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Pseudoscorpiones is a mesodiverse order of Arachnida, with more than 3600 described species in the world. Species delimitation is sometimes difficult due to the high variability of some characters,...

A new species of the pseudoscorpion genus Cystowithius Harvey, 2004 is described based on several males and females collected in the Cordillera Central near Manizales and Villamaria, Caldas, Colombia. The type series was collected under or on the bark of Eucalyptus grandis W. Hill ex Maiden (Myrtaceae). Cystowithius ankeri sp. nov. is the fifth species in the genus, differing from its four congeners by several characters, including the position of the male sternal invaginations, the length of the movable finger of the pedipalp, and the tactile setae of tarsus IV situated subdistally. A revised identification key to the five species of Cystowithius is also presented. The first barcode (COI gene) of a species of this genus is also provided.

In Colombia, the status of the Neotropical genus Pachychernes Beier, 1932 is unknown. The only available data in literature to support the presence of this genus is an adult of P. aff. subrobustus, possibly female, from copal resin without specific locality data, and a record at generic level from Northern Colombia. In this study, we extend the distribution of Pachychernes by describing a new species, P. florezi sp. n. and several reporting individuals of P. zehorum Muchmore, 1997 from Montes de María and the Caribbean coast of the country. These species are clearly differentiated from one another by the sexual dimorphism in the latter species, with a depression on the tarsus I in males. We also present an updated key for all species of the genus.

Propositions of homology are fundamental in systematics, since they provide the basis for supporting clades. Consequently, such phylogenetic propositions rely on correct character and character state definitions. Although male genital morphology is a key source of information for understanding the phylogeny and classification of the Withiidae (Pseudoscorpiones), they have only been subjected to examination in six of the 170 species of the family. The suprageneric classification of the Withiidae is unstable, as subfamilies and tribes are not well supported by morphological characters, and only the unranked group of genera Cacodemoniini is currently accepted. The aim of the present work is to characterize the male genital armature of the Cacodemoniini and propose homology statements for these structures based upon their morphological correspondence. Through direct examination and literature review of 12 of the 13 genera of the Cacodemoniini, we provide the first structural correspondence statements and descriptions of variation for the dorsal apodemes, the ejaculatory canal, the lateral apodemes, and the lateral rods; we also conclude that unlike other pseudoscorpions, the Cacodemoniini have paired, independent lateral rods and a long ejaculatory canal formed not by the dorsal apodemes exclusively, but by a fusion of the dorsal and the lateral apodemes. The proposed interpretations lay the groundwork for phylogenetic testing of homologies and may allow a better understanding of the formation of the spermatophore, given that it is molded by the genital armature.

El Bosque Seco Tropical (bs-T) es uno de los biomas mas diversos y amenazados de Colombia. Hay poca informacion de la riqueza del orden Pseudoscorpiones (Arachnida) en este ecosistema en el pais. En aspectos ecologicos, los pseudoescorpiones son interesantes ya que son indicadores potenciales de la conservacion del habitat. Sin embargo, es necesario reunir mas conocimientos relacionados con su variacion espacio-temporal. En este estudio se evaluo la variacion de la diversidad de seudoescorpiones en dos fragmentos del Bosque Seco Tropical en la region del Caribe de Colombia: Reserva Campesina La Montana (RCM) y Reserva La Flecha (RLF). Para lograr esto, se realizaron cuatro muestreos entre marzo y septiembre de 2016 para incluir la estacion seca y lluviosa. Los seudoescorpiones se recolectaron utilizando cernido de hojarasca (SL) y captura manual (MC). Un total de abundante fue Pachyolpium granulatum (Olpiidae) y la familia mas rica fue Chernetidae. Los metodos de recoleccion demostraron ser efectivos y complementarios. La variacion espacial fue significativa, pero no se observo variacion temporal. Sin embargo, hubo una marcada diferencia entre la abundancia en RCM en la estacion seca y en la estacion lluviosa. En contraste, en RLF la mayoria de los individuos se encontraron en la estacion seca en comparacion con la estacion lluviosa. Estos nuevos datos faunisticos son los primeros de su orden en los departamentos de Atlantico y Bolivar.

Colombia is a mega-biodiverse country and rich in ecosystems as different as the Amazon and the Andes. Much is known of the vertebrate fauna, however there is still an information-gap for many arthropod groups including the arachnids. Here, we compile all the information available for pseudoscorpions (Arachnida: Pseudoscorpiones) recorded from Colombia and include several new records and distribution extensions. For each described species, we present information on taxonomic history, type localities, global and local distributions, repository of Colombian specimens, and collection numbers when available. We document 12 families, 45 genera and 65 species of pseudoscorpions for Colombia and most species belong to the families Chernetidae (27 species) and Olpiidae (8 species). We record Beierolpium venezuelense Heurtault, 1982, Geogarypus amazonicus Mahnert, 1979, Sathrochthonius venezuelanus Muchmore, 1989, and Semeiochernes armiger (Balzan, 1892) for the first time for Colombia. We further extend the known ranges of Parachernes melonopygus Beier, 1959 and Paratemnoides nidificator (Balzan, 1888). The data suggest that the Caribbean region of Colombia has the highest number of records. Total numbers are not complete and many other new pseudoscorpion species are expected.

The pseudoscorpion genus Verrucachernes Chamberlin, 1947 is widely distributed in the Old World tropics, with three named Australasian and West Pacific species and two from Africa. A review of some pseudoscorpions described from India has revealed that Withius parvus Beier, 1930 (currently in the genus Metawithius) and Pselaphochernes indicus Beier, 1974 are misplaced and actually belong to the genus Verrucachernes Chamberlin, 1947, forming the new combinations V. parvus (Beier, 1930) comb. nov. and V. indicus (Beier, 1974) comb. nov., respectively. Both species possess the single, large, rounded spermatheca and other features typical of Verrucachernes.

A new species of the pseudoscorpion genus Metawithius Chamberlin, 1931 is described from Kerala, India. Detailed morphological descriptions, diagnostic features and illustrations of Metawithius keralensis Johnson, Mathew, Sebastian & Joseph, sp. nov. are provided. Detailed redescription and illustrations of M. nepalensis (Beier, 1974) are also provided. The current distribution of all the known Metawithius species is mapped. Metawithius parvus (Beier, 1930) from Travancore, India is recognised as a species of Chernetidae.