Genus ( / ˈ dʒ iː n ə s / ; pl. : genera / ˈ dʒ ɛ n ər ə / ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses . In binomial nomenclature , the genus name forms the first part of the binomial species name for each species within the genus.
41-466: Clitocybe is a genus of mushrooms characterized by white, off-white, buff, cream, pink, or light-yellow spores , gills running down the stem , and pale white to brown or lilac coloration. They are primarily saprotrophic , decomposing forest ground litter. There are estimated to be around 300 species in the widespread genus. Clitocybe means sloping head . A few members of the genus are considered edible ; many others are poisonous , containing
82-407: A genus is determined by taxonomists . The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including the idea that a newly defined genus should fulfill these three criteria to be descriptively useful: Moreover, genera should be composed of phylogenetic units of
123-651: A later homonym of a validly published name is a nomen illegitimum or nom. illeg. ; for a full list refer to the International Code of Nomenclature for algae, fungi, and plants and the work cited above by Hawksworth, 2010. In place of the "valid taxon" in zoology, the nearest equivalent in botany is " correct name " or "current name" which can, again, differ or change with alternative taxonomic treatments or new information that results in previously accepted genera being combined or split. Prokaryote and virus codes of nomenclature also exist which serve as
164-628: A long time and redescribed as new by a range of subsequent workers, or if a range of genera previously considered separate taxa have subsequently been consolidated into one. For example, the World Register of Marine Species presently lists 8 genus-level synonyms for the sperm whale genus Physeter Linnaeus, 1758, and 13 for the bivalve genus Pecten O.F. Müller, 1776. Within the same kingdom, one generic name can apply to one genus only. However, many names have been assigned (usually unintentionally) to two or more different genera. For example,
205-409: A reference for designating currently accepted genus names as opposed to others which may be either reduced to synonymy, or, in the case of prokaryotes, relegated to a status of "names without standing in prokaryotic nomenclature". An available (zoological) or validly published (botanical) name that has been historically applied to a genus but is not regarded as the accepted (current/valid) name for
246-412: A stalked, interrupted spike"). In Species Plantarum , these cumbersome names were replaced with two-part names, consisting of a single-word genus name, and a single-word specific epithet or "trivial name"; the two examples above became Plantago media and Nepeta cataria , respectively. The use of binomial names had originally been developed as a kind of shorthand in a student project about
287-427: A taxon; however, the names published in suppressed works are made unavailable via the relevant Opinion dealing with the work in question. In botany, similar concepts exist but with different labels. The botanical equivalent of zoology's "available name" is a validly published name . An invalidly published name is a nomen invalidum or nom. inval. ; a rejected name is a nomen rejiciendum or nom. rej. ;
328-516: A thousand genera, which were grouped into 24 classes, according to Linnaeus' sexual system of classification. There are no descriptions of the genera in Species Plantarum ; these are supplied in the companion volume Genera Plantarum ( lit. ' the genera of plants ' ), the fifth edition of which was printed at a similar time to the first edition of Species Plantarum . Linnaeus acknowledged his "sexual system"
369-455: A total of c. 520,000 published names (including synonyms) as at end 2019, increasing at some 2,500 published generic names per year. "Official" registers of taxon names at all ranks, including genera, exist for a few groups only such as viruses and prokaryotes, while for others there are compendia with no "official" standing such as Index Fungorum for fungi, Index Nominum Algarum and AlgaeBase for algae, Index Nominum Genericorum and
410-612: Is discouraged by both the International Code of Zoological Nomenclature and the International Code of Nomenclature for algae, fungi, and plants , there are some five thousand such names in use in more than one kingdom. For instance, A list of generic homonyms (with their authorities), including both available (validly published) and selected unavailable names, has been compiled by the Interim Register of Marine and Nonmarine Genera (IRMNG). The type genus forms
451-460: Is somewhat arbitrary. Although all species within a genus are supposed to be "similar", there are no objective criteria for grouping species into genera. There is much debate among zoologists about whether enormous, species-rich genera should be maintained, as it is extremely difficult to come up with identification keys or even character sets that distinguish all species. Hence, many taxonomists argue in favor of breaking down large genera. For instance,
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#1732798494263492-474: Is the type species , and the generic name is permanently associated with the type specimen of its type species. Should the specimen turn out to be assignable to another genus, the generic name linked to it becomes a junior synonym and the remaining taxa in the former genus need to be reassessed. In zoological usage, taxonomic names, including those of genera, are classified as "available" or "unavailable". Available names are those published in accordance with
533-705: Is the first work in which binomial nomenclature was consistently applied, Species Plantarum was chosen as the "starting point" for the nomenclature of most plants (the nomenclature of some non-vascular plants and all fungi uses later starting points). Species Plantarum contained descriptions of the thousands of plant species known to Linnaeus at the time. In the first edition, there were 5,940 names, from Acalypha australis to Zygophyllum spinosum . In his introduction, Linnaeus estimated that there were fewer than 10,000 plant species in existence; there are now thought to be around 400,000 species of flowering plants alone. The species were arranged in around
574-475: Is the first work to consistently apply binomial names and was the starting point for the naming of plants . Species Plantarum was published on 1 May 1753 by Laurentius Salvius in Stockholm, in two volumes. A second edition was published in 1762–1763, and a third edition in 1764, although this "scarcely differed" from the second. Further editions were published after Linnaeus' death in 1778, under
615-621: The International Code of Zoological Nomenclature ; the earliest such name for any taxon (for example, a genus) should then be selected as the " valid " (i.e., current or accepted) name for the taxon in question. Consequently, there will be more available names than valid names at any point in time; which names are currently in use depending on the judgement of taxonomists in either combining taxa described under multiple names, or splitting taxa which may bring available names previously treated as synonyms back into use. "Unavailable" names in zoology comprise names that either were not published according to
656-824: The International Plant Names Index for plants in general, and ferns through angiosperms, respectively, and Nomenclator Zoologicus and the Index to Organism Names for zoological names. Totals for both "all names" and estimates for "accepted names" as held in the Interim Register of Marine and Nonmarine Genera (IRMNG) are broken down further in the publication by Rees et al., 2020 cited above. The accepted names estimates are as follows, broken down by kingdom: The cited ranges of uncertainty arise because IRMNG lists "uncertain" names (not researched therein) in addition to known "accepted" names;
697-419: The nomenclature codes , which allow each species a single unique name that, for animals (including protists ), plants (also including algae and fungi ) and prokaryotes ( bacteria and archaea ), is Latin and binomial in form; this contrasts with common or vernacular names , which are non-standardized, can be non-unique, and typically also vary by country and language of usage. Except for viruses ,
738-404: The platypus belongs to the genus Ornithorhynchus although George Shaw named it Platypus in 1799 (these two names are thus synonyms ) . However, the name Platypus had already been given to a group of ambrosia beetles by Johann Friedrich Wilhelm Herbst in 1793. A name that means two different things is a homonym . Since beetles and platypuses are both members of the kingdom Animalia,
779-442: The base for higher taxonomic ranks, such as the family name Canidae ("Canids") based on Canis . However, this does not typically ascend more than one or two levels: the order to which dogs and wolves belong is Carnivora ("Carnivores"). The numbers of either accepted, or all published genus names is not known precisely; Rees et al., 2020 estimate that approximately 310,000 accepted names (valid taxa) may exist, out of
820-612: The direction of Karl Ludwig Willdenow , the director of the Berlin Botanical Garden ; the fifth edition was titled "fourth edition" and was published by Willdenow in four volumes, 1798 (1), 1800 (2), 1801 (3 ), 1803 (3 ), 1804 (3 ), 1805 (4 ), 1806 (4 ), rather than the dates printed on the volumes themselves. Species Plantarum was the first botanical work to consistently apply the binomial nomenclature system of naming to any large group of organisms (Linnaeus' tenth edition of Systema Naturae would apply
861-446: The form "author, year" in zoology, and "standard abbreviated author name" in botany. Thus in the examples above, the genus Canis would be cited in full as " Canis Linnaeus, 1758" (zoological usage), while Hibiscus , also first established by Linnaeus but in 1753, is simply " Hibiscus L." (botanical usage). Each genus should have a designated type , although in practice there is a backlog of older names without one. In zoology, this
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#1732798494263902-445: The future. In a 2003 paper, Finnish mycologist Harri Harmaja proposed C. geotropa and twelve other Clitocybe species be split off into a new genus Infundibulicybe on the basis of spore properties. His C. clavipes was later transferred to the genus Ampulloclitocybe by Redhead and colleagues, that genus name taking precedence over Harmaja's proposed Clavicybe . Other former Clitocybe species have been placed in
943-425: The genera Atractosporocybe , Leucocybe and Rhizocybe . The consumption of two species, Clitocybe acromelalga from Japan, and Clitocybe amoenolens from France, has led to several cases of mushroom-induced erythromelalgia which lasted from 8 days to 5 months. Many small Clitocybe species contain the toxin muscarine , which was originally found in small amounts in the famous fly agaric . However,
984-737: The generic name (or its abbreviated form) still forms the leading portion of the scientific name, for example, Canis lupus lupus for the Eurasian wolf subspecies, or as a botanical example, Hibiscus arnottianus ssp. immaculatus . Also, as visible in the above examples, the Latinised portions of the scientific names of genera and their included species (and infraspecies, where applicable) are, by convention, written in italics . The scientific names of virus species are descriptive, not binomial in form, and may or may not incorporate an indication of their containing genus; for example,
1025-466: The genus Agaricus . Friedrich Staude elevated it to generic status in 1857. Recent molecular work has shown the genus to be polyphyletic : many members are seemingly distantly related and other fungi, such as the field blewit and wood blewit , now known as Clitocybe saeva and C. nuda respectively, are more closely related. As C. nebularis is the type species, those most distantly related to it would be likely to be reclassified in
1066-633: The largest component, with 23,236 ± 5,379 accepted genus names, of which 20,845 ± 4,494 are angiosperms (superclass Angiospermae). By comparison, the 2018 annual edition of the Catalogue of Life (estimated >90% complete, for extant species in the main) contains currently 175,363 "accepted" genus names for 1,744,204 living and 59,284 extinct species, also including genus names only (no species) for some groups. The number of species in genera varies considerably among taxonomic groups. For instance, among (non-avian) reptiles , which have about 1180 genera,
1107-411: The lizard genus Anolis has been suggested to be broken down into 8 or so different genera which would bring its ~400 species to smaller, more manageable subsets. Species Plantarum Species Plantarum ( Latin for "The Species of Plants") is a book by Carl Linnaeus , originally published in 1753, which lists every species of plant known at the time, classified into genera . It
1148-403: The most (>300) have only 1 species, ~360 have between 2 and 4 species, 260 have 5–10 species, ~200 have 11–50 species, and only 27 genera have more than 50 species. However, some insect genera such as the bee genera Lasioglossum and Andrena have over 1000 species each. The largest flowering plant genus, Astragalus , contains over 3,000 species. Which species are assigned to a genus
1189-428: The name could not be used for both. Johann Friedrich Blumenbach published the replacement name Ornithorhynchus in 1800. However, a genus in one kingdom is allowed to bear a scientific name that is in use as a generic name (or the name of a taxon in another rank) in a kingdom that is governed by a different nomenclature code. Names with the same form but applying to different taxa are called "homonyms". Although this
1230-542: The plants eaten by cattle. After the specific epithet, Linnaeus gave a short description of each species, and a synonymy . The descriptions were careful and terse, consisting of few words in small genera; in Glycyrrhiza , for instance, the three species ( Glycyrrhiza echinata , Glycyrrhiza glabra and " Glycyrrhiza hirsuta ", respectively) were described as " leguminibus echinatis ", " leguminibus glabris " and " leguminibus hirsutis ". Because it
1271-541: The provisions of the ICZN Code, e.g., incorrect original or subsequent spellings, names published only in a thesis, and generic names published after 1930 with no type species indicated. According to "Glossary" section of the zoological Code, suppressed names (per published "Opinions" of the International Commission of Zoological Nomenclature) remain available but cannot be used as the valid name for
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1312-470: The same kind as other (analogous) genera. The term "genus" comes from Latin genus , a noun form cognate with gignere ('to bear; to give birth to'). The Swedish taxonomist Carl Linnaeus popularized its use in his 1753 Species Plantarum , but the French botanist Joseph Pitton de Tournefort (1656–1708) is considered "the founder of the modern concept of genera". The scientific name (or
1353-423: The same technique to animals for the first time in 1758). Prior to this work, a plant species would be known by a long polynomial, such as Plantago foliis ovato-lanceolatis pubescentibus, spica cylindrica, scapo tereti (meaning " plantain with pubescent ovate-lanceolate leaves, a cylindrical spike and a terete scape") or Nepeta floribus interrupte spicatis pedunculatis (meaning " Nepeta with flowers in
1394-408: The scientific epithet) of a genus is also called the generic name ; in modern style guides and science, it is always capitalised. It plays a fundamental role in binomial nomenclature , the system of naming organisms , where it is combined with the scientific name of a species : see Botanical name and Specific name (zoology) . The rules for the scientific names of organisms are laid down in
1435-453: The small white Clitocybe species contain muscarine in dangerous amounts, and two species in particular, the closely related Clitocybe dealbata and Clitocybe rivulosa , contain muscarine in such amounts that deaths have been recorded for eating those two Clitocybe species. The bioluminescent jack o'lantern mushroom ( Omphalotus olearius ) was formerly placed in this genus as Clitocybe illudens . Genus The composition of
1476-497: The specific name particular to the wolf. A botanical example would be Hibiscus arnottianus , a particular species of the genus Hibiscus native to Hawaii. The specific name is written in lower-case and may be followed by subspecies names in zoology or a variety of infraspecific names in botany . When the generic name is already known from context, it may be shortened to its initial letter, for example, C. lupus in place of Canis lupus . Where species are further subdivided,
1517-412: The standard format for a species name comprises the generic name, indicating the genus to which the species belongs, followed by the specific epithet, which (within that genus) is unique to the species. For example, the gray wolf 's scientific name is Canis lupus , with Canis ( Latin for 'dog') being the generic name shared by the wolf's close relatives and lupus (Latin for 'wolf') being
1558-403: The taxon is termed a synonym ; some authors also include unavailable names in lists of synonyms as well as available names, such as misspellings, names previously published without fulfilling all of the requirements of the relevant nomenclatural code, and rejected or suppressed names. A particular genus name may have zero to many synonyms, the latter case generally if the genus has been known for
1599-410: The toxin muscarine among others. Distinguishing individual species of Clitocybe is generally prohibitively difficult to non-experts, requiring the analysis of microscopic characters. Therefore, with the exception of a few charismatic and readily identified members, Clitocybe mushrooms are rarely collected for consumption. Clitocybe was originally proposed by Elias Fries in 1821 as a tribe in
1640-576: The values quoted are the mean of "accepted" names alone (all "uncertain" names treated as unaccepted) and "accepted + uncertain" names (all "uncertain" names treated as accepted), with the associated range of uncertainty indicating these two extremes. Within Animalia, the largest phylum is Arthropoda , with 151,697 ± 33,160 accepted genus names, of which 114,387 ± 27,654 are insects (class Insecta). Within Plantae, Tracheophyta (vascular plants) make up
1681-429: The virus species " Salmonid herpesvirus 1 ", " Salmonid herpesvirus 2 " and " Salmonid herpesvirus 3 " are all within the genus Salmonivirus ; however, the genus to which the species with the formal names " Everglades virus " and " Ross River virus " are assigned is Alphavirus . As with scientific names at other ranks, in all groups other than viruses, names of genera may be cited with their authorities, typically in