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.

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 family Withiidae is widely distributed around the world, with most of its diversity in tropical areas. Five new species and a new genus from Colombia are described: Cystowithius florezi sp. nov., Parawithius bromelicola sp. nov., Oligowithius achagua sp. nov., and the genus Paciwithius gen. nov. with two species Paciwithius valduparensis sp. nov. and Paciwithius chimbilacus sp. nov. A reassessment of the subgenus Dolichowithius (Oligowithius) Beier, 1936 allows the elevation to a full generic level, and the transfer of the only known species to Oligowithius, forming the new combination Oligowithius abnormis (Beier, 1936), comb. nov.

The Dry Tropical Forest (DTF) is one of the most diverse yet threatened biomes of Colombia. There is limited information about the richness of the order Pseudoscorpiones (Arachnida) in this ecosystem in the country. Pseudoscorpions are ecologically interesting, as they may be good indicators of habitat conservation. However, it is still necessary to gather more knowledge related to its spatio-temporal variation. In this study, pseudoscorpion diversity variation was assessed in two fragments of the Dry Tropical Forest in the Caribbean region of Colombian: Reserva Campesina La Montaña (RCM) and Reserva La Flecha (RLF). Four samplings were carried out between March and September of 2016 to include the dry and rainy season. Pseudoscorpions were collected using litter sifting (SL) and manual capture (MC). A total of 260 individuals belonging to five families and eight species were collected. The most abundant was Pachyolpium granulatum (Olpiidae) and the richest family was Chernetidae. The collection methods were effective and complementary. Spatial variation was significant, but no temporal variation was observed however, there was a marked difference between the abundance at RCM in the dry season and the rainy season. In contrast, at RLF most individuals were found in the dry season in comparison with the rainy season. These new faunistic data is the first of its order in the Atlántico and Bolívar department.

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.