Acanthostomum Looss, 1899 (original description)
Acanthostomum coronarium (Cobbold, 1861) Looss, 1899 accepted as Proctocaecum coronarium (Cobbold, 1861) Baugh, 1957 (new combination reference)
Acanthostomum spiniceps (Looss, 1896) Looss, 1899 (new combination reference)
Accacoelium Monticelli, 1893 (additional source)
Accacoelium contortum (Rudolphi, 1819) Looss, 1899 (new combination reference)
Anchitrema Looss, 1899 (original description)
Anchitrema sanguineum (Sonsino, 1894) Looss, 1899 (new combination reference)
Ascocotyle Looss, 1899 (original description)
Ascocotyle coleostoma (Looss, 1896) Looss, 1899 (new combination reference)
Ascocotyle coleostoma (Looss, 1896) Looss, 1899 (additional source)
Ascocotyle minuta Looss, 1899 (original description)
Astia Looss, 1899 accepted as Astiotrema Looss, 1900 (original description)
Astia impleta Looss, 1899 accepted as Astiotrema impletum (Looss, 1899) Stossich, 1904 (original description)
Astia renifera (Looss, 1898) Looss, 1899 accepted as Astiotrema reniferum (Looss, 1898) Stossich, 1904 (new combination reference)
Asymphylodora Looss, 1899 (original description)
Asymphylodora exspinosa (Hausmann, 1896) Looss, 1899 (new combination reference)
Asymphylodora imitans (Mühling, 1898) Looss, 1899 (new combination reference)
Asymphylodora perlata (von Nordmann, 1832) Looss, 1899 accepted as Asymphylodora tincae (Modeer, 1790) Lühe, 1909 (new combination reference)
Athesmia Looss, 1899 (original description)
Athesmia heterolecithodes (Braun, 1899) Looss, 1899. (new combination reference)
Azygia Looss, 1899 (original description)
Azygia tereticollis (Rudolphi, 1802) Looss, 1899 accepted as Azygia lucii (Müller, 1776) Lühe, 1909 (new combination reference)
Bilharziella Looss, 1899 (original description)
Bilharziella polonica (Kowalewski, 1895) Looss, 1899 (new combination reference)
Brachycladium Looss, 1899 (original description)
Brachycladium delphini (Poirier, 1886) Looss, 1899 (new combination reference)
Brachycladium palliatum (Looss, 1885) Looss, 1899 (new combination reference)
Brachycladium rochebruni (Poirier, 1886) Looss, 1899 accepted as Campula rochebruni (Poirier, 1886) Bittner & Sprehn, 1928 accepted as Oschmarinella rochebruni (Poirier, 1886) Gibson & Bray, 1997 (new combination reference)
Brachycoeliidae Looss, 1899 (original description)
Cathaemasia Looss, 1899 (original description)
Cathaemasia hians (Rudolphi, 1809) Looss, 1899 (new combination reference)
Centrocestus Looss, 1899 (original description)
Centrocestus cuspidatus (Looss, 1896) Looss, 1899 (new combination reference)
Cephalogonimidae Looss, 1899 (original description)
Coenogonimus Looss, 1899 accepted as Heterophyes Cobbold, 1866 (original description)
Coenogonimus fraternus Looss, 1894 accepted as Heterophyes fraterna (Looss, 1894) Looss, 1902 (taxonomy source)
Creadium Looss, 1899 accepted as Allocreadium Looss, 1900 (original description)
Creadium isoporum (Looss, 1894) Looss, 1899 accepted as Allocreadium isoporum (Looss, 1894) Looss, 1902 (new combination reference)
Cricocephalus Looss, 1899 (original description)
Cricocephalus albus (Kuhl & van Hasselt, 1822) Looss, 1899 (new combination reference)
Cricocephalus delitescens Looss, 1899 accepted as Cricocephalus albus (Kuhl & van Hasselt, 1822) Looss, 1899 (original description)
Cricocephalus ruber (Kuhl & van Hasselt, 1822) Looss, 1899 (new combination reference)
Cymatocarpus Looss, 1899 (original description)
Cymatocarpus undulatus Looss, 1899 accepted as Cymatocarpus solearis (Braun, 1899) Braun, 1901 (original description)
Dicrocoeliidae Looss, 1899 (original description)
Dicrocoeliinae Looss, 1899 (original description)
Dicrocoelium dendriticum (Rudolphi, 1819) Looss, 1899. (new combination reference)
Dicrocoelium strigosum Looss, 1899 accepted as Brachylecithum strigosum (Looss, 1899) Shtrom, 1940 (original description)
Echinostoma limicoli Johnson, 1930 accepted as Echinostoma revolutum (Fröhlich, 1802) Looss, 1899 (additional source)
Echinostoma mordax Looss, 1899 accepted as Echinochasmus mordax (Looss, 1899) Price, 1931 (original description)
Echinostoma revolutum (Fröhlich, 1802) Looss, 1899 (new combination reference)
Echinostomatidae Looss, 1899 (original description)
Echinostomatinae Looss, 1899 (original description)
Echinostomum bursicola Looss, 1899 accepted as Echinochasmus africanus (Stiles, 1901) Odhner, 1910 (original description)
Echinostomum elegans Looss, 1899 accepted as Echinoparyphium elegans (Looss, 1899) Dietz, 1909 (original description)
Echinostomum pendulum Looss, 1899 accepted as Stephanoprora pendula (Looss, 1899) Odhner, 1910 accepted as Mesorchis pendulus (Looss, 1899) Dietz, 1909 (original description)
Enodia Looss, 1899 accepted as Enodiotrema Looss, 1900 (original description)
Enodia megachondrus Looss, 1899 accepted as Enodiotrema megachondrus (Looss, 1899) Looss, 1901 (original description)
Fasciolopsis Looss, 1899 (original description)
Galactosomum Looss, 1899 (original description)
Galactosomum lacteum (Jägerskiöld, 1896) Looss, 1899 (new combination reference)
Glossidium Looss, 1899 (original description)
Glossidium pedatum Looss, 1899 (original description)
Gorgodera Looss, 1899 (original description)
Gorgodera amplicava Looss, 1899 (original description)
Gorgodera cygnoides (Zeder, 1800) Looss, 1899 (new combination reference)
Gorgoderidae Looss, 1899 (original description)
Gorgoderinae Looss, 1899 (original description)
Haematoloechus Looss, 1899 (original description)
Haematoloechus asper Looss, 1899 (original description)
Haematoloechus variegatus (Rudolphi, 1819) Looss, 1899 (new combination reference)
Halipegus Looss, 1899 (original description)
Halipegus ovocaudatus (Vulpian, 1859) Looss, 1899 (new combination reference)
Hapalotrema Looss, 1899 (original description)
Hapalotrema constrictum (Leared, 1862) Looss, 1899 accepted as Hapalotrema mistroides (Monticelli, 1896) Stiles & Hassall, 1908 (new combination reference)
Hapalotrema constrictum (Leared, 1862) Looss, 1899 accepted as Hapalotrema mistroides (Monticelli, 1896) Stiles & Hassall, 1908 (redescription)
Haplometra Looss, 1899 (original description)
Haplometra cylindracea (Zeder, 1800) Looss, 1899 (new combination reference)
Haplorchis Looss, 1899 (original description)
Haplorchis cahirinus (Looss, 1896) Looss, 1899 accepted as Monorchotrema cahirinum (Looss, 1896) Gohar, 1934 accepted as Haplorchoides cahirinus (Looss, 1896) Chen, 1949 (new combination reference)
Haplorchis pumilio (Looss, 1896) Looss, 1899 (new combination reference)
Hemiuridae Looss, 1899 (original description)
Hemiurinae Looss, 1899 (original description)
Hemiurus appendiculatus (Rudolphi, 1802) Looss, 1899 (new combination reference)
Hemiurus digitatus Looss, 1899 accepted as Lecithochirium digitatum (Looss, 1899) Lühe, 1901 accepted as Plerurus digitatus (Looss, 1899) Looss, 1907 (original description)
Heterolope Looss, 1899 accepted as Brachylaima Dujardin, 1843 (original description)
Heterolope aequans Looss, 1899 accepted as Brachylaima aequans (Looss, 1899) Skrjabin, 1948 (original description)
Holometra Looss, 1899 (original description)
Holometra exigua (Mühling, 1898) Looss, 1899 (new combination reference)
Holometra exigua (Mühling, 1898) Looss, 1899 (redescription)
Lecithodendrium hirsutum (Looss, 1896) Looss, 1899 (new combination reference)
Lepoderma Looss, 1899 accepted as Plagiorchis Lühe, 1899 (original description)
Leptalea Looss, 1899 accepted as Emoleptalea Looss, 1900 (original description)
Leptalea exilis Looss, 1899 accepted as Emoleptalea exilis (Looss, 1899) Looss, 1900 (original description)
Liopyge Looss, 1899 accepted as Derogenes Lühe, 1900 (original description)
Lyperosomum Looss, 1899 (original description)
Macrodera Looss, 1899 (original description)
Macrodera naja (Rudolphi, 1819) Looss, 1899 accepted as Macrodera longicollis (Abildgaard in Müller, 1789) Lühe, 1909 (new combination reference)
Metorchis Looss, 1899 (original description)
Metorchis albidus (Braun, 1893) Looss, 1899 accepted as Metorchis bilis (Braun, 1790) Odening, 1962 (new combination reference)