Coastal dunes as drivers of genetic differentiation in the honeypot ant Myrmecocystus baja (Formicidae: Formicinae).

Coastal dunes are unique habitats, threatened by human activities. In biogeographical terms, coastal dunes are habitat islands, being discrete and distinct patches of similar habitat among themselves, separated from each other by a different type of habitat. Furthermore, coastal dunes harbor endemic species, adapted to living solely in the habitats found on specific dune systems. For example, the honeypot ant Myrmecocystus baja is endemic and restricted to coastal dunes of Mexico's Baja California Pacific coast. This ecological and biogeographical scenario led to the questions whether their geographical isolation is reflected in their genetic diversity and structuring, and how their demographic history is related with the formation of the dune system habitats. To answer these questions, population genetic, isolation-with-migration, and phylogeographical analyses were carried out, based on mitochondrial and five nuclear intronic markers. Minimal gene flow was detected only between two of the dune systems sampled; otherwise, the M. baja populations were found to be isolated and genetically structured, and their divergence generally pre-dated the modern-day dune systems. It is therefore highly likely that these ants were already present in paleodunes and that each of the populations was established from founder populations as the dunes formed. These findings highlight the importance of coastal dunes for species such as the honeypot ant from Baja California, in promoting genetic differentiation.

Integrative taxonomy of Serrasentis gibsoni n. sp. (Acanthocephala: Isthmosacanthidae) from flatfishes in the Gulf of Mexico.

The Isthmosacanthidae acanthocephalan species of the genus Serrasentis are parasites of marine teleosts and an elasmobranch. In this study, Serrasentis gibsoni n. sp. is described from the intestines of four flatfish species (Paralichthyidae), namely Ancyclopsetta quadrocellata, Cyclopsetta chittendeni, Syacium gunteri, and S. papillosum from 10 oceanic sites in the Gulf of Mexico (GoM). Twenty sequences of the 'barcoding' region of cytochrome C oxidase subunit I gene were obtained from 20 adults of Serrasentis gibsoni n. sp. Additionally, five sequences of the barcoding region were obtained from five adults of rhadinorhynchid Gorgorhynchus lepidus from C. chittendeni, S. papillosum and one species of Haemulidae, Haemulom aurolineatum, from five oceanic sites from the GoM. Two phylogenetic approaches were followed: Bayesian inference and maximum likelihood. In both phylogenetic reconstructions, the sequences of Serrasentis gibsoni n. sp. were recovered as a monophyletic group within the genus Serrasentis and placed as a sister group to G. lepidus. However, due to the lack of molecular data for species of the Isthmosacanthidae and Rhadinorhynchidea, these phylogenetic inferences must be taken with caution. Serrasentis gibsoni n. sp. is the first species of Serrasentis described from Paralichthyidae flatfish species from marine waters of the Americas and from the GoM. Based on the barcoding data set analyzed, Serrasentis gibsoni n. sp. appears to have high intraspecific genetic variation; thus, it is necessary to continue exploring the genetic diversity of this species to infer its intraspecific evolutionary patterns.

Following the aridity: Historical biogeography and diversification of the Philodromidae spider genus Petrichus in South America.

Aridity conditions and expansion of arid biomes in South America are closely linked to the onset of Andean orogeny since at least 30 Mya. Among arid-associated taxa, spiders belonging to the genus Petrichus are found along the Andes mountains and across the diagonal of open formations of the Chaco and Cerrado domains. In this contribution, we asked whether Petrichus originated prior to the central Andean uplift and what historical processes have promoted their diversification. We time-calibrated the phylogenetic tree of Philodromidae and estimated the divergence times of Petrichus. Considering phylogenetic uncertainty, we assessed biogeographical hypotheses of the historical events associated with the diversification of these spiders in South America. Petrichus originated along the Pacific coastal deserts in the Central Andes during the Early Miocene. The species likely dispersed from the western to the eastern side of the Andes coincidently with the central Andean uplift. The diversification of these spiders is coeval with the expansion of open grassland formations during the Late Miocene and Early Pliocene. Multiple dispersal events occurred from the Monte desert to southern South America and eastward to Chaco between âˆ¼ 8 and 2.5 Mya. The Andes might have played a role as a corridor favoring geographical range expansions and colonization of new environments. In addition, we also suggest that Philodromidae might have an Oligocene origin or earlier. Future analyses based on further evidence and larger taxon sampling should be carried out to corroborate our findings.

Testing the Accuracy of Vegetation-Based Ecoregions for Predicting the Species Composition of Blow Flies (Diptera: Calliphoridae).

To properly define ecoregions, specific criteria such as geology, climate, or species composition (e.g., the presence of endemic species) must be taken into account to understand distribution patterns and resolve ecological biogeography questions. Since the studies on insects in Baja California are scarce, and no fine-scale ecoregions based on the region's entomofauna is available, this study was designed to test whether the ecoregions based on vegetation can be used for insects, such as Calliphoridae. Nine collecting sites distributed along five ecoregions were selected, between latitudes 29.6° and 32.0°N. In each site, three baited traps were used to collect blow flies from August 2017 to June 2019 during summer, winter, and spring. A total of 30,307 individuals of blow flies distributed in six genera and 13 species were collected. The most abundant species were Cochliomyia macellaria (Fabricius), Phormia regina (Meigen), and Chrysomya rufifacies (Macquart). The composition of the Calliphoridae community was different between the localities and three general groups have been distinguished, based on the species composition similarity (ANOSIM) results: Gulf-Desert, Mountains, and Pacific-Center. The vegetation-based ecoregions only reflect the blow fly species' distributions to a certain extent, meaning that care must be taken when undertaking ecological biogeographical studies using regionalization based on organisms other than the focal taxa because vegetation does not always reflect fauna species composition.

Phylogeny, genetics, and the partial life cycle of Oncomegas wageneri in the Gulf of Mexico.

Despite the diversity and ecological importance of cestodes, there is a paucity of studies on their life stages (i.e., complete lists of intermediate, paratenic, and definitive hosts) and genetic variation. For example, in the Gulf of Mexico (GoM) 98 species of cestodes have been reported to date; however, data on their intraspecific genetic variation and population genetic studies are lacking. The trypanorhynch cestode, Oncomegas wageneri, is found (among other places) off the American Western Atlantic Coast, including the GoM, and has been reported as an adult from stingrays and from several teleost species in its larval form (as plerocerci). This study represents the first report of 2 previously unregistered definitive hosts for O. wageneri, namely the Atlantic sharpnose shark Rhizoprionodon terraenovae and the southern stingray Hypanus americanus. In this work, partial sequences of the 28S (region D1-D2) ribosomal DNA were analyzed to include O. wageneri within an eutetrarhynchoid phylogenetic framework. All O. wageneri individuals (which included plerocerci and adults) were recovered as monophyletic and Oncomegas celatus was identified as the sister species of O. wageneri. Furthermore, population genetic analyses of O. wageneri from the southern GoM were carried out using DNA sequences of the mitochondrial cytochrome c oxidase subunit 1 (COI) gene, which reflected high genetic variation and a lack of genetic structure among the 9 oceanographic sampling sites. Based on these results, O. wageneri is panmictic in the southern GoM. More extensive sampling along the species entire distribution is necessary to make more accurate inferences of population genetics of O. wageneri.

Climate change and forest plagues: assessing current and future impacts of diprionid sawflies on the pine forests of north-western Mexico.

The imminent threat of climate change lies in its potential to disrupt the balance of ecosystems, particularly vulnerable areas such as mountain-top remnant forests. An example of such a fragile ecosystem is the Sierra San Pedro Mártir (SSPM) National Park of Mexico's Baja California state, where high levels of endemism can be found, and which is home to one of the country's few populations of the emblematic Jeffrey pine (Pinus jeffreyi). Recent outbreaks of pine-feeding sawfly larvae in SSPM increase the vulnerability of this forest ecosystem, calling for immediate assessments of the severity of this threat. Here, we present a thorough study of the sawfly's biology and distribution, carrying out molecular and morphology-based identification of the species and creating model-based predictions of the species distribution in the area. The sawfly was found to belong to an undescribed species of the genus Zadiprion (family Diprionidae) with a one-year life-cycle. The distribution of this species appears to be restricted to the SSPM national park and it will probably persist for at least another 50 years, even considering the effects of climate change.

The Grass was Greener: Repeated Evolution of Specialized Morphologies and Habitat Shifts in Ghost Spiders Following Grassland Expansion in South America.

While grasslands, one of Earth's major biomes, are known for their close evolutionary ties with ungulate grazers, these habitats are also paramount to the origins and diversification of other animals. Within the primarily South American spider subfamily Amaurobioidinae (Anyphaenidae), several species are found living in the continent's grasslands, with some displaying putative morphological adaptations to dwelling unnoticed in the grass blades. Herein, a dated molecular phylogeny provides the backbone for analyses revealing the ecological and morphological processes behind these spiders' grassland adaptations. The multiple switches from Patagonian forests to open habitats coincide with the expansion of South America's grasslands during the Miocene, while the specialized morphology of several grass-dwelling spiders originated at least three independent times and is best described as the result of different selective regimes operating on macroevolutionary timescales. Although grass-adapted lineages evolved towards different peaks in adaptive landscape, they all share one characteristic: an anterior narrowing of the prosoma allowing spiders to extend the first two pairs of legs, thus maintaining a slender resting posture in the grass blade. By combining phylogenetic, morphological, and biogeographic perspectives we disentangle multiple factors determining the evolution of a clade of terrestrial invertebrate predators alongside their biomes.

Light from dark: A relictual troglobite reveals a broader ancestral distribution for kimulid harvestmen (Opiliones: Laniatores: Kimulidae) in South America.

A new troglobitic harvestman, Relictopiolus galadriel gen. nov et sp. nov., is described from Olhos d'Água cave, Itacarambi, Minas Gerais State, Brazil. Morphological characters, including male genitalia and exomorphology, suggest that this species belongs to the family Kimulidae, and it appears to share the greatest similarities with Tegipiolus pachypus. Bayesian inference analyses of a molecular dataset strongly support the inclusion of this species in Kimulidae and confirm the hypothesized sister-group relationship between R. galadriel and T. pachypus. A time calibrated phylogeny indicates that these sister-taxa diverged from a common ancestor approximately 40 Mya, during the Paleogene. The current range of Kimulidae illustrates a remarkable disjunct distribution, and leads us to hypothesize that the ancestral distribution of Kimulidae was once much more widespread across eastern Brazil. This may be attributed to the Eocene radiation associated with the warming (and humidifying) events in the Cenozoic when the best conditions for evergreen tropical vegetation in South America were established and followed by the extinction of kimulid epigean populations together with the retraction of rain forests during the Oligocene to Miocene cooling. The discovery of this relictual troglobite indicates that the Olhos d'Água cave was a stable refugium for this ancient lineage of kimulids and acted as a "museum" of biodiversity. Our findings, considered collectively with the diverse troglofauna of the Olhos d'Água cave, highlight it as one of the most important hotspots of troglobite diversity and endemism in the Neotropics. Given the ecological stresses on this habitat, the cavernicolous fauna are at risk of extinction and we emphasize the urgent need for appropriate conservation actions. Finally, we propose the transfer of Acanthominua, Euminua, Euminuoides and Pseudominua from Kimulidae to Zalmoxidae, resulting in two new synonymies and 13 new combinations.

Multiple approaches to understanding the taxonomic status of an enigmatic new scorpion species of the genus Tityus (Buthidae) from the biogeographic island of Paraje Tres Cerros (Argentina).

Tityus curupi n. sp., belonging to the bolivianus complex, is described from the biogeographically distinct area of Paraje Tres Cerros in north-eastern Argentina. We also present a molecular species delimitation analysis between Tityus curupi n. sp. and its sister species Tityus uruguayensis Borelli 1901 to confirm species integrity. Furthermore, a cytogenetic analysis is presented for these two species which contain different multivalent associations in meiosis, as a consequence of chromosome rearrangements, and the highest chromosome numbers in the genus.

Dated phylogenetic studies of the southernmost American buthids (Scorpiones; Buthidae).

A dated molecular phylogeny of the southernmost American species of the family Buthidae, based on two nuclear and two mitochondrial genes, is presented. Based on this study, analyzed species of the subgenus Tityus (Archaeotityus) are neither sister to the remaining species of the genus Tityus, nor are they closely related to the New World microbuthids with decreasing neobothriotaxy. Analyzed species of the subgenus Tityus do not form a monophyletic group. Based on ancestral area estimation analyses, known geoclimatic events of the region and comparisons to the diversification processes of other epigean groups from the area, a generalized hypothesis about the patterns of historical colonization processes of the family Buthidae in southern South America is presented. Furthermore, for the first time, a Paleogene-African ingression route for the colonization of America by the family Buthidae is proposed as a plausible hypothesis.

Around the World in Eight Million Years: Historical Biogeography and Evolution of the Spray Zone Spider Amaurobioides (Araneae: Anyphaenidae).

Closely related organisms with transoceanic distributions have long been the focus of historical biogeography, prompting the question of whether long-distance dispersal, or tectonic-driven vicariance shaped their current distribution. Regarding the Southern Hemisphere continents, this question deals with the break-up of the Gondwanan landmass, which has also affected global wind and oceanic current patterns since the Miocene. With the advent of phylogenetic node age estimation and parametric bioinformatic advances, researchers have been able to disentangle historical evolutionary processes of taxa with greater accuracy. In this study, we used the coastal spider genus Amaurobioides to investigate the historical biogeographical and evolutionary processes that shaped the modern-day distribution of species of this exceptional genus of spiders. As the only genus of the subfamily Amaurobioidinae found on three Southern Hemisphere continents, its distribution is well-suited to study in the context of Gondwanic vicariance versus long-distance, transoceanic dispersal. Ancestral species of the genus Amaurobioides appear to have undergone several long-distance dispersal events followed by successful establishments and speciation, starting from the mid-Miocene through to the Pleistocene. The most recent common ancestor of all present-day Amaurobioides species is estimated to have originated in Africa after arriving from South America during the Miocene. From Africa the subsequent dispersals are likely to have taken place predominantly in an eastward direction. The long-distance dispersal events by Amaurobioides mostly involved transoceanic crossings, which we propose occurred by rafting, aided by the Antarctic Circumpolar Current and the West Wind Drift.

Phylogeny, species delimitation and convergence in the South American bothriurid scorpion genus Brachistosternus Pocock 1893: Integrating morphology, nuclear and mitochondrial DNA.

A phylogenetic analysis of the scorpion genus Brachistosternus Pocock, 1893 (Bothriuridae Simon, 1880) is presented, based on a dataset including 41 of the 43 described species and five outgroups, 116 morphological characters and more than 4150 base-pairs of DNA sequence from the nuclear 18S rDNA and 28S rDNA gene loci, and the mitochondrial 12S rDNA, 16S rDNA, and Cytochrome c Oxidase Subunit I gene loci. Analyses conducted using parsimony, Maximum Likelihood and Bayesian Inference were largely congruent with high support for most clades. The results confirmed the monophyly of Brachistosternus, the nominal subgenus, and subgenus Ministernus Francke, 1985, as in previous analyses based only on morphology, but differed in several other respects. Species from the plains of the Atacama Desert diverged basally whereas the high altitude Andean species radiated from a more derived ancestor, presumably as a consequence of Andean uplift and associated changes in climate. Species limits were assessed among species that contain intraspecific variation (e.g., different morphs), are difficult to separate morphologically, and/or exhibit widespread or disjunct distributions. The extent of convergence in morphological adaptation to life on sandy substrata (psammophily) and the complexity of the male genitalia, or hemispermatophores, was investigated. Psammophily evolved on at least four independent occasions. The lobe regions of the hemispermatophore increased in complexity on three independent occasions, and decreased in complexity on another three independent occasions.