Title

Taxonomy, Distribution, and Trait Data Sets of Japanese Collembola

Authors

Takuo Hishi^{1, *}, Saori Fujii², Seikoh Saitoh³, Tomohiro Yoshida⁴, Motohiro Hasegawa^{5, †}

1: Shiiba Research Forest, Kyushu University, 949 Ohkawauchi, Shiiba-son, Miyazaki 868-0402, Japan

2: Department of Forest Entomology, Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba City, Ibaraki, 305-8687 Japan

3: College of Economy and Environmental Policy, Okinawa International University, 2-6-1 Ginowan, Ginowan City, Okinawa, 901-2701 Japan

4: Field Science Center, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu City, Tokyo, 183-8509 Japan

5: Shikoku Research Center, Forestry and Forest Products Research Institute, 2-915 Asakuranishi, Kochi, Kochi City, 780-8077 Japan

†: Present affiliation

Department of Environmental Systems Science, Faculty of Science and Engineering, Doshisha University, 1-3 Tatara Miyakodani, Kyotanabe, Kyoto, 610-0394 Japan

*: Corresponding author:

Address: Shiiba Research Forest, Kyushu University, 949 Ohkawauchi, Shiiba-son, Miyazaki 868-0402, Japan

Tel: +81-983-38-1116

E-mail: hishi@forest.kyushu-u.ac.jp

Abstract

In community ecology, trait-based approaches have been strongly recommended in recent years to understand the responses of community functions against environmental changes. Trait-based approaches have been used to solve the mechanistic rules in the relationship between soil animal communities and environmental change. However, databases of functional traits of soil animals are still lacking. Collembola is one of the most abundant and diverse group in land ecosystems, with more than 400 identified species in Japan. This dataset provides taxonomic information, geographic, habitat distributions, and 13 morphological trait items of 407 species of Japanese Collembola: described in Japanese literature. The workshop of Japanese Collembola, supported by the Japanese Society of Soil Zoology, summarized the taxonomy for the Japanese Collembola species. The dataset presented here is mainly based on their work. The spatial coverage of this dataset is in the land area of Japan. Suborder, superfamily, family, subfamily, genus, and species names, as well as common Japanese names, are listed in this paper. The species distributions of Japanese Collembola in each global ecozone and in each area within Japan were described. Habitat preference for soil, cave, seashore, and tree trunk habitats were recorded. The 13 morphological traits of Collembola species, which are body length; body weight of adult individual; body form; antenna length; furca length; body pigmentation; pairs of ocelli (eyes); post-antennal organ (PAO); pseudocelli; body scale; anal spine; mandible; and molar plate are listed in this dataset. These 13 morphological traits in this dataset are covered the most of trait items which have been internationally used in Collembola study. Trait-based studies of Collembola have mainly been for European species, most of which are not found in Japan or East Asia. These datasets may provide an important first step to incorporating community data from the Asian region to the trait-based global ecology. Data files are stored in the Ecological Research Data Archives (ERDP-2019-03).

Keywords

• Community ecology
• Functional trait
• Geographic distribution
• Morphological trait
• Springtail
• Taxonomy of Japanese springtail

Introduction

In community ecology, trait-based approaches have been strongly recommended in recent years to understand the responses of community functions against environmental changes (McGill, Enquist, Weiher, & Westby, 2006; Webb, Hoeting, Ames, Pyne, & Poff, 2010). Previous community ecologists have traditionally used a nomenclatural approach by focusing on species identities, making it difficult to produce general principles in community processes (McGill et al., 2006). Trait-based approaches have been successful particularly in plant ecology. In these approaches, physiological and morphological traits can be linked to ecosystem processes (Díaz et al., 2016; Freschet et al., 2013; Kunsler et al., 2015). Soil-dwelling animals are found in high abundance and diversity in soil and have a critical function as a driver of litter decomposition. Trait-based approaches have been used to solve the mechanistic rules in the relationship between soil animal communities and environmental change, such as forest succession, land use, urbanization, soil drought, fire disturbance, and soil freezing (Pey et al., 2014). However, compared to large online trait databases such as TRY in plant ecology (Kattge et al., 2011), databases of functional traits of soil animals are still lacking.

Previous studies have also focused on the geographic distribution of organisms, as species dispersion is often the main determinant of local community structure (Hubbel, 2001). The range of habitats in which a species is found indicates whether the species are habitat specialists or generalists. Additionally, geographic and habitat preferences could be used to identify species within a sample of collected individuals.

Phylogenetic diversity, based on DNA sequences, is the index of evolutionary variation within a species assemblage (Webb, Ackerly, McPeek, & Donoghue, 2002), and has been widely applied to study assembly rules across ecosystems and taxa (Cadotte et al., 2011). However, DNA sequencing for all individuals or species is not always available, and as a result the phylogenetic distance between species is often unknown. Taxonomic diversity based on Linnaean taxonomy is a useful substitute of phylogeny to determine the evolutionary variation of a taxonomic group which includes either species without molecular data or undescribed species (Warwick & Clarke, 1995; Lefcheck et al., 2014).

Soil Collembola is one of the most abundant and diverse group in land ecosystems, worldwide, with more than 8,000 species described globally (Hopkin, 1997); and more than 400 identified species in Japan. In this study, we describe the taxonomic diversity of the Japanese Collembola in an illustrated bibliography of soil animals, including 407 individual species (Ichisawa et al., 2015), alongside a description of their distribution and morphological characteristics. This information is useful for taxonomy and for the progress of soil community ecology in Japan. However, the bibliography by Ichisawa et al. (2015) is only in Japanese, and therefore, our dataset in English is useful for international ecologists around the world. In our dataset, Linnean taxonomy, geographic and habitat preference, and 13 morphological traits of all 407 Japanese Collembola species are listed. The 13 morphological traits in this dataset are covered the most of trait items which have been internationally used in Collembola study (Pey et al., 2014). In addition, life-form score (Vandewalle et al., 2010) can be calculated using the morphological dataset, and classified into categorical lifeforms of epi-, hemi- and eu-edaphon using the scores (Oliveira Filho, Klauberg Filho, Baretta, Tanaka, & Sousa, 2016). Trait-based studies of Collembola have mainly been for European species, most of which are not found in Japan or East Asia. This dataset may provide an important first step to incorporating community data from the Asian region to the trait-based global ecology.

Metadata

1. TITLE

Taxonomy, distribution, and morphological trait dataset of Japanese Collembola

2. IDENTIFIER

ERDP-2019-03

3. CONTRIBUTORS

3.A. Dataset Owners and Contact Persons

Takuo Hishi

Affiliation: Shiiba Research Forest

Address: 949 Ohkawauchi, Shiiba-son, Miyazaki, Japan

E-mail address: hishi@forest.kyushu-u.ac.jp

Motohiro Hasegawa

Current affiliation: Department of Environmental Systems Science, Faculty of Science and Engineering, Doshisha University

Address: 1-3 Tatara Miyakodani, Kyotanabe, Kyoto, 610-0394 Japan

E-mail address: mohasega@mail.doshisha.ac.jp

3.B. Investigators

Takuo Hishi

Shiiba Research Forest, Kyushu University

949 Ohkawauchi, Shiiba Village, Miyazaki 868-0402, Japan

Motohiro Hasegawa

Department of Environmental Systems Science, Faculty of Science and Engineering, Doshisha University, 1-3 Tatara Miyakodani, Kyotanabe, Kyoto, 610-0394 Japan

Saori Fujii

Department of Forest Entomology, Forestry and Forest Products Research Institute

1 Matsunosato, Tsukuba City, Ibaraki, 305-8687 Japan

Tomohiro Yoshida

Field Science Center, Tokyo University of Agriculture and Technology

3-5-8 Saiwai-cho, Fuchu City, Tokyo, 183-8509 Japan

Seikoh Saitoh

College of Economy and Environmental Policy, Okinawa International University

2-6-1 Ginowan, Ginowan City, Okinawa, 901-2701 Japan

The workshop on Japanese Collembola

4. GEOGRAPHICAL COVERAGE

4.A. Geographic Description

Japan

4.B. Boundary Coverage

(Geographic coordinate system, WGS84)

West: 128° 13′ 05″

East: 144° 39′ 36″

North: 44° 21′ 44″

South: 26° 45′ 09″

5. METHODS AND DEFINITION OF VARIABLES

5.A. Species Taxonomy

Systematics of Collembola used in this study followed that of Ichisawa et al. (2015), which identified Collembola as an order. The systems used in recent studies (Deharveng, 2004; D’Haese, 2002; Janssens & Christiansen, 2011) are inconsistent with that of Ichisawa et al. (2015). Order Collembola was upgraded to ‘Class’ level, and suborder was also upgraded into order (Janssens & Christiansen, 2011). A recent taxonomic list is provided on the following website: Checklist of Collembola of the World (Bellinger, Christiansen, & Janssens, 1996-2019). The alternative classification is presented in the note section of the data sheet with the appropriate reference.

5.A.1. spID1

Species-specific ID number of all Japanese Collembola in this dataset.

5.A.2. spID2

Species-specific ID number for each family of Collembola. This ID correspond to the ID numbers of Ichisawa et al. (2015) in the illustrated bibliography of Japanese Soil Animals.

5.A.3. Suborder

Suborder name of the species

5.A.4. Superfamily

Superfamily name of the species

5.A.5. Family

Family name of the species.

5.A.6. Subfamily

Subfamily name of the species.

5.A.7. Genus

Genus name of the species.

5.A.8. Specific_name

Specific name.

5.A.9. JPN_N

Japanese name.

5.A.10. Abb_sp

Abbreviation of species name.

5.A.11. Note

Explanation of the differences in taxonomical classification between studies.

5.B. Geographic Distribution

Geographic distribution data was primarily based on records of Poduridae, Hypogastruridae (Nakamori et al., 2014), Onychiuridae (Furuno, Suma, & Niijima, 2014), Neanuridae (Hasegawa & Tanaka, 2013; Tanaka, 2010), Isotomidae (Hasegawa & Niijima, 2012; Niijima & Hasegawa, 2011), Tomoceridae (Suma, 2009), Entomobryidae, Orchesellidae, Paronellidae, Cyphoderidae, Oncopoduridae (Ichisawa, 2012), Neelipleona, and Symphypleona (Itoh et al., 2012). The findings from these studies were summarized into the illustrated bibliography (Ichisawa et al., 2015). The number 0 indicated absence and 1 indicated presence of a particular species in each region. When the descriptions in distributions of species are ambiguous in Ichisawa et al. (2015), especially those described as “cosmopolitan”, their geographic distributions were checked in the website “Checklist of the Collembola of the World” by Bellinger et al. (1996-2019).

Geographic distribution in ecozones

The global land mass can be divided into 8 ecozones: Palearctic, Indomalaya, Nearctic, Afrotropic, Australasia, Oceania, Neotropic, and Antarctic (Olson et al., 2001). Japan mainly belongs primarily to the Palearctic biogeographic realm, with some parts lying in the Indomalayan and Oceania ecozones. The geographic distribution of each Japanese Collembola species in each of the 8 ecozones was checked.

5.B.1. spID1

Species-specific ID number of all Japanese Collembola in this dataset. See 5. A.1.

5.B.2. spID2

Species-specific ID number in each family of Collembola. See 5. A.2.

5.B.3. Abb_sp

Abbreviation of species name. See 5. A.10.

5.B.4. Palearctic

Palearctic includes Europe, Asia (excluding Indomalaya), and North Africa. In Japan, Hokkaido, East and West Honshu, Shikoku, and Kyushu Island lie within the Palearctic ecozone. Izu, Ohsumi and the northern Tokara Islands are included in this zone.

5.B.5. Indomalaya

Indomalaya includes south and south-east Asia and the southern parts of east Asia. The Indomalayan ecozone is also sometimes referred to as the Oriental region. In Japan, most parts of the Nansei Islands excluding Ohsumi and the northern Tokara Islands are within the Indomalaya ecozone.

5.B.6. Nearctic

The Nearctic covers most parts of North America and Greenland.

5.B.7. Afrotropic

The Afrotropical ecozone includes all of the African continental land mass south of the Sahara Desert, the southern parts of the Arabian Peninsula, and Madagascar.

5.B.8. Australasia

The Australasian ecozone includes Australia, New Zealand, and New Guinea.

5.B.9. Oceania

The Oceania ecozone includes the islands of Polynesia (except New Zealand), Micronesia, and Fijian Islands. There is no continental land mass in the Oceania ecozone. In Japan, the Ogasawara islands are a part of Oceania ecozone.

5.B.10. Neotropic

The Neotropic ecozone covers Central America, South America, and the Caribbean.

5.B.11. Antarctic

The Antarctic ecozone covers Antarctica.

Geographic distribution within the Japanese archipelago

The Japanese archipelago can be separated into six areas: Hokkaido, East Honshu, West Honshu, Shikoku, Kyushu, and the Nansei Islands. The geographic distribution of each Collembola species in Japan was checked. The number 0 indicates absence and 1 indicates presence of each species in each region. Additionally, data were provided on whether the species were endemic to Japan (1) or not (0), and whether they were cosmopolitan (1) or not (0).

5.B.12. Hokkaido

Species was found on Hokkaido Island.

5.B.13. East_Honshu

Species was found in the eastern part of Honshu Island. The geographical boundary between East and West Honshu is around the Japanese Central Alps, which is the western boundary of the Niigata, Nagano and Shizuoka prefectures.

5.B.14. West_Honshu

Species was found in the western part of Honshu Island. The geographical boundary between East and West Honshu is around the Japanese Central Alps.

5.B.15. Shikoku

Species was found on Shikoku Island.

5.B.16. Kyushu

Species was found on Kyushu Island.

5.B.17. Nansei_Islands

Species has been found in the Nansei Islands, including Ohsumi, Tokara, Amami, Okinawa and Sakishima Islands.

5.B.18. Cosmopolitan

The definition of ‘cosmopolitan’ is the species distributed across more than five ecozones.

5.B.19. EndemicJ

A species is considered endemic if its distribution is restricted to Japan only.

5.B.20. all_areaJ

The species distribution spans all of Japan.

5.B.21. Note

Some cautions about species distribution.

5.C. Habitat

The habitats in which each Collembola species was found were recorded. Data were mainly obtained from Ichisawa et al. (2015). Additional information was obtained from Aoyama et al. (2015) for soil and Yoshida and Hijii (2005) for tree trunks. Habitat categories were classified into soil (forest, grassland and agricultural field), cave, sea shore, and tree stems.

5.C.1. spID1

Species-specific ID number of all Japanese Collembola in this data set. See 5. A.1.

5.C.2. spID2

Species-specific ID number in each family of Collembola. See 5. A.2.

5.C.3. Abb_sp

Abbreviation of species name. See 5. A.10.

5.C.4. Soil

Species generally found in litter, humus or soil in forest, grassland or agricultural ecosystems.

5.C.5. Cave

Species frequently found in caves.

5.C.6. Seashore

Species frequently found on the seashore.

5.C.7. Tree_Trunk

Species frequently found on tree trunks.

5.C.8. Note

Special habitats not specified above are noted in this field.

5.D. Morphological Traits

Morphological trait data was based on records found in studies of Poduridae, Hypogastruridae (Nakamori et al., 2014), Onychiuridae (Furuno et al., 2014), Neanuridae (Tanaka, 2010; Hasegawa & Tanaka, 2013), Isotomidae (Niijima & Hasegawa, 2011; Hasegawa & Niijima, 2012), Tomoceridae (Suma, 2009), Entomobryidae, Orchesellidae, Paronellidae, Cyphoderidae, Oncopoduridae (Ichisawa, 2012), Neelipleona and Symphypleona (Itoh et al., 2012). These studies were summarized in the illustrated bibliography of Ichisawa et al., (2015). Description and illustrations of each individual species were used to determine the morphological traits used in this study. The examples of traits of some species are shown in Fig. 1.

Fig. 1. Illustration of typical Collembola taxa and their morphological traits. Abbreviations used: BL (body length); BM (body mass); AL (antenna length); FL (furca length); BC (body color); OC (number of ocelli pairs); PAO (complexity of Post Antennal Organ); PSO (presence or absence of pseudocelli); SC (presence or absence of scale hair); AS (number of anal spines); MP (presence or absence of molar plate); MD (presence or absence of mandible).

5.D.1. spID1

Species-specific ID number of all Japanese Collembola in this data set. See 5. A.1.

5.D.2. spID2

Species-specific ID number in each family of Collembola. See 5. A.2.

5.D.3. Abb_sp

Abbreviation of species name. See 5. A.10.

5.D.4. Body Length

The body length (mm) was the length from apex of head to apex of abdomen. The precision of the data is 0.1 mm following to the descriptions in Ichisawa et al. (2015). The length was that of adult individuals used for taxonomic studies. Body length often relates with soil habitat in depth, as a large body allows organisms to disperse over long distances within surface soil with many aerial spaces, whereas a small body allows organisms to move in deeper soil with limited space (Petersen, 2002). A large body also protects the inner organs against physical stresses, such as desiccation and soil frost (Salmon, Ponge, Gachet, Deharveng, Lefebvre, & Delabrosse, 2014).

5.D.5. Body Mass

The body mass (µg) was calculated using double logarithm equations between body length and dry weight of each families. The equation used for each family was defined by Tanaka (1970) and Petersen (1975). The means of coefficients for each family shown in Tanaka (1970) and Petersen (1975) were used to estimate body mass:

log₁₀ W = a + b log₁₀ L

where W and L are body weight and body length of an adult individual, respectively; and a and b are the coefficients for each family. Only for Symphypleona, body mass was estimated starting from the thorax, excluding head length (L is thorax + abdomen length). Thorax + abdomen length was estimated using 0.738 of (thorax + abdomen)/body length ratio known from 53 species of Symphypleona (Ichisawa et al., 2015). The coefficients of equations of each family is shown in Table 1. The body mass data were rounded to one decimal place.

Body mass often relates with soil habitat in depth (Petersen, 2002). The reason is the same as that discussed in 5. D.4. body length. Additionally, biomass is more useful to evaluate the traits of species impacts on ecosystem processes, such as feeding attributes, nutrient release, and respiration.

Table 1. Coefficients for the equation for calculate body mass (µg). The equation is log₁₀ W = a + b log₁₀ L.

* L = thorax + abdomen length (Thorax + abdomen length was used to estimate body mass.)

5.D.6. Body Form

Body form is categorized into three types: spherical, stocky, and slender body types. Body form is also considered to relate with species habitat in soil depth: a slender body is more adapted to deep soil layers than spherical and stocky body types, whereas spherical and stocky bodies allow better protection of the inner organs against physical stresses on the soil surface, such as desiccation.

5.D.7. Antenna Length

Antennae length was classified into four categories: very short (shorter than twice as long as the head length); short (shorter than half of the body length); long (longer than half of the body length, but still shorter than the body length); and very long (equal in length or longer than the body). Antennae are air-sensitive sensors (Salmon et al., 2014), and their length is also considered to relate with species habitat in soil depth.

5.D.8. Furca Length

Furca (jumping organ) length was classified into three categories: lacking; short (shorter than half of the abdomen length), and long (longer than half of the abdomen length). Furca length has often been used as an index of dispersal ability (Ponge, Dubs, Gillet, Sousa, & Lavelle, 2006), and of the ability to escape from predators (Salmon et al., 2014).

5.D.9. Pigment

Body pigmentation level was categorized into pale, bright and dark in color. Pale color included white, cream and beige. Bright color included red, orange, light brown, light gray, and light blue. Dark color included black, dark gray, dark blue, and dark brown. Species with color pattern were also categorized into dark. The dark body color protects from UV light, and species living close to the surface in soil habitat tend to be darker-colored than those in deeper soil habitat (Salmon et al., 2014).

5.D.10. Ocelli

The number of ocelli (eyes) was ordered from 0 to 8 pairs. Ocelli are light-sensitive sensors (Salmon et al., 2014), and species in surface soil tend to have more eyes than species in darker, deeper habitats, or caves.

5.D.11. PAO

The PAO (Post-Antennal Organ) is positioned posterior to the base of the antennae. The complexity of PAO was categorized into absent, simple and complex. Simple PAO was only one segment, whereas complex PAO was composed of multiple segments. The function of PAO is not completely understood; it may have olfactory functions or may be sensitive to smell, humidity, or temperature (Hopkin, 1997). As it is an alternative sensor to antennae and ocelli, it is logical that species in deeper soil have more complex PAO than species in surface soil (Salmon et al., 2014).

5.D.12. Pseudocelli

Pseudocelli are organs specific to the family Onychiuroidea, most of which lack a jumping organ. This was categorized as either present or absent. Pseudocelli excrete toxins, which repel predators in deeper soil, where these organisms cannot escape in deeper soil, instead of jumping with furca (Negri, 2004).

5.D.13. Scale

Presence or absence of scales on the body. Scales may protect against UV light and desiccation (Hopkin, 1997).

5.D.14. Spine

The number of anal spines of adult individuals. Although the function of anal spines is not well known, the spine is often used for burrowing micro-holes (Rusek, 1998).

5.D.15. Molar Plate

Presence or absence of molar plate in mouth parts. The molar plate is positioned on the base of mandibles. Chewing species have a molar plate, which can crush plant and fungal material (Malcicka, Berg, & Ellers, 2017). Fluid-suckers, piercers, and scratchers do not have molar plates.

5.D.16. Mandible

Presence or absence of mandibles in mouth parts.

6. DATA STATUS

Latest update: 14th March, 2019

7. ACCESSIBILITY

7.A. License

This dataset is provided under a Creative Commons Attribution 4.0 International License (CC BY 4.0; https://creativecommons.org/licenses/by/4.0/).

7.B. Data Updates

This dataset will be updated. Please check the latest version of the data set.

7.C. Disclaimer

In no event shall the authors and the data set owners be liable for loss of profits, or for any indirect, incidental, or consequential damages arising from the use of the data set.

7.D. Dataset Owner

See 3.A.

8. DATA STRUCTURE

8.A. Species Taxonomy

8.A.1. Data set file

Identifier: A_sptaxon.csv

Format and storage mode: ASCII text, comma separated. No compression scheme was used.

Header information: The first row of the file contains the variable names detailed below.

8.A.2. Variable Information

8.B. Geographic Distribution

8.B.1. Dataset file

Identity: B_geodist.csv

Format and storage mode: ASCII text, comma separated. No compression scheme was used.

Header information: The first row of the file contains the variable names detailed below.

8.B.2. Variable Information

Missing value codes: ‘NA’ indicates that data are not available because the species geographic distribution is unknown.

8.C. Habitat

8.C.1. Data Set File

Identifier: C_habitat.csv

Format and storage mode: ASCII text, comma separated. No compression scheme was used.

Header information: The first row of the file contains the variable names detailed below.

8.C.2. Variable Information

Missing value codes: ‘NA’ indicates that data is not available because the species habitat distribution is unknown.

8.D. Morphological Traits

8.D.1. Data Set File

Identity: D_trait.csv

Format and storage mode: ASCII text, comma separated. No compression scheme was used.

Header information: The first row of the file contains the variable names detailed below.

8.D.2. Variable Information

Missing value codes: ‘NA’ represents missing or unspecified values.

9. ACKNOWLEDGEMENTS

This study was supported by members of the workshop on Collembola, organized by the Japanese Society of Soil Zoology. This study partly supported by JSPS KAKENHI (No. 17H01912). We thank the two anonymous reviewers for their comments, which have greatly helped in improving the data quality. All authors have no conflicts of interest to declare.

10. LITERATURE CITED

Aoyama, H., Saitoh, S., Fujii, S., Nagahama, H., Shinzato, N., Kaneko, N., Nakamori, T. (2015) A rapid method of non-destructive DNA extraction from individual springtails (Collembola). Applied Entomology and Zoology, 50, 419-425. doi:10.1007/s13355-015-0340-0

Bellinger, P. F., Christiansen, K. A., Janssens, F. (1996–2019) Checklist of the Collembola of the World. http://www.collembola.org/. (accessed last update 28th February 2019).

Cadotte, M. W., Carscadden, K., Mirotchnick, N. (2011) Beyond species: functional diversity and the maintenance of ecological processes and services. Journal of Applied Ecology, 48, 1079-1087. doi:10.1111/j.1365-2664.2011.02048.x

Deharveng, L. (2004) Recent advances in Collembola systematics. Pedobiologia, 48, 415-433. doi:10.1016/j.pedobi.2004.08.001

D’Haese, C. A. (2002) Were the first springtails semi-aquatic? A phylogenetic approach by means of 28S rDNA and optimization alignment. Proceeding of the Royal Society B, 269: 1143-1151. doi:10.1098/rspb.2002.1981

Díaz, S., Kattge, J., Cornelissen, J. H. C., Wright, I. J., Lavorel, S., Dray, S., … Gorne, L. D. (2016) The global spectrum of plant form and function. Nature, 529, 167-171. doi:10.1038/nature16489

Freschet, G. T., Cornwell, W. K., Wardle, D. A., Elumeeva, T. G., Liu, W., Jackson, B. G., … Cornelissen, J. H. C. (2013) Linking litter decomposition of above- and below-ground organs to plant-soil feedbacks worldwide. Journal of Ecology, 101, 943-952. doi:10.1111/1365-2745.12092

Furuno, K., Suma, Y., Niijima, K. (2014) Classification of the Family Onychiuridae Börner, 1913 (Hexapoda: Entognatha: Collembola) from Japan. Edaphologia, 95:15-42. doi:10.20695/edaphologia.95.0_15

Hasegawa, M., Niijima, K. (2012) Classification of the Family Isotomidae Börner, 1913 (Apterygota: Collembola) from Japan 2. Isotominae Schäffer, 1896. Edaphologia 90:31-59. doi:10.20695/edaphologia.90.0_31

Hasegawa, M., Tanaka, S. (2013) Classification of the family Neanuridae (Hexapoda: Entognatha: Collembola) from Japan 2. Subfamilies Brachystomellinae Massoud, 1967, Odontellinae Massoud, 1967, Frieseinae Massoud, 1967 and Pseudachorutinae Massoud, 1967. Edaphologia 92:37-73. doi:10.20695/edaphologia.92.0_37

Hopkin, S. P. (1997) Biology of the Springtails. Oxford University Press.

Hubbel, S. P. (2001) The Unified Neutral Theory of Biodiversity and Biogeography. Princeton University Press.

Ichisawa, K. (2012) Classification of the family Entomobryidae Schäffer, 1896 and related families (Hexapoda: Entognatha: Collembola) from Japan. Including the Family Orchesellidae Börner, 1906, Paronellidae Börner, 1913, Cyphoderidae Börner, 1913 and Oncopoduridae Carl & Lebedinsky, 1905. Edaphologia 91:31-97. doi:10.20695/edaphologia.91.0_31

Ichisawa, K., Itoh, R., Suma, Y., Tanaka, S., Tamura, H., Nakamori, T., …Furuno, K. (2015) Hexapoda Collembola. In: Aoki J (Ed.), Pictorial Keys to Soil Animals of Japan 2nd. edition. (pp. 1093-1482). Kanagawa, Japan: Tokai University Press.

Itoh, R., Hasegawa, M., Ichisawa, K., Furuno, K., Suma, Y., Tanaka, S., … Niijima, K. (2012) Classification of the Suborder Neelipleona Massoud, 1971 and Symphypleona Börner, 1901 (Hexapoda: Entognatha: Collembola) from Japan. Edaphologia, 91, 99-156. doi:10.20695/edaphologia.91.0_99

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