Scorpions are among the oldest terrestrial arthropods, which are distributed worldwide, except for Antarctica and some Pacific islands. Scorpion envenomation represents a public health problem in several parts of the world. Mexico harbors the highest diversity of scorpions in the world, including some of the world’s medically important scorpion species. The systematics and diversity of Mexican scorpion fauna has not been revised in the past decade; and due to recent and exhaustive collection efforts as part of different ongoing major revisionary systematic projects, our understanding of this diversity has changed compared with previous assessments. Given the presence of several medically important scorpion species, the study of their venom in the country is also important. In the present contribution, the diversity of scorpion species in Mexico is revised and updated based on several new systematic contributions; 281 different species are recorded. Commentaries on recent venomic, ecological and behavioral studies of Mexican scorpions are also provided. A list containing the most important peptides identified from 16 different species is included. A graphical representation of the different types of components found in these venoms is also revised. A map with hotspots showing the current knowledge on scorpion distribution and areas explored in Mexico is also provided.

The North American vinegaroon, Mastigoproctus giganteus (Lucas, 1835), is demonstrated to comprise a complex of range-restricted species rather than a single widespread polymorphic species. Seven species are recognized based on morphological characters of the adult males, including the arrangement of spines on the prodorsal margin of the pedipalp trochanter, the position of the epistoma on the carapace, the presence of a stridulatory organ on opposing surfaces of the chelicerae and the pedipalp coxa, the presence of a patch of setae on sternite V, and the shape and macrosculpture of the retrolateral surface of the pedipalp femur. The two currently recognized subspecies are elevated to species: Mastigoproctus mexicanus (Butler, 1872), stat. nov., and Mastigoproctus scabrosus (Pocock, 1902), stat. nov. Mastigoproctus floridanus (Lönnberg, 1897) is revalidated from synonymy with M. giganteus. Redescriptions of M. giganteus and the other three species, based on both sexes, are provided, and three new...

A cladistic analysis of the genus Karos Goodnight & Goodnight, 1944, was performed using morphological data of the somatic and male genitalia char

The ‘giant hairy scorpions’, genus Hadrurus Thorell, are the largest and most conspicuous scorpions in North America, but their systematics has long been confused. A new genus, Hoffmannihadrurus Fet et al. was recently created to accommodate the two species endemic to mainland Mexico, Hadrurus aztecus Pocock and Hadrurus gertschi Soleglad. In the present contribution, we review the taxonomic history of Hadrurus, re‐evaluate the phylogenetic relationships among its component species with an analysis based on morphological characters and a taxon sample representing the known morphological variation, and assess the validity of the new genus. Seven independent analyses of the morphological character matrix, under weighting regimes that minimised length as well as those that maximised fit, each located a single most parsimonious tree with the following scheme of relationships: (Iurus ((Caraboctonus + Hadruroides) (H. aztecus ((H. gertschi + H. pinteri) (H. concolorous + H. hirsutus)) ((H. obscurus + H. spadix) (H. a. arizonensis (H. a. austrinus + H. a. pallidus)))))). This topology supports the monophyly of Caraboctoninae, Caraboctonini, Hadrurini, the ’arizonensis’ subgroup, H. arizonensis and H. concolorous. It does not support the monophyly of Hoffmannihadrurus, Hadrurus, the ’aztecus’ group, the ’hirsutus’ group, and the ’hirsutus’ subgroup, all of which were rendered paraphyletic by the grouping of H. gertschi with H. pinteri, rather than with H. aztecus. The results unequivocally demonstrate that the creation of a new genus for the mainland Mexican species was unfounded. We therefore propose the following new synonymy: Hoffmannihadrurus Fet et al., 2004 = Hadrurus Thorell, 1876, syn. nov.

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