Volume 21 LOURENÇO W. R. & ROSSI A. 2-10 The genus Hemiscorpius Peters, 1861 (Scorpiones: Hemiscorpiidae) in Africa and description of a new species from the Omo Valley in Ethiopia LOURENÇO W. R., ROSSI A. & WILMÉ L. 11-25 Further clarifications on species of Tityus C. L. Koch, 1836, subgenus Atreus Gervais, 1843 (Scorpiones: Buthidae), from Amazonia, with the description of a new species LOURENÇO W. R. 26-35 Redescription of Tityus sabineae Lourenço, 1994, a poorly known scorpion species from Colombia (Scorpiones: Buthidae) MALAMEL J. J. & SUDHIKUMAR A. V. 36-44 Impact of Parawixia dehaani (Doleschall, 1859) on the population dynamics of the kleptoparasitic spider Argyrodes flavescens O. Pickard­ Cambridge, 1880 – A case study LOURENÇO W. R. 45-52 A third specimen of the Chiapas Mexican amber scorpion Centruroides knodeli Lourenço, 2017 (Scorpiones: Buthidae)