Biology subjects

Pinto-da-Rocha, R.

Publications and source records attributed to Pinto-da-Rocha, R..

3 recordsLinked to original sources

bioRxiv2021

Systematics and phylogeography of the Brazilian Atlantic Forest endemic harvestmen Neosadocus Mello-Leitao, 1926 (Arachnida: Opiliones: Gonyleptidae)

Neosadocus harvestmen are endemic to the Southern Brazilian Atlantic Forest. Although they are conspicuous and display great morphological variation, their evolutionary history and the biogeographical events underlying their diversification and distribution are still unknown. This contribution about Neosadocus includes the following: a taxonomic revision; a molecular phylogenetic analysis using mitochondrial and nuclear markers; an investigation of the genetic structure and species diversity in a phylogeographical framework. Our results show that Neosadocus is a monophyletic group and comprises four species: N. bufo, N. maximus, N. robustus and N. misandrus (which we did not find on fieldwork and only studied the female holotype). There is astonishing male polymorphism in N. robustus, mostly related to reproductive strategies. The following synonymies have resulted from this work: Bunoweyhia variabilis Mello-Leitao, 1935 = Neosadocus bufo (Mello-Leitao, 1926); and Bunoweyhia minor Mello-Leitao, 1935 = Neosadocus maximus (Giltay, 1928). Most divergences occurred during the Miocene, a geological epoch marked by intense orogenic and climatic events in the Brazilian Atlantic Forest. Intraspecific analyses indicate strong population structure, a pattern congruent with the general behavior and physiological constraints of Neotropical harvestmen.

zoology↗

bioRxiv2020

Phylogenomics of scorpions reveal a co-diversification of scorpion mammalian predators and mammal-specific sodium channel toxins

Scorpions constitute a charismatic lineage of arthropods and comprise more than 2,500 described species. Found throughout various tropical and temperate habitats, these predatory arachnids have a long evolutionary history, with a fossil record that began in the Silurian. While all scorpions are venomous, the asymmetrically diverse family Buthidae harbors nearly half the diversity of extant scorpions, and all but one of the 58 species that are medically significant to humans. Many aspects of scorpion evolutionary history are unclear, such as the relationships of the most toxic genera and their constituent venom peptides. Furthermore, the diversification age of toxins that act specifically on mammalian ion channels have never been inferred. To redress these gaps, we assembled a large-scale phylogenomic dataset of 100 scorpion venom transcriptomes and/or genomes, emphasizing the sampling of highly toxic buthid genera. To infer divergence times of venom gene families, we applied a phylogenomic node dating approach for the species tree in tandem with phylostratigraphic bracketing to estimate minimum ages of mammal-specific toxins. Our analyses establish a robustly supported phylogeny of scorpions, particularly with regard to relationships between medically significant taxa. Analysis of venom gene families shows that mammal-specific sodium channel toxins have independently evolved in five lineages within Buthidae. The temporal windows of mammal-specific toxin origins are contiguous with the basal diversification of major scorpion mammal predators such as carnivores, shrews, bats and rodents. These results suggest an evolutionary arms race model comprised of co-diversification of mammalian predators and NaTx homologs in buthid venom.

evolutionary biology↗

bioRxiv2016

Trade-offs in the use of multiple survey methods for spiders and harvestmen assemblages in an Amazonian upland forest

Invertebrates can be sampled using any of several well-established, rapid and cost-effective methods for documenting species richness and composition. Despite their many differences, different orders of arachnids have been often sampled together in various studies. Active nocturnal search has been long considered the most efficient method for sampling spiders and harvestmen in tropical forests. We compared the number of species and composition of spiders and harvestmen simultaneously sampled using three sampling methods: beating tray, active nocturnal search and Winkler traps at areas along the Urucu River, Coari, Amazonas. We found that a reasonable inventorying of harvestmen can be accomplished solely by nocturnal search, whereas the beating tray and Winkler approaches are redundant. For spiders, both the nocturnal and beating tray methods were complementary and are needed to provide a more complete picture of spider assemblages. An inventory based solely on nocturnal search saves 75% of the survey costs for harvestmen assemblages and 46% for spider assemblages. Based on our findings we propose that different taxonomic groups (e.g. harvestmen and spiders) should be sampled separately in tropical forests, especially for monitoring purposes, and different sets of methods should be combined for each according to their most efficient and best cost-benefit performance.

ecology↗