Over the past 30 years the British pseudoscorpion fauna and our understanding of it has grown. Three new species have been discovered, two of which, Larca lata Hansen, 1884 and Microbisium brevifemoratum (Ellingsen, 1903) have viable populations, whilst a third, Americhernes oblongus (Say, 1821), is a casual introduction. A further species, Chthonius (Chthonius) halberti (Kew, 1816) was rediscovered in 2016. An atlas was published in 1980 and a revised Linnean Society Synopsis in 1998. The rise of computers facilitated the digitization of records from 1992 onwards, and enabled the publication of distribution records online through the author's web site, chelifer.com, and the NBN Atlas. The interest in pseudoscorpions has subsequently blossomed and given rise to a Facebook page and a number of identification courses. All this interest will hopefully further our understanding of the British pseudoscorpion fauna.

A revised checklist of spider species found in Great Britain and Ireland is presented together with their national distributions, national and international conservation statuses and synonymies. The list allows users to access the sources most often used in studying spiders on the archipelago.

The British harvestman fauna amounted to 22 species in 1969, and increased by almost 30% to 31 species in the following 50 years. The recent additions are discussed, and an updated checklist is provided. Although some of these species had been considered as relicts, there is little evidence to suggest that they are anything other than recent immigrants, with distributions and patterns of spread largely consistent with that view. Possible future immigrants or overlooked species are considered, along with some of the pressures driving change.

Hybridization and introgression in the wild between two species in the Eratigena atrica group of large house spiders, E. duellica and E. saeva, are well documented. However, the morphology of known F₁ hybrids and subsequent F₂ and backcross generations has not previously been explored. The phenotypes of these interspecific offspring have implications for the ease of introgression and for the morphological identification of individuals of hybrid origin. Here, the progeny from laboratory crosses are analysed using both simple characters and multivariate statistical techniques. F₁ hybrids in both sexes are, morphologically, significantly biased towards E. duellica but backcross progeny tend to resemble their non-F₁ parents more than expected in a model of additive, unlinked quantitative trait loci (QTL). It is possible that loci on the X-chromosomes affect the phenotype or that there are maternal influences. These biases may have consequences for the ease and direction of gene flow between the species. While female F₁ hybrids can be distinguished from pure parents, for later generations, and for all generations of males, confusion with the parental species is highly likely and may have affected previous conclusions.

Pale lateral bands that contrast with somatic colouration are common to many semi-aquatic spider species and may contribute to camouflage. Dolomedes plantarius is dimorphic for the presence or absence of a broad, pale, lateral band on the abdomen and cephalothorax. Here, we investigate the heritability of this banding pattern by assessing the proportion of banded progeny in broods of spiderlings for which the phenotype of one or both parents was known. Our results indicate a single-gene system of inheritance with the banded allele dominant to the unbanded. This finding offers a simple way to investigate various aspects of the biology of this rare spider, which is classified as vulnerable to extinction. We consider the implications for further understanding the mating system of D. plantarius and for studying the function and maintenance of banding in wild populations.

Selenops ef sp. nov. (male) is described from Cambodia, Battambang Province. It represents the first record from a cave in Asia. A distribution map of Selenops species in Asia is given and the cave-dwelling habit of the new species is discussed.

A new genus name is proposed to replace the preoccupied genus LingaLavery & Snazell, 2013: Notolingan. gen. The type species Linga orquetaLavery & Snazell, 2013 is presented as a junior synoym of Neriene fuegianaSimon, 1902; therefore, Notolinga fuegianan. comb. is established.

In some spiders, nuptial gifts consist of prey or inedible items wrapped in silk by males and offered to females during courtship. Such gifts occur in the Neotropical family Trechaleidae, of which most species are semi-aquatic, associated with watercourses in riparian habitats. Here, we describe the sexual behaviour of the South American species Trechaleoides keyserlingi and report the presence of nuptial gift-giving behaviour for the first time in the genus.

An unidentified Siler species has been recorded from the central Ryukyus in Japan, but the taxonomic status of the species has not been clarified sufficiently until now. To make clear the taxonomic identity of the species, in addition to a morphological comparison with other Japanese congeners, we performed molecular analysis based on partial sequences of mitochondrial cytochrome oxidase subunit I (mt-COI). As the results, we concluded the unidentified species from the central Ryukyus is new to science. Therefore, we describe this species as Siler rubrum sp. nov. in the present paper. Siler rubrum sp. nov. is very similar to S. collingwoodi (O. Pickard-Cambridge, 1871). However, males of S. rubrum sp. nov. can be distinguished from the latter by the length of the tibial apophysis and the shape of the tegulum on the pedipalp. Females of S. rubrum sp. nov., in contrast, lack distinct diagnostic characters compared with males, but can be distinguished from S. collingwoodi by slight differences in the shape of the copulatory duct.

An illustrated redescription of Labahitha gibsonhilli (Savory, 1943) known only from two syntype females from Christmas Island, is given. The species is re-diagnosed and the lectotype and paralectotype are designated. Labahitha gibsonhilli differs from L. oonopiformis (Bristowe, 1938), the only other known congener, in having a reversed-cordate sternum, as well as in the shape of the receptacles.

The prey capture webs of Emblyna sp. and Mallos hesperius (Chamberlin, 1916) span gentle curves in the surfaces of single, rigid leaves. They share several traits with orb webs: geometrically regular and approximately planar arrangements of strong, non-sticky lines; geometrically regular arrays of sticky lines laid on these non-sticky lines; and frequent renewal (webs are routinely damaged by rain, and are often largely renewed daily). They generally differ from orbs in that neither the sticky nor the non-sticky lines are organized radially. Comparisons with the webs of 22 other dictynid species in seven other genera reveal little phylogenetic pattern. Comparisons with the orb-like para-orbs of six, distantly related species reveal variable combinations of orb-like traits in different groups, suggesting widespread convergence. New details of possible taxonomic interest concerning how silk is combed from the cribellum are described.

Lycosa inornata Blackwall, 1862 is a small wolf spider that inhabits open environments from Uruguay and, like other wolf spiders, little is known of their sexual behaviour, which we describe here. Male courtship behaviour includes leg rubbing, leg vibration and pedipalp drumming, as well as leg waving. Females respond to male courtship by running towards them and shoving them with her legs and body. Receptive females lower their body on the substrate and slightly raise and twist the abdomen, facilitating the mounting and subsequent pedipalp insertions. Copulation lasts less than an hour, has two behavioural copulatory patterns and one haematodochal expansion per pedipalp insertion, in turn intercalated by pedipalp chewing. Pattern I consists of several insertions with the same pedipalp before a side change. Pattern II consists of a single pedipalp insertion before a side change. Females construct a single egg sac within 40–45 days after copulation and an average of 65 spiderlings emerge after 35 days. As occurs in other species of lycosid, L. inornata presents a low rate of sexual cannibalism. This study adds to the few descriptions of sexual and reproductive behaviours in wolf spiders and we hope it will increase knowledge of this diverse family of spiders.

A new araneid species Paraplectana mamoniaesp. nov., with a characteristic glossy pink abdomen in females, is described and illustrated based on morphology of individuals collected from Assam, together with notes on its natural history.

Specimens of the widely distributed ischnocoline species Holothele longipes (L. Koch, 1875) are formally reported from Guyana and Panama for the first time, based on examination of material from the collections of Natural History Museum, London, Oxford University Museum of Natural History and Museo de Invertebrados G. B. Fairchild, Universidad de Panama.

Myrmarachne augusta (Peckham & Peckham, 1892), an ant-mimicking jumping spider (Araneae: Salticidae) is redescribed. This species has only been known from two records and three specimens from Madagascar so far. Its new locality is presented along with a detailed description and discussion on intraspecific variation of colour and morphology in relation to previously recorded specimens.

Many arachnids rely on substrate-borne vibrations and air displacement to detect prey. Air-flow stimuli may be detected by long setae called trichobothria, which occur on scorpion pedipalps, but seldom have their functions been addressed in these animals. We tested the hypothesis that trichobothria on scorpion pedipalps are important for capturing terrestrial prey in the scorpion Tityus serrulatus. We predicted that scorpions with trichobothria experimentally removed would be less successful in capturing terrestrial prey than the control groups. We also predicted that scorpions without trichobothria would have a higher number of capture attempts, that the latency to detect prey and to the first capture attempts would be higher, and the number of times that scorpions oriented their body towards the prey would be lower. We used an experimental subject and a cricket in an arena with a paper sheet as substrate. We did not find differences in the measured variables between the groups. Other sensory organs, such as basitarsal compound slit sensilla and tarsal hairs would enable scorpions to detect prey by substrate-borne vibrations, compensating for the lack of trichobothria. Our results suggest that the trichobothria of T. serrulatus may not be essential to capture terrestrial prey.

Two new species of the genera Coelotes and Tegecoelotes, from Central Honshu, Japan, are described under the name of Coelotes isensisn. sp. and Tegecoelotes kumadain. sp. respectively. The former is included in the species group that has four retromarginal teeth on the chelicera, but there is no Japanese species that has a similar form of genital organs when compared to the new species. The latter can be distinguished from all congeneric species by its unique tegulum protruding downward in the male palp. In addition, male of T. kumadai is characterized by the leg formula of I–IV–II–III.

Sexual cannibalism is common in spiders and can be advantageous for female fitness by increasing egg production. However, it is possible that, under low mate density, females will be at risk of consuming all of the males they encounter prior to copulation. Cannibalistic females may be able to mitigate the risk of virgin death if they reduce cannibalism rates in response to low mate availability. Here, we attempted to manipulate perceived mate density and observe whether it affected female aggression towards males in the fen raft spider (Dolomedes fimbriatus). We predicted that female attack rate would increase in response to an increasing number of male encounters. We also recorded male courtship effort. Despite previous literature finding that D. fimbriatus females were highly aggressive towards conspecific males, we found that females only attacked courting males in 14% of encounters. None of these attacks resulted in cannibalism. Moreover, attacks were not associated with how many males the female had previously been exposed to. Male courtship effort decreased in response to repeated exposure to females. Some of the virgin females laid and guarded unfertilized egg cases; this made them unattractive to males, potentially reducing their reproductive lifespan prematurely.