Hydrobiidae, commonly known as mud snails, is a large cosmopolitan family of very small freshwater and brackish water snails with an operculum, in the order Littorinimorpha.MolluscaBase eds. (2024). MolluscaBase. Hydrobiidae W. Stimpson, 1865. Accessed through: World Register of Marine Species at: https://www.marinespecies.org/aphia.php?p=taxdetails&id=120 on 2024-06-18
Distribution Hydrobiidae are found in much of the world, inhabiting all continents except Antarctica. In Australia alone there are over 260 species in the family.
Description These are very small or minute snails, with a shell height of less than 8 mm. The dextrally-coiled shells are smooth (except for growth lines conforming to the shape of the outer lip) and are usually rather nondescript. The shell offers very few robust characteristics to the systematist who is attempting to classify the species within this family. This difficulty is compounded by a high degree of intraspecific variation. Descriptions often have to be based on the characteristics of the operculum, radula and penis.
The shell of species within this family varies from planispiral to needle-shaped. The shell may have an open umbilicus or a plugged umbilicus. The thickness of the shell can vary from thin to fairly solid. The shell may be transparent and horn-colored, or colorless.
The number of whorls in the shell varies between two and eight. The shell can sometimes even assume a corkscrew or hornlike shape by loosening of the attachment of body whorl. The periostracum (outer layer of the shell) is usually thin, and is often colored. It can sometimes show hair-like projections.
The sinuous aperture is entire, not interrupted by a siphonal canal or other extensions. It is sometimes thickened. The protoconch is usually shaped like a dome, and usually shows a few spirals.
The corneous operculum is usually well-formed and shows only a few spirals.
The head, foot, mantle and visceral coil are colored pale gray to dark purple-black with melanin pigments. Subterranean species are often unpigmented.
The strong foot can be retracted into the shell. The mucous glands are situated at the anterior edge of the foot. There are no posterior mucous glands. The symmetrical cephalic tentacles are threadlike, with blunt or rounded tips. The eyes are located at the base of the tentacles.
The ctenidium (a comblike respiratory apparatus) goes along most of the length of the pallial cavity. This respiratory gill consists of 10 to 200 triangular filaments. The osphradium, the olfactory organ linked with the respiration organ, is usually relatively small.
The taenioglossate radula consists of more than fifty rows of teeth. The central tooth is trapezoidal. The lateral teeth have few to numerous cusps. The marginal teeth are usually with numerous cusps.
The species usually have both male and female individuals, but very rarely reproduction may be parthenogenic, caused by internal fertilization. The females lay eggs in single capsules on the leaves or stems of water plants. But sometimes they produce eggs that are hatched within the pallial gonoduct of the body, and in these cases the young are born alive. Species that inhabit estuaries sometimes produce veliger larvae.
The fossil record of this family extends back to the Early Carboniferous.
Ecology Habitat Most species of this family live in freshwater (lakes, ponds, rivers, streams), but some are found in brackish water or at the borders between freshwater and brackish water. A few occur in marine environments on sandy or muddy bottoms between algae and sea grass.
Feeding habits These small snails feed on algae, diatoms and detritus.
Taxonomy This is the largest family within the superfamily Truncatelloidea. At one time or another some 400 genera have been assigned to this family, and probably more than 1,000 species. The Hydrobiidae family is the most widespread and diverse family of freshwater molluscs in the world, occupying a range of habitats from streams and estuarine creeks to alpine bogs.
This family was originally named by Troschel in 1857, as the group Hydrobiae. Troschel was not certain of their rank, and he placed them in the Taenioglossata: Ctenobranchiata between the Lithoglyphi and Ancyloti. Over the years there have been numerous attempts to give an adequate and more finely divided classification. Thiele (1925, 1929 and 1931) set up the most comprehensive classification, with a review of the family at generic level.
Notable works about taxonomy of Hydrobiidae includes works by Radoman, for example Radoman (1983). book description.
The classification, as specified by Kabat and Hershler (1993), does not form a monophyletic group, and was in need of revision.
A study by Wilke et al. (2001) using molecular data from COI (Cytochrome c oxidase subunit I) and 18S genes has resulted in a new tentative set of subfamilies: Hydrobiinae, Pseudamnicolinae, Nymphophilinae, Islamiinae and Horatiinae.
2005 taxonomy The following subfamilies are recognized in the gastropod taxonomy of Bouchet & Rocroi from 2005: Hydrobiinae Stimpson, 1865 – synonyms: Paludestrinidae Newton, 1891; Pyrgorientaliinae Radoman, 1977; Pseudocaspiidae Sitnikova & Starobogatov, 1983 Belgrandiinae de Stefani, 1877 – synonyms: Horatiini D. W. Taylor, 1966; Sadlerianinae Radoman, 1973; Pseudohoratiinae Radoman, 1973; Orientaliidae Radoman, 1973 (inv.); Lithoglyphulidae Radoman, 1973; Orientalinidae Radoman, 1978 (inv.); Belgrandiellinae Radoman, 1983; Dabrianidae Starobogatov, 1983; Istrianidae Starobogatov, 1983; Kireliinae Starobogatov, 1983; lanzaiidae Starobogatov, 1983; Tanousiidae Starobogatov, 1983; Bucharamnicolinae Izzatulaev, Sitnikova & Starobogatov, 1985; Martensamnicolinae Izzatulaev, Sitnikova & Starobogatov, 1985; Turkmenamnicolinae Izzatulaev, Sitnikova & Starobogatov, 1985 Clenchiellinae D. W. Taylor, 1966Taylor D. W. (1966). The Veliger 9(2): 181, 199. Islamiinae Radoman, 1973 Navarriellinae García-Guerrero, Miller & Ramos, 2023 Nymphophilinae D. W. Taylor, 1966 Pseudamnicolinae Radoman, 1977 Pyrgulinae Brusina, 1882 (1869)Brusina (1882). Bulletino della Società Malacologica Italiana 7(13–19): 230. – synonyms: Caspiidae B. Dybowski, 1913; Microliopalaeinae B. Dybowski & Grochmalicki, 1914; Micromelaniidae B. Dybowski & Grochmalicki, 1914; Turricaspiinae B. Dybowski & Grochmalicki, 1915; Liosarmatinae B. Dybowski & Grochmalicki, 1920; Chilopyrgulinae Radoman, 1973; Micropyrgulidae Radoman, 1973; Falsipyrgulinae Radoman, 1983; Ohridopyrgulinae Radoman, 1983; Prosostheniinae Pana, 1989 Tateinae Thiele, 1925Thiele (1925). Handbuch der Zoologie 5(1): 80. – synonyms: Potamopyrgidae F. C. Baker, 1928; Hemistomiinae Thiele, 1929
The Amnicolidae and Cochliopidae are considered as distinct families according to the taxonomy of Bouchet & Rocroi (2005).
Genera Belgrandiellinae Radoman, 1983 Aetis Chertoprud, Grego & Mumladze, 2023 Andrusovia Brusina, 1903 Arganiella Giusti & Pezzoli, 1980 Balkanica Georgiev, 2011 Balkanospeum Georgiev, 2012 Belgrandiella A. J. Wagner, 1928 Boleana Radoman, 1975: synonym of Belgrandiella A. J. Wagner, 1928 Bucharamnicola Izzatullaev, Sitnikova & Starobogatov, 1985 Cavernisa Radoman, 1978 Chirgisia Glöer, Boeters & Pešić, 2014 Cilgia Schütt, 1968 Colchiella Chertoprud, Grego & Mumladze, 2023 Costellina Kuščer, 1933: synonym of Paladilhiopsis Pavlović, 1913 Graziana Radoman, 1975 Heraultiella Bodon, Manganelli & Giusti, 2002 Insignia Angelov, 1972 Istriana Velkovrh, 1971 Iverakia Glöer & Pešić, 2014 Kerkia Radoman, 1978 Kolevia Georgiev & Glöer, 2015 Meyrargueria Girardi, 2009 Microstygia Georgiev & Glöer, 2015 Motsametia Vinarski, Palatov & Glöer, 2014 Palacanthilhiopsis Bernasconi, 1988 Phreatica Velkovrh, 1970 Pontohoratia Vinarski, Palatov & Glöer, 2014 Sarajana Radoman, 1975 Sataplia Chertoprud, Grego & Mumladze, 2023 Sogdamnicola Izzatullaev, Sitnikova & Starobogatov, 1984 Tadzhikamnicola Izzatullaev, 2004 Tschernomorica Vinarski & Palatov, 2019 Turkmenamnicola Izzatullaev, Sitnikova & Starobogatov, 1985 Valvatamnicola Izzatullaev, Sitnikova & Starobogatov, 1984 Zeteana Glöer & Pešić, 2014
Belgrandiinae de Stefani, 1877 Antibaria Radoman, 1983 Belchatovia Kadolsky & Piechocki, 2000 Belgrandia Bourguignat, 1870 Bracenica Radoman, 1973 Cyclothyrella Neubauer, Mandic, Harzhauser & Hrvatović, 2013 Dalmatella Velkovrh, 1970 Daphniola Radoman, 1973 Gloeria Georgiev, Dedov & Cheshmedjiev, 2012 Gocea Hadžišče, 1956 Graecorientalia Radoman, 1983 Grossuana Radoman, 1983 Guadiella Boeters, 2003 Hadziella Kuščer, 1932 Isimerope Radea & Parmakelis, 2013 Karucia Glöer & Pešić, 2013 Litthabitella Boeters, 1970 Lyhnidia Radoman, 1962 Malaprespia Radoman, 1973 Martensamnicola Izzatullaev, Sitnikova & Starobogatov, 1985 Martinietta Schlickum, 1974 Microprososthenia Kadolsky & Piechocki, 2000 Myrtoessa Radea, 2016, named after greek nymph Myrtoessa Narentiana Radoman, 1973 Ohridohauffenia Hadžišče, 1959 Ohridohoratia Hadžišče, 1959 Ohrigocea Hadžišče, 1959 Pauluccinella Fo. Giusti & Pezzoli, 1990 Plesiella Boeters, 2003 Prespiana Radoman, 1973 Prespolitorea Radoman, 1983 Pseudavenionia Bodon & Giusti, 1982 Pseudohoratia Radoman, 1967 Pseudoislamia Radoman, 1979 Strugia Radoman, 1973 Sumia Glöer & Mrkvicka, 2015 Tarraconia Ramos & Arconada, 2000 Trichonia Schütt, 1980 Turcorientalia Radoman, 1973 Zaumia Radoman, 1983 Zavalia Radoman, 1974
Bullaregiinae Delicado, Hauffe & Wilke, 2023 (unavailable name, description in Supplementary Material does not fulfill the requirements of the Code for e-only publications ) Belgrandiellopsis Khalloufi, Béjaoui & Delicado, 2020 Biserta Khalloufi, Béjaoui & Delicado, 2020 Bullaregia Khalloufi, Béjaoui & Delicado, 2017 Caspiinae B. Dybowski, 1913 † Alizadella Kabakova, 1966 † Azeria Kabakova, 1967 Caspia Clessin & W. Dybowski, 1887 Clathrocaspia Lindholm, 1930 Erosiconcha Delicado & Gürlek, 2021 Graecoanatolica Radoman, 1973 Ulskia Logvinenko & Starobogatov, 1969
Horatiinae D.W. Taylor, 1966 Anagastina Radoman, 1978 Caucasogeyeria Grego & Mumladze, 2020 Caucasopsis Grego & Mumladze, 2020 Dalmatinella Radoman, 1973 Daudebardiella O. Boettger, 1905 Graecoarganiella Falniowski & Szarowska, 2011 Hausdorfenia Grego & Mumladze, 2020 Horatia Bourguignat, 1887 Iglicopsis Falniowski & Hofman, 2021 Imeretiopsis Grego & Mumladze, 2020 Kartvelobia Grego & Mumladze, 2020 Lerniana Delicado & Hauffe, 2022 Montenegrospeum Pešić & Glöer, 2013 Pezzolia Bodon & Giusti, 1986 Radomaniola Szarowska, 2007 Sadleriana Clessin, 1890 Sardohoratia Manganelli, Bodon, Cianfanelli, Talenti & Giusti, 1998 Tanousia Servain, 1881 Travunijana Grego & Glöer, 2019 Vinodolia Radoman, 1973
Hydrobiinae Stimpson, 1865 Achaiohydrobia Falniowski, 2021 Adriohydrobia Radoman, 1977 Cariohydrobia Delicado & Gürlek, 2021 Ecrobia Stimpson, 1865 † Harzhauseria Neubauer & Wesselingh, 2023 Hoyia F. C. Baker, 1926 Hydrobia W. Hartmann, 1821 Peringia Paladilhe, 1874 † Polycirsus Cossmann, 1888 Romania Cossmann, 1913 Salenthydrobia Wilke, 2003 † Tournoueria Brusina, 1870
Islamiinae Radoman, 1973 Actenidia Arconada & Ramos, 2024 Alzoniella Giusti & Bodon, 1984 Aretiana Delicado & Ramos, 2021 Avenionia Nicolas, 1882 Beatrix J. P. Miller, García-Guerrero, Delicado & Ramos, 2024 Boetersiella Arconada & Ramos, 2001 Chondrobasis Arconada & Ramos, 2001 Corbellaria Callot-Girardi & Boeters, 2012 Deganta Arconada & Ramos, 2019 Fissuria Boeters, 1981 Hauffenia Pollonera, 1898 Iberhoratia Arconada & Ramos, 2007 Islamia Radoman, 1973 Josefus Arconada & Ramos, 2006 Milesiana Arconada & Ramos, 2006 Spathogyna Arconada & Ramos, 2002
Mercuriinae Boeters & Falkner, 2017 Mercuria Boeters, 1971
Navarriellinae García-Guerrero, Miller & Ramos, 2023 Navarriella Boeters, 2000
Nymphophilinae Birgella Baker, 1926 Cincinnatia Pilsbry, 1891