''Mankyua'' is a

monotypic genus In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispe ...

and fern in the

Ophioglossales Ophioglossaceae, from Ancient Greek ὄφις (''óphis''), meaning "snake", and γλῶσσα (''glôssa''), meaning "tongue", also known as the adder's-tongue family, is a small family of ferns. In the Pteridophyte Phylogeny Group classificatio ...

. Its only species, ''M. chejuense'', grows only on

Jeju Island Jeju Island (Jeju language, Jeju/) is South Korea's largest island, covering an area of , which is 1.83% of the total area of the country. Alongside outlying islands, it is part of Jeju Province and makes up the majority of the province. The i ...

South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia. It constitutes the southern half of the Korea, Korean Peninsula and borders North Korea along the Korean Demilitarized Zone, with the Yellow Sea to the west and t ...

. While this plant is clearly ophioglossoid in the broad sense, its precise cladistic position is uncertain. It has a fused sporangial structure similar to ''

Ophioglossum ''Ophioglossum'', the adder's-tongue ferns, is a genus of about 50 species of ferns in the family Ophioglossaceae. The genus name comes from Ancient Greek ὄφις (''óphis''), meaning "snake", and γλῶσσα (''glôssa''), meaning "tongue". ...

'', but a vegetative structure, with palmately-radiating pinnae, reminiscent of ''

Helminthostachys ''Helminthostachys'' is a fern genus in the Ophioglossaceae (adder's tongue) family.details
Tropicos.org. Missouri Botanical Garden. ...

''. It may be a basal offshoot of the ophioglossoid clade ''sensu stricto''. The genus name of ''Mankyua'' is in honour of Man Kyu Pak (1906-1988), who was a South Korean researcher and botanist (

Pteridology The ferns (Polypodiopsida or Polypodiophyta) are a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. They differ from mosses by being vascular, i.e., having specialized tissue ...

). The genus was

circumscribed In geometry, a circumscribed circle for a set of points is a circle passing through each of them. Such a circle is said to ''circumscribe'' the points or a polygon formed from them; such a polygon is said to be ''inscribed'' in the circle. * Circum ...

by Byung Yun Sun, Moon Hong Kim and Chul Hwan Kim in

Taxon In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...

vol.50 (Issue 4) on page 1020 in 2001.

Origin

Three phylogenetic analyses are performed on two cpDNA regions from 42 accessions representing the major lycophyte groups that were obtained from

GenBank The GenBank sequence database is an open access, annotated collection of all publicly available nucleotide sequences and their protein translations. It is produced and maintained by the National Center for Biotechnology Information (NCBI; a par ...

to pinpoint the exact phylogenetic position of M. chejuense (maximum parsimony, maximum likelihood, and Bayesian inference). In addition, a relaxed molecular clock with four fossil calibration points is used to estimate the divergence time. According to these finding, Mankyua may represent the oldest diverging lineage within the

Ophioglossaceae Ophioglossaceae, from Ancient Greek ὄφις (''óphis''), meaning "snake", and γλῶσσα (''glôssa''), meaning "tongue", also known as the adder's-tongue family, is a small family of ferns. In the Pteridophyte Phylogeny Group classificatio ...

or a sister clade to the group that includes

and

Helminthostachys ''Helminthostachys'' is a fern genus in the Ophioglossaceae (adder's tongue) family.details
Tropicos.org. Missouri Botanical Garden. ...

, depending on the phylogenetic position that is still unknown. Ophioglossaceae and its sister family,

Psilotum ''Psilotum'' is a genus of fern-like vascular plants. It is one of two genera in the family Psilotaceae commonly known as whisk ferns, the other being ''Tmesipteris''. Plants in these two genera were once thought to be descended from the earlies ...

, are thought to have shared a common ancestor as recently as 256 Ma, whereas Mankyua diverged as early as 195 Ma in the early

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

References

Sun, B.-Y., M.H. Kim, C.H. Kim, and C.-W. Park. 2001. Mankyua (Ophioglossaceae): a new fern genus from Cheju Island, Korea. Taxon 50: 1019-1024.

Line Notes

{{fern-stub Ophioglossaceae Endemic flora of Korea Monotypic fern genera Ferns of Korea Taxa described in 2001