The genus Mayazomus currently contains two species from southeastern Mexico. It was originally characterized by a strongly elongated pedipalp trochanter, united in its entire width to the femur; the patella strongly curved; the tibia with a large mesal apophysis opposable to tarsus; the spermathecae with two pairs of thin lobes subequal in length; and the presence of four or more setae on tergite II. In the present contribution, the species of the genus Mayazomus are revised and new diagnostic characters for the genus are proposed, including the correction that the female flagellum bears three rather than two annuli. The two known species are redescribed based on examination of the holotypes, plus newly acquired material representing both sexes (female previously unknown for one). Five new species from the Mexican state of Chiapas are described, based on adult males and females: Mayazomus tzotzil new species, Mayazomus aluxe new species, Mayazomus kaamuul new species, Mayazomus yaax new species, and Mayazomus loobil new species. Dimorphism in male pedipalps is reported for the first time for the genus. A dichotomous key is provided for identification of the seven species in the genus; and a distribution map is included.

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The schizomid genus Mayazomus Reddell & Cockendolpher, 1995, endemic to south‐eastern Mexico, currently comprises seven species. It was originally proposed to accommodate two species, from Chiapas and Tabasco. Recently, five additional species from Chiapas were described. The monophyly of the genus has never been tested using cladistic analysis. We undertook a phylogenetic analysis using the seven described species of Mayazomus as the ingroup, ten exemplar species representing the most similar New World hubbardiids as the outgroup, and one protoschizomid species to root the tree. The analysis was based on 130 morphological characters (continuous and discrete characters). The resulting topologies recovered Mayazomus as paraphyletic, with Heteronochrus estor Armas & Viquez, 2010, from Guatemala nested within the genus; therefore, we formally propose its synonymy herein. Mayazomus appears to be most closely related to Rowlandius Reddell & Cokendolpher, 1995, a South American genus. This contribution also provides new characters derived from the pedipalp setae with important phylogenetic information; as well as the implementation of morphometric ratios, as continuous characters, to partially codify the shape of the male flagellum. The relationships recovered amongst the outgroups used in this contribution are a reliable baseline for future analyses of the phylogeny of the New World schizomids.

The short-tailed whipscorpion genus, Stenochrus Chamberlin, 1922 (Schizomida: Hubbardiidae Cook, 1899), occurring in North and Central America, is redefined and revised based on simultaneous phylogenetic analysis of 61 morphological characters and 2968 aligned DNA nucleotides from two markers in the nuclear genome, the internal transcribed spacer (ITS) and 28S rDNA, and two markers in the mitochondrial genome, cytochome c oxidase subunit I (COI) and 12S rDNA, for a comprehensive taxon sample. Six new genera are described: Ambulantactus, gen.

Among Opiliones (Arachnida), there are many taxa either with no familial assignment or erroneously located in their current family. This is the case of Ethobunus pilosus, formerly in Phalangodidae and before this work in Zalmoxidae. To assess the phylogenetic position of this taxon, we started with a revision of the male genitalia; followed by the inclusion of three molecular markers: nuclear 28S and 18S, and mitochondrial protein-encoding cytochrome c oxidase subunit I (COI) from E. pilosus in the previously published phylogenies of the Samooidea + Zalmoxoidea clade. The results revealed that E. pilosus is a derived lineage within the family Icaleptidae, thus it is transferred from Zalmoxidae, and the new name Trypophobica gen. nov. is proposed to accommodate it, with the new combination Trypophobica pilosa comb. nov. With its inclusion in Icaleptidae, and the description of Trypophobica llama sp. nov., the current diagnosis of the family needs updating, and further morphological characters should be considered as putative synapomorphies. In addition, the reconstruction of the ancestral ranges of Icaleptidae suggests a mid-Cretaceous origin c. 104 Ma in South America, with a subsequent colonisation to north Mesoamerica c. 80 Ma.

A new species of the genus Protosduzomus Rowland 1975 is described with adult males and females. We collected Proloschizomu.s frcmckei new species from Cueva del Diablo in the state of Guerrero, Mexico. Currently, the genus Protoschizonnis is composed of eight species including the new species described here, of which five have been found inside caves.

The North American genus Stenochrus is represented by 22 species distributed mainly in Mexico, Central America and the U.S.A.; the genus was erected originally to place the species Stenochrus portoricensis and was characterized by the presence of lateral lobes reduced on female spermathecae, male flagellum without important dorsal relief, pedipalps without distinctive armature and without posterodorsal process on segment XII. Here we describe five new species from the Mexican state of Oaxaca; we discuss the presence of dimorphic males in the genus. With this contribution the genus Stenochrus reaches 27 species, becoming the second most diverse genus of schizomids in the New World.

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