Two new and unusual species of Tibelloides Mello-Leitão, 1939 (Araneae: Philodromidae).

Tibelloides Mello-Leitão, 1939 currently comprises four species of Neotropical grass-dwelling spiders. Herein, we describe and illustrate Tibelloides castelo sp. nov.

Solving a running crab spider puzzle: delimiting Cleocnemis Simon, 1886 with implications on the phylogeny and terminology of genital structures of Philodromidae.

Background: Among the 16 Neotropical genera of Philodromidae, Cleocnemis has the most troublesome taxonomic situation. Remarkable morphological differences among several genera historically said to be related to Cleocnemis denote controversial notions and general uncertainty about the genus identity. Thus, to clarify the genus limits and contribute to the understanding of Neotropical Philodromidae, we conducted a morphological analysis, along with Bayesian Inference and Maximum Likelihood molecular phylogenetic analyses focusing on Cleocnemis and related genera of Thanatinae.

Notes on slender species of the long-jawed spider genus Tetragnatha (Araneae, Tetragnathidae) with description of three new species.

New data about slender orb-weaving species of the cosmopolitan genus Tetragnatha are presented. Tetragnatha chauliodus (Thorell, 1890) and Tetragnatha tenuissima O. Pickard-Cambridge, 1889 are redescribed, including one synonymy for each species and the first record of the first species to the Neotropical region.

Three new species of Ochyrocera (Araneae, Ochyroceratidae) from Southeastern Brazil.

Three new species of the six-eyed  haplogyne and ecribellate spiders from the genus Ochyrocera Simon, 1891 are illustrated and described based on males and females from southeastern Brazil: Ochyrocera tinocoi new species (Sooretama, Espírito Santo state), Ochyrocera garayae new species (Linhares and Sooretama, Espírito Santo state) and Ochyrocera itatinga new species (Rio de Janeiro city, Rio de Janeiro state). The new species expand the distribution range of Ochyrocera in Brazil and increase to 50 the total number of species described, from which hitherto 33 species occur in South America, acknowledging the high diversity of the genus for the region.

Taxonomic review of Epicadinus Simon, 1895 (Araneae: Thomisidae).

The genus Epicadinus Simon, 1895 can easily be distinguished from the other Neotropical Stephanopines by their abundant and robust setiferous tubercles, topped by elongated macrosetae, which cover most of the tegument. Additionally, the genus can be recognized by a pair of conical ocular mounds above the ALE, the anterior eye row very recurved, posterior one slightly procurved; carapace flattened and without tubercles, and opisthosoma with three conical projections ("tubercles") of variable size and shape. This work is a taxonomic review of the 12 valid species of Epicadinus as listed in version 19 of the World Spider Catalogue (2018), whose hitherto known distribution included few records from Brazil, French Guiana, Bolivia and Peru, and only one from Mexico.

Comments on the genus C. L. Koch, 1850, with description of two new species (Araneae, Mygalomorphae, Dipluridae).

Two new species of C. L. Koch 1850 are described from Brazil: , from the state of Rondônia in southeastern Amazonia, northern Brazil, and , known from southeastern and central west regions of Brazil.

Notes on the orb-weaving spider genus Alpaida (Araneae, Araneidae) with description of four new species from Rio de Janeiro, Brazil.

Four new species of the orb-weaving spider genus Alpaida O. P.-Cambridge, 1889 from Rio de Janeiro state, Brazil are illustrated and described based on males and females from the following municipalities: Alpaida imperatrix new species (Macaé and Rio de Janeiro); Alpaida imperialis new species (Mendes and Rio de Janeiro); Alpaida marista new species (Mendes and Pinheiral); and Alpaida mendensis new species (Mendes).

Spider diversity (Arachnida: Araneae) in Atlantic Forest areas at Pedra Branca State Park, Rio de Janeiro, Brazil.

Background: There has never been any published work about the diversity of spiders in the city of Rio de Janeiro using analytical tools to measure diversity. The only available records for spider communities in nearby areas indicate 308 species in the National Park of Tijuca and 159 species in Marapendi Municipal Park. These numbers are based on a rapid survey and on an one-year survey respectively.

A new troglomorphic species of Harmonicon (Araneae, Mygalomorphae, Dipluridae) from Pará, Brazil, with notes on the genus.

A new species of Harmonicon F. O. Pickard-Cambridge, 1896 (Araneae, Dipluridae) is described, from a medium-sized lateritic cave in Parauapebas, Pará, Brazil.

Troglobitic scorpions: a new genus and species from Brazil.

A new genus and species of troglobitic buthid scorpion are described on the basis of a single specimen collected in Brazil. This is the first cavernicolous scorpion ever found in Brazil, and only the second to be found in South America. Some considerations on troglobitic scorpions are proposed.