We deal with the only three Neotropical tailed species once placed at the genera EuctaSimon, 1881 and PrionolaemaSimon, 1894, both now considered as junior synonyms of TetragnathaLatreille, 1804. Tetragnatha caudataEmerton, 1884 is redescribed and recorded from South America for the first time. Tetragnatha paraguayensis (Mello-Leitão, 1939) is redescribed and has its distribution expanded. Also, we consider Tetragnatha australis (Mello-Leitão, 1945) as its new junior synonym. Tetragnatha aetherea (Simon, 1894) is still considered valid but is not redescribed. Additionally, a fourth species, Tetragnatha caudicula (Karsch, 1879), is recorded for Mexico.

The extreme sexual size dimorphism of some spiders has long attracted the attention of biologists and triggered countless prominent studies on the phenomenon. This, in turn, has resulted in a widespread bias in the view of spider sexual dimorphisms, even in reviews on sexual dimorphism that looked beyond size. The present article challenges this view by exemplarily documenting sexual dimorphisms in a single family of spiders, the Pholcidae. It offers a comprehensive overview of sexual dimorphisms in this group, derived from the taxonomic literature. Sexual dimorphisms occur in the prosoma (ocular area, clypeus, sternum), abdomen, chelicerae, legs, sensory organs (setae, tarsal organs), and in colouration. In addition, this review provides a rough and conservative estimate of the number of independent origins of sexual dimorphisms in Pholcidae, based on published morphological and molecular phylogenies and character mapping; more than 120 independent origins are hypothesized. The first general conclusion is that spiders show a wealth of sexual dimorphisms beyond size, even in a family that is virtually absent from the general literature on spider sexual dimorphism. The second conclusion is that the taxonomic literature should be more widely appreciated as a rich source of information, not just as a provider of names. However, much of this information is not easily extracted from taxonomic papers. It is primarily the responsibility of taxonomists to do that.

A new species of the burrowing wolf spider, Karakumosa reshetnikovin. sp. (♀), from Tajikistan is diagnosed, illustrated and described. A brief discussion of the state of knowledge of the genus KarakumosaLogunov & Ponomarev, 2020 is provided.

Two species of the genus DipluraC. L. Koch, 1850, described from the Brazilian Amazon region: Diplura nigra (F. O. Pickard-Cambridge, 1896) and Diplura sanguinea (F. O. Pickard-Cambridge, 1896), are redescribed based on the examination of types and abundant new Amazonian material. The males of D. nigra and D. sanguinea are described for the first time, ecological data is presented and, for the first time, the female spermathecae are illustrated. New distributional data for these species is presented from the Amazonian region. We also give a short summary of species placements within Diplura based on the dorsal colour of the opisthosoma.

A small faunistic survey has been carried out in the Bulgarian part of Sakar Mountain. As a result, the list of species known from the studied region increased from 17 to 149. Eleven species are new to the Bulgarian fauna, while 6 of them are also reported for the first time from the Balkan Peninsula. Zelotes boluensisWunderlich, 2011 is reported for the first time from Europe. New photographs and drawings are provided for Mesiotelus annulipes (Kulczyński, 1897), that has not been depicted since its original description. New photographs are given also for 11 other species. Short zoogeographical notes are provided for selected species.

Scorpions exhibit extreme forms of sexual dimorphism, with a number of recent studies highlighting general patterns. Explanations surrounding the potential drivers of these patterns remain speculative, even though static allometry offers a method for testing specific hypotheses. Importantly, a recent study describes a method of reference character choice when investigating sexual dimorphism and static allometry in scorpions. Here, commonly measured morphometric characters are used to investigate patterns of sexual dimorphism and static allometry in the South African scorpion Uroplectes lineatus C. L. Koch, 1844. Several analyses were used to select telson length as the sexually neutral reference character. Sexual body component dimorphism characterises U. lineatus males, while females generally display sexual size dimorphism. Similar patterns of static allometry characterise both sexes, with negative allometry retrieved for most characters, while three characters display positive allometry. For negatively allometry characters, inter-sexual selection likely favours a standard size of body parts in the population to facilitate inter-sexual interaction during courtship. In contrast, positively allometric characters may be under intrasexual selection, following the utility of features during contests. Even so, the differences in allometric slopes between the sexes indicate the possible functions of male features during courtship, while the female morphology is adapted to enhance reproductive output and parental care. Here, we demonstrate that a set of verification analyses may be effective in choosing an appropriate neutral reference character, but the selective forces which shape scorpion morphology are complex, and standardized methods need to be established to allow for robust inferences and inter-study comparability.

A new species of the schismatotheline genus GuyruitaGuadanucci, Lucas, Indicatti & Yamamoto, 2007, Guyruita guadanuccii sp. nov., is described based on a female specimen from French Guiana.

Spider webs can be invaded by other species of spiders. While the majority involve spiders that build webs of their own, there are reports of wandering spiders invading webs. Most wolf spiders (Lycosidae) do not build webs and web invasion behaviour has never been reported in this family. Here, we report wandering wolf spiders invading webs of Aglaoctenus lagotis, one of the few wolf spiders that build webs. We collected observations of ten web invasions by the wandering species Lycosa erythrognatha, L. poliostoma, and Schizocosa malitiosa. We discuss the possible implications of these invasions for moulting and speculate that the webs are safe refuges.

The agelenid spider Trichopus libratus C. M. [Templeton], 1834 is discussed in the context of its authorship, and its availability and formation, following the International Code of Zoological Nomenclature.

The huntsman spider genus ThunbergaJäger, 2020 is revised. Twenty-five species are described for the first time: Thunberga alienaspec. nov. (♂), T. befotakaspec. nov. (♂), T. boyanslatspec. nov. (♀), T. calaspec. nov. (♀), T. conductorspec. nov. (♂, ♀), T. darainaspec. nov. (♂, ♀), T. elongataspec. nov. (♀), T. gosuraspec. nov. (♀), T. jaerviispec. nov. (♀), T. jyotispec. nov. (♀), T. mafiraspec. nov. (♂, ♀), T. malalaspec. nov. (♂, ♀), T. mamaspec. nov. (♂, ♀), T. matomaspec. nov. (♀), T. millotispec. nov. (♂), T. paulyispec. nov. (♂, ♀), T. panusilemspec. nov. (♀), T. platnickispec. nov. (♂, ♀), T. rothorumspec. nov. (♂), T. rugosaspec. nov. (♀), T. samsagalaspec. nov. (♂), T. soruagspec. nov. (♀), T. v-insignitaspec. nov. (♀), T. wasserthalispec. nov. (♀), T. woodaespec. nov. (♂, ♀). The male of T. greta is described for the first time. One species is transferred to Thunberga: T. laterifusca (Strand, 1908) comb. nov. (from Eusparassus), it is considered a nomen dubium. The distribution range of the genus includes now Madagascar with adjacent islands and Mayotte. Photos of living spiders are shown for the first time revealing a possible new diagnostic character: a small white patch in front of the fovea. Another new diagnostic character is a distal V- to U-shaped field of bristles situated ventrally on metatarsus IV, the metatarsus III exhibits ventro-distally a short to very stout bristle embedded in a scopula. Metatarsi I and II possess only scopula without bristles distally. In the female genitalia, plugs were observed not only at the copulatory openings, but in few cases also at the unpaired anterior pocket, the first known case within the Entelegynae that structures other than the copulatory openings are plugged. Externally recognisable mating plugs to various degrees were found in twelve out of twenty-three species known from females. Sixteen of these exhibited paired scars at the dorsal prosoma. It is hypothesized that males grab the females with their chelicerae and cause small punctuations in the cuticle (so-called “love bites”). Morphological and possible behavioural characters of Thunberga species are discussed.

Three Plexippoides species are diagnosed, illustrated and (re)described: P. flavescens (O. Pickard-Cambridge, 1872) (♂♀) from the Near East and Central Asia, P. gestroiDalmas, 1920 (♂♀) from the eastern Mediterranean and Asia Minor, and P. insperatussp. n. (♂♀) from Pakistan and Iran. An updated diagnosis of and comments on a taxonomic validity of the genus Plexippoides are provided. Two new combinations are proposed: Plexippoides guangxi (Peng & Li, 2002), comb. n., ex Epeus; and Ptocasius linzhiensis (Hu, 2001) comb. n., ex Plexippoides.

Behavioural adjustments to changing environmental conditions are advantageous for spiders, as such adjustments likely allow spiders to remain in good hunting sites. Here, we describe the behavioural response of seven araneoid species to heavy rain in the neotropics. Five of the seven spiders drastically modified their position on the web, relative to the typical resting position. Four of these species (Allocyclosa bifurca, Argiope argentata, Cyrtophora citricola, and Leucauge mariana) hung from hub threads using their legs III and IV, oriented the anterior section of the prosoma downward, and moved legs I and II forward in front of the spider's eyes. Trichonephila clavipes had a similar response, but hung from only its legs IV. Two other species (Gasteracantha cancriformis and Micrathena duodecimspinosa) did not show an apparent response to heavy rain. The change in position reduces the spider's surface that heavy rain could impact, and speeds water drainage which may reduce pathogen infection.

Widow spiders belong to the cosmopolitan genus Latrodectus (Araneae: Theridiidae), of which five species are found in North America. In part due to their medical importance and common occurrence, they are ever-more popular study organisms in a wide variety of fields. However, the literature is widely dispersed, and a broad synthesis has not been attempted since 1970. Here, we review and synthesize published information on the five North American Latrodectus species: L. hesperus, L. mactans, L. variolus, L. bishopi, and the introduced L. geometricus. We focus on distribution, ecology, anatomy, physiology, reproduction, ontogeny, behaviour, web structure, silk, venom, genetics, and phylogeny. We also include some of our own observations on L. hesperus. We conclude by highlighting areas where further research would be especially fruitful.