors concerning land use and management, agrarian landforms and relief properties) on the distribution of vegetation and selected invertebrate groups (spiders, millipedes, grasshoppers, and crickets). We also explored whether maintaining traditional land use and traditional management helped to enhance the biodiversity. We found that the management regime is the most important factor determining the species composition of vascular plants and all studied animal groups. Also, present land use and agrarian landforms character (type, skeleton content, continuity) are significant factors. Our expectation of a positive relationship between biodiversity and the maintaining traditional land use and traditional management was, in general, not confirmed: such a relation was only found in Svätý Jur for biodiversity of spiders.

In this work, the results of a survey for species of Fluda Peckham & Peckham, 1892 in primary forest in five Bolivian forest ecoregions are reported. Fluda dauca sp. nov. is described from Southwest Amazon forest and F. thuruampara sp. nov. from Bolivian Yungas forest. Fluda perdita (Peckham & Peckham, 1892) is reported from Bolivia for the first time. Both new species exhibited polymorphic mimicry; dark females of both species resembled the turtle ant Cephalotes pusillus (Klug, 1824) and dark males of F. thuruampara sp. nov. the carpenter ant Camponotus sanctaefidei Dalla Torre, 1892. Orange males and females of F. dauca sp. nov. are likely mimics of Camponotus latangulus Roger, 1863. Males of Fluda may compensate lower mimetic accuracy by the broadened femora I, resembling an ant head in lateral view and ant mandibles when moving the face towards a potential threat. As in other Simonellini, the turnover of Fluda species between the South American superregions suggests that significant shifts in seasonality and related conditions are major factors triggering speciation in the tribe Simonellini.

Loxoscelism occurs when the dermonecrotic venom produced by spiders of the genus Loxosceles, known as \"violin spiders,\" enters a person\'s organism through their bite. In Mexico there is an underreporting of loxoscelism cases due to the absence of laboratory tests for its diagnosis and the complexity of the clinical picture. The aim of this paper is to describe a case of cutaneous loxoscelism caused by the bite of Loxosceles yucatana in a resident of Yucatan, Mexico. Cutaneous loxoscelism is the most frequent and less severe type. This case was diagnosed by means of the symptomatology registered in the medical records, the initial lesion, and the identification of L. yucatana spiders. This study represents the first description of a case of cutaneous loxoscelism with favorable outcome in Yucatan.
El loxoscelismo es ocasionado cuando el veneno dermonecrótico producido por las arañas del género Loxosceles, conocidas como «arañas violinistas», ingresa al organismo de una persona a través de su mordida. En México ocurre un subregistro de los casos de loxoscelismo por la ausencia de pruebas de laboratorio para su diagnóstico y la dificultad del cuadro clínico. El objetivo de este trabajo es describir un caso de loxoscelismo cutáneo ocasionado por mordedura de Loxosceles yucatana en un residente de Yucatán, México. El loxoscelismo cutáneo es el tipo más frecuente y menos severo. El presente caso se diagnosticó por medio de la sintomatología registrada en la historia clínica, la lesión inicial y la identificación de arañas L. yucatana. Este trabajo representa la primera descripción de un caso de loxoscelismo cutáneo con resolución favorable en Yucatán.

A 63-year-old man presented with two days of palpable purpura over the right anterior shin and calf with notable point tenderness on the distal mid-calf without any palpable deep abnormality. Localized right calf pain worsened with walking and was associated with headache, chills, fatigue, and low-grade fevers. A punch biopsy of the anterior right lower leg showed necrotizing neutrophilic vasculitis of superficial and deep vessels. Direct immunofluorescence showed non-specific focal granular deposition of C3 within vessel walls. Three days after presentation, a live spider was found and microscopically identified as a male hobo spider. The patient suspected the spider arrived via packages shipped from Seattle, Washington. The patient was treated with a prednisone taper with full resolution of his cutaneous symptoms. Given the unilaterality of his symptoms and otherwise unexplained etiology, the patient was diagnosed with acute unilateral vasculitis secondary to hobo spider bite. Microscopic examination is required for identification of hobo spiders. Although not deadly, there have been several reports of cutaneous and systemic reactions resulting from hobo spider bites. Our case illustrates the importance of considering hobo spider bites in areas outside of their native regions, as they are known to travel in packaged items.

Tarantulas are commonly kept as pets and bites from some species can cause severe symptoms. Here we describe a case of a patient with transient atrial fibrillation (afib) and painful muscle cramps requiring hospitalization for pain management after being bitten by a Poecilotheria tigrinawesseli (Wessel\'s Tiger Ornamental) spider. He was discharged with a cardiac event monitor and outpatient cardiology follow-up. The event monitor documented transient afib which decreased in frequency then resolved halfway through the three-week monitoring period. In conclusion, tarantula envenomation is usually mild with local pain and edema most reported. However, bites by some species, such as P. tigrinawesseli may have local and more systemic, long-lasting effects.