Oscar F. Francke

Troglomorphism, trichobothriotaxy and typhlochactid phylogeny (Scorpiones, Chactoidea): more evidence that troglobitism is not an evolutionary dead-end

The scorpion family Typhlochactidae Mitchell, 1971 is endemic to eastern Mexico and exclusively troglomorphic. Six of the nine species in the family are hypogean (troglobitic), morphologically specialized for life in the cave environment, whereas three are endogean (humicolous) and comparably less specialized. The family therefore provides a model for testing the hypotheses that ecological specialists (stenotopes) evolve from generalist ancestors (eurytopes) and that specialization (in this case to the cavernicolous habitat) is an irreversible, evolutionary dead‐end that ultimately leads to extinction. Due to their cryptic ecology, inaccessible habitat, and apparently low population density, Typhlochactidae are very poorly known. The monophyly of these troglomorphic scorpions has never been rigorously tested, nor has their phylogeny been investigated in a quantitative analysis. We test and confirm their monophyly with a cladistic analysis of 195 morphological characters (142 phylogenetically informative), the first for a group of scorpions in which primary homology of pedipalp trichobothria was determined strictly according to topographical identity (the “placeholder approach”). The phylogeny of Typhlochactidae challenges the conventional wisdom that ecological specialization (stenotopy) is unidirectional and irreversible, falsifying Cope’s Law of the unspecialized and Dollo’s Law of evolutionary irreversibility. Troglobitism is not an evolutionary dead‐end: endogean scorpions evolved from hypogean ancestors on more than one occasion.

Scorpions from Mexico: from species diversity to venom complexity

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.

Temperature preferences of four species of fire ants (Hymenoptera: Formicidae: Solenopsis)

Temperature preferences are predicted to occur in insects due to homeostatic considerations. Enzymes should be adapted to function optimally within the narrow range of temperatures encountered by an organism during its peak activity periods (Heinrich, 1981). In ectotherms adapted to function optimally at low temperatures (e.g., living at higher latitudes or higher elevations), their biochemical machinery becomes inactivated or denatured at high temperatures. Conversely, those adapted to function optimally at high temperatures (e.g., living in the tropics or at lower elevations), experience reduced rates of biochemical activity at lower temperatures. Opti-mality theory predicts that ectotherms which habitually encounter temperature gradients should have the physiological and behavioral adaptations necessary to detect and respond to those gradients. A temperature gradient which fluctuates with daily and seasonal changes in solar radiation exists in the soil. This gradient is used by ground-nesting organisms to achieve some thermoregulatory homeo-stasis: they can move up and down their burrows to avoid temperature extremes, especially those occurring near the soil surface. Superimposed on this temperature gradient is a moisture gradient, because the higher temperatures reached at the soil surface during the day promote evaporation. Ants which nest in the soil are known to respond to the temperaturelhumidity gradients in the soil, and this response is particularly noticeable by the movement of brood among the various nest chambers (Ceusters, 1977; Seeley and Heinrich, 1981). Our research has focused on the responses of four species of fire ants to these soil gradients: elsewhere we (Potts el a/.,

Two DNA barcodes and morphology for multi-method species delimitation in Bonnetina tarantulas (Araneae: Theraphosidae).

Determining species boundaries is a central debate in biology. Several recently developed molecular delimitation methods have highlighted extensive inconsistency in classical morphological taxonomy. However, choosing between them is contentious. Molecular studies on theraphosid spiders have found considerable cryptic diversity and many species redundantly described. Most of these studies have relied only on COI, a mitochondrial marker that has proven its efficacy in animal studies, but which also might lead to an over-estimation of diversity. Here we present an integrative approach to species delimitation in Bonnetina, a poorly known group of tarantulas endemic to Mexico. We employed morphological evidence, as well as different setups with distance-based (Hard-Gap barcoding and ABGD) and tree-based (GMYC, PTP and BPP) molecular barcoding approaches, using one mitochondrial (COI) and one nuclear (ITS1) rapidly evolving loci. BPP is also used as a multi-locus method. We also explored the influence of ambiguous alignment choice and of coding gaps as characters in phylogenetic inference and in species delimitation with that marker. Different delimitation methods with COI gave moderately variable results and this gene exhibited a universal barcode gap. The ITS1 gene tree was well supported and robust to alignment choice; with this locus, coding gaps improved branch support and species delimitation with PTP. No universal barcode gap was found with ITS1, and single locus delimitations returned disparate results. However, this locus helped to highlight cases of under- and overestimations by COI. BPP gave solutions with many lineages, in single locus and combined analyses, especially with the recently implemented unguided methodology. We recognize 12 robustly supported species in our data set, of which seven remain undescribed, and three are morphologically cryptic. For COI Bonnetina species identification, we propose intra- and inter-specific thresholds of 2% and 6% sequence divergence, respectively. We conclude that morphological signal for species delimitation in Bonnetina is higher than for other studied tarantulas, but it fails to recognize several lineages in the genus. COI is a functional barcoding marker, and the most reliable source of evidence that we used, but it may also lead to inaccurate delimitations. ITS1 is a highly informative locus for species delimitation and species-level phylogeny, but it performs poorly as a barcoding marker. Due to variability between delimitation methods, we suggest combining evidence from multiple approaches to get better-supported results.

Four new species of the genus Pseudocellus (Arachnida: Ricinulei: Ricinoididae) from Mexico

Abstract Four new species of ricinuleids are described: Pseudocellus chankin from caves and surface collections in southern Mexico (Chiapas & Tabasco) and Guatemala (Petén); Pseudocellus jarocho from a single surface collection in Veracruz, México; Pseudocellus oztotl, a troglobitic and troglomorphic species from Cueva de Las Tres Quimeras in the Sierra Negra, Puebla, Mexico; and Pseudocellus platnicki, also troglobitic and troglomorphic, known from a single cave in Coahuila, Mexico. The number of known species in the genus increases to 24, and Mexican species to 14. An identification key for adult males of the species found in Mexico and southern USA is provided.

The first phylogenetic analysis of Palpigradi (Arachnida)—the most enigmatic arthropod order

Abstract. Palpigradi are a poorly understood group of delicate arachnids, often found in caves or other subterranean habitats. Concomitantly, they have been neglected from a phylogenetic point of view. Here we present the first molecular phylogeny of palpigrades based on specimens collected in different subterranean habitats, both endogean (soil) and hypogean (caves), from Australia, Africa, Europe, South America and North America. Analyses of two nuclear ribosomal genes and COI under an array of methods and homology schemes found monophyly of Palpigradi, Eukoeneniidae and a division of Eukoeneniidae into four main clades, three of which include samples from multiple continents. This supports either ancient vicariance or long-range dispersal, two alternatives we cannot distinguish with the data at hand. In addition, we show that our results are robust to homology scheme and analytical method, encouraging further use of the markers employed in this study to continue drawing a broader picture of palpigrade relationships.

New and poorly known species of the mexicanus group of the genus Vaejovis (Scorpiones: Vaejovidae) from Oaxaca, Mexico

Abstract Four new species belonging to the mexicanus group of the genus Vaejovis C.L. Koch 1836 from Oaxaca, Mexico are described. The number of species of this group for the state is raised to seven. The males of V. franckei and V. setosus are described for the first time. A key to Oaxacan species of the mexicanus group is provided.

Phylogeny and classification of the giant hairy scorpions, Hadrurus Thorell (Iuridae Thorell): A reappraisal

Abstract 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.

SYMBIOTIC RELATIONSHIPS BETWEEN PSEUDOSCORPIONS (ARACHNIDA) AND PACKRATS (RODENTIA)

Abstract Thirty-two species of pseudoscorpions have been found co-existing with nine packrat (or woodrat) species of the genus Neotoma, and this association has been referred to as phoresy. Phoresy is a term for passive dispersal when an animal literally hitches a ride on another to reach a new habitat. The pseudoscorpions reported above live in or on the nests of the packrats and do not ride on the rats themselves, eliminating a truly phoretic association. All life-history stages of the small arachnids have been found in packrat nests, indicating at least a commensalistic relationship exists, whereby the pseudoscorpion benefits from shelter and food found in the nests, and reproduces there as well. Two pseudoscorpion species have been reported feeding on packrat ectoparasites, specifically larval and adult fleas, and thus a mutualistic relationship beneficial to both “guest” and “host” exists.

A new genus and a new species of scorpion (Scorpiones: Buthidae) from southeastern Mexico

Abstract Chaneke fogoso gen. nov. et sp. nov., are described based on specimens collected near the coast in southeastern Guerrero, Mexico. The genus is characterized by the peculiar rhomboidal shape of the subaculear tubercle, and the lack of at least one trichobothrium on the femur, patella and chela of the pedipalp, which make it the second known buthid genus with decreasing neobothriotaxy on those three pedipalpal segments, together with Alayotityus Armas 1973. Tityopsis aliciae Armas & Martin-Frias 1998, from Oaxaca, Mexico, is transferred to the new genus, resulting in Chaneke aliciae (Armas & Martin-Frias 1998), comb. nov. A cladistic analysis including all other New World “microbuthids” with decreasing neobothriotaxy, with 30 morphological characters, indicates that Chaneke is monophyletic, clearly distinct from Alayotityus Armas 1973 (from eastern Cuba) and Tityopsis Armas 1974 (from western Cuba).