Neocarus coronatus n. sp., is described from caves and the surrounding epigean habitats from a karst area of São Desidério county, Bahia state, Brazil. A dissection procedure is presented for the better use of scarce Opilioacaridae material, especially to analyze gut contents. Sexual dimorphism is presented, mainly differences in the density of setae on the dorsal shield in the prominent triangular anterior region. Females have an ovipositor with 3 pairs of smooth digitiform projections and 6-8 eugenital setae. Adults have a palpal tibiotarsus with 4 d setae. Using Low-Temperature Scanning Electron Microscopy (LT-SEM), evaluation of the chaetotaxy (especially setal shape) and morphology are greatly improved over standard light microscopy techniques enhancing the interpretation of characters for species differentiation. Also, we discuss the fragility of microinvertebrates in cave habitats.

No living Opilioacarus species have been described from Europe for more than a century since the first finding and species description in the early twentieth century. Using the material deposited in Museo Civico di Storia Naturale of Verona, Italy, it was possible to identify and describe a new Opilioacarus species and review the genus diagnosis, using the shape of setae d and setation of the preanal segment. The new species is also briefly compared with the other Opilioacarus species; Opilioacarus italicus (With, 1904) is considered a nomen dubium.

A catalog of the described Opilioacaridae species and their type depository institutions is presented. Opilioacaridae comprises 53 valid taxa (with 2 subspecies and 3 fossil species) distributed in 13 genera. The zoogeographical distribution, described life stages and years of description are also provided and discussed. Recent work on the American continent has resulted in a great diversity from these zoogeographical zones, but the family has a worldwide distribution. In addition, we move Neocarus ojastii Lehtinen, 1980 into Caribeacarus, i.e., Caribeacarus ojastii (Lehtinen, 1980) n. comb.

The present study aimed at assessing the effects of climate seasonality on poneromorph ants in the Brazilian Amazon, by studying variations in composition, richness, and taxonomic and functional diversity. The study was carried out in the Tapirapé-Aquiri National Forest, southeastern Pará State. We collected poneromorph ants in three areas of native forest with pitfall traps and sardine baits on the ground and vegetation, in two dry and rainy seasons. We collected 46 species of poneromorph ants, which belong to two subfamilies and eleven genera. The species composition, richness and taxonomic diversity did not vary significantly between seasons. There was no significant difference in the frequency of species of functional groups between dry and rainy seasons. There was no significant difference in the average richness and average diversity of functional groups between the dry and rainy seasons. In our study we found no seasonal differences in composition, taxonomic and functional richness and diversity of poneromorph ants in the Amazon, which is useful for future studies that aim at using those ants as bioindicators. In addition, the identification of the species made in the present study has special relevance as it contributes to advance the knowledge of poneromorph ant diversity in the Amazon.

Collections of Opilioacaridae made close to 50 years ago in Manaus in the Amazonian Region have allowed the description of a new genus and two new species from Brazil, Amazonacarus setosus n.gen, n.sp. and A. paraensis n.gen, n.sp. These species show a unique combination of characters in the Opilioacaridae: a high number of foliate setae (10) on the palp tarsus with each seta bearing many lobes (6-7), a group of large, serrate setae (26-31) on the palp tibia (this group of setae is much smaller in other species), and 5-7 dorsal setae on idiosomal segment XVIII. Indiacarus and some Opilioacarus show 3-5 setae on segment XVIII, but these genera (and Caribeacarus) have fewer foliate setae on the palp (3-4). Females of Amazonacarus have an ovipositor of the "complex" type, with spiny projections and 2-4 genital setae, while males have two pairs of rounded, large glands.

Documenting how diversity patterns vary at fine‐ and broad scales may help answer many questions in theoretical and applied ecology. However, studies tend to compare diversity patterns at the same scale and within the same taxonomic group, which limits the applicability and generality of the results. Here, we have investigated whether vegetation‐dwelling arthropods from different trophic ranks and with distinct life histories (i.e., ants, caterpillars, cockroaches, and spiders) have different beta‐diversity patterns at multiple scales. Specifically, we compared their beta diversity across architecturally distinct plant species (fine‐scale process) and a latitudinal gradient of sites (broad‐scale process) along 2040 km of coastal restinga vegetation in the Neotropics. Over 50 percent of the compositional changes (β‐diversity) in ants, caterpillars, and spiders and 41 percent of those in cockroaches were explained by plant identity within each site. Even groups that do not feed on plant tissues, such as omnivores and predators, were strongly affected by plant identity. Fine‐scale variation was more important than large‐scale processes for all studied groups. Performing a cross‐scale comparison of diversity patterns of groups with distinct life histories helps elucidate how processes that act at regional scales, such as dispersal, interact with local processes to assemble arthropod communities.

The rosette architecture of some bromeliad species traps water and organic matter from the canopy in leaf axils (forming phytotelmata) and harbors many species of invertebrate animals (Frank & Lounibos 2009). Some water mites are adapted to live in phytotelmata; typically recorded from water-filled tree holes, bromeliad tanks, and a range of plant axils. Karl Viets (1939) was the first acarologist who discovered Micruracaropsis phytotelmaticola (Viets, 1939) in the water contained in the leaf bases of epiphytic Bromeliaceae in Surinam. Later on, Orghidan et al. (1977) described Arrenurus bromeliacearum Orghidan, Gruia & Viña Bayés, 1977 from phytotelmata in Cuba. Orghidan & Gruia (1987) reported Arrenurus andrewfieldi Orghidan & Gruia, 1983 from phytotelmata of epiphytic bromeliad Vriesea platynema in Venezuela. Smith & Harvey (1989) described Arrenurus kitchingi Smith & Harvey, 1989 from water-filled tree holes in Queensland, Australia. The same authors (Smith & Harvey 1989) also reported that members of genus Thyopsis occur in water-filled tree holes in Ohio, USA. Rosso de Ferradás & Fernández (2001) reported two Arrenurus species from water accumulated in Guzmania mucronata (Bromeliaceae) in Venezuela, A. andrewfieldi Orghidan & Gruia, 1983 and A. caquetiorum Rosso de Ferradás & Fernández, 2001.

Neocarus jonasi n.sp. is described from three limestone caves of the Bambuí Group geomophological formation, Minas Gerais state, Brazil, with a combination of a higher number of palp genu and tibia r setae and palp tarsus sm and d setae. Its relationship to Neocarus spelaion and the importance of setae variation in Opilioacaridae is discussed. A key to the genus Neocarus is also provided.