A member of the Cryptobranchidae family, hellbenders are the only members of the Cryptobranchus genus, and are joined only by one other genus of salamanders ( Andrias, which contains the Japanese and Chinese giant salamanders ) at the family level.

Crowhurst et al., for instance, found that the “ Ozark subspecies ” denomination is insufficient for describing genetic ( and therefore evolutionary ) divergence within the Cryptobranchus genus in the Ozark region.

The researchers found three equally divergent genetic units within the genus: Cryptobranchus alleganiensis alleganiensis, and two distinct eastern and western populations of Cryptobranchus alleganiensis bishopi.

In the genus Ensatinas, she has been observed to coil around them and press her throat area against them, effectively massaging them with a mucous secretion.

The challenge to the status has focused on the Agnostina partly because juveniles of one genus have been found with legs greatly different from those of adult trilobites, suggesting they are not members of the lamellipedian clade, of which trilobites are a part.

The family also has important ornamentals, mainly from the dominant genus Allium, but also including genera such as Ipheion.

Heinrich Göppert named the common amber-yielding pine of the Baltic forests Pinites succiniter, but as the wood does not seem to differ from that of the existing genus it has been also called Pinus succinifera.

Although the family ( Amaranthaceae ) is distinctive, the genus has few distinguishing characters among the 70 species included.

This complicates taxonomy and Amaranthus has generally been considered among systematists as a " difficult " genus.

The taxonomy of the genus has been controversial.

Although it has previously been assigned to its own genus Alopex, genetic evidence places it in Vulpes ( Mammal Species of the World ) with the majority of the other foxes.

Some South American plants formerly thought of as Daturas are now treated as belonging to the distinct genus Brugmansia ( Brugmansia differs from Datura in that it is woody, making shrubs or small trees, and in that it has pendulous flowers, rather than erect ones ).

The brown hyena has sometimes been placed in a separate genus Parahyaena, or even included in the otherwise fossil genus Pachycrocuta, but recent sources have tended to place it in Hyaena.

Although the word jackal has been historically used to refer to many small-to medium-sized species of the wolf genus of mammals, Canis, today it most properly and commonly refers to three species: the black-backed jackal and the side-striped jackal of sub-Saharan Africa, and the golden jackal of northern Africa and south-central Eurasia.

Heller's names and the designations he gave to various jackal species and subspecies live on in current taxonomy, although the genus has been changed from Thos to Canis.

Although it has morphological similarities with the pygmy killer whale, the false killer whale and the pilot whales, a study of cytochrome b gene sequences by Richard LeDuc indicated that its closest extant relatives are the snubfin dolphins of the genus Orcaella.

Also, a genus of lichen has been named Zamenhofia rosei in his honour.

The genus has a subcosmopolitan distribution across Europe, Africa, Asia, Australia, and North America.

The taxonomy of the genus Mimosa has had a tortuous history, having gone through periods of splitting and lumping, ultimately accumulating over 3, 000 names, many of which have either been synonymized under other species or transferred to other genera.

Fossil Olea pollen has been found in Macedonia, Greece, and other places around Mediterranean, indicating that this genus is an original element of the Mediterranean flora.

Much rethinking has come to be regarded as only a special case of the property genus.

The Passenger Pigeon is a member of the Columbidae family ( pigeons and doves ) that has been assigned to the genus Ectopistes.

As the senior synonym, Cuvier's name has precedence, so applying modern rules for the combination of the genus name and the specific epithet, the valid species name became Ptéro-Dactyle antiquus.

Unaware of Rafinesque's publication Cuvier himself in 1819 again Latinized the genus, but the specific name he then gave, longirostris, has to give precedence to von Soemmerring's antiquus.

However, it has been difficult to determine exactly of what genus and species P. micronyx might be the juvenile form.

It has sometimes been placed in the genus Diopecephalus because Harry Govier Seeley based this genus partly on the P. longicollum material.

The Southern Hemisphere genus Nothofagus, commonly the southern beeches, was historically placed in the Fagaceae sister to the genus Fagus, but recent molecular evidence suggests otherwise.

The taxonomy of the genus has historically been confused, with some authors applying the acouchy name to the Green Acouchi, in which case the Red Acouchi is called Myoprocta exilis.

It is generally considered to belong to the genus Ferula, probably as an extinct species ( although the currently extant plants Ferula tingitana, Ferula narthex, and Thapsia garganica have historically been suggested as possible identities ).

It is a historically important genus with a convoluted taxonomy that has been all but abandoned by modern dinosaur paleontologists.

As historically defined, the genus contains over 700 species ( see the list of Aedes species ).

It was historically considered to be closely related to Ardea but for some time it was placed in its own genus because of the absence of the plumes typical in that genus.

It has also historically been a Wastebasket taxon, and many large carnivorous dinosaurs from Europe and elsewhere were referred to the genus without justification.

Saponins are indeed found in many plants, and derive their name from the soapwort plant ( genus Saponaria, family Caryophyllaceae ), the root of which was used historically as a soap.

Siegel's work spans analytic number theory ; and his theorem on the finiteness of the integer points of curves, for genus > 1, is historically important as a major general result on diophantine equations, when the field was essentially undeveloped.

This animal has been historically considered a member of genus Arvicola, but molecular evidence demonstrates that it is more closely related to North American Microtus species.

Alternate spellings of the genus name have also been reported, with as many as 30 variants historically.

Although in close resemblance to Pfiesteria piscicida, it differs in two important precingular plates 5 " and 6 ", which historically, only one plate difference would be sufficient to place in a separate genus.

It has always been considered a monotypic genus Sapayoa and historically regarded as a New World suboscine ; in particular, it was assigned to the manakin family ( Pipridae ).

Blandfordia is the only genus in the family Blandfordiaceae, with four species distributed in eastern Australia.

The two species of Doryanthes, the only genus of the family, are huge rosette-forming herbs that are a conspicuous element of the flora in the vicinity of Sydney, Australia, being hard not to notice when in flower.

The family consists of a single genus Xeronema with two species, one found only on the Poor Knights islands in New Zealand and the other in New Caledonia.

In the narrowest definition, the Xanthorrhoeaceae sensu stricto consists only of the genus Xanthorrhoea.

It contains only one genus, Xanthorrhoea, endemic to Australia.

The APG III system ( 2009 ) differs only in that the Limnocharitaceae are combined with the Alismataceae ; it was also suggested that the genus Maundia ( of the Juncaginaceae ) could be separated into a monogeneric family, Maundiaceae, but the authors noted that more study was necessary before Maundiaceae could be recognized.

Allieae contains only one genus Allium ( Milula is merged with Allium in the latest systems ).

The family Haliotidae contains only one genus, Haliotis.

Formerly, Sauer ( 1955 ) classified the genus into two subgenera, differentiating only between monoecious and dioecious species: Acnida ( L .) Aellen ex K. R.

The okapi ( a genus restricted to Africa ) is found only in the dense forests of the Congo basin.

This is the only reliable manifestation of polyembryony in the class Mammalia, and only exists within the genus Dasypus and not in all armadillos, as is commonly believed.

and reiterates in no uncertain terms: " Nothing, then, which is not a species of a genus will have an essence – only species will have it ...."

In a single sentence, parallel to Aristotle's statement asserting that being is substance, St. Thomas pushes away from the Aristotelian doctrine: " Being is not a genus, since it is not predicated univocally but only analogically.

The genus Dendrosicyos with the only species cucumber tree, is adapted to arid semi desert island of Socotra.

It is the only species classified in the genus Conuropsis.

The genus Candida includes about 150 different species ; however, only a few are known to cause human infections.

The species name troglodytes, Greek for " cave-dweller ", was coined by Johann Friedrich Blumenbach in his book De generis humani varietate nativa liber (" on the natural varieties of the human genus ") published in 1776, This book was based on his dissertation presented one year before ( it had a date 16 Sep 1775 printed on its title page ) to the University of Göttingen for internal use only, thus the dissertation did not meet the conditions for published work in the sense of zoological nomenclature.

It is the only extant member of the genus Cuon, which differs from Canis by the reduced number of molars and greater number of teats.

The African elephant genus contains two living species ; whereas the Asian elephant species is the only surviving member of the Asian elephant genus, but can be divided into four subspecies.

While it began with the last common ancestor of all life, the topic usually only covers the evolutionary history of primates, in particular the genus Homo, and the emergence of Homo sapiens as a distinct species of hominids ( or " great apes ").

In contrast, the multiregional hypothesis proposed that Homo genus contained only a single interconnected population like it does today ( not separate species ), and that its evolution took place worldwide continuously over the last couple million years.

Homo sapiens is the only extant species of its genus, Homo.

At least five genera are recognised, but only a single species from one genus is still alive, the gray whale, Eschrichtius robustus.