The purpose of this application, under Article 23.9.3 of the Code, is to conserve the name Calliactis Verrill, 1869 for a genus of sea anemones (Cnidaria, Actiniaria) that has been widely studied in the context of crustacean-cnidarian symbiosis. This name is threatened by a senior subjective synonym, Adamsia Forbes, 1840. In the interest of nomenclatural stability, we ask the ICZN Commission to use its plenary power to reverse the precedence of Calliactis Verrill, 1869 and Adamsia Forbes, 1840 whenever the two names are considered synonyms.

The purpose of this application, under Article 23.9.5 of the ICZN Code, is to conserve current usage of the name Taenia asiatica Eom & Rim, 1993 (Cestoda, Cyclophyllidea, Taeniidae) for a human-infecting species of East, Southeast and South Asian Taenia saginata-like tapeworm by disregarding the priority of its senior primary homonym Taenia asiatica Linstow, 1901 (Cestoda, Cyclophyllidea, davaineidae). The older species was transferred in 1926 to the genus Raillietina Fuhrmann, 1920 (Cestoda, Cyclophyllidea, davaineidae), giving rise to the currently prevailing combination Raillietina asiatica (Linstow, 1901), and neither species has ever been considered congeneric with the other. Taenia asiatica Eom & Rim, 1993 is a widespread species with a substantial literature. Conservation of this name would do much more to avoid confusion in the medical and/or veterinary fields concerning this important human parasite than the alternative, i.e., introducing a new replacement name.

The purpose of this application, under Article 55.3 of the ICZN Code, is to remove the homonymy between the unused Cricosaurinae Koken, 1888 (Archosauria, Crocodylomorpha, Metriorhynchidae) (type genus Cricosaurus Wagner, 1858) and the in-use senior homonym Cricosaurinae Cope, 1875 (Lepidosauria, Squamata, Xantusiidae) (type genus Cricosaura Gundlach & Peters in Peters, 1863). We propose to emend the stem of the name of the type genus of the unused Cricosaurinae Koken, 1888 from Cricosaur- to Cricosaurus-, which would result in Cricosaurusinae Koken, 1888. Reversal of precedence (Article 23.9 of the Code) is invoked for the subjective synonymy between Cricosaurini Koken, 1888, herewith treated as a nomen oblitum, and Rhacheosaurini Young, Bell & Brusatte, 2011, herewith treated as a nomen protectum.

The purpose of this application, under Article 75.5 of the ICZN Code, is to conserve the current usage of the specific name Andrena ovatula (Kirby, 1802) by setting aside all previous types and designating a neotype for Melitta ovatula. The name Andrena ovatula has been used as the senior name for what is a complex of species for more than 100 years. The principal confusion has been with Andrena afzeliella (Kirby, 1802), described from a female specimen, whereas Andrena ovatula was described from three male specimens. Within this group, males are morphologically more challenging to recognise than females, and as the existing male type material of A. ovatula possibly does not conform to the current use of A. ovatula, this poses a risk of nomenclatural instability. A female neotype is designated for Andrena ovatula, fixing the current interpretation of Andrena ovatula as distinct from A. afzeliella.

The purpose of this application, under Articles 23.9.3 and 75.6 of the ICZN Code, is to conserve the current usage of the generic name Platygaster Latreille, 1809 (Hymenoptera, Platygastridae) by designating a neotype for the type species Scelio ruficornis Latreille, 1805. The current usage of Platygaster is threatened because the name-bearing type of the type species does not match the prevailing concept of Platygaster, but rather matches the concept of Isocybus Foerster, 1856. This would place Isocybus as a junior synonym of Platygaster and require the transfer of more than 650 species from Platygaster to its next junior synonym, Parepimeces Kieffer, 1926, and the transfer of 32 species from Isocybus to Platygaster. In order to prevent confusion and retain nomenclatural stability, we propose a neotype for Scelio ruficornis Latreille, 1805 that is consistent with the prevailing usage of Platygaster.

The purpose of this revised application, as in Case 3829, is to conserve the current usage of the generic name Halitherium Kaup, 1838 and the specific name of its type species, Pygmeodon schinzii Kielmeyer & Jäger, 1835 (currently Halitherium schinzii), for a taxon of fossil sirenians from Europe, by designating a neotype for this nominal species. The name Halitherium schinzii has been used in a substantial body of literature extending over nearly two centuries to the near exclusion of other names. Stability of nomenclature will be served by designating the holotype of Kaupitherium gruelli Voss & Hampe, 2017 as neotype of P. schinzii as well as of Halianassa studeri Studer, 1887 under the ICZN Commission's plenary power, thereby rendering Kaupitherium Voss & Hampe, 2017 and K. gruelli Voss & Hampe, 2017, along with Halianassa Meyer, 1838 and Halianassa studeri Studer, 1887, junior objective synonyms of Halitherium Kaup, 1838 and H. schinzii (Kielmeyer & Jäger, 1835), respectively.

The purpose of this application, under Article 75.6 of the ICZN Code, is to conserve the widely used specific name of the clownfish-hosting sea anemone Priapus giganteus Forsskål, 1775 (currently Stichodactyla gigantea), originally described from the Red Sea, in its current usage. This nominal species of sea anemone is commonly cited in the scientific literature on ecology, behavior, evolution, mutualism and taxonomy, and is among the most recognizable species in the group outside the scientific realm, e.g., in tourism and the ornamental aquarium trade. Current usage of the name S. gigantea is based on Dunn's 1981 misattribution of Forsskål's name to a different species that was later shown not to occur in the Red Sea (S. gigantea's type locality). Recently, the incompatibility between the current usage of the name S. gigantea and its original meaning was pointed out, and the name S. gigantea has been used to refer to a different species than the one Dunn fixed the name to in 1981. In the interest of the stability and universality of nomenclature, we request that the International Commission on Zoological Nomenclature use its plenary power to set aside all previous type fixations for the nominal species Priapus giganteus Forsskål, 1775 and designate a neotype from elsewhere than the Red Sea that corresponds to the current usage of S. gigantea, i.e., sensu Dunn.

The purpose of this application, under Articles 1.1.1, 11 and 13 of the ICZN Code, is to confirm that the nominal genus Alexandrium Halim, 1960, proposed for an ecologically and economically important group of dinoflagellates, was originally treated as an animal taxon for the purposes of nomenclature, and that the genus-group name is available under the ICZN, even though the taxon is currently not classified as animal.

The purpose of this application, under Article 75.5 of the ICZN Code, is to conserve current usage of the generic name Trimorus Foerster, 1856 (Hymenoptera, Scelionidae) by setting aside all previous name-bearing types of the type species, Gryon nanno Walker, 1836 and designating a neotype for it. The original description of Gryon nanno is insufficient for recognizing the species, and the name-bearing type is lost. Trimorus is presently considered a large and morphologically variable genus (∼400 species). A type specimen for Gryon nanno that is in accordance with the prevailing usage of Trimorus and can be identified at the species level is needed to maintain nomenclatural stability.

The purpose of this application, under Article 23.9.5 of the ICZN Code, is to conserve the specific name Gyrinus (Enhydrus) australis Brullé, 1835 (currently Macrogyrus (Macrogyrus) australis), which is threatened by Gyrinus australis Fabricius, 1775 (currently Dineutus (Cyclous) australis) (both in Gyrinidae, Gyrininae, Dineutini). Although the names were transferred out of the genus Gyrinus Geoffroy, 1762 and have never been treated as congeneric, they are nevertheless primary homonyms. The Fabrician name has been treated as valid since it was proposed, was combined with the generic name Cyclous by Dejean, and has always been placed in Dineutus since its transfer to this genus by Aubé in 1838—with the exception of a single work of Motschulsky, where it was given again in Cyclous. After its publication, Brullé's name was never again given in combination with the generic name Gyrinus and was not accepted as a valid name during a period of almost 60 years. Only Régimbart treated the name as valid in 1892, and it has since always been placed in the genus Macrogyrus Régimbart, 1892. It is proposed that Gyrinus australis Brullé, 1835 be conserved by ruling that it is not invalid by reason of being a junior homonym of Gyrinus australis Fabricius, 1775.

The purpose of this application, under Article 23.9.3 of the ICZN Code, is to conserve the specific name Gyrinus (Gyretes) dorsalis Brullé, 1837 (currently Gyretes dorsalis; Gyrinidae, Gyrininae, Orectochilini). Brullé's name is threatened by the senior primary homonym Gyrinus dorsalis Gyllenhal, 1808 (currently Gyrinus (Gyrinus) dorsalis; Gyrinidae, Gyrininae, Gyrinini), which already in the 19th century was only rarely used as a valid name, mostly as variety, aberration or synonym of Gyrinus (Gyrinus) marinus Gyllenhal, 1808. After 1899, the name was used only once as valid by Ádám in 1996. The use of the older homonym, G. dorsalis Gyllenhal, would considerably threaten nomenclatural stability. Since the conditions of Article 23.9.1 are not met, the matter is referred to the Commission for a ruling. It is proposed that the name Gyrinus (Gyretes) dorsalis Brullé, 1837 be conserved by ruling that it is not invalid by reason of being a junior homonym of Gyrinus dorsalis Gyllenhal, 1808.

The purpose of this application, under Article 23.9.5 of the ICZN Code, is to conserve the specific name Gyrinus glaucus Aubé, 1838 (currently Macrogyrus (Andogyrus) glaucus; Gyrinidae, Gyrininae, Dineutini). The name is threatened by the senior primary homonym Gyrinus glaucus Klug, 1834 (currently Orectogyrus (Orectogyrus) glaucus; Gyrinidae, Gyrininae, Dineutini). Although the two names were transferred out of the genus Gyrinus Geoffroy, 1762 and have never been treated as congeneric, they are nevertheless primary homonyms. Both names have been treated as valid since they were proposed. Klug's name was classified by Aubé with the generic name Orectochilus and since its transfer to Orectogyrus by Régimbart in 1884, it has always been given with this generic name. Aubé's name was combined with the generic name Macrogyrus by Régimbart, with the generic name Andogyrus since Ochs in 1924, and with Macrogyrus (Andogyrus) since Gustafson and Miller in 2017. It is proposed that Gyrinus glaucus Aubé, 1838 be conserved by ruling that it is not invalid by reason of being a junior homonym of Gyrinus glaucus Klug, 1834.

The purpose of this application, under Article 75.5 of the ICZN Code, is to conserve the usage of the generic name Furagrion Petrulevičius, Wappler, Wedmann, Rust & Nel, 2008 for a genus of fossil damselflies, by setting aside the existing holotype of Phenacolestes jutlandicus Henriksen, 1922 (now Furagrion jutlandicus) and designating a neotype. The existing holotype (MGUH 1819; in the Natural History Museum of Denmark, Copenhagen) is an incomplete fossil comprised of the distal two-thirds of the abdomen, the distal half of two wings and a small, unplaceable wing fragment. The diagnostic characters for determining genus-level affiliations of fossil Odonata are generally found in the venation of the basal third of the wings, and the genus Furagrion (type species P. jutlandicus) was diagnosed based on a non-type wing (FUM-N-13856; in the Fur Museum, Nederby, Denmark) using characters in the basal part that are not visible in the holotype of P. jutlandicus. It is not possible to determine whether the holotype of P. jutlandicus is conspecific with the nominal species F. morsi Zessin, 2011, known only from the basal half of a wing, nor whether Furagrion is synonymous with the nominal genus Morsagrion Zessin, 2011 (type species M. ansorgei Zessin, 2011). Recent research has shown that the placement of Furagrion within a suborder and family cannot be established without examining characters of the head and eyes, which are missing in the holotype. We therefore propose that the holotype of P. jutlandicus be set aside and that a complete fossil with all four wings clearly preserved and a complete body including the head (specimen MM-10752 in Museum Mors, Nykøbing Mors, Denmark) be designated as neotype.

The purpose of this application, under Articles 23.9.3 and 81.2.3 of the ICZN Code, is to conserve the usage of the genus-group names Megascolia Betrem, 1928 and Regiscolia Betrem & Bradley, 1964 by suppression of their senior synonym Ascoli Agassiz, 1846. Ascoli has been subject to persistent confusion regarding its availability, leading to uncommon and inconsistent usage. Its suppression will maintain the status of two names consistently used since their introduction.

The International Commission on Zoological Nomenclature has used its plenary power to conserve the usage of the name Acarus putrescentiae Schrank, 1781 (currently Tyrophagus putrescentiae) by replacing the current neotype with specimen BMOC 08–1010–002–1 at the University of Michigan Museum of Zoology, Ann Arbor, Michigan, USA, as the current neotype belongs to the species Tyrophagus fanetzhangorum Klimov & OConnor, 2009.

The International Commission on Zoological Nomenclature has hereby removed the homonymy between the family-group names Chilodontidae Bronn, 1859, Chilodontinae, an emendation of Chilodinae Eigenmann, 1910, and Chilodontinae Wenz, 1938, by: 1) using its plenary power to suppress the genus-group name Chilodon Ehrenberg, 1834 (Ciliophora) for the purposes of the Principle of Priority but not for those of the Principle of Homonymy, and the family-group name Chilodontidae Bronn, 1859 (Ciliophora) for the purposes of both the Principle of Priority and the Principle of Homonymy; and 2) using its specific powers to rule that the family-group name Chilodontinae, as emended by Fowler, is an unjustified emendation of the original spelling Chilodinae Eigenmann, 1910 (Pisces). Therefore, the family-group name Chilodontidae Wenz, 1938 (Gastropoda) remains unchanged, the family-group name Chilodontidae Bronn, 1859 (Ciliophora) is placed on the Official Index of Rejected and Invalid Family-Group Names in Zoology and Chilodinae Eigenmann, 1910 is to be used in Pisces.

The International Commission on Zoological Nomenclature has used its specific powers to rule that the name Tapirus pygmaeus van Roosmalen & van Hooft, 2013 was made available in a book titled “Barefoot through the Amazon: on the path of evolution” and that this name has priority over Tapirus kabomani Cozzuol, Clozato, Holanda, Rodrigues, Nienow, De Thoisy, Redondo & Santos, 2013 whenever both names are considered to be synonyms.

The International Commission on Zoological Nomenclature has declined to use its plenary power to set aside all previous type fixations for seven taxa belonging to the Hesperia comma-group of butterflies (Lepidoptera, Hesperiidae) and replacing them with seven neotypes.

The International Commission on Zoological Nomenclature has used its plenary power to conserve the usage of the genus-group name Pachnaeus Schoenherr, 1826 by suppressing its senior objective synonym, Docorhinus Schoenherr, 1823.

The International Commission on Zoological Nomenclature has used its plenary power to stabilise the spelling of various junior subjective synonyms proposed before 2000 and belonging to the fish family Rivulidae (Osteichtyes, Cyprinodontiformes), by confirming -lebi- as the correct stem for fish genera with names ending in -lebias.

The International Commission on Zoological Nomenclature has used its plenary power to conserve the usage of the specific name minuta Eliason, 1962, as published in the binomen Magelona minuta, by suppressing the specific name minuta Wilson, 1959, as published in the trinomen Magelona filiformis minuta.

The International Commission on Zoological Nomenclature has used its plenary power to conserve the specific name Onthophagus anthracinus Harold, 1873 by ruling that it is not invalid by reason of being a junior primary homonym of Onthophagus anthracinus Faldermann, 1835.

The International Commission on Zoological Nomenclature has used its plenary power to conserve the specific name Choeridium latum Boucomont, 1928 (currently Ateuchus latus) by ruling that it is not invalid by reason of being a junior primary homonym of Choeridium latum Blanchard, 1846 (currently Canthidium latum).

The International Commission on Zoological Nomenclature has used its plenary power to remove the homonymy between the family-group names Acalyptini Thomson, 1859 (type genus Acalyptus Schöenherr, 1833) (Hexapoda, Coleoptera, Curculionidae) and Acalyptini Blatchley, 1926 (type genus Acalypta Westwood, 1840) (Hexapoda, Heteroptera, Tingidae). The stem of the genus-group name Acalypta Westwood, 1840 has been emended to Acalypta-, thereby making the family-group name Acalyptaini Blatchley, 1926 (Heteroptera), while the family-group name Acalyptini Thomson, 1859 (Coleoptera), based on Acalyptus Schöenherr, 1833, remains unchanged.

The International Commission on Zoological Nomenclature has used its plenary power to conserve the family-group name Tyrannosauridae Osborn, 1906 by giving it precedence over Deinodontidae Cope, 1866 and Dryptosauridae Marsh, 1890 whenever it is considered to be a synonym of either of the two.

The International Commission on Zoological Nomenclature has hereby used its plenary power to conserve the usage of the family-group name Mecynostomatidae Kukalová, 1969 (Insecta, Paleodictyoptera) by suppressing its senior homonym Mecynostomatidae Lameere, 1917 (Insecta, Paleodictyoptera).

The International Commission on Zoological Nomenclature has used its plenary power to remove the homonymy of the family-group names Euchromiini Léger, Landry & Nuss, 2019 (type genus Euchromius Guenée, 1845) and Euchromiinae Butler, 1876 (type genus Euchromia Hübner, 1819 in Hübner, [1816]) by emending the stem of the genus-group name Euchromius Guenée, 1845 to Euchromius-, thereby emending the former family-group name to Euchromiusini.

The International Commission on Zoological Nomenclature has used its plenary power to remove the homonymy of the family-group names Hemiarthrinae Markham, 1972 (type genus Hemiarthrus Giard & Bonnier, 1887) and Hemiarthridae Sirenko, 1997 (type genus Hemiarthrum Carpenter in Dall, 1876) by emending the stem of the genus-group name Hemiarthrum Carpenter in Dall, 1876 to Hemiarthrum-, thereby emending the latter family-group name to Hemiarthrumidae.

The International Commission on Zoological Nomenclature has declined to use its plenary power to conserve the genus-group name Halitherium Kaup, 1838 and the specific name of its type species, Pugmeodon schinzii Kaup, 1838 (currently Halitherium schinzii), by designating a neotype for this nominal species.

The purpose of this note is to suggest additions to the Latin genitive suffixes present in Article 31.1.2 of the International Code of Zoological Nomenclature, to include non-binary people in the regulation of species-group names formed from modern personal names. Use of the suffixes of the third declension of the Latin genitive is proposed.

The purpose of this Nomenclatural Note is to demonstrate that 1) the objective junior synonym Trogontherium cuvieri Fischer, 1814 should have precedence over Castor trogontherium Cuvier, 1809, and 2) the binomen should be attributed to Fischer (1814) instead of the widely cited Fischer (1809). When, in 1809, Johann Gotthelf Fischer described the fossil skull of a beaver found near the Sea of Azov (Russia), he erected for it the genus name Trogontherium without proposing a species name. The skull later became the holotype of what is now commonly cited as Trogontherium cuvieri Fischer, 1809, even though this binomen had not been formally proposed that year. Later that year, Georges Cuvier used the name Castor trogontherium to refer to the same specimen. We found an apparently previously-overlooked 1814 publication by Fischer in which the binomen Trogontherium cuvieri was used for the first time. Although an objective junior synonym of Castor trogontherium Cuvier, 1809, that senior synonym has not been used as a valid name since 1884 and, in compliance with the Code, we suggest reversing precedence and conclude that the correct name for the European giant beaver is Trogontherium cuvieri Fischer, 1814.