This review presents the main species of venomous and poisonous arthropods, with commentary on the clinical manifestations provoked by the toxins and therapeutic measures used to treat human envenomations. The groups of arthopods discussed include the class Arachnida (spiders and scorpions, which are responsible for many injuries reported worldwide, including Brazil); the subphylum Myriapoda, w...

Including more than 6500 species, Opiliones is the third most diverse order of Arachnida, after the megadiverse Acari and Araneae. This database is part 2 of 12 of a project containing an intended worldwide checklist of species and subspecies of Opiliones, and it includes the members of the suborder Laniatores, infraorder Grassatores of the superfamilies Samooidea and Zalmoxoidea plus the gener...

A new trigonotarbid (Arachnida: Trigonotarbida: Trigonotarbidae) is described as Archaeomartus roessleri n. sp. from the Upper Carboniferous (Pennsylvanian; Namurian B, higher Marsdenian) of Hagen-Vorhalle, Germany. Originally assigned to Trigonotarbus johnsoni Pocock, 1911, our new fossil has a distinctly lobed carapace and thus resembles more closely the Early Devonian species Archaeomartus l...

New members of the spider family Caponiidae from Brazil and Chile are presented. Three new species in previously known genera are described: Taintnops papososp. n. from Chile, and the Brazilian Tisentnops mineirosp. n. and Tisentnops onixsp. n., both belonging to a genus known only from its damaged type. Additionally, two new non-nopine Brazilian genera are proposed: Nasutonopsgen. n. including...

This article focuses on the medically relevant arachnid species found in North America and selected other arachnids from around the world. While it is largely still true that the geographic location of the envenomation assists in determining the species responsible, the booming trade in arachnids as exotic pets should prompt the clinician to inquire into this possibility. Expert advice should b...

Two new species of the arachnid order Schizomida, Rowlandius ubajara sp.nov. and Rowlandius potiguar sp.nov., are described based on both male and female specimens collected in caves from northeastern Brazil. Rowlandius ubajara is known only from the Ubajara Cave, in the state of Ceará; R. potiguar is recorded from 20 caves of the Apodi Limestone Group, in the state of Rio Grande do Norte. A re...

Three new hypogean species of the Iberian genus Roncocreagris Mahnert, 1974 are described from mainland Portugal: R. borgesi sp. nov. and R. gepesi sp. nov. from caves in the Sicó massif, and R. occidentalis sp. nov. from caves in the Montejunto and Cesaredas karst plateau. This brings to nine the number of known hypogean species of the mostly Iberian genus Roncocreagris: five from Portugal and...

Certain leg joints in arachnids lack extensor muscles and have elastically deformable transarticular sclerites spanning their arthrodial membranes, an arrangement consistent with a model in which flexor muscles load transarticular sclerites during flexion and energy from elastic recoil is used for extension. This study quantifies the potential contribution of elastic recoil to extension torque ...

1 Department of Biological Sciences, Northern Arizona University, PO Box 5640, Flagstaff, AZ, 86011-5640, USA 2 Department of Entomology, California Academy of Sciences, 55 Music Concourse, Dr., Golden Gate Park, San Francisco, California, U.S.A. 3 Canadian National Collection of Insects, Arachnids and Nematodes, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, Ontario, K1A 0C6, Ca...

The genus Acanthomegabunus Tsurusaki, Tchemeris & Logunov 2000 is diagnosed and redescribed. A key to species is presented. A new species, Acanthomegabunus altaicus sp. n. from the Аltai Mountains of Russia and NE Kazakhstan is diagnosed, described and figured; its distribution is mapped, along with new records of A.sibiricus Tsurusaki, Tchemeris & Logunov 2000.