''Kaonashia insperata'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

single-celled A unicellular organism, also known as a single-celled organism, is an organism that consists of a single cell (biology), cell, unlike a multicellular organism that consists of multiple cells. Organisms fall into two general categories: prokaryotic ...

phagotroph Phagocytosis () is the process by which a cell uses its plasma membrane to engulf a large particle (≥ 0.5 μm), giving rise to an internal compartment called the phagosome. It is one type of endocytosis. A cell that performs phagocytosis i ...

stramenopiles The stramenopiles, also called heterokonts, are Protist, protists distinguished by the presence of stiff tripartite external hairs. In most species, the hairs are attached to flagella, in some they are attached to other areas of the cellular sur ...

. Described in 2023 from flagellates found in a

soda lake A soda lake or alkaline lake is a lake on the strongly base (chemistry), basic side of neutrality, typically with a pH, pH value between 9 and 12. They are characterized by high concentrations of carbonate salts, typically sodium carbonate (and ...

, it is the sole species within the genus ''Kaonashia'' and family Kaonashiidae. Cells of this organism have cortical alveoli, extrusomes, a ventral groove, a short anterior flagellum covered in mastigonemes, and a longer posterior flagellum covered in thinner hairs. The cells are most similar to those found in developayellids, but a molecular phylogenetic analysis found no well-supported affinity to any specific stramenopile group.

Etymology

The

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

''Kaonashia'' is named after the fictional ghost from the

Hayao Miyazaki is a Japanese animator, filmmaker, and manga artist. He co-founded Studio Ghibli and serves as honorary chairman. Throughout his career, Miyazaki has attained international acclaim as a masterful storyteller and creator of Anime, Japanese ani ...

film ''

Spirited Away is a 2001 Japanese Anime film, animated fantasy film written and directed by Hayao Miyazaki. It was produced by Toshio Suzuki, animated by Studio Ghibli, and distributed by Toho.specific epithet In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

''insperata'' () references the unanticipated phylogenetic placement of this organism given its appearance.

Description

Cellular organization

''Kaonashia insperata'' is a

of free-living

flagellate A flagellate is a cell or organism with one or more whip-like appendages called flagella. The word ''flagellate'' also describes a particular construction (or level of organization) characteristic of many prokaryotes and eukaryotes and the ...

s. The cells are roughly ovoid or bean-shaped, 7–13 μm long, abundant in simple

extrusome Extrusomes are membrane-bound organelles found in eukaryotic cells that are capable of discharging material contained within to the exterior of the cell. Due to the diversity in structure and function, it is unlikely that different types of extruso ...

s and flattened cortical alveoli underlying much of the

cell membrane The cell membrane (also known as the plasma membrane or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of a cell from the outside environment (the extr ...

, and with a conspicuous ventral groove. The

mitochondria A mitochondrion () is an organelle found in the cells of most eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is us ...

have tubular

crista A crista (; : cristae) is a fold in the inner mitochondrial membrane, inner membrane of a mitochondrion. The name is from the Latin for ''crest'' or ''plume'', and it gives the inner membrane its characteristic wrinkled shape, providing a large a ...

e. The cell shape and size is distorted when containing

food vacuole The food vacuole, or digestive vacuole, is an organelle found in simple eukaryotes such as protists. This organelle is essentially a lysosome. During the stage of the symbiont parasites' lifecycle where it resides within a human (or other mammalia ...

s and prey cells. Each cell has two flagella: a long, posterior flagellum (2.5 times the cell length) that lies inside the ventral groove and trails behind when swimming; and a shorter,

anterior Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

flagellum (1.5 times the cell length) that points forward in a rapid beating motion. Along the anterior flagellum are long mastigonemes (flagellar "hairs") arranged in two opposing rows. Each mastigoneme has two unequal terminal filaments. The mastigonemes appear near the insertion of the flagellum up until the distal portion where they are absent, not extending to the tip as is usual in other stramenopiles. The posterior flagellum sometimes anchors to the substrate through sparse, thinner hair-like filaments. The general

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...

of their cells is consistent with

, but their cellular structures are also found across other members of the Sar clade and even more distantly related eukaryotes. The extrusomes of ''K. insperata'' are smaller and simpler than most extrusomes in Sar species, and are most similar to those observed in telonemids and some

rhizaria The Rhizaria are a diverse and species-rich clade of mostly unicellular eukaryotes. Except for the Chlorarachniophytes and three species in the genus '' Paulinella'' in the phylum Cercozoa, they are all non-photosynthetic, but many Foraminifera ...

ns. The cortical alveoli are the unifying trait of

alveolate The alveolates (meaning "pitted like a honeycomb") are a group of protists, considered a major unranked clade or superphylum within Eukaryota. They are currently grouped with the Stramenopiles and Rhizaria among the protists with tubulocristate ...

s; among phagotrophic stramenopiles they have been identified in developayellids, although larger and more limited than those found in ''K. insperata''. The ventral groove is observed in many distantly related eukaryotes such as excavates; among stramenopiles, the highest similarity corresponds to developayellids. Regarding the flagella, a longer posterior flagellum is also seen in developayellids. The mastigonemes of the anterior flagellum are typical of stramenopiles, particularly placidideans and oomycetes due to the unequal terminal filaments, and the thinner hairs of the posterior one are similar to those used by some oomycetes to adhere to plant matter.

Reproduction

The cells reproduce asexually through

binary fission Binary may refer to: Science and technology Mathematics * Binary number, a representation of numbers using only two values (0 and 1) for each digit * Binary function, a function that takes two arguments * Binary operation, a mathematical o ...

. The flagella are duplicated and positioned at opposite sides of the anterior end of the cell. Throughout the

cell division Cell division is the process by which a parent cell (biology), cell divides into two daughter cells. Cell division usually occurs as part of a larger cell cycle in which the cell grows and replicates its chromosome(s) before dividing. In eukar ...

, cells are still capable of movement, and appear two-lobed at the anterior end, frequently with a food vacuole located near the site of

cytokinesis Cytokinesis () is the part of the cell division process and part of mitosis during which the cytoplasm of a single eukaryotic cell divides into two daughter cells. Cytoplasmic division begins during or after the late stages of nuclear division ...

Nutrition and habitat

''Kaonashia insperata'' is one of the few described

heterotroph A heterotroph (; ) is an organism that cannot produce its own food, instead taking nutrition from other sources of organic carbon, mainly plant or animal matter. In the food chain, heterotrophs are primary, secondary and tertiary consumers, but ...

protist A protist ( ) or protoctist is any eukaryotic organism that is not an animal, land plant, or fungus. Protists do not form a natural group, or clade, but are a paraphyletic grouping of all descendants of the last eukaryotic common ancest ...

s found in

s. It is a species of eukaryotrophic

aerobe An aerobic organism or aerobe is an organism that can survive and grow in an oxygenated environment. The ability to exhibit aerobic respiration may yield benefits to the aerobic organism, as aerobic respiration yields more energy than anaerobic ...

s, meaning they consume other eukaryotes and breathe oxygen. They feed on various species of unicellular algae, particularly those that are larger than 5 μm, such as '' Guillardia theta''.

Systematics

Cells of this species were first obtained from the

photic zone The photic zone (or euphotic zone, epipelagic zone, or sunlight zone) is the uppermost layer of a body of water that receives sunlight, allowing phytoplankton to perform photosynthesis. It undergoes a series of physical, chemical, and biological ...

of Soap Lake, Washington, USA, initially under the name of isolate SC, together with residual '' Guillardia theta'' prey cells and

bacteria Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...

. The flagellates were cultivated and studied under light and electron microscopy, which unveiled numerous morphological traits associated with the

Stramenopiles The stramenopiles, also called heterokonts, are Protist, protists distinguished by the presence of stiff tripartite external hairs. In most species, the hairs are attached to flagella, in some they are attached to other areas of the cellular sur ...

. A phylogenetic analysis performed with the SSU rDNA gene placed these flagellates within the Stramenopiles

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

. Despite the close resemblance with developayellids, there is no well-supported affinity to any particular stramenopile subgroup. As a result, the organism was classified as a new

and

''Kaonashia insperata'' in a new separate

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Kaonashiidae, placed directly in the Stramenopiles. The description was published in 2023 in an article by protistologists Elizabeth J. Weston, Yana Eglit, and Alastair G. B. Simpson. Resin-embedded cells of isolate SC were assigned as the hapantotype of ''Kaonashia insperata'' and deposited in the Institute of Parasitology of the

Czech Academy of Sciences The Czech Academy of Sciences (abbr. CAS, , abbr. AV ČR) was established in 1992 by the Czech National Council as the Czech successor of the former Czechoslovak Academy of Sciences and its tradition goes back to the Royal Bohemian Society of Sc ...

under the code ICPAS_Pro_77.

References

{{taxonbar, from1=Q130312921, from2=Q130312932, from3=Q130312940 Taxa described in 2023 Stramenopile genera