2026 in arthropod paleontology

Arachnids Araneae Ixodida Tick research • Chitimia-Dobler et al. (2026) redescribe Haemaphysalis (Alloceraea) cretacea on the basis of data from a new specimen from the Cretaceous amber from Myanmar, and recombine the species as Alloceraea cretacea. Opiliones Opiliones research • A harvestman with pedipalp morphology distinct from those of other fossil and extant members of the group is described from the Eocene Baltic amber by Gerbe et al. (2026). Scorpiones Trombidiformes Xiphosurans Xiphosuran research • Fossils of large-bodied horseshoe crabs, associated with trace fossils assigned to the new ichnospecies Selenichnites sursumdeorsum, are described from the Ordovician (Darriwilian) Saq Formation (Saudi Arabia) by Bicknell et al. (2026), who interpret the presence of the studied specimens in a nearshore environment and their preservation in storm-deposited layers as possible evidence of similarity of spawning behaviors of Ordovician and modern horseshoe crabs. • Feng et al. (2026) report trace fossils from the Lower Triassic Daye Formation (China) interpreted as evidence of predation of horseshoe crabs on polychaetes. Other chelicerates ==Crustaceans==

Malacostracans Malacostracan research • Evidence of sexual dimorphism in the length and shape of the carapace of Soomicaris ordosensis is presented by Liu et al. (2026). • Revision of pygocephalomorphs belonging to the genus Pygocephalus from the Carboniferous strata from Nova Scotia (Canada) is published by Laville, Andréo & Atkins (2026). • A study on the moulting patterns and growth of Cretapenaeus berberus from the Cretaceous Kem Kem Group (Morocco) is published by Lynch et al. (2026). • Burrow casts interpreted as the first evidence of crayfish activity in the main Karoo Basin are reported from the Middle Triassic Burgersdorp Formation (South Africa) by Wolvaardt et al. (2026). • Luque et al. (2026) report the discovery of new fossil material of tepexicarcinoid crabs from the Cenomanian–Turonian strata of the Eagle Ford succession in Coahuila (Mexico), providing new information on the morphology of members of the superfamily. • Bicknell et al. (2026) study the exoskeletal elemental composition of Bombur complicatus, Caryocaris curvilata, Mecochirus sp., Sculda syriaca and Tealliocaris woodwardi, reporting evidence of higher levels of phosphorus in the studied taxa compared with modern crustaceans, either resulting from diagenetic phosphatization of fossil crustaceans or reflecting genuine composition of their original exoskeletons. • A study on changes of diversity of decapod crustaceans throughout their evolutionary history, as indicated by their fossil record, is published by Schweitzer, De Grave & Hyžný (2026). Ostracods Ostracod research • A study on the composition of the Devonian (Pragian) ostracod assemblage from the Lilydale Limestone (Australia) is published by Camilleri et al. (2026). • Golfinopoulos et al. (2026) report the first discovery of ostracods from the Lower Jurassic strata exposed in Greece. • Evidence of impact of environmental changes in the Lake Pannon area on diversification of members of the genus Cyprideis during the middle and late Miocene is presented by Pipík, Gross & Starek (2026). Thecostracans Other crustaceans Other crustacean research • Wang et al provide an detailed description update for Weichangiops trangularis based on new fossil materials. The new fossils allow for the discussion of early Notostraca evolutionary processes. == Insects ==

Trilobite research • Evidence supporting the interpretation of trilobite exopodites as having respiratory function is presented by Losso et al. (2026). • Tortello et al. (2026) study the composition of two trilobite assemblages from the Umachiri Inlier of the Peruvian Altiplano, providing evidence of presence of cosmopolitan taxa in the Cambrian Llallahue Formation and presence of taxa with Gondwanan affinities in the Ordovician Umachiri Formation. • Zhu (2026) reports the discovery of an internal mold of Archikainella vomerinus from the Cambrian (Furongian) Sandu Formation (China), providing new information on the ventral structure of lichakephalid trilobites. • Beech et al. (2026) evaluate possible functions of cephalic brims of trilobites of the order Harpetida and the superfamily Trinucleioidea, finding no evidence that the brims were an adaptation that prevented sinking into soft sediments, and finding no evidence of clear evolutionary trend in the evolution of the brims that would make them more efficient at ploughing through sediments. • Vargas-Parra & Hopkins (2026) report evidence of decrease of modularity of the head Lonchodomas chaziensis across its metamorphosis from three to two modules, and evidence of mosaic shifts in shape and degree of integration of modules before and during metamorphosis. • Mahata & Pates (2026) revise the fossil record of abnormalities in specimens of Paradoxides davidis, and interpret the studied abnormalities as more likely resulting from injuries than from developmental aberrations. • A study on changes of geographical distribution of olenid trilobites throughout their evolutionary history, and on factors influencing their expansion and eventual decline, is published by Monti & Serra (2026). • Evidence from the study of the spatio-temporal distribution of trilobites during the Ordovician-Silurian transition, indicating that trilobites began to recover immediately following the second episode of the Late Ordovician mass extinction, is presented by Wei et al. (2026). • Kudo & Shiino (2026) study the taphonomy of fossils of members of the genus Pseudophillipsia from the Permian Kamiyasse Formation (Japan), interpreted as indicative of adaptations of the two studied species to different benthic conditions. • Bicknell et al. (2026) revise the record of trilobite specimens with malformations from the collections of the Yale Peabody Museum. ==Other arthropods==

• Evidence from the study of the anatomy of Zonozoe drabowiensis and Zonoscutum solum, interpreted as supporting their placement within Artiopoda and strengthening the case for a their affinity with Vicissicaudata, is presented by Lustri et al. (2026). • Yang et al. (2026) provide new information on the morphology of Acanthomeridion serratum and study its phylogenetic affinities, recovering it as a member of Vicissicaudata closely related to Sidneyia. • Mai et al. (2026) revise Pisinnocaris subconigera and interpret it as a valid, distinct taxon within Fuxianhuiida. == General research ==

• Lakeram et al. (2026) describe borings in a coal ball from the Carboniferous strata from the Mt. Rorah Coal Member of the Tradewater Formation (Illinois, United States), interpreted as produced by arthropods (possibly roachoid insects or millipedes) feeding on the roots of Psaronius, and report preservation of two types of arthropod-produced coprolites in the studied borings, including smaller pellets possibly produced by oribatid mites feeding on larger pellets. == References ==