Peter Michalik

Universität Greifswald · Zoologisches Institut und Museum

Until recently, three-dimensional reconstruction on an ultrastructural level was only possible using serial section transmission electron microscopy (ssTEM). However, ssTEM is highly challenging and prone to artifacts as, e.g., section loss and image distortions. New methods, such as serial block-face scanning electron microscopy (SBFSEM) overcome...

Complexity is an important aspect of evolutionary biology, but there are many reasonable concepts of complexity, and its objective measurement is an elusive matter. Here we develop a simple measure of complexity based on counts of elements, incorporating the hierarchical information as represented in anatomical ontologies. Neomorphic and transforma...

Classical histology or immunohistochemistry combined with fluorescence or confocal laser scanning microscopy are common techniques in arthropod neuroanatomy, and these methods often require time-consuming and difficult dissections and sample preparations. Moreover, these methods are prone to artifacts due to compression and distortion of tissues, w...

Web-building spiders are an extremely diverse predatory group due to their use of physiologically differentiated silk types in webs. Major shifts in silk functional properties are classically attributed to innovations in silk genes and protein expression. Here, we disentangle the effects of spinning behavior on silk performance of the earliest type...

Spiders are a diverse group with a high eco-morphological diversity, which complicates anatomical descriptions especially with regard to its terminology. New terms are constantly proposed, and definitions and limits of anatomical concepts are regularly updated. Therefore, it is often challenging to find the correct terms, even for trained scientist...

A new species of the staphylinid genus Megalopinus Eichelbaum, 1915 is described from Australia, Queensland, Cape York Peninsula: Megalopinus casuarius Mainda sp. nov. Furthermore, a new term for elytral puncture-rows is introduced: epipleural complex: merged sublateral and epipleural rows. In addition, new distribution data of Megalopinus acaciae...

While there is extensive information about sperm nuclear basic proteins (SNBP) in vertebrates, there is by comparison, very little information in Arthropoda. This paper aims to contribute to filling this gap by analyzing these proteins in the sperm of the noble false widow spider Steatoda nobilis (Order Araneae, Family Theridiidae). To this end, we...

Human-induced environmental change and globalization facilitate biological invasions, which can lead to the displacement of native species by non-native ones. Analogously, biodiversity loss may occur within species when habitat modifications facilitate the expansion of a specific population’s range, leading to genetic admixture with native local po...

Spider silk is a tough and versatile biological material combining high tensile strength and extensibility through nanocomposite structure and its nonlinear elastic behaviour. Notably, spiders rarely use single silk fibres in isolation, but instead process them into more complex composites, such as silk fibre bundles, sheets and anchorages, involvi...

While there is extensive information about sperm nuclear basic proteins (SNBP) in vertebrates, there is very little information about Arthropoda by comparison. This paper aims to contribute to filling this gap by analyzing these proteins in the sperm of the noble false widow spider Steatoda nobilis (Order Araneae, Family Theridiidae). To this end,...

Though recent investigations have contributed substantially to our understanding of the Alpine-Dinaric radiation of the genus Zospeum Bourguignat, 1856, its southernmost member, Zospeum troglobalcanicum Absolon, 1916, has remained a taxonomic ghost. The assumed absence of type material, the insufficient original description, and the lack of new sam...

Though recent investigations have contributed substantially to our understanding of the Alpine-Dinaric radiation of the genus Zospeum Bourguignat, 1856, its southernmost member, Zospeum troglobalcanicum Absolon, 1916, has remained a taxonomic ghost. The assumed absence of type material, the insufficient original description, and the lack of new sam...

Odd-clawed spiders (Gradungulinae), which are considered to be ‘living fossils’, are a faunal element of the mesic forests of eastern Australia and the South Island of New Zealand. To date, 16 species in seven genera are known, with most being highly endemic and hard to find, explaining their scarcity in collections worldwide. Particularly notewort...

Ninetinae is a group of small to tiny short-legged spiders largely restricted to arid habitats. Among daddy-long-legs spiders (Pholcidae) this is by far the least diverse subfamily but this may partly be a result of inadequate collecting, poor representation in collections or scientific neglect. We build on a large recent collection of the ninetine...

Natural range shifts offer the opportunity to study the phenotypic and genetic changes contributing to colonization success. The recent range shift of the Southern small white butterfly (Pieris mannii) from the South to the North of Europe offers a prime example to examine a potential dispersal syndrome in range-expanding individuals. We compared b...

Silk production is a prominent characteristic of spiders. The silk is extruded through spigots located on the spinnerets, which are single‐ to multimembered paired appendages at the end of the abdomen. Most extant spiders have three pairs of spinnerets, and in between either a cribellum (spinning plate) or a colulus (defunct vestigial organ), divid...

Paludiculture, the productive use of wet or rewetted peatlands, offers an option for continued land use by farmers after rewetting formerly drained peatlands, while reducing the greenhouse gas emissions from peat soils. Biodiversity conservation may benefit, but research on how biodiversity responds to paludiculture is scarce. We conducted a multi-...

Spiders evolved a distinctive sperm transfer system, with the male copulatory organs located on the tarsus of the pedipalps. In entelegyne spiders, these organs are usually very complex and consist of various sclerites that not only allow the transfer of the sperm themselves but also provide a mechanical interlock between the male and female genita...

Venom is one of the most potent chemical secretions in nature which has played a significant role in the evolutionary success of many animal groups, including spiders. However, the family Uloboridae has seemingly lost the venom-producing organs, leaving the presence and function of toxins in question. Uloborids employ a distinct hunting method invo...

Seasonality considerably impacts on the life of organisms and leads to numerous evolutionary adaptations. Some species face seasonal changes by entering a diapause during different life stages. During adulthood, a diapause in the non-reproductive period can affect male gametogenesis as, for example, it occurs in insects. Spiders are distributed wor...

The male genitalia of pholcid spiders, which is one of the most species-rich spider families, are characterized by a procursus, which is a morphologically diverse projection of the copulatory organ. It has been shown that the procursus interacts with the female genitalia during copulation. Here, we investigate the function of the procursus in Gerts...

Sperm transfer in spiders is achieved by copulatory organs on the male pedipalps (i.e., copulatory bulbs), which can be simple or a complex set of sclerites and membranes. During copulation, these sclerites can be used to anchor in corresponding structures in the female genitalia by means of hydraulic pressure. In the most diverse group of Entelegy...

Paludiculture, the productive use of wet or rewetted peatlands, offers an option for continued land use by farmers after rewetting formerly drained peatlands, while reducing the greenhouse gas emissions from peat soils. Biodiversity conservation may benefit, but research on how biodiversity responds to paludiculture is scarce. We conducted a multi-...

Spiders are among the most diverse animals, which developed different morphological and behavioral traits for capturing prey. We studied the anatomy and functionality of the rare and apomorphic raptorial spider feet using 3D reconstruction modeling, among other imaging techniques. The evolutionary reconstruction of the raptorial feet (tarsus plus p...

Geometric regularity of spider webs has been intensively studied in orb-weaving spiders, although it is not exclusive of orb weavers. Here, we document the geometrically regular, repetitive elements in the webs of the non-orb-weaving groups Leptonetidae and Telemidae for the first time. Similar to orb weavers, we found areas with regularly spaced p...

Caeculus fedrae sp. nov. is described from a series of three exemplars from Baltic amber (Eocene). This species is the first fossil representative of the genus Caeculus, the first fossil species of the family not belonging to the genus Procaeculus, and the second species of the genus in Europe. Phylogenetic relationships, morphological features and...

Background Pholcidae represent one of the largest and most diverse spider families and have been subject to various studies regarding behavior and reproductive biology. In contrast to the solid knowledge on phylogeny and general reproductive morphology, the primary male reproductive system is strongly understudied, as it has been addressed only for...

Ricinulei Thorell, 1876 is an order of Arachnida currently represented in the New and Old Worlds by 103 living species. The order is also represented in the fossil record from the Carboniferous (ca. 305–319 Ma) and the Cretaceous (ca. 99 Ma) periods. In the present contribution, Hirsutisoma grimaldii sp. nov., a new extinct species of the suborder...

Caves of Zospeum’s Eastern Alpine and Dinaride range have historically been unevenly sampled such that the northern half of the distribution is richly represented by shells in certain European museum collections while that of the southernmost, Croatian and Western Balkan extension is hardly known. Up to now, only one southern Dinaride species has b...

Insekten sind die artenreichste Tiergruppe auf der Erde. Nahezu überall zu finden, überleben sie auch unter extremen Bedingungen. Für uns Menschen erbringen sie wertvolle Ökosystemdienstleistungen, wie zum Beispiel die Bestäubung, und haben dennoch oft einen schlechten Ruf. Insekten sind aber auch stark gefährdet: Ihre Populationen gehen so stark z...

History, methods and importance of taxonomy

Within populations, phenotypic plasticity may allow adaptive phenotypic variation in response to selection generated by environmental heterogeneity. For instance, in multivoltine species, seasonal changes between and within generations may trigger morphological and physiological variation enhancing fitness under different environmental conditions....

The modification of male pedipalps into secondary sexual intromittent organs is one of the hallmark characteristics of spiders, yet understanding the development and evolution of male genitalia across the order remains a challenging prospect. The embolus – the sclerite bearing the efferent spermatic duct or spermophor, and used to deliver sperm dir...

Spiders are unique in having a dual respiratory system with book lungs and tracheae, and most araneomorph spiders breathe simultaneously via book lungs and tracheae, or tracheae alone. The respiratory organs of spiders are diverse but relatively conserved within families. The small araneoid spiders of the symphytognathoid clade exhibit a remarkably...

Spiders are a highly diversified group of arthropods and play an important role in terrestrial ecosystems as ubiquitous predators, which makes them a suitable group to test a variety of eco-evolutionary hypotheses. For this purpose, knowledge of a diverse range of species traits is required. Until now, data on spider traits have been scattered acro...

Aim Fossil data may be crucial to infer biogeographical history, especially in taxa with tropical trans-Pacific distributions. Here, we use extinct and extant trochanteriid flattened spiders to test hypotheses that could explain its trans-Pacific disjunct distribution, including a Boreotropical origin with a North Atlantic dispersal, an African ori...

Changing species assemblages represent major challenges to ecosystems around the world. Retracing these changes is limited by our knowledge of past biodiversity. Natural history collections represent archives of biodiversity and are therefore an unparalleled source to study biodiversity changes. In the present study, we tested the value of natural...

Investigations on the internal anatomy of stalked jellyfishes (Staurozoa) are crucial for species descriptions and systematic studies on this taxon. Contrast-enhanced X-ray micro computed tomography (micro-CT) has increased the opportunities for morphological descriptions of soft-bodied invertebrates in the last decade, but only few studies have fo...

Synopsis Spider web anchors are attachment structures composed of the bi-phasic glue-fiber secretion from the piriform silk glands. The mechanical performance of the anchors strongly correlates with the structural assembly of the silk lines, which makes spider silk anchors an ideal system to study the biomechanical function of extended phenotypes a...

Rhopalosomatidae, currently considered the sister group of the Vespidae, are an enigmatic family of aculeate wasps that originated in the Late Jurassic or Early Cretaceous. Despite their considerable age, very few fossils of the family have been reported – all of them in amber (Miocene Dominican, Miocene Mexican, and mid-Cretaceous Burmese ambers)....

A protonymph of the snout mite genus Odontoscirus Thor, 1913, O. cretacico sp. nov., is described and illustrated from Cretaceous amber of Myanmar is described and illustrated, constituting the earliest fossil species described of the family Bdellidae (ca. 99 Ma). After reexamining the literature and recollected specimens from type localities, we c...

Procheiridium judsoni n. gen. et n. sp. is described from Burmese cretaceous amber. This species represents the earliest record of the pseudoscorpion subfamily Pycnocheiridiinae and the first fossil taxon of the subfamily to be recorded. The phylogenetic position of the new genus in the superfamily Cheiridioidea is discussed.

Mating plugs have been proposed as a mechanism that has evolved to avoid sperm competition. Their structure and composition vary across taxa and are related to the effectiveness of its function. This effectiveness could be related to different evolutionary interests of the sexes. Urophonius brachycentrus and Urophonius achalensis (Scorpiones, Bothr...

Spiders of the genus Micaria are ground‐living mimics of ants. Species delineation in these spiders is challenging, mainly because of exceptional high levels of intraspecific variation masking species boundaries. As implied by preliminary DNA barcode data from Central Europe, the Holarctic and very widely distributed glossy ant‐spider M. pulicaria...

Studies in evolutionary biology and biogeography increasingly rely on the estimation of dated phylogenetic trees using molecular clocks. In turn, the calibration of such clocks is critically dependent on external evidence (i.e. fossils) anchoring the ages of particular nodes to known absolute ages. In recent years, a plethora of new fossil spiders,...

This study explores the web-building behavior of Gradungulidae for the first time, using the Otway odd-clawed spider Progradungula otwayensisMilledge, 1997. The web consists of a signal line leading to a retreat, an upper scaffold and a cribellate catching ladder connected to the substrate. The construction sequence and final structure of the catch...

Genital traits are among the fastest to evolve, and the processes that drive their evolution are intensively studied. Spiders are characterized by complex genitalia, but the functional role of the different structures during genital coupling is largely unknown. Members of one of the largest spider groups, the retrolateral tibial apophysis (RTA) cla...

Background: Nervous tissue is an inherent component of the many specialized genital structures for transferring sperm directly into the female's body. However, the male copulatory organ of spiders was considered a puzzling exception. Based on the recent discovery of nervous tissue in the pedipalps of two distantly related spider species, we invest...

Natural history collections are fundamental for biodiversity research as well as for any applied environment-related research. These collections can be seen as archives of earth´s life providing the basis to address highly relevant scientific questions such as how biodiversity changes in certain environments, either through evolutionary processes i...

Physical structures built by animals challenge our understanding of biological processes and inspire the development of smart materials and green architecture. It is thus indispensable to understand the drivers, constraints and dynamics that lead to the emergence and modification of building behaviour. Here, we demonstrate that spider web diversifi...

The monotypic family Trogloraptoridae was only recently described from caves and old‐growth forest of Oregon and California (Western USA). These enigmatic spiders are characterized by striking raptorial claws, and based on their spinneret morphology, a close relationship to dysderoid spiders, a large clade within Synspermiata, was suggested. Here,...

Procaeculus coineaui sp. nov. from Cretaceous Burmese amber is described and its phylogenetic position discussed. This fossil taxon is the first caeculid mite known from Burmese amber and constitutes the earliest record of the family. The genus Procaeculus is redefined to include the new fossil species and internal relationships between genera of t...

We would like to present FAIR Research Data: Semantic Knowledge Graph Infrastructure for the Life Sciences (in short, FAIR.ReD), a project initiative that is currently being evaluated for funding. FAIR.ReD is a software environment for developing data management solutions according to the FAIR (Findable, Accessible, Interoperable, R eusable; Wilkin...

Rhopalosomatidae are a family of aculeate wasps that are ectoparasitoids of crickets as larvae and are predominantly distributed pantropically. The published fossil record of the family is scarce. Here, we report three new fossil rhopalosomatid wasp specimens from Dominican and Mexican amber. Rhopalosoma hispaniola Lohrmann sp. nov. is described an...

In 1844, the famous German biologist Fritz Müller published his dissertation about the leech fauna of lakes in Berlin. This study not only addressed the occurrence of leeches in the different lakes, but also contains the description of a new species - Glossiphoniaverrrucata (Fr. Müller, 1844). Unfortunately, he never mentioned how many specimens he...

Epidermal organs are multicellular units spread over the integument of Sipuncula. They usually combine both sensory and glandular functions. Given their frequent occurrence and direct connection to the lateral nerves, epidermal organs are among the most relevant sense organs of sipunculans, if not the most relevant. However, the organization of epi...

Specimens of the genus Acanthogorgia (Acanthogorgiidae, Octocorallia) show different sclerite types in the colonie parts like axis coenenchym, polyps and tentacles. Applying high resolution images and three dimensional µCT-scans we compared five Acanthogorgia species (A. aspera, A. armata, A. granulata, A. hirta, A. muricata) from the North Atlanti...

The Zoological Museum forms a unit with the Zoological Institute of the University Greifswald. It was established by the university in 1836 with a focus on the Pomeranian fauna. In the course of the last centuries, the museum grew quickly mainly based on numerous international expeditions, and nowadays it houses approximately 3.5 million specimens...

Organismal biology has been steadily losing fashion in both formal education and scientific research. Simultaneous with this is an observable decrease in the connection between humans, their environment, and the organisms with which they share the planet. Nonetheless, we propose that organismal biology can facilitate scientific observation, discove...

Official biological record held by spiders in the Guinness World Records database (www.guinnessworldrecords.com). This file contains comments about the official biological records held by spiders as listed in the Guinness World Records database (www.guinnessworldrecords.com). For each record, we report the record holder according to the Guinness Wo...

The public reputation of spiders is that they are deadly poisonous, brown and nondescript, and hairy and ugly. There are tales describing how they lay eggs in human skin, frequent toilet seats in airports, and crawl into your mouth when you are sleeping. Misinformation about spiders in the popular media and on the World Wide Web is rampant, leading...

The spider genus Austrochilus comprises only six species known from Chile and Argentina. Here, we describe a new species, Austrochilus parwis sp. n., based on a single male and several females. The new species was found in Chile (Region IX) and, based on characters in the male and female genitalia, seems to be closely related to A. forsteri Grismad...

The public reputation of spiders is that they are deadly poisonous, brown and nondescript, and hairy and ugly. There are tales describing how they lay eggs in human skin, frequent toilet seats in airports, and crawl into your mouth when you are sleeping. Misinformation about spiders in the popular media and on the World Wide Web is rampant, leading...

The tip of the legs concentrates the interactions that a spider has with the substrate where it lives. We review the morphology and evolution of spider feet, discussing the functional anatomy of their articulations and proposing a coherent terminology. All spiders consistently have two tendons to operate their feet and show a stereotyped sequence o...

The interplay between an animal’s environmental niche and its behavior can influence the evolutionary form and function of its sensory systems. While intraspecific variation in sensory systems has been documented across distant taxa, fewer studies have investigated how changes in behavior might relate to plasticity in sensory systems across develop...