PeerJ Award Winners at the 22nd International Arachnology Congress

The 22nd International Arachnology Congress (ICA) is the most iconic event for Arachnid Research. This last edition occurred at Montevideo, Uruguay, between 5th and 11th March 2023. Our country has a long tradition in Arachnology, reflected by the large number of researchers and students working in various disciplines as taxonomy, systematics, ecology and animal behavior. Arachnology in Latin American has shown a remarkable growth during the last decades and this congress has been the opportunity to share these advances with the arachnological scientific community. We received researchers and students from 37 countries along the world, working at the most diverse disciplines. With 87 orals and 110 poster presentations, four prestigious plenary speakers, eight Early Career plenaries, sessions honoring referent researchers to arachnology (Fernando Costa, Maria Elena Galiano, Yael Lubin and William G. Eberhard), a tribute to Norman I. Platnick, the avant-premiere of the documentary film ‘Unexpected Beauty through the eyes of explorers of the tiny world’, and much more, the congress has been a success and an unforgettable experience to all of us.

– Anita Aisenberg, President of the ICA Organization Committee

Ben Klementz Ph.D. student, University of Wisconsin-Madison, USA.

Can you tell us a bit about yourself and your research interests?

There are several areas of arachnid biology that I hope to incorporate throughout my Ph.D. study. On the taxonomic side, I’m currently working on descriptions of several new species of harvestmen in the family Assamiidae alongside reevaluation of the validity of some current genera. From a phylogenomic perspective, I hope to help clarify the internal relationships of the “neglected cousins” of the arachnid tree of life, initially centered on the order Solifugae (camel spiders). Finally, while my evo-devo work has focused primarily on the biology of harvestmen body plan patterning, my dream is to establish vinegaroons (order Uropygi) as a tractable system for functional genetics. I’ve begun laboratory rearing of the North American vinegaroon Mastigoproctus tohono, with the hopes of developing protocols for gene expression assay and gene silencing.

During my first year as a graduate student, I’ve also become interested in collections-based research. As such, I’ve begun assisting in the curation of the UW-Madison Zoological Museum’s invertebrate collection, identifying arthropods and other invertebrates. I’ve become passionate about increasing the scope of the invertebrate collection, including donations of my own field collected arachnids.

What first interested you in this field of research?

My interest in arthropod biology started as a teenager after reading Dr. Justin Schmidt’s book, “The Sting of the Wild.” After a prolonged obsession with stinging insects and his iconic Schmidt sting pain index, I noticed his additional interest in the arachnids of the Southwest, including scorpions, tarantulas, and the poorly known vinegaroons. I found myself wanting to help advance our understanding of the biology of these poorly understood, but incredibly charismatic animals. It also helped that my time as an undergraduate student at UW-Madison was filled with courses from a world-class entomology department.

It seemed the perfect marriage of my love for creepy-crawlies and evo-devo to pursue a graduate degree understanding how structures like the acid-spraying pygidial glands and spiked pedipalps of vinegaroons evolved. I’m hopeful that by disseminating our lab’s new discoveries, we can help increase both public awareness and appreciation for these animals.

Adult vinegaroon

Can you briefly explain the research you presented at ICA 2023?

Harvestman leg genes

The research I presented at the 22nd ICA was the result of a re-evaluation of our current understanding of the genetic patterning and evolutionary origin of the patella segment of arachnid appendages. Previously, it was suggested that a duplicated copy of a leg patterning gene called dachshund took on a new function in patterning the more distal patella segment. This hypothesis was seemingly validated based on gene silencing experiments yielding a fusion of the patella and tibia.

But this duplicated gene is restricted to only 6 orders of arachnids (collectively the Arachnopulmonata) which are united by an ancient whole genome duplication in their common ancestor. Thus, dachshund could not be responsible for the patella in groups like harvestmen (Opiliones) not sharing this duplication. Our research team noticed that another leg patterning gene called extradenticle also showed a unique distal territory of expression in the developing patella across groups like scorpions, spiders, and harvestmen. To link causally this gene to the origin of the patella, we performed gene silencing of extradenticle in the model harvestman Phalangium opilio. Knockdown of extradenticle expression yielded a fusion of patella and tibia, suggesting this gene likely played the ancestral role in delimiting this additional arachnid leg segment.

How will you continue to build on this research?

To further expand the scope of these findings, we plan to develop protocols for gene expression assays in pseudoscorpions, solifugae, and parasitiform ticks. We also hope to survey the chelicerate outgroups of horseshoe crabs and sea spiders. Many of these groups are subject to particular taxonomic nomenclature as it relates to their appendage segments. Thus, these survey efforts will hopefully elucidate where in the chelicerate tree of life extradenticle took on its role in patterning the patella, as well as resolve our understanding of appendage segment homology across these groups.

Anna Luiza O. Martins Undergraduate Student, State University of Campinas (UNICAMP), Brazil.

Can you tell us a bit about yourself and your research interests?

Greetings, I am Anna Luiza, currently a final year undergraduate student in Biological Sciences at Unicamp and a member of the Animal-Plant Interactions Laboratory within the Department of Animal Biology. My research interests are focused on aspects of Animal Ecology, particularly the interactions between spiders and their natural enemies, such as parasitoid wasps, and how these interactions may modify spider population dynamics and their web-building behavior.

What first interested you in this field of research?

During my second year of undergraduate studies, I took a class on Arachnids. From that moment on, I became completely fascinated by these animals and everything related to them. When I learned about parasitoid wasps and how they can manipulate spiders for their own benefit, my interest in the subject grew even more. At a certain point, I met my co-advisor, Dr. Yuri Fanchini Messas, who mentioned to me that there was an abandoned project in the laboratory that could be revitalized with a new approach. From that moment on, we started our field research with great enthusiasm.

Can you briefly explain the research you presented at ICA 2023?

Typical orb web of L. argyra (top) and a cocoon web induced by the wasp

The work presented at the 22nd ICA is about the behavioral manipulation induced by the Darwin wasp Hymenoepimecis pinheirensis (Ichneumonidae) in the spider Leucauge argyra (Tetragnathidae). Initially, we were surprised to find that this was a new interaction, which adds a second host for H. pinheirensis and a second parasitoid for L. argyra to the literature. Therefore, this research helps to corroborate Gonzaga and Eberhard’s hypothesis that the interactions between spiders and polysphincta wasps are not species-specific, as previously believed. Thus, for almost two years, we monitored a population of L. argyra in an urbanized park in southeastern Brazil, analyzed the frequency of parasitism, and collected spiders found with an egg or larva of the parasitoid. This allowed us to follow the parasitoid’s development inside the spider’s abdomen. As is commonly observed in these interactions, the larva of H. pinheirensis induces a modification in the spider’s behavior. Between the second and third instars of the larva, the spider builds a modified web called a cocoon-web. We believe that the wasp can induce the synthesis the hormone responsible for ecdysis in arthropods, to prompt the spider to build a differentiated web. Another observation we made was that the population of L. argyra was frequently high in young and juvenile individuals, i.e., individuals of intermediate size. Thus, the parasitoidism rate was higher in these individuals, suggesting that H. pinheirensis has a preference for intermediate-sized individuals in the absence of larger hosts. This indicates that there is a phenological adjustment between populations.

How will you continue to build on this research?

The next step now is to collect more data on the modified and non-modified webs to perform a comparison with other described webs, in addition to increasing the data on the natural history of the interaction. We will test the hypotheses proposed by Gonzaga and Eberhard (2019) on Ecdysone, as well as observe other aspects that affect the population, such as prey availability and selection of host plants. We will likely be able to publish the first article by mid-year, and next year I will start my Master’s degree and continue the project.

Júlia Andrade de Sá Undergraduate student, Federal University of Bahia, Brazil.

Can you tell us a bit about yourself and your research interests?

I currently work at the Nucleo of Ofiology and Venomous Animals of Bahia (NOAP/UFBA) so I’m really interested in venomous animals in general, but spiders have a special place in my heart. I´ve been dedicating my research to the Sicariidae family, which I find to be very amazing animals in different aspects, especially the brown-spider Loxosceles. I´m interested in their natural history, state of art, distribution, biology, behavior, venom and accidents.

What first interested you in this field of research?

At first I started taking care of the live animals at the Nucleo of Ofiology and Venemous Animals of Bahia (NOAP/UFBA) and I was very captivated about how such small animals as spiders could be so complex. As much as I read about their biology, more my mind was opened about them. But what interested me the most, was the feeling that this work had a link and connection to people, that mostly fear them, and I got excited about learning more about animals that I found to be so amazing and somehow also communicate and collaborate to the community around them. I was very inspired by colleagues at the NOAP/UFBA and especially the teachers Tania Brazil and Rejâne Lira-da-Silva, references in this field.

Can you briefly explain the research you presented at ICA 2023?

Basically we wanted to know who are and where are the Sicariidae spiders of Bahia and try to figure if there was a pattern in their distribution related to environment variables. So we consulted collections archives from the Natural History Museum of Bahia and aracnological collections from Minas Gerais Federal University and Butantan Institute to obtain registers of these family in Bahia. We also consulted follow-up files from Loxosceles kept in captivity in the Nucleo of Ofiology and Venomous Animals of Bahia trying to understand more about their biology. We effort to supply the lack of knowledge about these animals in the state, as the last species list with their distribution for the region were from more than ten years ago. Also, knowing where these animals are located, as medical important spiders, we could collaborate to public polites for mitigating the risk of accidents especially in localites with an influx of tourists .

How will you continue to build on this research?

We have already started a new project and now our goal is to study the natural history of the Loxosceles chapadensis at a cave in the National Park of Chapada Diamantina – Bahia, Brazil. Described more than twelve years ago, that spider doesn’t have any publication further their description, beyond the fact that the types were destroyed in the fire that unfortunately occurred at the National Museum (Federal University of Rio de Janeiro).

Pietro Tardelli Canedo PhD student at The George Washington University, USA.

Can you tell us a bit about yourself and your research interests?

I was born and raised in São Paulo, Brazil. However, I was fortunate to be awarded scholarships that allowed me to finish my high school degree at UWC Costa Rica, and graduate with a Bachelor’s Degree from Macalester College in Minnesota, USA. I am fascinated with all things invertebrates, but their biogeography and systematics have a special place in my heart. My work is driven by a desire to better understand how species have achieved their current distributions and how their ecologies have shaped their morphology. When not thinking about animals, I am usually baking, playing volleyball or watching RuPaul’s Drag Race.

What first interested you in this field of research?

During my first semester at Macalester College, I enrolled in a course called “Creatures and Curiosities” with Dr. Sarah Boyer. The course dealt with the cultural role of organisms as curiosities, and the biology of invertebrates. Even as a lover of zoology, I had been largely oblivious to the astounding diversity of the invertebrate fauna. Each lecture was an opportunity to dive into their ecology, anatomy and novel adaptations. Additionally, it was Dr. Boyer’s research that first introduced me to the outstanding world of Opiliones (also known as harvesters or daddy longlegs). The ancient age of these organisms (410-470 million years old) and their global distribution made them excellent models for historical biogeography – the study of organismal diversity and distribution over geological time. Despite their diversity and distribution, there’s a lot of work to be done on harvesters and their evolutionary history.

Can you briefly explain the research you presented at ICA 2023?

Neopilionidae is an opilionid family found in the temperate regions of the Southern Hemisphere, most of which are Gondwanan in origin. It’s 21 genera and 80+ species are divided into three subfamilies, although their relationships have been unresolved by both morphological and molecular phylogenies. This work is a collaboration between myself, Dr. Shahan Derkarabetian, Dr. Gonzalo Giribet and Dr. Gustavo Hormiga. We have used UCEs (ultra-conserved elements) to reconstruct the family’s evolutionary relationships and this is the first next-generation sequencing project on this taxon. Our results highlighted the need for taxonomic reassignment for many of the species and some of the genera. Furthermore, it showcased the widespread occurrence of male polymorphism in many of the species. Some males have different morphotypes in respect to the size and shape of their chelicerae (grasping appendages). This stark variation has been hypothesized to play a role in male-male combat and mate courtships, but behavioral observations and experiments are few to none. However, this phylogeny provided the foundation for a greater work that will explore all facets of these organisms. from biogeography to functional morphology.

Credit: Gustavo Hormiga

How will you continue to build on this research?

This phylogeny will be greatly improved with the addition of more than 150 specimens in subsequent analyses, both from museum loans and some we have recently collected in the field. Through that, I will be able to test the monophyly of the family, its subfamilies and their respective genera. Many of the species remain yet to be described, so I will be undertaking a significant share of taxonomic work in the coming months. In addition, this phylogeny will serve as the blueprint for which to investigate questions on neopilionid biogeography, functional morphology and ecology. This increased taxon sampling will allow us to answer more complex questions about the biogeographic relationships of these organisms and their long journey across Gondwana. I am most excited, however, to explore the male polymorphism in the neopilionid chelicerae. These unusual variations lend themselves to excellent vessels for questions on behavior and functional morphology. We are currently imaging males of different morphotypes on the micro-CT with Dr. Hannah Wood and Tom Nguyen at the National Museum of Natural History. We hope that these analyses will provide a foundation for which to further explore this fascinating group and its biology!