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The troglomorphic scorpion genus Troglotayosicus Lourenço, 1981, occurs in hypogean and epigean habitats in the Andean and Amazonian rainforests of Colombia and Ecuador. The phylogenetic relationships among the species of Troglotayosicus are currently unknown. In the present contribution, a new species, Troglotayosicus akaido, sp. nov., is described from specimens collected in the leaf litter of a primary rainforest in the Colombian Amazon, near the border with Peru, raising the number of species in the genus to seven. The new species represents the easternmost record of the genus and further extends its distribution into the Amazon. Its phylogenetic position was tested in an analysis of all species of the genus and two outgroup taxa, scored for 131 morphological characters (16 new and 115 legacy; 104 binary and 27 mulstistate) analyzed with maximum likelihood under the MK model. Troglotayosicus was recovered as monophyletic and composed of two main clades. The morphological survey revealed that the ventral macrosetae of the leg telotarsi of the type species, Troglotayosicus vachoni Lourenço, 1981, are simple, subspiniform macrosetae, irregularly distributed, but not arranged into clusters nor forming elongated clusters of setae/spinules, as previously suggested. A distribution map and key to the identification of the species of Troglotayosicus are provided. Further research, incorporating molecular data, is needed to understand the evolution and biogeographical history of this enigmatic scorpion genus. 

The ancient, enigmatic whip spider family Paracharontidae Weygoldt, 1996, representing the basalmost lineage of the arachnid order Amblypygi Thorell, 1883, is revised. The monotypic West African genus Paracharon Hansen, 1921, from Guinea Bissau, is redescribed, based on a reexamination and reinterpretation of the newly designated lectotype. A new troglobitic whip spider, Jorottui ipuanai, gen. et sp. nov., is described from a cave system in the upper basin of the Camarones River in the La Guajira Department of northeastern Colombia. This new taxon is the second extant representative of Paracharontidae and the first outside Africa. It is unambiguously assigned to the family based on several characters shared with Paracharon caecus Hansen, 1921, notably a projection of the anterior carapace margin, the tritosternum not projecting anteriorly, similar pedipalp spination, a reduced number of trichobothria on the tibia of leg IV, and cushionlike female gonopods. A detailed examination confirmed the absence of ocelli in both genera and the presence of three (Paracharon) vs. four (Jorottui, gen. nov.) prolateral teeth on the basal segment of the chelicera, the dorsalmost tooth bicuspid in both genera. The male gonopods of Paracharontidae are described for the first time. Paracharonopsis cambayensis Engel and Grimaldi, 2014, is removed from Paracharontidae and placed incertae sedis in Euamblypygi Weygoldt, 1996; amended, comparative diagnoses are presented for Paracharontidae and Paracharon; and previous interpretations of various diagnostic characters for Paracharontidae are discussed. 

The arachnid fauna of Angola and Namibia is diverse and includes high levels of endemism, much of which is associated with the arid zone, especially the Namib Desert. The endemic arachnid fauna of the highlands and escarpments, including mountain ranges, plateaus and inselbergs, has received less attention. The study presented here is the first to compile existing distributional data for three arachnid orders – whip spiders (Amblypygi Thorell, 1883), scorpions (Scorpiones C.L. Koch, 1837) and solifuges (Solifugae Sundevall, 1833) – occurring in the highlands and escarpments of Angola and Namibia from published literature, online databases and natural history collections. Distribution maps were used, together with available data or expert knowledge of taxon habitat requirements, to prepare a list of described arachnid taxa considered endemic or nearendemic to the western highlands and escarpments of these two countries. In addition, arachnid endemism was assessed more broadly by scoring the presence of described and potential undescribed endemics in relevant highlands and escarpments, tallying the scores for each order, and ranking the highlands and escarpments based on the sum of all three ordinal tallies. These scores provide a rough index of the relative importance of highlands and escarpments in Angola and Namibia for prioritising decisions regarding conservation as well as further survey and inventory from the arachnid perspective. Although the highlands and escarpments of Angola and Namibia probably serve as refugia for taxa requiring cooler, more humid habitats than are available in the surrounding arid lowlands, including palaeoendemics, they appear to contain fewer endemic arachnid taxa than the lowlands. This may be because: (1) the highlands and escarpments of Angola and Namibia are relatively low, on average, providing few opportunities for insular speciation; (2) much arachnid endemism in the arid lowlands is associated with unique substrates that are absent in the highlands, including sand dunes, gravel plains and clays associated with drainage systems, all of which facilitate burrowing to escape the arid conditions and promote diversification; and (3) much of the taxonomy of the arachnids of both countries remains unresolved, and the distributions poorly understood, especially in Angola. More intensive surveys, with an emphasis on collecting genetic samples from disjunct populations across the distributions of each putative species, are needed to better understand arachnid diversity and endemism in the region.