''Macrobiotus shonaicus'' () is a species of tardigrade in the family

Macrobiotidae Macrobiotidae is a family of tardigrade. , it consists of the following genera: * '' Biserovus'' * '' Calcarobiotus'' ** ''C.'' (''Calcarobiotus'') ** ''C.'' (''Discrepunguis'') * '' Famelobiotus'' * '' Insuetifurca'' * '' Macrobiotus'' * ...

. it is only known from its type locality: Tsuruoka, Japan. The species description was published in 2018. The insides of their first three pairs of legs have a slight fold above their claws, and their eggs have processes whose terminal discs split off into thin filaments.

Taxonomic history

The species description was written by Daniel Stec, Kazuharu Arakawa, and Łukasz Michalczyk; it was published in '' PLOS One'' in February 2018. Arakawa collected ten ''M. shonaicus'' specimens in May 2016 from moss growing in his apartment building's parking lot, in Tsuruoka, Japan. The moss, '' Bryum argenteum'', was growing on a concrete surface. One pair of these tardigrades successfully reproduced in vitro, yielding an isogenic strain. The holotype, 57 paratypes, and 34 eggs were deposited at

Jagiellonian University The Jagiellonian University (Polish: ''Uniwersytet Jagielloński'', UJ) is a public research university in Kraków, Poland. Founded in 1364 by King Casimir III the Great, it is the oldest university in Poland and the 13th oldest university in ...

in Kraków. An additional 17 paratypes and 7 eggs were deposited at

Keio University , mottoeng = The pen is mightier than the sword , type = Private research coeducational higher education institution , established = 1858 , founder = Yukichi Fukuzawa , endowmen ...

, Tsuruoka. The

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

, ''shonaicus'', is named after Shōnai, which the authors describe as "the region in Japan where the new species was collected".

Distribution

The type locality is , "Otsuka-machi, Tsuruoka-City, Japan". It is found widely throughout Japan. []

Description

Juveniles have a white body, while the body of adults is a slightly yellowish. They have eyes. Round pores with a diameter of 0.2–0.4 μm are scattered over the surface of their legs, their sides, and their backs. The internal surface of their first three pairs of legs have a bulge; these pairs also have an inside fold above the claws. This species is

dioecious Dioecy (; ; adj. dioecious , ) is a characteristic of a species, meaning that it has distinct individual organisms (unisexual) that produce male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproductio ...

, but there are no secondary sex characteristics. The measurements of their body lengths range 218–743 μm. The eggs' color ranges from white to pale yellow and their shape ranges from spherical to slightly ovoid. The full diameter of the eggs range 56.4–70.8 μm. Their surface is covered with protruding inverted goblet-shaped platforms, whose terminal disc is surrounded by "teeth" which extend out into thin, fragile filaments. Stec and colleagues performed an experiment to see if females could reproduce

parthenogenetically Parthenogenesis (; from the Greek grc, παρθένος, translit=parthénos, lit=virgin, label=none + grc, γένεσις, translit=génesis, lit=creation, label=none) is a natural form of asexual reproduction in which growth and development ...

. Reproduction was not observed when individuals were separated and not allowed to mate, suggesting they cannot. Stec and colleagues sequenced four molecular markers:

18S rRNA 18S may refer to: *18S ribosomal RNA *18S rRNA (adenine1779-N6/adenine1780-N6)-dimethyltransferase *18SEH The Family II is a straight-4 piston engine that was originally developed by Opel in the 1970s, debuting in 1979. Available in a wide ran ...

28S rRNA Crazy Eights is a shedding-type card game for two to seven players and the best known American member of the Eights Group which also includes Pig and Spoons. The object of the game is to be the first player to discard all of their cards. The ga ...

ITS-2 Internal transcribed spacer (ITS) is the spacer DNA situated between the small-subunit ribosomal RNA (rRNA) and large-subunit rRNA genes in the chromosome or the corresponding transcribed region in the polycistronic rRNA precursor transcript. ...

, and mitochondrial COI. DNA was sequenced from four specimens. The sequences were submitted to GenBank. Their analysis yielded a single

haplotype A haplotype ( haploid genotype) is a group of alleles in an organism that are inherited together from a single parent. Many organisms contain genetic material ( DNA) which is inherited from two parents. Normally these organisms have their DNA or ...

each for the 18S rRNA and the 28S rRNA and two haplotypes each for the ITS-2 and COI. The most conservative marker with respect to other species in the ''M. hufelandi'' complex was 18S rRNA, which differed 0.3–3.3% from the available sequences in GenBank. This was followed by 28S rRNA (5.0–9.8%), ITS-2 (11.2–29.7%), and COI (19.6–26.9%).

Phylogeny

Stec and colleagues' analysis placed ''M. shonaicus'' in a

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

along with '' M. paulinae'', '' M. polypiformis'', '' M. scoticus'' and '' M. kristenseni''. This clade is within the ''hufelandi'' group.

References

External links