Spiders are one of the eleven orders of the class Arachnida, which also includes groups such as harvestmen (Opiliones), ticks and mites (Acari), scorpions (Scorpiones), false scorpions (Pseudoscorpiones), windscorpions (Solifugae), and vinegaroons (Uropygi). All arachnid orders occur in North America. Arachnida today comprises approximately 640 families, 9000 genera, and 93,000 described specie...

background: the best-known dangerous spiders belong to the six genera. the genus loxosceles or violin spiders are well known for their ability to cause skin necrosis or loxoscelism. all loxosceles species have medical im­portance due to their necrotizing venom. the present article reports the occurrence of l. rufescens in charkhab cave, south of iran (larestan). methods: the specimens were coll...

The basal phylogeny of Chelicerata is one the opaquest parts animal Tree Life, defying resolution despite application thousands loci and millions sites. At forefront debate over chelicerate relationships monophyly Arachnida, which has been refuted by most analyses molecular sequence data. A number phylogenomic datasets have suggested that Xiphosura (horseshoe crabs) are derived arachnids, refut...

Arthropods are part of important functional groups in soil food webs. Recognizing these arthropods and understanding their function in the ecosystem as well as when they are active is essential to understanding their roles. In the present work, the abundance and diversity of soil arthropods is examined in olive groves in the northeast region of Portugal during the spring. Five classes of arthro...

A new fossil site near Gilboa, New York, is one of only three where fossils of terrestrial arthropods of Devonian age have been found. The new Gilboan fauna is younger than the other two but richer in taxa. Fragmentary remains and nearly whole specimens assigned to Eurypterida, Arachnida (Trigonotarbida, Araneae, Amblypygi, and Acari), Chilopoda [Craterostigmatomorpha(?) and Scuterigeromorpha(?...

We present the karyotype of the Australian harvestman Austropurcellia arcticosa (Cantrell, 1980) (Arachnida: Opiliones: Cyphophthalmi: Pettalidae), which represents the first cytogenetic analysis of Opiliones from the Australasian ecozone. The diploid complement comprised 30 chromosomes, as reported earlier for two other species of Cyphophthalmi in the family Sironidae, but with a predominance ...

The re-colonization of soil arthropods was monitored for five months (April to August) 2007 ascertain whether the application Endosulfan (an organochlorine pesticide) in varying concentration levels would adversely affect sampling arthropod groups within a 0-5cm depth. Berlese Tullgren Extraction technique, extraction, sorting and identification were adopted some physiochemical parameters (soil...

Morphological evidence for resolving relationships among arachnid orders was surveyed and assembled in a matrix comprising 59 euchelicerate genera (41 extant, 18 fossil) and 202 binary and unordered multistate characters. Parsimony analysis of extant genera recovered a monophyletic Arachnida with the topology (Palpigradi (Acaromorpha (Tetrapulmonata (Haplocnemata, Stomothecata nom. nov. )))), w...

A history of the family is presented. All of the genera and species previously assigned to the family are reviewed, and 4 new species are described: Leucohya parva from Venezuela and Guyana, Mexobisiunz venii from Belize and Guatemala, M. dorninicanu~n from the Dominican Republic, and Paravachoniuln sprousei from Mexico. Two subfamilies are established: Bochicinae (including the genera Alatillo...