The role of Central American barriers in shaping the evolutionary history of the northernmost glassfrog, Hyalinobatrachium fleischmanni (Anura: Centrolenidae)

Systematics, distribution patterns and historical biogeography of the Central America wandering spider genus Kiekie Polotow & Brescovit, 2018 (Araneae: Ctenidae)

Kiekie Polotow & Brescovit, 2018 is a Neotropical genus of Ctenidae, with most of its species occuring in Central America. In this study, we review the systematics of Kiekie and describe five new species and the unknown females of K. barrocolorado Polotow & Brescovit, 2018 and K. garifuna Polotow & Brescovit, 2018, and the unknown male of K. verbena Polotow & Brescovit, 2018. In addition, we described the female of K. montanense which was wrongly assigned as K. griswoldi Polotow & Brescovit, 2018 (both species are sympatric). We provided a modified diagnosis for previously described species based on the morphology of the newly discovered species and in situ photographs of living specimens. We inferred a molecular phylogeny using four nuclear (histone H3, 28S rRNA, 18S rRNA and ITS-2) and three mitochondrial genes (cytochrome c oxidase subunit I or COI, 12S rRNA and 16S rRNA) to test the monophyly of the genus and the evolutionary relationships of its species. Lastly, we reconstruct the historical biogeography and map diversity and endemism distributional patterns of the different species. This study increased the number of known species of Kiekie from 13 to 18, and we describe a new genus, Eldivo which is sister lineage of Kiekie. Most of the diversity and endemism of the genus Kiekie is located in the montane ecosystems of Costa Rica followed by the lowland rainforest of the Pacific side (Limon Basin). Kiekie originated in the North America Tropical region, this genus started diversifying in the Late Miocene and spread to Lower Central America and South America. In that region, Kiekie colonized independently several times the montane ecosystems corresponding to periods of uplifting of Talamanca and Central Cordilleras.

Genomic differentiation and niche divergence in the Hetaerina americana (Odonata) cryptic species complex

The evolution of reproductive barriers, that is, the speciation process, implies the limitation of gene flow between populations. Different patterns of genomic differentiation throughout the speciation continuum may provide insights into the causal evolutionary forces of species divergence. In this study, we analysed a cryptic species complex of the genus Hetaerina (Odonata). This complex includes H. americana and H. calverti; however, in H. americana two highly differentiated genetic groups have been previously detected, which, we hypothesize, may correspond to different species with low morphological variation. We obtained single nucleotide polymorphism (SNP) data for 90 individuals belonging to the different taxa in the complex and carried out differentiation tests to identify genetic isolation. The results from STRUCTURE and discriminant analysis of principal components (DAPC), based on almost 5000 SNPs, confirmed the presence of three highly differentiated taxa. Also, we found FST values above 0.5 in pairwise comparisons, which indicates a considerable degree of genetic isolation among the suggested species. We also found low climatic niche overlap among all taxa, suggesting that each group occurs at specific conditions of temperature, precipitation and elevation. We propose that H. americana comprises two cryptic species, which may be reproductively isolated by ecological barriers related to niche divergence, since the morphological variation is minimal and, therefore, mechanical barriers are probably less effective compared to other related species such as H. calverti.

Late Pleistocene Altitudinal Segregation and Demography Define Future Climate Change Distribution of the Peromyscus mexicanus Species Group: Conservation Implications

Mountains harbor a significant number of the World's biodiversity, both on tropical and temperate regions. Notably, one crucial gap in conservation is the consideration of historical and contemporary patterns influencing differential distribution in small mammal mountain species and how climate change will affect their distribution and survival. The mice Peromyscus mexicanus species group is distributed across mountains in Guatemala-Chiapas and Central America, which experienced significant effects of glacial and interglacial cycles. We determined phylogeographic and demographic patterns of lowlands and highlands mountain lineages, revealing that the radiation of modern P. mexicanus lineages occurred during the Pleistocene (ca. 2.6 mya) along Nuclear Central America. In concert with climatic cycles and the distribution of habitats, lowland and highland lineages showed recent population size increase and decrease, respectively. We also estimated the current and future distribution ranges for six lineages, finding marked area size increase for two lineages for which vegetation type and distribution would facilitate migrating towards higher elevations. Contrastingly, three lineages showed range size decrease; their ecological requirements make them highly susceptible to future habitat loss. Our findings are clear evidence of the negative impacts of future climate change, while our ability to manage and conserve these vulnerable ecosystems and mountain species is contingent on our understanding of the implications of climate change on the distribution, ecology, and genetics of wildlife populations.

Revision and phylogenetics of the Neotropical sheet weaving spider genus

The Mounded Posterior Median Eyes (MPME) clade is a group of linyphiid spiders characterized by having posterior median eyes (PME) on a mound. The species diversity of this lineage, especially in the Neotropical region, is still largely unknown. In this study, we tackled one of the MPME groups, the genus Diplothyron Millidge, 1991. We have studied numerous specimens from both museums and freshly collected specimens to monograph Diplothyron. We also compiled both morphological and behavioral data from Diplothyron and representatives of higher-level lineages within Linyphiidae and several potential MPME groups to infer the phylogenetic relationships. We redescribed the type species, Diplothyron fuscus Millidge, 1991 and described the previously unknown male, and six new species: Diplothyron ballesterosi sp. nov., D. dianae sp. nov., D. monteverde sp. nov., D. nubilosus sp. nov., D. sandrae sp. nov. and D. solitarius sp. nov. We also transferred the following species from Linyphia to Diplothyron based on the study of the type material: D. chiapasia (Gertsch & Davies, 1946) comb. nov., D. linguatulus (F.O. Pickard-Cambridge, 1902) comb. nov., D. nigritus (F.O. Pickard-Cambridge, 1902) comb. nov., D. simplicatus (F.O. Pickard-Cambridge, 1902) comb. nov. and D. trifalcatus (F.O. Pickard-Cambridge, 1902) comb. nov. Diplothyron species are mainly found in the cloud forests of Central and South America, with the distribution stretching from the Colombian Andes to the Mexican Sierra Madre across the Central American mountain chains. We also provide a detailed morphological comparison between Diplothyron and closely related genera in the MPME clade, focusing on the genital morphology, including identification keys to both the MPME genera and species of Diplothyron. Our cladistic analyses recovered Diplothyron as a monophyletic group placed within the MPME clade. A newly circumscribed lineage now includes the genera Diplothyron, Dubiaranea Mello-Leitão, 1943; Linyphia Latreille, 1804; Lomaita Bryant, 1948; Microlinyphia Gerhardt, 1928; Neriene Blackwall, 1833; Notiohyphantes Millidge, 1985; Novafrontina Millidge, 1991 and Pityohyphantes Simon, 1929.

Revision of the freshwater crabs of the genus Tehuana Rodríguez & Smalley in Smalley 1970 (Decapoda, Pseudothelphusidae), with the descriptions of two new species

The freshwater crab genus Tehuana Rodríguez & Smalley in Smalley, 1970 includes eight species distributed in southeastern Mexico. A recent review of organisms belonging to this genus uncovered new variations in the male gonopod morphology. A phylogenetic analysis based on molecular characters using three genes (H3, 16S, and COI) resulted in the identification of two new species which are described herein: Tehuanaayotzintepecensis sp. nov. from Oaxaca and Tehuanacol sp. nov. from Veracruz. New diagnoses are provided for those species that had very brief descriptions lacking the treatment of important taxonomic characters and an identification key for all the species in the genus is also given. A discussion of the distribution of all the species in Tehuana in the Isthmus of Tehuantepec is presented.

Phylogeography of the white-crowned parrot (Pionus senilis)

Abstract The white-crowned parrot Pionus senilis (von Spix, 1824) is distributed throughout Middle America, inhabiting the Gulf of Mexico coastal area from Tamaulipas (Mexico) to northern Panama. We used mitochondrial data (COI, ND2 and ND4) from 55 specimens to infer phylogenetic relationships, and analyzed the phylogeographic structure, genetic diversity, divergence periods, and historical demography to explore phylogeographic patterns. We found three divergent lineages: two geographically separated by the Isthmus of Tehuantepec, and the third, in Costa Rica by the Nicaragua Depression. The analysis of molecular variance and statistical analyses were consistent with genetically distinct populations. The Central American lineage diverged 1.33 million years ago, whereas the other two lines branched off 1.19 million years ago. This phylogenetic pattern has been reported in other species of Middle American birds.

Testing spatial and environmental factors to explain body shape variation in the widespread Central American Blackbelt cichlid Vieja maculicauda (Teleostei: Cichlidae)

Abstract Body-shape variability may respond to the interaction between history and environment, particularly in species whose range includes known biogeographical barriers. Central America has traditionally been regarded to have functioned as a complete land-bridge connecting two continents since the Plio-Pleistocene and as an incomplete one since much earlier. This history has helped shape species diversification and distributions. Vieja maculicauda is a widely distributed cichlid, found throughout most of the Atlantic slope of Central America, across three of the four geological blocks that make up this region and whose borders are known dispersal barriers. We asked whether there is an effect of geologic blocks on body shape of V. maculicauda as determined by geometric morphometric assessment of 151 individuals from across its range. We asked how much variance in body shape is explained by environmental variables. We used a CVA and a MANCOVA to determine whether a relationship between body shape and geologic blocks exists. For testing body shape correlation against geographic and environmental variables, we used a Mantel test. Our results suggest that body shape in V. maculicauda can be segregated by geologic blocks, while the correlation results showed no strong correlation between our sets of variables.

Historical biogeography of the genus Rhadinaea (Squamata: Dipsadinae)

Multiple geological and climatic events have created geographical or ecological barriers associated with speciation events, playing a role in biological diversification in North and Central America. Here, we evaluate the influence of the Neogene and Quaternary geological events, as well as the climatic changes in the diversification of the colubrid snake genus Rhadinaea using molecular dating and ancestral area reconstruction. A multilocus sequence dataset was generated for 37 individuals of Rhadinaea from most of the biogeographical provinces where the genus is distributed, representing 19 of the 21 currently recognized species, and two undescribed species. Our analyses show that the majority of the Rhadinaea species nest in two main clades, herein identified as "Eastern" and "Southern". These clades probably diverged from each other in the early Miocene, and their divergence was followed by 11 divergences during the middle to late Miocene, three divergences during the Pliocene, and six divergences in the Pleistocene. The ancestral distribution of Rhadinaea was reconstructed across the Sierra Madre del Sur. Our phylogenetic analyses do not support the monophyly of Rhadinaea. The Miocene and Pliocene geomorphology, perhaps in conjunction with climate change, appears to have triggered the diversification of the genus, while the climatic changes during the Miocene probably induced the diversification of Rhadinaea in the Sierra Madre del Sur. Our analysis suggests that the uplifting of the Trans-Mexican Volcanic Belt and Chiapan-Guatemalan highlands in this same period resulted in northward and southward colonization events. This was followed by more recent, independent colonization events in the Pliocene and Pleistocene involving the Balsas Basin, Chihuahuan Desert, Pacific Coast, Sierra Madre Occidental, Sierra Madre Oriental, Sierra Madre del Sur, Trans-Mexican Volcanic Belt, and Veracruz provinces, probably driven by the climatic fluctuations of the time.

Glassfrogs of Ecuador: Diversity, Evolution, and Conservation

Glassfrogs (family: Centrolenidae) represent a fantastic radiation (~150 described species) of Neotropical anurans that originated in South America and dispersed into Central America. In this study, we review the systematics of Ecuadorian glassfrogs, providing species accounts of all 60 species, including three new species described herein. For all Ecuadorian species, we provide new information on the evolution, morphology, biology, conservation, and distribution. We present a new molecular phylogeny for Centrolenidae and address cryptic diversity within the family. We employ a candidate species system and designate 24 putative new species that require further study to determine their species status. We find that, in some cases, currently recognized species lack justification; specifically, we place Centrolene gemmata and Centrolene scirtetes under the synonymy of Centrolene lynchi; C. guanacarum and C. bacata under the synonymy of Centrolene sanchezi; Cochranella phryxa under the synonymy of Cochranella resplendens; and Hyalinobatrachium ruedai under the synonymy of Hyalinobatrachium munozorum. We also find that diversification patterns are mostly congruent with allopatric speciation, facilitated by barriers to gene flow (e.g., valleys, mountains, linearity of the Andes), and that niche conservatism is a dominant feature in the family. Conservation threats are diverse, but habitat destruction and climate change are of particular concern. The most imperiled glassfrogs in Ecuador are Centrolene buckleyi, C. charapita, C. geckoidea, C. medemi, C. pipilata, Cochranella mache, Nymphargus balionotus, N. manduriacu, N. megacheirus, and N. sucre, all of which are considered Critically Endangered. Lastly, we identify priority areas for glassfrog conservation in Ecuador.