# 2021 in arthropod paleontology

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2021 in arthropod paleontology is a list of new arthropod fossil taxa, including arachnids, crustaceans, insects, trilobites, and other arthropods that were announced or described, as well as other significant arthropod paleontological discoveries and events which occurred in 2021.

## Arachnids
### New taxa

| Name | Novelty | Status | Authors | Age | Type locality | Location | Notes |
| Allochthonius balticus | Sp. nov | In press | Schwarze et al. | Eocene | Baltic amber | Europe (Baltic Sea region) | A pseudoscorpion belonging to the family Pseudotyrannochthoniidae. |
| Alterphyxioschemoides | Gen. et sp. nov | Valid | Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | Possibly a member of the family Dipluridae. The type species is A. spicula. |
| Alticorona | Gen. et sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A member of the family Tetrablemmidae. The type species is A. plenfemur. |
| Autotomiana brevisetosa | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A member of Araneomorphae belonging to the family Pholcochyroceridae. |
| Barbutia theroni | Sp. nov | Valid | Khaustov et al. | Late Eocene | Rovno amber | Ukraine | A mite belonging to the group Raphignathoidea and the family Barbutiidae. |
| Boavista | Gen. et sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Uloboridae. The type species is B. crassifemora. |
| Burmadictyna crassembolus | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the group Deinopoidea and the family Salticoididae. |
| Burmadictyna fissura | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the group Deinopoidea and the family Salticoididae. |
| Burmadictyna similis | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the group Deinopoidea and the family Salticoididae. |
| Burmaspiralis | Gen. et sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the group Araneoidea and the family Zarqaraneidae. The type species is B. trispinae. |
| Burmesiana | Nom. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Nemesiidae; a replacement name for Burmesia Wunderlich (2020). |
| Burmorchestina bo | Sp. nov | Valid | Jiang & Li in Xin et al. | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Oonopidae. |
| Burmorchestina convexa | Sp. nov | Valid | Jiang & Li in Xin et al. | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Oonopidae. |
| Burmorsolus longitibia | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A member of Araneomorphae belonging to the family Burmorsolidae. |
| Centrochthonius bitterfeldicus | Sp. nov | In press | Schwarze et al. | Eocene | Bitterfeld amber | Germany | A pseudoscorpion belonging to the family Pseudotyrannochthoniidae. |
| Chaerilobuthus meggeri | Sp. nov | Valid | Lourenço in Lourenço & Velten | Cretaceous | Burmese amber | Myanmar | A scorpion belonging to family Chaerilobuthidae. |
| Cornutheridion | Gen. et sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Theridiidae. The type species is C. concavum. |
| Crassicephalus | Gen. et sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the group Deinopoidea and the new family Crassicephalidae. The type species is C. parvibulbus. |
| Crassitibia sicilicula | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the group Araneoidea and the family Zarqaraneidae. |
| Cretaceousopisthacanthus | Gen. et sp. nov | Valid | Lourenço in Lourenço & Velten | Cretaceous | Burmese amber | Myanmar | A scorpion belonging to the family Protoischnuridae. The type species is C. smeelei. |
| Cretapalpus | Gen. et sp. nov | Valid | Downen & Selden | Early Cretaceous | Crato Formation | Brazil | A spider belonging to the family Palpimanidae. Genus includes new species C. vittari. |
| Dolichocybe elongata | Sp. nov | Valid | Khaustov et al. | Late Eocene | Rovno amber | Ukraine | A mite belonging to the group Heterostigmata and the family Dolichocybidae. |
| Dubiodeinopsis | Gen. et sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the group Deinopoidea and the new family Dubiodeinopsidae. The type species is D. spinifemora. |
| Dubiouloborix | Gen. et sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the group Deinopoidea and the new family Dubiouloboridae. The type species is D. incompletus. |
| Dubiouloborus | Gen. et 2 sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the group Deinopoidea and the new family Dubiouloboridae. The type species is D. praeta; genus also includes D. procerembolus. |
| Electroblemma spermaferens | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A member of the family Tetrablemmidae. |
| Eoagelenomorphus | Gen. et sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider of uncertain phylogenetic placement, possibly a member of an early branch of the RTA clade. The type species is E. cretaceus. |
| Furcembolus chuandiani | Sp. nov | Valid | Jiang & Li in Xin et al. | Late Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Pacullidae. |
| Furcembolus fengzheni | Sp. nov | Valid | Jiang & Li in Xin et al. | Late Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Pacullidae. |
| Furcembolus martensi | Sp. nov | Valid | Jiang & Li in Xin et al. | Late Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Pacullidae. |
| Hiatomegops | Gen. et sp. nov | Valid | Guo, Selden & Ren | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Lagonomegopidae. Genus includes new species H. spinalis. |
| Hoplocheylus neosimilis | Sp. nov | Valid | Khaustov et al. | Late Eocene | Rovno amber | Ukraine | A mite belonging to the group Heterostigmata and the family Tarsocheylidae. |
| Hungarosilia | Gen. et sp. nov | In press | Szabó et al. | Late Cretaceous (Santonian) | Ajka Coal Formation | Hungary | A spider belonging to the family Hersiliidae. Genus includes new species H. verdesi. |
| Kachinarachne | Gen. et sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A member of Araneomorphae belonging to the family Pholcochyroceridae. The type species is K. oblonga. |
| Levantoglyphus | Gen. et sp. nov | Valid | Klimov et al. | Early Cretaceous (Barremian) | Lebanese amber | Lebanon | A mite belonging to the group Astigmata. The type species is L. sidorchukae. |
| Liacarus (Procorynetes) shtanchaevae | Sp. nov | In press | Arillo & Subías in Arillo, Subías & Álvarez-Parra | Early Cretaceous (Albian) | Escucha Formation | Spain | A mite belonging to the family Liacaridae. |
| Longissipalpus cochlea | Sp. nov | Junior homonym | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A member of Araneomorphae belonging to the family Pholcochyroceridae. The specific name is preoccupied Longissipalpus cochlea Wunderlich (2017). Wunderlich (2022) coined a replacement name Longissipalpus aliter. |
| Longissipalpus impudicus | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A member of Araneomorphae belonging to the family Pholcochyroceridae. |
| Megasetae | Gen. et sp. nov | Valid | Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A member of Araneomorphae belonging to the new family Megasetidae. The type species is M. colphepeiroides. |
| Metaphalangium martensi | Sp. nov | Valid | Mitov, Perkovsky & Dunlop | Eocene | Rovno amber | Ukraine | A harvestman, a species of Metaphalangium. |
| Micropalpimanus gibber | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the group Palpimanoidea and the family Micropalpimanidae. |
| Microtheridion | Gen. et sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Theridiidae. The type species is M. longissispinae. |
| Microuloborus oblongus | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Uloboridae. |
| Neoveterator | Nom. nov | | Ceccolini & Cianferoni | Miocene | Mexican amber | Dominican Republic  Mexico | A spider belonging to the family Trochanteriidae; a replacement name for Veterator Petrunkevitch (1963). |
| Orchestina globus | Sp. nov | Valid | Jiang & Li in Xin et al. | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Oonopidae, a species of Orchestina. |
| Palaeodiplothrombidium | Gen. et sp. nov | In press | Rivas & Vega | Miocene | Mexican amber | Mexico | A mite belonging to the family Johnstonianidae. The type species is P. microscutum. |
| Palaeoleptoneta fissura | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Leptonetidae. |
| Palaeothele onoi | Sp. nov | Valid | Selden | Carboniferous (Moscovian) | Mazon Creek fossil beds | United States ( Illinois) | A spider belonging to the group Mesothelae and to the new family Palaeothelidae. |
| Palaeozearchaea | Gen. et sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Mecysmaucheniidae. The type species is P. depressa. |
| Paradactylidium sineunguis | Sp. nov | Valid | Khaustov et al. | Late Eocene | Rovno amber | Ukraine | A mite belonging to the group Heterostigmata and the family Acarophenacidae. |
| Parahistricostoma | Gen. et comb. nov | Valid | Mitov, Perkovsky & Dunlop | Eocene | Baltic amber Bitterfeld amber Rovno amber | Germany  Ukraine | A harvestman belonging to the family Nemastomatidae; a new genus for "Nemastoma" tuberculatum Koch & Berendt (1854). |
| Paramiagrammopes appendix | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Uloboridae. |
| Paramiagrammopes curvatus | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Uloboridae. |
| Paramiagrammopes furca | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Uloboridae. |
| Paramiagrammopes granulatus | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Uloboridae. |
| Paramiagrammopes inaequalis | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Uloboridae. |
| Paramiagrammopes inclinatus | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Uloboridae. |
| Paramiagrammopes multifemurspinae | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Uloboridae. |
| Paramiagrammopes paracurvatus | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Uloboridae. |
| Paramiagrammopes pilosus | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Uloboridae. |
| Paramiagrammopes pollex | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Uloboridae. |
| Paramiagrammopes semiapertus | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Uloboridae. |
| Paramiagrammopes simplex | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Uloboridae. |
| Paramiagrammopes sulcus | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Uloboridae. |
| Paramiagrammopes texter | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Uloboridae. |
| Paramiagrammopes unibrevispina | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Uloboridae. |
| Planarchaea incompleta | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the group Palpimanoidea and the family Planarchaeidae. |
| Platythelae | Gen. et sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the group Palpimanoidea and the family Planarchaeidae. The type species is P. longicorpus. |
| Praetervetiator | Gen. et sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the group Palpimanoidea and the family Vetiatoridae. The type species is P. circulus. The paper naming it also uses the spelling of the genus name Praetervetianus; both names refer to the same genus. |
| Prionochthonius | Gen. et sp. nov | Valid | Wriedt et al. | Cretaceous | Burmese amber | Myanmar | A pseudoscorpion belonging to the family Chthoniidae. Genus includes new species P. burmiticus. |
| Priscaleclercera christae | Sp. nov | Valid | Magalhaes et al. | Late Cretaceous (Cenomanian) | Burmese amber | Myanmar | A spider belonging to the family Psilodercidae. |
| Proadactylidium fossibilis | Sp. nov | Valid | Khaustov et al. | Late Eocene | Rovno amber | Ukraine | A mite belonging to the group Heterostigmata and the family Acarophenacidae. |
| Proalbiorix | Gen. et 2 sp. nov | In press | Geißler et al. | Late Cretaceous (Cenomanian) | Burmese amber | Myanmar | A pseudoscorpion belonging to the family Ideoroncidae. Genus includes new species P. gracilis and P. compactus. |
| Proaraneoides lanceatum | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the group Leptonetoidea and the family Protoaraneoididae. |
| Procerclypeus | Gen. et sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A member of the family Tetrablemmidae. The type species is P. deformans. |
| Procervetiator | Gen. et sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the group Palpimanoidea and the family Vetiatoridae. The type species is P. fruticosus. |
| Propterkachin bispinatus | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Uloboridae. |
| Propterpsiloderces similis | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A member of Araneomorphae belonging to the family Eopsilodercidae. |
| Protolycosa suazoi | Sp. nov | Valid | Selden | Carboniferous (Kasimovian) | Atrasado Formation | United States ( New Mexico) | A spider belonging to the group Mesothelae and the family Arthrolycosidae. |
| Pseudokachin | Gen. et sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Uloboridae. The type species is P. tuberculatus. |
| Scopomegops | Gen. et sp. nov | Valid | Guo, Selden & Ren | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Lagonomegopidae. Genus includes new species S. fax. |
| Scutuloborella | Gen. et sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the group Deinopoidea and the new family Scutuloboridae. The type species is S. admirabilis. |
| Scutuloboroides | Gen. et sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the group Deinopoidea and the new family Scutuloboridae. The type species is S. pumilio. |
| Scutuloborus | Gen. et sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the group Deinopoidea and the new family Scutuloboridae. The type species is S. spiralembolus. |
| Spiniarchaea | Gen. et sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Archaeidae. The type species is S. aberrans. |
| Spinicymbium unispina | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the group Araneoidea and the family Zarqaraneidae. |
| Spiniuloborus | Gen. et sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Uloboridae. The type species is S. crux. |
| Spinoburmesebuthus knodelorum | Sp. nov | Valid | Lourenço | Cretaceous | Burmese amber | Myanmar | A scorpion belonging to the group Buthoidea and the family Palaeoburmesebuthidae. |
| ?Telemofila ovalis | Sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A spider belonging to the family Telemidae, possibly a species of Telemofila. |
| Tenuicephalus | Gen. et sp. nov | Valid | Wunderlich in Wunderlich & Müller | Cretaceous | Burmese amber | Myanmar | A member of the family Tetrablemmidae. The type species is T. penicillus. |

### Research

* Revision of the fossil record of whip spiders is published by Haug & Haug (2021).
* Guo, Selden & Ren (2021) describe an adult lagonomegopid female, part of an egg sac and lagonomegopid spiderlings preserved in four pieces of Burmese amber, and interpret this finding as evidence of maternal care in fossil spiders.
* An exuvium of a member of the genus Myrmecarchaea is described from the Eocene Cambay amber (India) by Wood, Singh & Grimaldi (2021), representing the first member of the family Archaeidae from Cambay amber reported to date.
* An indeterminate deutonymph belonging to the family Sejidae is described by Joharchi, Vorontsov and Walter (2021) from Burmese amber, which represents the oldest record of the parasitiform mite clade Mesostigmata.

## Crustaceans
### New taxa
#### Malacostracans

| Name | Novelty | Status | Authors | Age | Type locality | Country | Notes |
| Agolambrus rathbunae | Sp. nov | Valid | Schweitzer, Hyžný & Feldmann | | | Venezuela | A crab belonging to the family Parthenopidae. |
| Aptanacalliax | Gen. et sp. nov | In press | Ferratges, Hyžný & Zamora | Early Cretaceous (Aptian) | Forcall Formation | Spain | A member of Axiidea belonging to the family Anacalliacidae. Genus includes new species A. enigma. |
| Aptaxiopsis | Gen. et sp. nov | In press | Ferratges, Hyžný & Zamora | Early Cretaceous (Aptian) | Forcall Formation | Spain | A member of Axiidea. Genus includes new species A. longimanus. |
| Autrigoniscus | Gen. et sp. nov | Valid | Sánchez-García et al. | Early Cretaceous (Albian) | Spanish amber | Spain | A member of Isopoda belonging to the family Trichoniscidae. The type species is A. resinicola. |
| Bajoprosopon | Gen. et sp. nov | Valid | Van Bakel et al. | Middle Jurassic (Bajocian) | | France | A crab belonging to the superfamily Homolodromioidea and the family Prosopidae. The type species is B. piardi. |
| Bavaricaris | Gen. et sp. nov | Valid | Winkler | Late Jurassic (Tithonian) | Altmühltal Formation | Germany | A member of Caridea, possibly belonging to the family Palaemonidae. The type species is B. haereri. |
| Berglundus | Gen. et sp. nov | In press | Nyborg et al. | Early to middle Miocene | Astoria Formation | United States ( Washington) | A crab belonging to the group Cyclodorippoida and the family Cyclodorippidae. The type species is B. bretoni. |
| Bericirinia | Gen. et sp. nov | In press | De Angeli & Garassino | Eocene (Priabonian) | | Italy | A crab belonging to the family Epialtidae. The type species is B. bretoni. |
| Blaculla anjobea | Sp. nov | Valid | Winkler | Late Jurassic (Tithonian) | Altmühltal Formation | Germany | A member of Caridea. |
| Bucculentum arnosavelkouli | Sp. nov | Valid | Wallaard et al. | Late Jurassic (Tithonian) | Mörnsheim Formation | Germany | A crab belonging to the group Homolodromioidea and the family Bucculentidae. |
| Bucculentum horstkuscheli | Sp. nov | Valid | Krzemińska et al. | Late Jurassic (Kimmeridgian) | | Germany | A crab belonging to the group Homolodromioidea and the family Bucculentidae. |
| Bucculentum plettenbergense | Sp. nov | Valid | Krzemińska et al. | Late Jurassic (Oxfordian) | | Germany | A crab belonging to the group Homolodromioidea and the family Bucculentidae. |
| Carpilius cantellii | Sp. nov | Valid | De Angeli & Alberti | Eocene (Bartonian-Priabonian) | | Italy | A crab, a species of Carpilius. |
| Cirolana aptiana | Sp. nov | In press | Bruce et al. | Early Cretaceous (Aptian) | Sierra Madre Formation | Mexico | A member of Isopoda, a species of Cirolana. |
| Cirolana bretoni | Sp. nov | In press | Bruce et al. | Early Cretaceous (Aptian) | Sierra Madre Formation | Mexico | A member of Isopoda, a species of Cirolana. |
| Cirolana longirostra | Sp. nov | In press | Bruce et al. | Early Cretaceous (Aptian) | Sierra Madre Formation | Mexico | A member of Isopoda, a species of Cirolana. |
| Clampethildella | Gen. et sp. nov | Valid | Beschin, Busulini & Tessier | Eocene | | Italy | A crab belonging to the family Mathildellidae. The type species is C. spinosa. |
| Collodes cumarebensis | Sp. nov | Valid | Schweitzer, Hyžný & Feldmann | | | Venezuela | A crab belonging to the family Inachoididae. |
| Cretacocalcinus | Gen. et sp. nov | In press | Ferratges, Hyžný & Zamora | Early Cretaceous (Aptian) | Forcall Formation | Spain | A hermit crab. Genus includes new species C. josaensis. |
| Cretapsara | Gen. et sp. nov | Valid | Luque in Luque et al. | Late Cretaceous (Cenomanian) | Burmese amber | Myanmar | A crab belonging to the group Eubrachyura and to the new family Cretapsaridae. The type species is C. athanata. |
| Cristinagalathea | Gen. et sp. nov | Valid | Beschin, Busulini & Tessier | Eocene | | Italy | A member of the family Munidopsidae. The type species is C. striata. |
| Crosniera forcallensis | Sp. nov | In press | Ferratges, Hyžný & Zamora | Early Cretaceous (Aptian) | Forcall Formation | Spain | A member of Axiidea belonging to the family Callianideidae. |
| Cryptolacruma | Gen. et sp. nov | Valid | Schädel et al. | Late Cretaceous (Cenomanian) | Burmese amber | Myanmar | A member of Isopoda belonging to the group Epicaridea. The type species is C. nidis. |
| Daciapagurus suebiorum | Sp. nov | Valid | Fraaije, Van Bakel & Jagt | Late Jurassic (Kimmeridgian) | | Germany | A hermit crab belonging to the family Schobertellidae. |
| Electrolana | Gen. et sp. nov | Disputed | Schädel, Hyžný & Haug | Late Cretaceous (Cenomanian) | Burmese amber | Myanmar | A member of Isopoda belonging to the group Cymothoida. The type species is E. madelineae. Bruce & Rodcharoen (2023) considered Electrolana to be a junior synonym of the genus Cirolana, though the authors maintained E. madelineae as a distinct species within the latter genus. |
| Emplastron | Gen. et comb. nov | Valid | O'Flynn, Audo & Kawai | Paleocene (Thanetian) | | France | A member of the family Astacidae; a new genus for "Astacus" edwardsi Van Straelen (1928). |
| Eocalcinus gerardbretoni | Sp. nov | Valid | Ferratges, Artal & Zamora | Eocene (Priabonian) | Arguis Formation | Spain | A hermit crab belonging to the family Calcinidae. |
| Eoinachoides bretoni | Sp. nov | In press | Garassino, Feldmann & Schweitzer | Eocene (Bartonian) | Castle Hayne Limestone | United States ( North Carolina) | A crab belonging to the family Epialtidae. |
| Eoligiiscus | Gen. et sp. nov | Valid | Sánchez-García et al. | Early Cretaceous (Albian) | Spanish amber | Spain | A member of Isopoda belonging to the family Ligiidae. The type species is E. tarraconensis. |
| Ethusa orgianensis | Sp. nov | Valid | De Angeli & Garassino | Late Eocene | | Italy | A crab, a species of Ethusa. |
| Gammaroidorum yooling | Sp. nov | Valid | Wei et al. | Late Neogene | Xiaobai Formation | China | A member of Amphipoda. |
| Glypheopsis tubantiensis | Sp. nov | Valid | Becker, Fraaije & Mulder | Early Cretaceous | | Netherlands | A member of the family Glypheidae. |
| Harthofia heidenreichetfauseri | Sp. nov | Valid | Winkler | Late Jurassic (Tithonian) | Altmühltal Formation | Germany | A member of Caridea. |
| Heraclitus | Gen. et sp. nov | Valid | Sánchez-García et al. | Early Cretaceous (Albian) | Spanish amber | Spain | A member of Isopoda belonging to the group Crinocheta, possibly a member of the family Detonidae. The type species is H. helenae. |
| Homarus fami | Sp. nov | Valid | Garassino, Pasini & Nyborg in Garassino et al. | Early Cretaceous (Albian) | | Canada ( British Columbia) | A species of Homarus. |
| Hoploparia bretoni | Sp. nov | In press | Feldmann & Schweitzer | Late Cretaceous (Campanian) | Point Loma Formation | United States ( California) | A lobster. |
| Jurastenopus | Gen. et sp. nov | Valid | Winkler et al. | Late Jurassic (Tithonian) | Painten Formation | Germany | A member of Stenopodidea. The type species is J. frattigianii. |
| Linuparus qualitus | Sp. nov | Valid | Feldmann et al. | Late Cretaceous (Turonian) | Kaskapau Formation | Canada ( British Columbia) | A species of Linuparus. |
| Mecochirus tuberculatus | Sp. nov | Valid | Garassino, Pasini & Nyborg in Garassino et al. | Early Cretaceous (Albian) | | Canada ( British Columbia) | A member of the family Mecochiridae. |
| Metanephrops serendipitus | Sp. nov | Valid | Gašparič et al. | Early Miocene | | Slovenia | A species of Metanephrops. Announced in 2021; validated in 2023. |
| Meticonaxius gracilis | Sp. nov | In press | Ferratges, Hyžný & Zamora | Early Cretaceous (Aptian) | Forcall Formation | Spain | A member of Axiidea. |
| Meyeria libanotica | Sp. nov | Valid | Charbonnier et al. | Early Cretaceous (Barremian) | | Lebanon | A member of the family Mecochiridae. |
| Miocrangon | Gen. et sp. nov | Valid | Garassino, Pasini & Nazarkin | Miocene | | Russia ( Sakhalin Oblast) | A member of the family Crangonidae. Genus includes new species M. tartaricus. |
| Mothocya vallecillae | Sp. nov | In press | Stinnesbeck et al. | Late Cretaceous (Turonian) | | Mexico | A member of Isopoda belonging to the family Cymothoidae. |
| Muellermunida | Gen. et comb. nov | Valid | Beschin, Busulini & Tessier | Eocene | Szépvölgy Formation | Hungary  Italy | A member of the family Munididae. The type species is "Protomunida" pentacantha Müller & Collins (1991); genus also includes "Eumunida" veronensis Beschin, Busulini & Tessier in Beschin et al. (2019). |
| Nahecaris sabineae | Sp. nov | Valid | Poschmann | Devonian (Emsian) | | Germany | A member of Phyllocarida. |
| Orgianocarcinus | Gen. et sp. nov | In press | De Angeli & Garassino | Eocene (Priabonian) | | Italy | A crab belonging to the family Dairidae. The type species is O. bericus. |
| Palaeastacus haidaensis | Sp. nov | Valid | Garassino, Pasini & Nyborg in Garassino et al. | Early Cretaceous (Albian) | | Canada ( British Columbia) | A member of the family Erymidae. |
| Paradasygyius rodriguezi | Sp. nov | Valid | Lima, Aguilera & Tavares | Late Miocene | | Venezuela | A spider crab belonging to the family Inachoididae. |
| Parapetrochirus | Gen. et sp. nov | Valid | Ferratges, Artal & Zamora | Eocene (Ypresian) | Roda Formation | Spain | A hermit crab belonging to the family Diogenidae. The type species is P. robustus. |
| Paromola bretoni | Sp. nov | Valid | Ferratges, Domínguez & Ossó | Eocene (Ypresian) | Roda Formation | Spain | A crab belonging to the family Homolidae. |
| Paronapaguropsis | Gen. et sp. nov | Valid | Beschin et al. | Late Eocene | | Italy | A hermit crab. Genus includes new species P. scaligera. |
| Parvucymoides | Gen. et sp. nov | Valid | Van der Wal et al. | Late Eocene | | Czech Republic | An isopod belonging to the family Cymothoidae. The type species is P. dvorakorum. |
| Petersbuchia | Gen. et sp. nov | Valid | Schweigert | Late Jurassic (Kimmeridgian) | Treuchtlingen Formation | Germany | A crab belonging to the group Homolodromioidea and the family Prosopidae. The type species is P. thauckei. Announced in 2021 in an online-only journal; validated in 2023. |
| Plakolana chiapaneca | Sp. nov | In press | Bruce et al. | Early Cretaceous (Aptian) | Sierra Madre Formation | Mexico | A member of Isopoda belonging to the family Cirolanidae. |
| Platuropodus | Gen. et sp. nov | Valid | Pazinato et al. | Permian (Kungurian) | Irati Formation | Brazil | A member of Isopoda. The type species is P. odysseus. |
| Protaxius paucisaetosus | Sp. nov | In press | Andrada et al. | Early Cretaceous (Hauterivian) | Agrio Formation | Argentina | A member of the family Axiidae. |
| Pseudonecrocarcinus eichhorni | Sp. nov | In press | Nyborg et al. | Late Cretaceous (Coniacian) | | United States ( Montana) | A crab belonging to the group Raninoida and the family Paranecrocarcinidae. |
| Stenodactylina shotoverigiganti | Sp. nov | Valid | Devillez & Charbonnier | Late Jurassic (Oxfordian) | | United Kingdom | A member of Erymoidea. |
| Tyrannosculda | Gen. et sp. nov | Valid | Haug & Haug | Late Jurassic (Tithonian) | Altmühltal Group (Eichstätt Subformation) | Germany | A mantis shrimp. The type species is T. laurae. |
| Vicetitrapezia | Gen. et sp. nov | Valid | Beschin, Busulini & Tessier | Eocene | | Italy | A crab belonging to the superfamily Trapezioidea; the type genus of the new family Vicetitrapeziidae. The type species is V. exaltissimo. |
| Willinachoides | Gen. et sp. nov | Valid | Lima, Aguilera & Tavares | Early-middle Miocene | | Brazil | A spider crab belonging to the family Inachoididae. Genus includes new species W. santanai. |
| Xanthodius falconensis | Sp. nov | Valid | Schweitzer, Hyžný & Feldmann | | | Venezuela | A species of Xanthodius. |
| Xiaopenaeus | Gen. et sp. nov | Valid | Xing et al. | Late Cretaceous (Cenomanian) | Burmese amber | Myanmar | A member of the family Penaeidae. Genus includes new species X. electrinus. |

#### Ostracods

| Name | Novelty | Status | Authors | Age | Type locality | Country | Notes |
| Aracajuia separatta | Sp. nov | In press | Vázquez García et al. | Cretaceous (Albian–Cenomanian) | Riachuelo Formation | Brazil | |
| Aurikirkbya guadalupensis | Sp. nov | Valid | Crasquin in Tarnac et al. | Permian (Roadian) | Cutoff Formation | United States ( Texas) | A member of Palaeocopida belonging to the family Kirkbyidae. |
| Aurila bassiounii | Sp. nov | Valid | Sciuto & Reitano | Early Pliocene | | Italy | |
| Aurila burolleti | Sp. nov | Valid | Sciuto, Temani & Ammar | Miocene (Messinian) | | Tunisia | |
| Aurila castanyi | Sp. nov | Valid | Sciuto, Temani & Ammar | Miocene (Messinian) | | Tunisia | |
| Aurila dipattii | Sp. nov | Valid | Sciuto & Reitano | Early Pliocene | | Italy | |
| Aurila doruki | Sp. nov | Valid | Sciuto, Temani & Ammar | Miocene (Messinian) | | Tunisia | |
| Aurila nocellae | Sp. nov | Valid | Sciuto & Reitano | Early Pliocene | | Italy | |
| Aurila violai | Sp. nov | Valid | Sciuto & Reitano | Early Pliocene | | Italy | |
| Aurila zargounii | Sp. nov | Valid | Sciuto, Temani & Ammar | Miocene (Messinian) | | Tunisia | |
| Bairdia elcapitanensis | Sp. nov | Valid | Crasquin in Tarnac et al. | Permian (Roadian) | Cutoff Formation | United States ( Texas) | A member of the family Bairdiidae. |
| Baschkirina tesakovae | Sp. nov | Valid | Melnikova et al. | Silurian | Syadai Formation | Russia | |
| Bythoceratina antetumida | Nom. nov | Valid | Slipper | Late Cretaceous (Turonian) | | United Kingdom | |
| Callistocythere sissinghi | Sp. nov | Valid | Sciuto, Temani & Ammar | Miocene (Messinian) | | Tunisia | |
| Candona dawenkouensis | Sp. nov | In press | Wang et al. | Middle Eocene to Oligocene | Dawenkou Formation | China | A species of Candona. |
| Candona phaseolus | Sp. nov | In press | Kshetrimayum et al. | Late Cretaceous (Maastrichtian) | | India | A species of Candona. |
| Capsacythere narjessae | Sp. nov | Valid | Sciuto & Reitano | Early Pliocene | | Italy | |
| Carinocythereis carboneli | Sp. nov | Valid | Sciuto, Temani & Ammar | Miocene (Messinian) | | Tunisia | |
| Cavellina septima | Sp. nov | Valid | Jones, Kelman & Laurie | Carboniferous (Mississippian) | | Australia | |
| Ceratobairdia mescaleroella | Sp. nov | Valid | Forel in Tarnac et al. | Permian (Capitanian) | Bell Canyon Formation | United States ( Texas) | A member of the family Bairdiidae. |
| Ceratobairdia pratti | Sp. nov | Valid | Forel in Tarnac et al. | Permian (Roadian) | Cutoff Formation | United States ( Texas) | A member of the family Bairdiidae. |
| Ceratobairdia sexagintaduella | Sp. nov | Valid | Forel in Tarnac et al. | Permian (Roadian) | Cutoff Formation | United States ( Texas) | A member of the family Bairdiidae. |
| Chrysocythere nevianii | Sp. nov | Valid | Sciuto, Temani & Ammar | Miocene (Messinian) | | Tunisia | |
| Cimbaurila mariellae | Sp. nov | Valid | Sciuto, Temani & Ammar | Miocene (Messinian) | | Tunisia | |
| Cistacythereis merzeraudi | Sp. nov | Valid | Sciuto, Temani & Ammar | Miocene (Messinian) | | Tunisia | |
| Cistacythereis purii | Sp. nov | Valid | Sciuto, Temani & Ammar | Miocene (Messinian) | | Tunisia | |
| Cypridea khandae | Sp. nov | In press | Choi et al. | Early Cretaceous (Albian) | Jinju Formation | South Korea | |
| Cytherelloidea alexanderi | Sp. nov | Valid | Sciuto & Reitano | Early Pliocene | | Italy | |
| Cytherelloidea ardita | Sp. nov | Valid | Sciuto & Reitano | Early Pliocene | | Italy | |
| Cytherelloidea slipperi | Sp. nov | Valid | Sciuto & Reitano | Early Pliocene | | Italy | |
| Cytherelloidea temaniae | Sp. nov | Valid | Sciuto & Reitano | Early Pliocene | | Italy | |
| Cytheridea jonesi | Sp. nov | Valid | Sciuto, Temani & Ammar | Miocene (Messinian) | | Tunisia | |
| Cytheropterina crassicostata | Sp. nov | Valid | Wannenmacher et al. | Middle Jurassic (Aalenian) | Achdorf Formation | Germany | A member of the family Cytheruridae. |
| Cytheropteron laranjeirensis | Sp. nov | In press | Vázquez García et al. | Cretaceous (Albian–Cenomanian) | Riachuelo Formation | Brazil | |
| Denticupachydomella bellcanyonensis | Sp. nov | Valid | Crasquin in Tarnac et al. | Permian (Capitanian) | Bell Canyon Formation | United States ( Texas) | A member of Podocopida belonging to the family Microcheilinellidae. |
| Echinocythereis clavata | Sp. nov | Valid | Sciuto & Reitano | Early Pliocene | | Italy | |
| Echinocythereis multituberculata | Sp. nov | Valid | Sciuto & Reitano | Early Pliocene | | Italy | |
| Eucytherura eberti | Sp. nov | Valid | Wannenmacher et al. | Middle Jurassic (Aalenian) | Achdorf Formation | Germany | A member of the family Cytheruridae. |
| Eucytherura fossapunctata | Sp. nov | In press | Maia et al. | Late Pleistocene | | Brazil | |
| Eucytherura foveolata | Sp. nov | Valid | Wannenmacher et al. | Middle Jurassic (Aalenian) | Opalinuston Formation | Germany | A member of the family Cytheruridae. |
| Eucytherura regina | Sp. nov | Valid | Sciuto & Reitano | Early Pliocene | | Italy | |
| Eurybolbina uralica | Sp. nov | Valid | Melnikova et al. | Silurian | Syadai Formation | Russia | |
| Evlanella? conversa | Sp. nov | Valid | Jones, Kelman & Laurie | Carboniferous (Mississippian) | Bonaparte Basin | Australia | |
| Geisina culbersonensis | Sp. nov | Valid | Crasquin in Tarnac et al. | Permian (Roadian) | Cutoff Formation | United States ( Texas) | A member of Palaeocopida belonging to the family Geisinidae. |
| Glyptolichvinella acrista | Sp. nov | Valid | Jones, Kelman & Laurie | Carboniferous (Mississippian) | | Australia | |
| Gomphocythere testudo | Sp. nov | In press | Kshetrimayum et al. | Late Cretaceous (Maastrichtian) | | India | |
| Healdia cutoffella | Sp. nov | Valid | Crasquin in Tarnac et al. | Permian (Roadian) | Cutoff Formation | United States ( Texas) | A member of Podocopa belonging to the family Healdiidae. |
| Healdia mckittrickensis | Sp. nov | Valid | Crasquin in Tarnac et al. | Permian (Roadian to Capitanian) | Bell Canyon Formation | United States ( Texas) | A member of Podocopa belonging to the family Healdiidae. |
| Healdia veeversi | Sp. nov | Valid | Jones, Kelman & Laurie | Carboniferous (Mississippian) | Bonaparte Basin | Australia | |
| Healdiacypris drucei | Sp. nov | Valid | Jones, Kelman & Laurie | Carboniferous (Mississippian) | Bonaparte Basin | Australia | |
| Healdianella ogmoconchelloides | Sp. nov | Valid | Jones, Kelman & Laurie | Carboniferous (Mississippian) | Bonaparte Basin | Australia | |
| Hollinella locula | Sp. nov | In press | Forel in Forel, Poulet-Crovisier & Korat | Late Permian and Early Triassic | Daye Formation Feixianguan Formation Kayitou Formation Longtan Formation Xuanwei Formation | China | A member of Palaeocopida. |
| Hollinella williamsranchensis | Sp. nov | Valid | Crasquin in Tarnac et al. | Permian (Roadian to Capitanian) | Bell Canyon Formation | United States ( Texas) | A member of Palaeocopida belonging to the family Hollinellidae. |
| Idiocythere caburnensis | Sp. nov | Valid | Slipper | Late Cretaceous (Turonian) | | United Kingdom | |
| Isocythereis postelongata | Sp. nov | Valid | Slipper | Late Cretaceous (Turonian) | | United Kingdom | |
| Jenningsina guilinensis | Sp. nov | In press | Song et al. | Late Devonian | | China | |
| Karsteneis oculocosta | Sp. nov | Valid | Slipper | Late Cretaceous (Turonian) | | United Kingdom | |
| Mauritsina? paradordoniensis | Sp. nov | Valid | Slipper | Late Cretaceous (Turonian) | | United Kingdom | |
| Mediocytherideis hornei | Sp. nov | Valid | Sciuto, Temani & Ammar | Miocene (Messinian) | | Tunisia | |
| Microxestoleberis riachuelensis | Sp. nov | In press | Vázquez García et al. | Cretaceous (Albian–Cenomanian) | Riachuelo Formation | Brazil | |
| Monoceratina minangulata | Sp. nov | Valid | Slipper | Late Cretaceous (Turonian) | | United Kingdom | |
| Neomonoceratina lajmii | Sp. nov | Valid | Sciuto, Temani & Ammar | Miocene (Messinian) | | Tunisia | |
| Neomonoceratina morkhoweni | Sp. nov | Valid | Sciuto, Temani & Ammar | Miocene (Messinian) | | Tunisia | |
| Neomonoceratina mostafawii | Sp. nov | Valid | Sciuto, Temani & Ammar | Miocene (Messinian) | | Tunisia | |
| Neomonoceratina reussi | Sp. nov | Valid | Sciuto, Temani & Ammar | Miocene (Messinian) | | Tunisia | |
| Okadaleberis azouzi | Sp. nov | Valid | Sciuto, Temani & Ammar | Miocene (Messinian) | | Tunisia | |
| Pachycaudites yassinii | Sp. nov | Valid | Sciuto & Reitano | Early Pliocene | | Italy | |
| Paracavellina olempskae | Sp. nov | Valid | Jones, Kelman & Laurie | Carboniferous (Mississippian) | Bonaparte Basin | Australia | |
| Parahemingwayela fauthi | Sp. nov | In press | Vázquez García et al. | Cretaceous (Albian–Cenomanian) | Riachuelo Formation | Brazil | |
| Paraparchites pecosensis | Sp. nov | Valid | Crasquin in Tarnac et al. | Permian (Roadian to Capitanian) | Cutoff Formation | United States ( Texas) | A member of Podocopa belonging to the family Paraparchitidae. |
| Patellacythere weaveri | Sp. nov | Valid | Slipper | Late Cretaceous (Turonian) | | United Kingdom | |
| Peteraurila carbonneli | Sp. nov | Valid | Sciuto, Temani & Ammar | Miocene (Messinian) | | Tunisia | |
| Peteraurila moisettei | Sp. nov | Valid | Sciuto, Temani & Ammar | Miocene (Messinian) | | Tunisia | |
| Peteraurila nachitei | Sp. nov | Valid | Sciuto, Temani & Ammar | Miocene (Messinian) | | Tunisia | |
| Peteraurila ulicznyi | Sp. nov | Valid | Sciuto, Temani & Ammar | Miocene (Messinian) | | Tunisia | |
| Pleurocythere khapissovi | Sp. nov | Valid | Glinskikh & Tesakova | Middle Jurassic (Callovian) | | Russia | |
| Polycope lazarusi | Sp. nov | Valid | Forel in Forel & Grădinaru | Triassic | | Romania | A member of the family Polycopidae. |
| Polycope legio | Sp. nov | Valid | Forel in Forel & Grădinaru | Triassic | | Romania | A member of the family Polycopidae. |
| Polycope ludwigi | Sp. nov | Valid | Forel in Forel & Grădinaru | Triassic | | Romania | A member of the family Polycopidae. |
| Pontopolycope jeanlouisi | Sp. nov | Valid | Forel in Forel & Grădinaru | Triassic | | Romania | A member of the family Polycopidae. |
| Pontopolycope papai | Sp. nov | Valid | Forel in Forel & Grădinaru | Triassic | | Romania | A member of the family Polycopidae. |
| Pseudocytherura carolinae | Sp. nov | Valid | Sciuto & Reitano | Early Pliocene | | Italy | |
| Pseudomutilus | Gen. et sp. nov | Valid | Sciuto in Sciuto & Benkhedda | Miocene (Tortonian) | | Algeria | A member of the family Trachyleberididae. The type species is P. benkheddai. |
| Pterygocythereis carolinae | Sp. nov | Valid | Slipper | Late Cretaceous (Turonian) | | United Kingdom | |
| Quasiagrenocythere | Gen. et sp. nov | Valid | Sciuto in Sciuto & Benkhedda | Miocene (Tortonian) | | Algeria | A member of the family Trachyleberididae. The type species is Q. tevestaensis. |
| Quasihermanites? punctata | Sp. nov | In press | Vázquez García et al. | Cretaceous (Albian–Cenomanian) | Riachuelo Formation | Brazil | |
| Rehacythereis stellatus | Sp. nov | Valid | Slipper | Late Cretaceous (Turonian) | | United Kingdom | |
| Reversocypris australis | Sp. nov | Valid | Jones, Kelman & Laurie | Carboniferous (Mississippian) | Bonaparte Basin | Australia | |
| Schuleridea langdonensis | Sp. nov | Valid | Slipper | Late Cretaceous (Turonian) | | United Kingdom | |
| Syadaikinia | Gen. et sp. nov | Valid | Melnikova et al. | Silurian | Syadai Formation | Russia | The type species is S. tumidosa. |
| Tenedocythere uffenordei | Sp. nov | Valid | Sciuto & Reitano | Early Pliocene | | Italy | |
| Tschigovana thomasi | Sp. nov | Valid | Jones, Kelman & Laurie | Carboniferous (Mississippian) | | Australia | |
| Urocythere (Pokornyella) bremani | Sp. nov | Valid | Sciuto, Temani & Ammar | Miocene (Messinian) | | Tunisia | |

#### Other crustaceans

| Name | Novelty | Status | Authors | Age | Type locality | Country | Notes |
| Carapacestheria? lulworthensis | Sp. nov | In press | Li, Teng & Wimbledon | Late Jurassic/Early Cretaceous | Purbeck Group | United Kingdom | A clam shrimp. |
| Chelonibia zanzibarensis | Sp. nov | In press | Collareta & Newman in Collareta et al. | Miocene | Chake-Chake beds | Tanzania | A barnacle, a species of Chelonibia. |
| Concinnalepas bessinensis | Sp. nov | In press | Gale | Middle Jurassic (Bathonian) | | France | A barnacle. |
| Concinnalepas rugosa | Sp. nov | In press | Gale | Late Jurassic (Tithonian) | Kimmeridge Clay | United Kingdom | A barnacle. |
| Cornia cheni | Sp. nov | Valid | Liao & Shen | Early Devonian | | China | A clam shrimp. |
| Gibbosaverruca milazzoensis | Sp. nov | Valid | Gale | Plio-Pleistocene | | Italy | A barnacle. |
| Malayacyclus | Gen. et sp. nov | Valid | Tang, Mychko, Feldmann & Schweitzer in Tang et al. | Carboniferous (Viséan) | | Malaysia | A member of Cyclida. Genus includes new species M. terengganuensis. Announced in 2021; validated in 2023. |
| Palaeolimnadiopsis zhangi | Sp. nov | Valid | Liao & Shen | Early Devonian | | China | A clam shrimp. |
| Solidobalanus digeronimoi | Sp. nov | Valid | Gale | Plio-Pleistocene | | Italy | A barnacle. |

### Research

* A study on the anatomy and phylogenetic relationships of the species "Penaeus" natator from the Santonian of Lebanon is published by Audo, Winkler & Charbonnier (2021), who interpret this species as a relative of Pseudodrobna kenngotti from the Late Jurassic of Germany, and transfer it to the genus Pseudodrobna
* A study on the anatomy and morphological variation in Beurlenia araripensis, based on data from fossil samples from the Crato Formation (Brazil), is published by Barros et al. (2021).
* A study on the anatomy of the eyes of Callichimaera perplexa, and on their growth during the ontogeny of this crab, is published by Jenkins, Briggs & Luque (2021).
* A study on the anatomy and phylogenetic relationships of Oxyuropoda is published by Robin et al. (2021), who interpret this arthropod as the oldest known member of the crown group of Peracarida.
* Fossil evidence of early colonization of estuarine settings by ostracods is reported from the Silurian Si Ka Formation (Vietnam) by McGairy et al. (2021)
* A study on evolutionary trends in sexual dimorphism of cytheroid ostracods from the Gulf and Atlantic coastal plain from the Late Cretaceous to the late Eocene is published by Matzke-Karasz & Smith (2021).

## Radiodonts
### New taxa

| Name | Novelty | Status | Authors | Age | Type locality | Country | Notes | Images |
| Buccaspinea | Gen. et sp. nov | Valid | Pates et al. | Cambrian (Drumian) | Marjum Formation | United States ( Utah) | A hurdiid radiodont. The type species is B. cooperi. | |
| Houcaris | Gen. et comb. nov | Valid | Wu et al. | Cambrian Series 2 | Carrara Formation Maotianshan Shales Pioche Formation | China  United States | A tamisiocaridid radiodont. Type species "Anomalocaris" saron (1995); Also includes "Anomalocaris" magnabasis (2019). | Houcaris saron |
| Lenisicaris | Gen. et sp. et comb. nov | In press | Wu et al. | Cambrian | | China  United States | An anomalocaridid radiodont. Type species L. lupata, L. pennsylvanica moved from "Anomalocaris" pennsylvanica (1929). | Lenisicaris lupata |
| Paranomalocaris simplex | Sp. nov | Valid | Jiao et al. | Cambrian Stage 4 | Wulongqing Formation | China | An anomalocaridid radiodont. | |
| Titanokorys | Gen. et sp. nov | Valid | Caron & Moysiuk | Cambrian (Wuliuan) | Burgess Shale | Canada ( British Columbia) | A hurdiid radiodont. The type species is T. gainesi. | |

### Research

* A study on the morphologies of frontal appendages and probable modes of feeding of radiodonts from the Burgess Shale is published by De Vivo, Lautenschlager & Vinther (2021).

## Trilobites
### New taxa

| Name | Novelty | Status | Authors | Age | Type locality | Location | Notes |
| Acuticryphops prorotundus | Sp. nov | In press | Feist & Klapper | Devonian (Frasnian) | | France | A member of the family Phacopidae. |
| Acutiphacops | Gen. et 2 sp. et comb. nov | In press | Feist & Klapper | Late Devonian | | France  Morocco | A member of the family Phacopidae. The type species is A. medius; genus also includes new species A. tchrafinensis, as well as "Phacops" erfoudensis Richter & Richter (1943). |
| Ampulliglabella arakii | Sp. nov | Valid | Flick & Shiino | Permian (probably Wordian) | Hoso-o Formation | Japan | |
| Anadesma | Gen. et comb. nov | Valid | Holloway | Silurian (late Aeronian to early Telychian) | | Canada | A member of Lichida belonging to the family Lichidae; a new genus for "Amphilichas" shallopensis Twenhofel (1928). |
| Arctinurus aorter | Sp. nov | Valid | Holloway | Silurian | | United States | A member of Lichida belonging to the family Lichidae. |
| Asioptychaspis lata | Sp. nov | In press | Wernette et al. | Cambrian (Furongian) | Myet-Ye Formation | Myanmar | |
| Belenopyge bellerophon | Sp. nov | Valid | Flick | Devonian | Greifenstein Limestone | Germany | |
| Bollandia reviviscens | Sp. nov | Valid | Gandl | Carboniferous | | Spain | A member of the family Phillipsiidae belonging to the subfamily Bollandiinae. |
| Brachymetopus (Acutimetopus) laticeps | Sp. nov | Valid | Gandl | Carboniferous | | Spain | A member of the family Brachymetopidae belonging to the subfamily Brachymetopinae. |
| Celadiella | Gen. et sp. nov | Valid | Gandl | Carboniferous | | Spain | A member of the family Phillipsiidae belonging to the subfamily Ditomopyginae. Genus includes new species C. celadensis. |
| Cheiropyge radula | Sp. nov | Valid | Flick & Shiino | Permian (probably Wordian) | Hoso-o Formation | Japan | |
| Chlupacops angularis | Sp. nov | In press | Feist & Klapper | Devonian (Frasnian) | | France | A member of the family Phacopidae. |
| Chlupacops clapassousensis | Sp. nov | In press | Feist & Klapper | Devonian (Frasnian) | | France | A member of the family Phacopidae. |
| Chlupacops migrans | Sp. nov | In press | Feist & Klapper | Devonian (Frasnian) | Serre Formation | France | A member of the family Phacopidae. |
| Chlupacops narbonnensis | Sp. nov | In press | Feist & Klapper | Devonian (Frasnian) | | France | A member of the family Phacopidae. |
| Chlupacops rectannulatus | Sp. nov | In press | Feist & Klapper | Devonian (Frasnian) | Serre Formation | France | A member of the family Phacopidae. |
| Chotecops morrisoni | Sp. nov | Valid | Flick | Devonian | Günterod Limestone | Germany | |
| Cinerana | Gen. et sp. nov | Valid | Gandl | Carboniferous | | Spain | Possibly a member of the family Phillipsiidae. Genus includes new species C. matallanensis. |
| Cronierella | Gen. et 3 sp. et comb. nov | In press | Feist & Klapper | Late Devonian | Serre Formation | France  Poland | A member of the family Phacopidae. The type species is C. gallica; genus also includes new species C. postera and C. expansa, as well as "Phacops" zofiae Chlupáč (1993). |
| Ctenopyge magna | Sp. nov | Valid | Nielsen & Andersen | Cambrian (Furongian) | Alum Shale Formation | Denmark | A member of the family Olenidae. |
| Cydonocephalus tiffanyae | Sp. nov | Valid | Adrain & Pérez-Peris | Ordovician (Darriwilian) | Table Cove Formation | Canada ( Newfoundland and Labrador) | A member of Acanthoparyphinae. |
| Diacanthaspis tricosa | Sp. nov | Valid | Holloway | Silurian | | United States | A member of the family Odontopleuridae. |
| Dicranopeltis eretes | Sp. nov | Valid | Holloway | Silurian | | United States | A member of Lichida belonging to the family Lichidae. |
| Dicranopeltis kallaion | Sp. nov | Valid | Holloway | Silurian | | United States | A member of Lichida belonging to the family Lichidae. |
| Ditomopyge benkei | Sp. nov | Valid | Flick & Shiino | Permian (probably Wordian) | Hoso-o Formation | Japan | |
| Ditomopyge (Carniphillipsia) cantamudensis | Sp. nov | Valid | Gandl | Carboniferous | | Spain | A member of the family Phillipsiidae belonging to the subfamily Ditomopyginae. |
| Ditomopyge (Carniphillipsia) castelleriae | Sp. nov | Valid | Gandl | Carboniferous | | Spain | A member of the family Phillipsiidae belonging to the subfamily Ditomopyginae. |
| Dohmiella pachyacanthophilia | Sp. nov | Valid | Van Viersen | Devonian (Emsian) | | Spain | |
| Dohmiella pooka | Sp. nov | Valid | Van Viersen | Devonian (Eifelian) | | Belgium | |
| Eccaparadoxides epimetheus | Sp. nov | In press | Geyer, Landing & Żylińska | Cambrian (Miaolingian) | Jbel Wawrmast Formation | Morocco | A member of the family Paradoxididae. |
| Eccaparadoxides? hestia | Sp. nov | In press | Geyer, Landing & Żylińska | Cambrian (Miaolingian) | Jbel Wawrmast Formation | Morocco | A member of the family Paradoxididae. |
| Eccaparadoxides zelus | Sp. nov | In press | Geyer, Landing & Żylińska | Cambrian (Miaolingian) | Delitzsch Formation | Germany | A member of the family Paradoxididae. |
| Ehmaniella tupeqarfik | Sp. nov | Valid | Peel | Cambrian (Wuliuan) | Telt Bugt Formation | Greenland | A member of the family Alokistocaridae. |
| Eisarkaspis jonesi | Sp. nov | Valid | Smith & Laurie | Ordovician (Darriwilian) | | Australia | |
| Eldoradia caerulioris | Sp. nov | Valid | Peel | Cambrian (Guzhangian) | Blue Cliffs Formation | Greenland | A member of the family Bolaspididae. |
| Fieldaspis? iubilaei | Sp. nov | Valid | Peel | Cambrian (Wuliuan) | Telt Bugt Formation | Greenland | A member of the family Zacanthoididae. |
| Gerastos cornix | Sp. nov | Valid | Van Viersen | Devonian (Eifelian) | | Belgium | |
| Ghanaspis | Gen. et sp. nov | Valid | Smith & Laurie | Ordovician (Darriwilian) | | Australia | Genus includes new species G. ritchiei. |
| Girardina | Gen. et 2 sp. nov | In press | Feist & Klapper | Devonian (Frasnian) | | France  Germany | A member of the family Phacopidae. The type species is G. konradbartzschi; genus also includes new species G. consimilis, and possibly also "Phacops" liopyga Richter (1863). |
| Gonioteloides moffitti | Sp. nov | Valid | Adrain & Karim | Ordovician (Tremadocian) | | United States | Possibly a member of the family Dimeropygidae. |
| Gonioteloides pankowskii | Sp. nov | Valid | Adrain & Karim | Ordovician (Tremadocian) | | United States | Possibly a member of the family Dimeropygidae. |
| Griffithides inexpectatus | Sp. nov | Valid | Gandl | Carboniferous | | Spain | A member of the family Phillipsiidae belonging to the subfamily Griffithidinae. |
| Harebayaspis | Gen. et sp. nov | Valid | Adrain & Pérez-Peris | Ordovician (Darriwilian) | Table Cove Formation | Canada ( Newfoundland and Labrador) | A member of Pilekiinae. The type species is H. plurima. |
| Illaenus taoyuanensis | Sp. nov | Valid | Wei et al. | Ordovician (Darriwilian) | | China | |
| Iridis | Gen. et sp. nov | Valid | Smith & Laurie | Ordovician (Darriwilian) | | Australia | Genus includes new species I. schoonorum. |
| Kaotaia xuanensis | Sp. nov | In press | Hughes et al. | Cambrian (Miaolingian) | | Vietnam | |
| Kawina stougei | Sp. nov | Valid | Adrain & Pérez-Peris | Ordovician (Darriwilian) | Table Cove Formation | Canada ( Newfoundland and Labrador) | A member of Acanthoparyphinae. |
| Koneprusia dongesi | Sp. nov | Valid | Alberti & Müller | Devonian (Emsian) | Rupbach Shales | Germany | A member of the family Odontopleuridae. |
| Koneprusites amicalis | Sp. nov | Valid | Flick | Devonian | Günterod Limestone | Germany | |
| Koneprusites cervisiaemontis | Sp. nov | Valid | Flick | Devonian | Günterod Limestone | Germany | |
| Leonaspis glaux | Sp. nov | Valid | Flick & Flick | Devonian (Emsian) | Ballersbach Limestone | Germany | A member of the family Odontopleuridae. |
| Lycophron titan | Sp. nov | Valid | Smith & Laurie | Ordovician (Darriwilian) | | Australia | |
| Mainbrookia | Gen. et sp. nov | Valid | Adrain & Pérez-Peris | Ordovician (Darriwilian) | Table Cove Formation | Canada ( Newfoundland and Labrador) | A member of Deiphoninae. The type species is M. becki. |
| Mioptychopyge chengkouensis | Sp. nov | Valid | Wei et al. | Ordovician | Houping Formation | China | |
| Miraspis capnica | Sp. nov | Valid | Holloway | Silurian | | United States | A member of the family Odontopleuridae. |
| Morocops richterorum | Sp. nov | Valid | Flick | Devonian | Greifenstein Limestone | Germany | A member of the family Phacopidae. |
| Namuropyge alfredi | Sp. nov | Valid | Müller, Hahn & Paul | Carboniferous (Viséan) | | Germany | A member of the family Brachymetopidae. |
| Namuropyge brooksi | Sp. nov | Valid | Müller, Hahn & Paul | Carboniferous (Mississippian) | Cuyahoga Formation | United States ( Ohio) | A member of the family Brachymetopidae. |
| Namuropyge ulrichi | Sp. nov | Valid | Müller, Hahn & Paul | Carboniferous (Viséan) | | Germany | A member of the family Brachymetopidae. |
| Neogriffithides extremorientalis | Sp. nov | Valid | Flick & Shiino | Permian (probably Wordian) | Hoso-o Formation | Japan | |
| Newfoundlandops | Gen. et sp. nov | Valid | Adrain & Pérez-Peris | Ordovician (Darriwilian) | Table Cove Formation | Canada ( Newfoundland and Labrador) | Possibly a member of Sphaerexochinae. The type species is N. karimae. |
| Nileus yichongqiaoensis | Sp. nov | Valid | Wei et al. | Ordovician (Darriwilian) | | China | |
| Norasaphus (Norasaphus) patersoni | Sp. nov | Valid | Smith & Laurie | Ordovician (Darriwilian) | | Australia | |
| Nyterops fugax | Sp. nov | Valid | Van Viersen & Koppka | Devonian (Givetian) | Hanonet Formation | Belgium | A member of the family Phacopidae. |
| Nyterops gerolsteinensis | Sp. nov | Valid | Van Viersen & Koppka | Devonian (Eifelian?) | | Germany | A member of the family Phacopidae. |
| Occitanella | Gen. et 2 sp. nov | In press | Feist & Klapper | Devonian (Frasnian) | | France  Australia? | A member of the family Phacopidae. The type species is O. hexagonalis; genus also includes new species O. postinflexa, and possibly also "Trimerocephaloides" linguiformis Feist et al. (2009). |
| Octobronteus? incertus | Sp. nov | Valid | Holloway | Silurian | | United States | A member of the family Scutelluidae. |
| Octobronteus? ormistoni | Sp. nov | Valid | Holloway | Silurian | | United States | A member of the family Scutelluidae. |
| Octobronteus? petasus | Sp. nov | Valid | Holloway | Silurian | | United States | A member of the family Scutelluidae. |
| Panderia striolatus | Sp. nov | Valid | Wei et al. | Ordovician (Darriwilian) | | China | |
| Paratiresias peculiaris | Sp. nov | Valid | Wei et al. | Ordovician (Darriwilian) | | China | |
| Pedinopariops apsconditus | Sp. nov | Valid | Van Viersen & Koppka | Devonian (Eifelian) | Jemelle Formation | Belgium | A member of the family Phacopidae. |
| Planiscutellum apollo | Sp. nov | Valid | Holloway | Silurian (Aeronian) | | Canada | A member of the family Scutelluidae. |
| Pseudohelmutia | Gen. et sp. nov | Valid | Basse & Müller | Early Devonian | | Germany | A member of the subfamily Proetinae. Genus includes new species P. feisti. |
| Rupbachella | Gen. et sp. nov | Disputed | Alberti | Devonian (Emsian) | Rupbach Shale | Germany | A member of the family Odontopleuridae. The type species is R. paedomorpha. Van Viersen (2024) considered R. paedomorpha to be a junior synonym of Leonaspis kleini. |
| Sinagnostus | Gen. et sp. nov | Valid | Wei et al. | Ordovician (Darriwilian) | | China | Genus includes new species S. mirabilis. |
| Solenoparia changi | Sp. nov | Valid | Sun, Bentley & Laurie | Cambrian (Guzhangian) | Warburton Basin | Australia | |
| Timsaloproetus alissae | Sp. nov | Valid | Van Viersen & Lerouge | Devonian (Emsian) | | Morocco | A member of the family Proetidae. |
| Trochurus searcyensis | Sp. nov | Valid | Holloway | Silurian | | United States | A member of Lichida belonging to the family Lichidae. |
| Unguliproetus chamaeleo | Sp. nov | Valid | Flick | Devonian | Ballersbach Limestone | Germany | |
| Unguliproetus fredknoppi | Sp. nov | Valid | Basse & Müller | Early Devonian | | Germany | A member of the subfamily Proetinae. |
| Valberzosa | Gen. et sp. nov | Valid | Gandl | Carboniferous | | Spain | A member of the family Phillipsiidae belonging to the subfamily Bollandiinae. Genus includes new species V. rara. |
| Waideggula (Camasobrina) verdenensis | Sp. nov | Valid | Gandl | Carboniferous | | Spain | A member of the family Phillipsiidae belonging to the subfamily Ditomopyginae. |
| Waideggula (Waideggula) cantabrica tabardina | Ssp. nov | Valid | Gandl | Carboniferous | | Spain | A member of the family Phillipsiidae belonging to the subfamily Ditomopyginae. |
| Waideggula (Waideggula) pedregalensis | Sp. nov | Valid | Gandl | Carboniferous | | Spain | A member of the family Phillipsiidae belonging to the subfamily Ditomopyginae. |
| Weania insulana | Sp. nov | Valid | Flick & Shiino | Permian (probably Wordian) | Hoso-o Formation | Japan | |
| Yanpingia | Gen. et sp. nov | Valid | Wei et al. | Ordovician (Darriwilian) | | China | Genus includes new species Y. punctata. |

### Research

* A study on middle–late Cambrian trilobite diversity patterns in South China is published by Zhang et al. (2021).
* Sun, Zeng & Zhao (2021) describe digestive structures of representatives of five trilobite genera from the Cambrian Mantou Formation and Zhangxia Formation (Liaoning, China).
* Hou, Hughes & Hopkins (2021) report structural details of the upper limb branch of Triarthrus eatoni and Olenoides serratus, and interpret their findings as indicating that the upper limb branch of trilobites served a respiratory function.
* A study on the morphology of Redlichia rex and Olenoides serratus, aiming to determine whether these trilobites were adapted for durophagy, is published by Bicknell et al. (2021).
* A study exploring the existence and the nature of growth gradients along the main body axis of Oryctocarella duyunensis is published by Dai et al (2021), who interpret O. duyunensis as the first trilobite with documented determinate growth.
* Description of all meraspid stages of Oryctocarella duyunensis, based on data from specimens from the Cambrian Balang Formation (Hunan, South China), is published by Dai et al. (2021).
* A study on the ontogenic moulting sequence of Arthricocephalites xinzhaiheensis, based on data from specimens from the Balang Formation, is published by Wang et al. (2021).
* A study on post-embryonic axial growth in Estaingia bilobata is published by Holmes, Paterson & García-Bellido (2021).
* A study on the functional performance of Placoparia cambriensis in water is published by Esteve et al. (2021), who interpret their findings as indicating that this trilobite was not able to swim, but it was capable of hopping locomotion, and it might represent a transitional form between benthic animals without swimming skills and animals able to swim near the benthos.
* A study on the phylogenetic relationships within Harpetida, and on the impact of the Ordovician–Silurian extinction events on this group, is published by Beech & Lamsdell (2021).
* The first known Silurian trilobite specimen preserved with soft parts reported to date (a specimen of Dalmanites preserved with appendages and alimentary system) is described from the Herefordshire Lagerstätte (United Kingdom) by Siveter et al. (2021).
* A study on the long-term evolutionary history of Devonian trilobites in North Africa is published by Bault et al. (2021).
* A study on the hydrodynamics of queuing behaviour in Trimerocephalus chopini is published by Song et al. (2021).
* Evidence from trace and body fossils indicative of the presence of trilobites in brackish-water settings is presented by Mángano et al. (2021).
* A study on the chemical changes in the exoskeleton of trilobites induced by diagenesis, based on data from pygidia of Athabaskia anax from the Miaolingian of San Isidro (Argentina), is published by D'Angelo et al. (2021), is published by D'Angelo et al. (2021), who argue that some morphological characteristics of the trilobite pygidia are in fact results of chemical and structural changes taking place during fossilization, and evaluate possible systematic implications of the chemical data, advising caution when using morphological characteristics of the exoskeletons to establish new taxa.
* The study on the internal structures of eyes of trilobites belonging to the genera Asaphus and Archegonus published by Scholtz, Staude & Dunlop (2019) is criticized by Schoenemann & Clarkson (2021).
* A study on the biomechanics of the trilobite cephalon is published by Esteve et al. (2021), who interpret their findings as indicating that in the sutured trilobites the cephalon was able to withstand greater stresses than in their non-sutured counterparts, and argue that the ability to withstand greater burrowing loads enabled trilobites to successfully invade bioturbated and more consolidated sediments during the Cambrian substrate revolution.
* A study on the compound eyes of trilobites belonging to the group Phacopina is published by Schoenemann et al. (2021), who interpret their findings as indicating that these trilobites had hyper-compound eyes hiding an individual compound eye below each of the big lenses, resulting in each of the compound eyes comprising tens or hundreds of small compound eye systems.
* A study on the systematics of Devonian trochurine trilobites is published by Van Viersen (2021).

## Other arthropods
### New taxa

| Name | Novelty | Status | Authors | Age | Type locality | Location | Notes |
| Attenborolimulus | Gen. et sp. nov | Valid | Bicknell & Shcherbakov | Early Triassic (Olenekian) | Petropavlovka Formation | Russia ( Orenburg Oblast) | A member of Xiphosura belonging to the family Austrolimulidae. The type species is A. superspinosus. |
| Bailongia | Gen. et sp. nov | In press | Jiao et al. | Cambrian Stage 4 | Wulongqing Formation | China | A non-trilobite artiopod. The type species is B. longicaudata. |
| Bohemiacaris | Gen. et sp. nov | Valid | Van Roy et al. | Ordovician (Sandbian) | Letná Formation | Czech Republic | A member of Thylacocephala. Genus includes new species B. libori. |
| Caudicaella | Gen. et comb. nov | Valid | Sun et al. | Cambrian Stage 3 | Shuijingtuo Formation | China | A bivalved arthropod belonging to the family Sunellidae. The type species is "Sunella" bispinata Cui & Huo (1990). |
| Duplapex | Gen. et sp. nov | In press | Ma et al. | Cambrian Stage 3 | | China | A bivalved arthropod related to Tuzoia. Genus includes new species D. anima. |
| Electrocambala | Gen. et 2 sp. nov | Valid | Moritz & Wesener | Cretaceous | Burmese amber | Myanmar | A millipede belonging to the order Spirostreptida and the suborder Cambalidea. The type species is E. ornata; genus also includes E. cretacea. |
| Eodollocaris | Gen. et sp. nov | Valid | Laville, Haug & Haug | Carboniferous (middle Pennsylvanian) | Mazon Creek fossil beds | United States ( Illinois) | A member of Thylacocephala. The type species is E. keithflinti. |
| Franconiolimulus | Gen. et sp. nov | Valid | Bicknell, Hecker & Heyng | Early Jurassic (Hettangian) | Bayreuth Formation | Germany | A member of Xiphosura belonging to the family Austrolimulidae. Genus includes new species F. pochankei. |
| Houia guangxiensis | Sp. nov | In press | Wang et al. | Early Devonian | Cangwu Formation | China | |
| Kachincambala | Gen. et 2 sp. nov | Valid | Moritz & Wesener | Cretaceous | Burmese amber | Myanmar | A millipede belonging to the order Spirostreptida and the suborder Cambalidea. The type species is K. muelleri; genus also includes K. distorta. |
| Lihuacaris | Gen. et sp. nov | | Jiao et al. | Cambrian Stage 4 | Wulongqing Formation | China | A stem-group euarthropod of uncertain phylogenetic placement, with possible close affinities with either radiodonts or fuxianhuiids. The type species is L. ferox. |
| Myrmecodesmus antiquus | Sp. nov | Valid | Riquelme & Hernández-Patricio in Riquelme, Hernández-Patricio & Álvarez-Rodríguez | Miocene | Mexican amber | Mexico | A millipede belonging to the family Pyrgodesmidae. |
| Ostenolimulus | Gen. et sp. nov | Valid | Lamsdell et al. | Early Jurassic (Sinemurian) | Moltrasio Formation | Italy | A horseshoe crab. Genus includes new species O. latus. |
| Pakucaris | Gen. et sp. nov | Valid | Izquierdo-López & Caron | Cambrian (Wuliuan) | Burgess Shale | Canada ( British Columbia) | A stem mandibulate bivalved arthropod. Genus includes new species P. apatis. |
| Pectocaris inopinata | Sp. nov | Valid | Jin et al. | Cambrian | | China | A stem mandibulate bivalved arthropod. |
| Pseudoprotozoea | Gen. et sp. nov | Valid | Van Roy et al. | Ordovician (Sandbian) | Letná Formation | Czech Republic | A member of Thylacocephala. Genus includes new species P. irenae. |
| Terropterus | Gen. et sp. nov | Valid | Wang et al. | Silurian (Llandovery) | Xiushan Formation and Fentou Formation | China | A member of Eurypterida. Genus includes new species T. xiushanensis. |
| ?Woodwardopterus freemanorum | Sp. nov | In press | Poschmann & Rozefelds | Permian (Changhsingian) | Bowen Basin (Baralaba Coal Measures) | Australia | A member of Eurypterida. |

### Research

* Lan et al. (2021) report exquisite preservation of bilaterally symmetric brain in leanchoiliid specimens from the Cambrian Kaili biota (China), and evaluate the implications of these fossils for the knowledge of the evolution of the central nervous system in arthropods.
* A study on carapace shape variation and hydrodynamic performance of members of the genus Isoxys is published by Pates et al. (2021), who argue that members of this genus occupied a variety of distinct niches in Cambrian oceans, and some were adapted for vertical movement in the water column.
* A study on the composition and microstructure of the carapace of Chuandianella ovata is published by Liu, Fu & Zhang (2021), who interpret their findings as indicating that this arthropod reinforced its carapace with phosphatic mineralization.
* A study on the post-embryonic development of Chuandianella ovata is published by Liu, Fu & Zhang (2021).
* Braddy & Dunlop (2021) argue that Parioscorpio venator was a cheloniellid-like arthropod with large raptorial appendages.
* New information on the anatomy of the head of Fuxianhuia is presented by Aria, Zhao & Zhu (2021), who interpret fuxianhuiids as mandibulates.
* Partial remains of a member of the genus Arthropleura, representing one of the largest arthropod fossils reported to date and providing new information on the exoskeleton of Arthropleura, are described from the Carboniferous (Serpukhovian) Stainmore Formation (Northumberland, England, United Kingdom) by Davies et al. (2021), who also evaluate the implications of this finding for the knowledge of arthropleurid habitat and factors that enabled the evolution of large body size in arthropleurids.
* Revision of the morphological diversity, relationships and taxonomy of Early Triassic thylacocephalans is published by Laville et al. (2021).
* Description of new fossil material of Mayrocaris bucculata from the Solnhofen Limestone, providing new information on the anatomy of this thylacocephalan, is published by Laville et al. (2021), who evaluate the implications of these fossils for the knowledge of the body organization and phylogenetic affinities of thylacocephalans.
* A study on the morphology and possible intraspecific variability of Sinoburius lunaris is published by Schmidt et al. (2021).
* A fossil larva lacking segmentation of the carapace, closely resembling the trilobite protaspis, is described from the Ordovician (Darriwilian) of central Siberia by Dzik (2021), found associated with other skeletal elements of the angarocaridid Girardevia; however, Lerosey-Aubril & Laibl (2021) subsequently interpret this specimen as actually belonging to the trilobite genus Isotelus or a related taxon, and conclude that protaspid larvae represent a developmental trait unique to trilobites.
* A study on the possible relationships between eurypterid morphology, the ease with which members of this group experienced ecdysis, and longevity of eurypterid species is published by Brandt (2021).
* A geometric morphometric analysis of data from eurypterine eurypterid specimens is presented by Bicknell & Amati (2021).
* Redescription of Leiopterella tetliei is published by Braddy, Dunlop & Bonsor (2021).
* Bicknell, Melzer & Schmidt (2021) reconstruct prosomal appendages of Eurypterus tetragonophthalmus and Pentecopterus decorahensis, model the flexure and extension of these appendages.
* A study on the range of motion of prosomal appendages in Megalograptus ohioensis and Mixopterus kiaeri, and on its implications for the knowledge of the likely foraging strategies of these eurypterids, is published by Schmidt et al. (2021).
* Bicknell et al. (2021) report the discovery of exceptionally preserved central nervous system in a specimen of Euproops danae from the Carboniferous Mazon Creek fossil beds (Illinois, United States).
* A specimen of Euproops danae preserving anatomical details of the prosomal musculature is described from the Carboniferous Lawrence Formation (Kansas, United States) by Bicknell et al. (2021).
* Redescription and a study on the phylogenetic relationships of Prolimulus woodwardi is published by Lustri, Laibl & Bicknell (2021).
* Revision of Sloveniolimulus rudkini, based on data from new fossil material from the Anisian Strelovec Formation (Slovenia), is published by Bicknell et al. (2021).
* A study on the anatomy and phylogenetic relationships of Parioscorpio venator is published by Anderson et al. (2021).

## General research

* A study on the evolution of the arthropod labrum is published by Budd (2021), who reevaluates the morphology of the Cambrian stem-euarthropod Parapeytoia and evaluates its implications for the knowledge of the origin of the labrum.
* Liu et al. (2021) report the discovery a previously undetected exite at the base of most appendages of Leanchoilia illecebrosa, as well as morphologically similar (and likely homologous) exite in the same position in Naraoia spinosa and Retifacies abnormalis, and evaluate the implications of this discovery for the knowledge of the origin of exites in arthropod phylogeny.