Portal:Arthropods

Ralph Vary Chamberlin (January 3, 1879 – October 31, 1967) was an American biologist, ethnographer, and historian from Salt Lake City, Utah. He was a faculty member of the University of Utah for over 25 years, where he helped establish the School of Medicine and served as its first dean, and later became head of the zoology department. He also taught at Brigham Young University and the University of Pennsylvania, and worked for over a decade at the Museum of Comparative Zoology at Harvard University, where he described species from around the world.

Chamberlin was a prolific taxonomist who named over 4,000 new animal species in over 400 scientific publications. He specialized in arachnids (spiders, scorpions, and relatives) and myriapods (centipedes, millipedes, and relatives), ranking among the most prolific arachnologists and myriapodologists in history. He described over 1,400 species of spiders, 1,000 species of millipedes, and the majority of North American centipedes, although the quantity of his output was not always matched with quality, leaving a mixed legacy to his successors. He also did pioneering ethnobiological studies with the Goshute and other indigenous people of the Great Basin, cataloging indigenous names and cultural uses of plants and animals. Chamberlin was celebrated by his colleagues at the University of Utah, however he was disliked among some arachnologists, including some of his former students. After retirement he continued to write, publishing on the history of education in his home state, especially that of the University of Utah.

Chamberlin was a member of the Church of Jesus Christ of Latter-day Saints (LDS Church). In the early twentieth century, Chamberlin was among a quartet of popular Mormon professors at Brigham Young University whose teaching of evolution and biblical criticism resulted in a 1911 controversy among University and Church officials, eventually resulting in the resignation of him and two other professors despite widespread support from the student body, an event described as Mormonism's "first brush with modernism". (Full article...)

Phengaris rebeli (formerly Maculinea rebeli), common name mountain Alcon blue, is a species of butterfly in the family Lycaenidae. It was first found and described in Styria, Austria, on Mount Hochschwab around 1700. Although it was initially classified as a subspecies of P. alcon, a European researcher, Lucien A. Berger, designated it as a separate species in 1946. Genetic similarities between P. rebeli and P. alcon have led many researchers to argue that the two are the same species and differences are due to intraspecific variation.

Although P. rebeli is found across the Palearctic (see subspecies), it is difficult to determine the species' precise range due to confusion with P. alcon.

Behavioral ecologists have found its role as a brood parasite to be of particular interest as, unlike many brood parasites, it does not directly oviposit in the hosts' nests. P. rebeli parasitizes the colony ant species Myrmica schencki as a larva by using chemical mimicry to trick the ants into believing that they are ant larvae; thus, the ants bring P. rebeli caterpillars back to their nests and feed them. P. rebeli is dependent on the plant Gentiana cruciata early in its life cycle and is vulnerable to parasitism by Ichneumon eumerus while inside the nest of M. schencki. It was placed on the IUCN Red List in 2000 and is classified as a species vulnerable to extinction. (Full article...)

Tylopterella is a genus of eurypterid, a group of extinct aquatic arthropods. Only one fossil of the single and type species, T. boylei, has been discovered in deposits of the Late Silurian period (Ludlow epoch) in Elora, Canada. The name of the genus is composed by the Ancient Greek words τύλη (túlē), meaning "knot", and πτερόν (pteron), meaning "wing". The species name boylei honors David Boyle, who discovered the specimen of Tylopterella.

It is a poorly-known genus whose carapace (dorsal plate of the prosoma, head) was semiovate bordered by a marginal rim, with eyes laterally placed, a preabdomen and postabdomen (the two halves of the abdomen) with six segments each and a short spike-like telson (which was the posteriormost division of the body). It reached a total length of 7.5 centimetres (2.9 inches). These characteristics place Tylopterella in the family Onychopterellidae together with Onychopterella and Alkenopterus.

Tylopterella is notable for its thick ornamentation and general body surface. Its paired tubercles or knobs in the top of its second to fifth segments differentiates it from many other eurypterids. This thickness that its body possessed is due to the highly saline conditions to which Tylopterella had to adapt in the Guelph Formation; other organisms with reinforced shells have also been found in the same place. (Full article...)

Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from vespoid wasp ancestors in the Cretaceous period. More than 13,800 of an estimated total of 22,000 species have been classified. They are easily identified by their geniculate (elbowed) antennae and the distinctive node-like structure that forms their slender waists.

Ants form colonies that range in size from a few dozen individuals often living in small natural cavities to highly organised colonies that may occupy large territories with a sizeable nest (or nests) that consist of millions of individuals, in some cases they reach hundreds of millions of individuals in super colonies. Typical colonies consist of various castes of sterile, wingless females, most of which are workers (ergates), as well as soldiers (dinergates) and other specialised groups. Nearly all ant colonies also have some fertile males called "drones" and one or more fertile females called "queens" (gynes). The colonies are described as superorganisms because the ants appear to operate as a unified entity, collectively working together to support the colony.

Ants have colonised almost every landmass on Earth. The only places lacking indigenous ants are Antarctica and a few remote or inhospitable islands. Ants thrive in moist tropical ecosystems and may exceed the combined biomass of wild birds and mammals. Their success in so many environments has been attributed to their social organisation and their ability to modify habitats, tap resources, and defend themselves. Their long co-evolution with other species has led to mimetic, commensal, parasitic, and mutualistic relationships. (Full article...)

Sphecius grandis, also called the western cicada killer, is a species of cicada killer wasp (Sphecius). The western species shares the same nesting biology as its fellow species, the eastern cicada killer (S. speciosus). S. grandis, like all other species of the genus Sphecius, mainly provides cicadas for its offspring. It forms nest aggregations and mates and broods once in a year, in July and early August. The wasp is on average 3 cm (1 in) to 5 cm (2 in) in length and is amber-yellow with yellow rings on its abdomen.

Wasps in the genus Sphecius are not habitually aggressive and use their venom mainly to paralyse cicadas which they take back to their nests to feed their young. The females catch around four or more cicadas for provisioning, place them in brood cells and lay eggs in the cells. S. grandis is endemic to Central America, Mexico and the Western United States, and is found at a higher mean altitude than other species of Sphecius. The western cicada killer males emerge earlier than females, but generally die after only a couple of days.

Sphecius grandis can be distinguished from S. convallis (the Pacific cicada killer wasp) by the coloration pattern of the gastral tergites. Formerly, the two species were distinguished on the basis of the number of tergites with yellow markings (five in S. grandis and three in S. convallis), but a more recent study showed that this character was insufficient to distinguish the two species. However, they can be distinguished by the density of the punctation on the first and second tergites. (Full article...)

Eusarcana (meaning "true flesh") is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of Eusarcana have been discovered in deposits ranging in age from the Early Silurian to the Early Devonian. Classified as part of the family Carcinosomatidae, the genus contains three species, E. acrocephalus, E. obesus and E. scorpionis, from the Silurian-Devonian of Scotland, the Czech Republic and the United States respectively.

Eusarcana is known for its odd proportions and features; the broad abdomen, thin and long tail, spined and forward-facing walking appendages and sharp and curved tail spike differentiate it from most other eurypterids, but are shared with other carcinosomatid eurypterids. The triangular carapace, oddly positioned forward-facing eyes differentiate the genus further from its closest relatives. At 80 centimetres (31.5 in) in length, E. scorpionis represents a moderately large species of eurypterid, and far exceeded other representatives of the genus in size, such as the 4 cm (1.5 in) long E. obesus.

Originally described under the name Eusarcus, this name was preoccupied by a genus of living harvestmen in the family Gonyleptidae. Following the discovery of this homonym, the genus was also wrongly recognized as synonymous with the related Carcinosoma and was only given replacement names for the older name decades after the error was discovered, first as Eusarcana in 1942 and later as Paracarcinosoma (assumed to have been named without knowledge of the earlier replacement name) in 1964. (Full article...)

Ypresiomyrma is an extinct genus of ants in the subfamily Myrmeciinae that was described in 2006. There are four species described; one species is from the Isle of Fur in Denmark, two are from the McAbee Fossil Beds in British Columbia, Canada, and the fourth from the Bol’shaya Svetlovodnaya fossil site in Russia. The queens of this genus are large, the mandibles are elongated and the eyes are well developed; a stinger is also present. The behaviour of these ants would have been similar to that of extant Myrmeciinae ants, such as solitary foraging for arthropod prey and never leaving pheromone trails. The alates were poor flyers due to their size, and birds and animals most likely preyed on these ants. Ypresiomyrma is not assigned to any tribe, and is instead generally regarded as incertae sedis within Myrmeciinae. However, some authors believe Ypresiomyrma should be assigned as incertae sedis within Formicidae. (Full article...)

Spiders (order Araneae) are air-breathing arthropods that have eight limbs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species diversity among all orders of organisms. Spiders are found worldwide on every continent except Antarctica, and have become established in nearly every land habitat. As of June 2025, 53,034 spider species in 136 families have been recorded by taxonomists. However, there has been debate among scientists about how families should be classified, with over 20 different classifications proposed since 1900.

Anatomically, spiders (as with all arachnids) differ from other arthropods in that the usual body segments are fused into two tagmata, the cephalothorax or prosoma, and the opisthosoma, or abdomen, and joined by a small, cylindrical pedicel. However, as there is currently neither paleontological nor embryological evidence that spiders ever had a separate thorax-like division, there exists an argument against the validity of the term cephalothorax, which means fused cephalon (head) and the thorax. Similarly, arguments can be formed against the use of the term "abdomen", as the opisthosoma of all spiders contains a heart and respiratory organs, organs atypical of an abdomen.

Unlike insects, spiders do not have antennae. In all except the most primitive group, the Mesothelae, spiders have the most centralized nervous systems of all arthropods, as all their ganglia are fused into one mass in the cephalothorax. Unlike most arthropods, spiders have no extensor muscles in their limbs and instead extend them by hydraulic pressure. (Full article...)

Arthropleura, from Ancient Greek ἄρθρον (árthron), meaning "joint", and πλευρά (pleurá), meaning "rib", is an extinct genus of massive myriapod that lived in what is now Europe and North America around 344 to 292 million years ago, from the Viséan stage of the lower Carboniferous period to the Sakmarian stage of the lower Permian period. It is a millipede, and was capable of reaching at least 2 metres (6 ft 7 in) in length, possibly up to over 2.5 metres (8 ft 2 in), making it the largest known land arthropod of all time. Arthropleura is known from body fossils as well as trace fossils, particularly giant trackways up to 50 centimetres (20 in) wide, and potentially also large burrows. It lived in open, sparsely wooded environments near water, and was possibly amphibious. (Full article...)

Opabinia regalis is an extinct, stem group marine arthropod found in the Middle Cambrian Burgess Shale Lagerstätte (505 million years ago) of British Columbia. Opabinia was a soft-bodied animal, measuring up to 7 cm in body length, and had a segmented trunk with flaps along its sides and a fan-shaped tail. The head showed unusual features: five eyes, a mouth under the head and facing backwards, and a clawed proboscis that most likely passed food to its mouth. Opabinia lived on the seafloor, using the proboscis to seek out small, soft food. Fewer than twenty good specimens have been described; 3 specimens of Opabinia are known from the Greater Phyllopod bed, where they constitute less than 0.1% of the community.

When the first thorough examination of Opabinia in 1975 revealed its unusual features, it was thought to be unrelated to any known phylum, or perhaps a relative of arthropod and annelid ancestors. However, later studies since late 1990s consistently support its affinity as a member of basal arthropods, alongside the closely related radiodonts (Anomalocaris and relatives) and gilled lobopodians (Kerygmachela and Pambdelurion).

In the 1970s, there was an ongoing debate about whether multi-celled animals appeared suddenly during the Early Cambrian, in an event called the Cambrian explosion, or had arisen earlier but without leaving fossils. At first Opabinia was regarded as strong evidence for the "explosive" hypothesis. Later the discovery of a whole series of similar lobopodian animals, some with closer resemblances to arthropods, and the development of the idea of stem groups, suggested that the Early Cambrian was a time of relatively fast evolution, but one that could be understood without assuming any unique evolutionary processes. (Full article...)

Jaekelopterus is a genus of predatory eurypterid, a group of extinct aquatic arthropods. Fossils of Jaekelopterus have been discovered in deposits of Early Devonian age, from the Pragian and Emsian stages. There are two known species: the type species J. rhenaniae from brackish to fresh water strata in the Rhineland, and J. howelli from estuarine strata in Wyoming. The generic name combines the name of German paleontologist Otto Jaekel, who described the type species, and the Greek word πτερόν (pteron) meaning 'wing'.

Based on the isolated fossil remains of a large chelicera (claw) from the Klerf Formation of Germany, J. rhenaniae has been estimated to have reached a size of around 2.3–2.6 metres (7.5–8.5 ft), making it the largest arthropod ever discovered, surpassing other large arthropods such as fellow eurypterids Acutiramus and Pterygotus; the millipede Arthropleura. J. howelli was much smaller, reaching 80 centimetres (2.6 ft) in length.

In overall appearance, Jaekelopterus is similar to other pterygotid eurypterids, possessing a large, expanded telson (the hindmost segment of the body) and enlarged pincers and forelimbs. Both species of Jaekelopterus were first described as species of the closely related Pterygotus but were raised as a separate genus based on an observed difference in the genital appendage. Though this feature has since proved to be a misidentification, other features distinguishing the genus from its relatives have been identified, including a telson with a triangular shape and a different inclination of the denticles of the claws. (Full article...)

Evarcha ignea is a species of jumping spider in the genus Evarcha that is endemic to Africa. The male spider's face, or clypeus, is covered in bright scarlet scale-like hairs, which gives the spider its species name, which can be translated "fiery". It is ground-dwelling spider, living in leaf litter, but has also been observed living on the walls of houses. First discovered living in Zimbabwe, it has been found to have a wide distribution that also includes Nigeria and South Africa. A small spider, it has a rounded cephalothorax that is usually between 1.9 and 2.5 mm (0.07 and 0.10 in) long and an ovoid abdomen that is between 1.6 and 2.2 mm (0.06 and 0.09 in) long. The female is slightly larger than the male. The male has a mostly dark brown carapace and russet-brown abdomen, while the female's carapace is whitish-yellow and abdomen creamy. To distinguish this species from others in the genus, it is necessary to compare their copulatory organs. The male Evarcha ignea has a distinctive small notch on the spike, or apophysis on its reproductive organs. The female has shorter insemination ducts than other species, and spermathecae that have a large first chamber. The male of species was first described in 2008 by Wanda Wesołowska and Meg Cumming and the female described the year after. (Full article...)

Prionomyrmecini is an ant tribe belonging to the subfamily Myrmeciinae established by William Morton Wheeler in 1915. Two members are a part of this tribe, the extant Nothomyrmecia and the extinct Prionomyrmex. The tribe was once considered a subfamily due to the similarities between Nothomyrmecia and Prionomyrmex, but such reclassification was not widely accepted by the scientific community. These ants can be identified by their long slender bodies, powerful stingers and elongated mandibles. Fossil Prionomyrmecini ants were once found throughout Europe, possibly nesting in trees and preferring jungle habitats. Today, Prionomyrmecini is only found in Australia, preferring old-growth mallee woodland surrounded by Eucalyptus trees. Nothomyrmecia workers feed on nectar and arthropods, using their compound eyes for prey and navigational purposes. Owing to their primitive nature, they do not recruit others to food sources or create pheromone trails. Nothomyrmecia colonies are small, consisting of 50 to 100 individuals. (Full article...)

Beetles are insects that form the order Coleoptera (/koʊliːˈɒptɛrə/), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 described species, is the largest of all orders, constituting almost 40% of described arthropods and 25% of all known animal species; new species are discovered frequently, with estimates suggesting that there are between 0.9 and 2.1 million total species. However, the number of beetle species is challenged by the number of species in dipterans (flies) and hymenopterans (wasps).

Found in almost every habitat except the sea and the polar regions, they interact with their ecosystems in several ways: beetles often feed on plants and fungi, break down animal and plant debris, and eat other invertebrates. Some species are serious agricultural pests, such as the Colorado potato beetle, while others such as Coccinellidae (ladybirds or ladybugs) eat aphids, scale insects, thrips, and other plant-sucking insects that damage crops. Some others also have unusual characteristics, such as fireflies, which use a light-emitting organ for mating and communication purposes.

Beetles typically have a particularly hard exoskeleton including the elytra, though some such as the rove beetles have very short elytra while blister beetles have softer elytra. The general anatomy of a beetle is quite uniform and typical of insects, although there are several examples of novelty, such as adaptations in water beetles which trap air bubbles under the elytra for use while diving. Beetles are holometabolans, which means that they undergo complete metamorphosis, with a series of conspicuous and relatively abrupt changes in body structure between hatching and becoming adult after a relatively immobile pupal stage. Some, such as stag beetles, have a marked sexual dimorphism, the males possessing enormously enlarged mandibles which they use to fight other males. Many beetles are aposematic, with bright colors and patterns warning of their toxicity, while others are harmless Batesian mimics of such insects. Many beetles, including those that live in sandy places, have effective camouflage. (Full article...)

Actinote zikani is a species of butterfly belonging to the family Nymphalidae that is endemic to Brazil. Its habitat is the Brazilian Atlantic forest at an altitude of approximately 1,000 metres (3,280 ft), located in the Serra do Mar. Considered extinct after 1981, the species was rediscovered in 1991 in the state of São Paulo, in the southeast of the country.

The species is classified as critically endangered on the national red list of Brazil by the Chico Mendes Institute for Biodiversity Conservation. It is one of two butterflies on the list of the 100 Most Endangered Species in the World published by the International Union for Conservation of Nature (IUCN) and the Zoological Society of London in September 2012, the other being Parides burchellanus. (Full article...)