Proceratium itoi

A colony of P. itoi collected in Japan by Masuko and collaborators (1985) was formed of 202 workers and 1 queen. Workers are usually collected under stones and within the leaf-litter of glossy-leaved evergreen, deciduous broad-leaved and bamboo forests (Onoyama & Yoshimura 2002).

Identification
A member of the Proceratium itoi clade. Differing from the two ingroup species, Proceratium bhutanense and Proceratium malesianum, in the worker, by the palp formula 4,3 instead 3,2 and by the broader frontal carinae, from bhutanense only, by the presence of erect hairs over the whole body, and from malesianum only, by the mid basitarsi with hairs never as much as 1/2 of the mid basitarsal length.

Staab et al. (2018) - Proceratium itoi differs from the other members of the Proceratium itoi clade by the following character combination: medium-sized species (TL 3.46–3.82); sides of head very weakly convex, almost straight, broadest at level of eyes and gently narrowing anteriorly and posteriorly, vertex weakly convex, almost straight; frontal carinae well developed, with large lamellae that extend laterally above the antennal insertions; frontal furrow inconspicuous; posterodorsal corners of propodeum rounded, propodeal declivity superficially punctured (more so dorsally) but largely shiny; posterior face of petiolar node in profile steeper as anterior face; petiole almost as broad as long (DPeI 86–93), apex of petiolar node broader than long in dorsal view; subpetiolar process developed and triangular (but may be small); in addition to dense pubescence abundant erect hairs present on scapes and dorsal surface of body, longest of those hairs shorter than maximum dorsoventral diameter of metafemur.

Proceratium itoi is a typical member of its clade of intermediate size (WL 0.96–1.04) and is similar to most other species in body proportions and indices. Proceratium itoi can be separated from Proceratium williamsi and Proceratium zhaoi by the presence of erect hairs on the dorsal body surface (absent in Proceratium williamsi and Proceratium zhaoi); from Proceratium longmenense by the presence of erect hairs on the scape (absent in Proceratium longmenense) and by the frontal carinae separated at their anteriormost level (touching each other at their anteriormost level in Proceratium longmenense). In Proceratium itoi the posterodorsal corners of propodeum are rounded and this character distinguishes this species from Proceratium bruelheidei and Proceratium kepingmai (posterodorsal corners of the propodeum angular), which are also larger species (WL 1.03–1.10 and 1.14–1.24). The rounded posterodorsal corners of propodeum are shared between Proceratium malesianum and Proceratium itoi, but Proceratium malesianum is a smaller species (WL 0.71–0.90) with a broadly rounded vertex (weakly convex, almost straight in Proceratium itoi) and a broadly rounded petiolar node in profile (posterior face of petiolar node in profile steeper than anterior face in Proceratium itoi).

Volumetric raw data (in DICOM format), a 3D rotation video (in .mp4 format, see Suppl. material 4: Video 2), still images of surface volume rendering, a 3D surface (in PLY format), and montage photos illustrating the head, profile and dorsal views of the body of a non-type specimen (OKENT0016142) were all generated as part of this study (Staab et al 2018). Data and images are freely available for download from a Dryad repository (there is a download link at the top right of the webpage) and a 3D surface model can be viewed online at Sketchfab.

Distribution
China, Japan and Republic of Korea.

Staab et al. (2018) - This species is widely distributed, occurring from Japan (except Hokkaido) and South Korea to Vietnam. It has been recorded from Taiwan and the Chinese provinces Zhejiang and Hunan. Thus, we expect that it will be collected from the geographically intermediate provinces in the future.

Distribution based on Regional Taxon Lists
Oriental Region: Taiwan. Palaearctic Region: China, Japan, Republic of Korea.

Biology
Staab et al (2018) - No direct biological observations from China are available, but the Japanese populations are comparatively well studied (Onoyama and Yoshimura 2002). Nests are found in the soil or rotting wood of various deciduous or evergreen forest types and workers forage hypogeic or in leaf litter. Mature colonies have 100–200 workers and densities can reach 0.3 colonies per m² (Masuko 2010). Larval hemolymph feeding has been observed (Masuko 1986).

Masuko (2019) describes larval hemolymph feeding (LHF) in Proceratium itoi, where the queen feeds exclusively on the older final instar larvae by breaking open a specialized dorsal area. Proceratium itoi are predatory on spider eggs, and it is intriguing that the queen does not feed directly on this easy prey. It is possible that the larvae function as a filter, affording protection against toxins or parasites. Importantly, trophallaxis is lacking among the adults in almost all poneroid ants, so it is unsurprising that other trophic behaviours exist instead. Intuitively, ant queens are privileged beneficiaries of LHF exchanges given that their higher fecundity benefits colony fitness. The larvae that are subjected to LHF successfully eclose as adults. However, this vampirism unavoidably slows down larval growth, causing a cost to the colony. This seems to be confirmed by the absence of LHF in small incipient colonies. Although wounds quickly close by coagulation of hemolymph and cuticular melanization, LHF may be favoured by the high degree of hygiene inside ant nests. (Vampirism in the ant Proceratium itoi)

Nomenclature

 *  itoi. Sysphincta itoi Forel, 1918a: 717 (w.) JAPAN. Ogata, 1987: 107 (m.); Onoyama & Yoshimura, 2002: 35 (q.). Combination in Proceratium: Brown, 1958g: 247. See also: Baroni Urbani & De Andrade, 2003b: 267.

Worker
Baroni Urbani and de Andrade (2003) - Head longer than broad, its sides weakly convex. Vertex in full face view almost straight. Clypeus medially reduced, triangular, between and slightly longer than the antennal socket. Clypeal dorsum with a longitudinal carina. Antenna1 socket with broad torulus. Frontal carinae far (sic) each other, partially covering the antennal insertions. Frontal area behind the frontal carinae convex. Lateral expansions of the frontal carinae relatively narrow, raised, diverging. Genal carinae prominent. Eyes small, represented by a dark dot below the integument. Eyes on the midline of the head. First funicular joint subequal in length and width. Funicular joints 2-10 much broader than long. Last funicular joint about as long as the sum of joints 7- 10. Scapes clearly not reaching the vertexal margin and gently thickening apically. Masticatory margin of the mandibles with 3-4 denticles before the pointed apical tooth. Palp formula 4,3.

Mesosoma slightly longer than the maximum head length (mandibles included). Promesopleural and meso-melapleural sutures impressed ventrally only. Basal face of the propodeurn weakly declivous. Declivous face of the propodeum gently concave. Basal and declivous faces of the propodeum separate laterally by a weakly carinate angle. Sides of the declivous face of the propodeum carinate. Propodeal lobes surrounded by a narrow lamella. Propodeal spiracle round and above mid height in lateral view.

Petiole in profile with declivous anterior face and convex posteriorly. Petiole in dorsal view with diverging sides and convex posteriorly. Anterior border of the petiole variably concave and carinate, the carina dcnticulate on each side. Ventral process of the petiole small and triangular. Postpetiole anteriorly broader than the petiole; its sides diverging or gently convex. Postpetiolar sternite anteromedially with a weakly marked subtriangular projection. Postpetiolar sternite straight in side view. Constriction between postpetiole and first gastral segment impressed. Gastral tergite I strongly convex on the curvature. Remaining gastral tergites and sternites curved ventrally.

Legs slender but not very elongate. All tibiae with a pectinate spur. Spurs of fore legs without a basal spine. Fore basitarsi longer than the mid ones. Hind basitarsi about 1/4 shorter than hind tibiae. Second tarsomere of hind legs shorter than pretarsus. Pretarsal claws simple. Arolia present.

Sculpture. Head, mesosoma, petiole and postpetiole granulate. First gastral tergite smooth and covered by piligerous punctures; its sides and the posterior border with additional granulation. Legs granulate, the granulation less marked than in the other body parts.

Pilosity. Body covered by hairs of three main types: (1) short, dense, subdecumbent on the whole body, sparse and suberect on the funicular joints; (2) longer than type (I), sparse, erect or suberect on the whole body, slightly shorter on the scapes, absent on the funiculi; (3) shorter than hair type (I), dense and decumbent on the funicular joints only. In addition the funicular joints bear whitish, thick, appressed, sparse hairs.

Colour brown.

Measurements in mm and Indices: TL 3.65-3.82; HL 0.81-0.83; HW 0.71-0.74; EL 0.03; SL 0.49-0.50; WL 1.00-1.04; PeL 0.32-0.35; Pew 0.31-0.32; HFeL 0.64; HTiL 0.53-0.56; MBaL 0.38-0.41; LS4 0.25-0.30; LT4 0.86-0.92; CI 87.6-89. I; SI 60.2-60.5; IGR 0.34-0.35.

Queen
Baroni Urbani and de Andrade (2003) - Differing from the worker in the following details: eyes about 1/5 of the head length and with well defined ommatidia. Ocular pilosity present. Ocelli present.

Mesosoma robust. Scutellum large; its sides converging into a convex posterior border. Basal face of the propodeum gently declivous posteriorly; dorsally medially incised and as flat as the declivous face; its sides subangulate and carinate. Metanotum without denticle. Propodeal lamellae narrower.

Measurements in mm and Indices: TL 4.46-4.62; HL 0.86-0.88; HW 0.78-0.8 1 ; EL 0.17; SL 0.5 1; WL 1.28- 1.32; ; PeL 0.38-0.40; Pew 0.37; HFeL 0.75; HTiL 0.61 -0.62; HBaL 0.46; LS4 0.36-0.38; LT4 1.10- 1.12; CI 90.7-92.0; SZ 57.9-59.3; ICR 0.33-0.34.

Male
Head subequal in size or slightly broader than long. Vertex in full face view convex. Vertexal margin carinate. Clypeus dorsomedially convex. Frontal carinae thin, low, diverging posteriorly. Frontal area with a sulcus. Ocelli large. Compound eyes large and placed mostly on the anterior part of the head sides. Scapes reaching the anterior ocellus. First funicular joint about 1/4 shorter than second joint. Joints 2-12 longer than broad. Last funicular joint slightly longer than the sum of joints 10-11. Mandibles edentate and only with a pointed apical tooth. Palp formula 4,3.

Mesosoma robust. Pronotum and anterior third of rnesonotum almost perpendicular to the posterior two thirds of the mesonotum. Posterior two thirds of mesonotum almost flat. Parapsidal furrows marked. Scutellum slightly higher than the mesonotum; its posterior border round. Basal and declivous faces of the propodeum convex in side and dorsal view. Sides of the propodeum gently converging. Declivous face of propodeum laterally superficially carinate. Metanotum with a median tooth. Propodeal lobes round and partially lamellaceous. Propodeal spiracles small.

Petiole in profile declivous in the anterior third and convex in the two posterior thirds. Sides of the petiole convex in dorsal view. Anterior border of the petiole concave and laterally carinate. Subpetiolar process absent; petiolar sternite gently convex. Postpetiole anteriorly broader than the petiole; postpetiolar sides diverging posteriorly. Anterior border of the postpetiolar sternite with a superficial triangular "lip". Gastral tergite I large and convex in side view. Remaining gastral tergites and sternites slightly curved ventrally.

Legs as in the worker but more elongate. Hind basitarsi slightly shorter than hind tibiae.

Fore wings of our type 2, hind wings of our type 3 as defined in the description of the genus.

Genitalia as in Fig. 114.

Sculpture. Head irregularly reticulorugose. Mesosoma minutely granulopunctate, the granulation more superficial on the mesonoturn. Scutellum, propodeum and pleurae with additional, thin, irregular rugosities. Postpetiole and gaster smooth and with minute piligerous punctures. Legs minutely granulopunctate.

Pilosity as in the worker but with hairs of type (2) sparser on the petiole, postpetiole and gaster.

Colour. Back with lighter antennae and legs.

Measurements in mm and Indices: TL 3.63-3.74; HL 0.59-0.60; HW 0.61-0.64; EL 0.30-0.31; SL 0.33; WL 1.20-1.28; PeL 0.34-0.35; PeW 0.25-0.26; HFeL 0.76-0.79; HTiL 0.65; HBaL 0.58-0.60; LS4 0.48; LT4 0.84; CI 103.4-106.7; SI 55.0-55.9; IGR 0.57.

Type Material
Worker. Type locality. Tokyo, Japan Type materlal 3 syntype workers labelled "Sysphincta itoi" For, worker type, Tokio, Japan (Ito)" in, examined.

References based on Global Ant Biodiversity Informatics

 * Abe T. 1977. A preliminary study on the ant fauna of the Tokara Islands and Amami-Oshima. Ecol. Stud. Nat. Cons. Ryukyu Isl. 3: 93-102.
 * Baroni Urbani C., and M.L de Andrade. 2003. The ant genus Proceratium in the extant and fossil record (Hymenoptera: Formicidae). Museo Regionale di Scienze Naturali, Monografie 36: 1-480.
 * CSIRO Collection
 * Choi B.-M. 1987. Taxonomic study on ants (Formicidae) in Korea (1). On the genus Monomorium. Journal of the Institute of Science Education (Cheongju National Teachers' College) 11:17-30.
 * Choi B.M. 1996. Distribution of ants (Formicidae) in Korea (16) - Ant fauna from Chollabukdo. Korean J. Soil. Zoology 1(1): 5-23.
 * Choi B.M. 1996. Distribution of ants (Formicidae) in Korea (16): Ant fauna from Chollabukdo. Korean Journal of Soil Zoology 1(1): 5-23.
 * Choi B.M. 1996. Studies on the distribution of ants (Formicidae) in Korea (15) -Ant fauna islands Ullungdo and Dokdo. Journal of Chongju National University of Education 33: 201-219.
 * Choi B.M., I. H. Lee. 1995. Studies on the distribution of ants (Formicidae) in Korea (14). Ant fauna in island Sohuksando. Korean Journal of Applied Entomology 34(3): 191-197.
 * Choi B.M., K. Ogata, and M. Terayama. 1993. Comparative studies of ant faunas of Korea and Japan. 1. Faunal comparison  among islands of Southern Korean and northern Kyushu, Japan. Bull. Biogeogr. Soc. Japan 48(1): 37-49.
 * Choi B.M., Kim, C.H., Bang, J.R. 1993. Studies on the distribution of ants (Formicidae) in Korea (13). A checklist of ants from each province (Do), with taxonomic notes. Cheongju Sabom Taehakkyo Nonmunjip (Journal of Cheongju National University of Education) 30: 331-380.
 * Choi B.M., and J. R. Bang. Studies on the distribution of ants (Formicidae) in Korea (12): the analysis of ant communities in 23 islands. Journal of Cheongju National University of Education 30:317-330.
 * Choi B.M., and Park, K.S. 1991. Studies on the distribution of ants (Formicidae) in Korea (7). Ant fauna in Mt. Kyeryongsan. Korean Journal of Applied Entomology 30: 80-85.
 * Fukumoto S., Jaitrong W. and Yamane S.K. 2013. Ant Fauna of Kuro-shima, Iwo-jima and Take-shima islands, Kagoshima Prefecture, southwestern Japan. Nature of Kagoshima 39: 119-125
 * Fukumoto S., R. Satria, T. Maeda, and S. Yamane. 2014. Ant fauna of Gaja-jima, Tokara Islands, southwestern Japan. Nature of Kagoshima 40: 127131.
 * Fukumoto S., W. Jaitrong, and S. Yamane. 2013. Ant fauna of Take-shima, Iwo-jima and Kuro-shima islands, Kagoshima Prefecture, southwestern Japan. Nature of Kagoshima 39: 99-105.
 * Guénard B., and R. R. Dunn. 2012. A checklist of the ants of China. Zootaxa 3558: 1-77.
 * Ha S.J, S.J. Park, and B.J. Kim. 2002. Comparative ant faunas between Seonyudo and seven other islands of West Sea in Korea. Korean Journal of Entomology 32(2): 75-79.
 * Harada Y. S. Koto, N. Kawaguchi, K. Sato, T. Setoguchi, R. Muranaga, H. Yamashita, A. Yo, and S. Yamane. 2012. Ants of Jusso, Isa City, Kagoshima Prefecture, southwestern Japan. Bull. biogeogr. Soc. Japan 67: 143-152.
 * Harada Y., H. Yadori, M. Yoneda, R. Takinami, K. Nagahama, Y. Matsumoto, A. Oyama, S. Maeda, and S. Yamane. 2009. Ant fauna of Tanegashima (Hymenoptera, Formicidae). Nankiseibutu, the Nanki Biological Society 51(1): 15-21.
 * Harada Y., M. Enomoto, N. Nishimata, and K. Nishimuta. 2014. Ants of the Tokara Islands, northern Ryukyus, Japan. Nature of Kagoshima 40: 111121.
 * Harada Y., Y. Matsumoto, S. Maeda, A. Oyama, and S. Yamane. 2009. Comparison of ant fauna among different habitats of Yaku-shima Island, southern Japan. Bull. Biogeogr. Soc. Japan 64: 125-134.
 * Hosoichi S., W. Tasen, S. H. Park. A. Le Ngoc, Y. Kuboki, and K. Ogata. 2015. Annual ﬁre resilience of ground-dwelling ant communities in Hiraodai Karst Plateau grassland in Japan. Entomological Science 18: 254–261.
 * Hosoishi S. 2006. Ant fauna of Noko Island. pp99-107. In: The floristic and faunistic surveys of the Noko Island.
 * Hu C.-H. 2006. Indigenized conservation and biodiversity maintenance on Orchid Island. PhD Thesis, graduate school of the University of Minnesota. 150 pages.
 * Ichikawa A. 1999. Records of ants observed from several localities of Osaka Prefecture, Japan, -1. Ari 23: 1-3.
 * Ikeshita Y., A. Gotoh, K. Yamamoto, N. Taniguchi, and F. Ito. 2007. Ants collected in Mt. Linoyama, Marugame, Kagawa Prefecture (Hymenoptera, Formicidae). Kagawa Seibutsu 34: 59-62.
 * Katayama M., T. Hosoya, and W. Toki. 2013: First survey of ground-dwelling ants (Hymenoptera: Formicidae) on the uninhabitedGaja-jima Island, theRyukyu archipelago, Japan.Entomol. Fennica 24: 216222.
 * Kim B.J. 1996. Synonymic list and distribution of Formicidae (Hymenoptera) in Korea. Entomological Research Bulletin Supplement 169-196.
 * Kim B.J., K.G. Kim, J.H. Kim, S.J. Park. Ants from Mt. Mirok. Korean J. Soil Zoology 2(2): 115-128.
 * Kim B.J.; Kim, J.H.; Kim K 1998. Systematic study of Ponerinae (Hymenoptera: Formicidae) from Korea. Korean Journal of Entomology 28:145-154.
 * Kim C.H., B.M. Choi, and J.R. Bang. 1992. Studies on the distribution of ants (Formicidae) in Korea (8)-Ant fauna in 10 islands, Chollanam-do. Korean J. Appl. Entomol. 31(4): 345-359.
 * Kim et al. 1993. Systematic study of ants from Chejudo Province. Koran Journal of Entomology 23(3): 117-141.
 * Kubota S., and M. Terayama. 1982. Ant fauna of Kanagawa Prefecture, Japan (IV) Ants of Kakio. Kanagawa-chuho (Journal of the Kanagawa Entomologists Association) 21-28.
 * Kubota. S., and M. Terayama. 1988. Ant fauna of Tokyo. (1) A list of ants collected at the parks. ARI Reports of the Myrmecologists Society (Japan) 16: 14-16
 * Kwon T. S. 2012. Korean ant atlas. Korea Forest Research Institute 162 pages.
 * Kwon T.S., C. M. Lee, J. H. Chun, J. H. Sung, and S. K. Kim. 2011. Ants in Hongneung forest. Korea Forest Research Institute, 92 pages.
 * Li Z.h. 2006. List of Chinese Insects. Volume 4. Sun Yat-sen University Press
 * Lyu D. 2008. Taxonomic study on the Poneromorph subfamilies group (Hymenoptera: Formicidae) in Korea. Korean J. Appl. Entomol. 47(4): 315-331.
 * Manabe K. 1994. Ants of the shrine forest in Fukuoka Prefecture (First report; Ants of lowland). Ari 17: 6.
 * Manabe K. 1994. Ants of the shrine forest in Fukuoka Prefecture (first report; ants of lowland). Ari 18: 6.
 * Masuko K. 2019. Predation on non-ppider arthropod eggs and colony bionomics of the ant Proceratium itoi (Hymenoptera: Formicidae). Annals of the Entomological Society of America doi: 10.1093/aesa/saz012
 * Masuko K., H. Yamaoka, T. Kannari, and S. Usuba. 1985. Ants of Mt. Kiyosumi (4). Kiyosumi 11: 9-12.
 * Matsumura S. and Yamane Sk. 2012. Species composition and dominant species of ants in Jigenji Park, Kagoshima City, Japan. Nature of Kagoshima 38: 99107
 * Matsumura S., and S. Yamane. 2012. Species composition and dominant species of ants in Jigenji Park, Kagoshima City, Japan. Nature of Kagoshima 38: 99-107.
 * Mizota K. 2002. A check list of insects in Kinkazan Island, Miyagi Pref., Northeastern Japan: A bibliographical Survey. Bulletin of Miyagi University of Education Environmental Education 5: 69-78.
 * Nijima K., Y. Mizutani, and K. Masaki. 2003. Soil fauna in a Japanese red pine (Pinus densiflora) forest and the influence of the application of bark compost 1. Ants. Edaphologia 71: 35-40.
 * Okamoto H. 1972. Ants from Shikoku, Japan (7). Gensei 23:11-14.
 * Onoyama K., and M. Yoshimura. 2002. The ants of the genus Proceratium (Hymenoptera: Formicidae) in Japan. Entomological Science 5(1): 29-49.
 * Our results Winkler 2009
 * Park S. H., S. Hosoishi, K. Ogata, and Y. Kuboki. 2014. Clustering of ant communities and indicator species analysis using self-organizing maps. Comptes Rendus Biologies http://dx.doi.org/10.1016/j.crvi.2014.07.003
 * Park S.J., and B.J. Kim. 2002. Faunal comparison of ants among Cheongsando and other islands of South Sea in Korea. Korean Journal of Entomology 32(1): 7-12.
 * Park, Seong, Joon and Byung, and Kim, Jin. 2002. Faunal Comparison of Ants among Cheongsando and Other Islands of South Sea in Korea. Korean Jornal of Entomology. 32(1):7-12.
 * Sakai H. 2002. Reproductive flight season of Japanese ants. Ari 26: 33-39.
 * Sato T., N. Tsurusaki, K. Hamaguchi, and K. Kinomura. 2010. Ant fauna of Tottori prefecture, Honshu, Japan. Bulletin of the Tottori Prefectural Museum 47: 27-44.
 * So, Ha, Seong, Jin, Park, Joon and Byung, and Kim, Jin. 2002. Comparitive Ant Faunas between Seonyudo and Seven other Islands of West Sea in Korea. Korean Journal of Entomology. 32:75-79.
 * Staab M., F. Hita Garcia, C. Liu, Z. H. Xu, and E. P. Economo. 2018. Systematics of the ant genus Proceratium Roger (Hymenoptera, Formicidae, Proceratiinae) in China – with descriptions of three new species based on micro-CT enhanced next-generation-morphology. ZooKeys 770: 137-192.
 * Terayama M. 1992. Structure of ant communities in East Asia. A. Regional differences and species richness. Bulletin of the Bio-geographical Society of Japan 47: 1-31.
 * Terayama M. 2009. A synopsis of the family Formicidae of Taiwan (Insecta: Hymenoptera). Research Bulletin of Kanto Gakuen University. Liberal Arts 17:81-266.
 * Terayama M., K. Ogata, and B.M. Choi. 1994. Distribution records of ants in 47 prefectures of Japan. Ari (report of the Myrmecologists Society of Japan) 18: 5-17.
 * Terayama M., S. Kubota, and K. Eguchi. 2014. Encyclopedia of Japanese ants. Asakura Shoten: Tokyo, 278 pp.
 * Terayama M., and K. Murata. 1990. Effects of area and fragmentation of forests for nature conservation: Analysis by ant communities. Bull. Biogeogr. Soc. Japan 45(2): 11-17.
 * Terayama M., and S. Kubota. 2002. Ants of Tokyo, Japan. ARI 26: 1-32.
 * Terayama, M. 2009. A synopsis of the family Formicidae of Taiwan (Insecta; Hymenoptera). The Research Bulletin of Kanto Gakuen University 17: 81-266.
 * Terayama. M. and Inoue. N. 1988. Ants collected by the members of the Soil Zoological Expedition to Taiwan. ARI Reports of the Myrmecologists Society (Japan) 18: 25-28
 * Teruyama. M. 1988. Ant fauna of Saitama Prefecture, Japan. ARI Reports of the Myrmecologists Society (Japan) 16: 4-13
 * Touyama Y. 2000. Estimating species richness: an application of the time unit sampling method to a myrmecofaunal survey. Jpn. J. Enviro. Entomol. Zool. 11: 51-60.
 * Touyama Y., N. Nakagoshi, and T. Yamamoto. 1997. Myrmecofauna of lucidophyllous forests in different developmental stages in south-western Japan. Ecological Research 12: 131-138.
 * Xu Z. H. 2000. A systematic study of the ant genus Proceratium Roger from China (Hymenoptera: Formicidae). Acta Zootaxonomica Sinica 25(4): 434-437.
 * Xu Z. 2000. A systematic study of the ant genus Proceratium Roger from China (Hymenoptera: Formicidae). Acta Zootaxonomica Sinica 25(4): 434-437.
 * Yamane S. 2016. How many species of Ants in Amami Islands? (in Japanese). Part 2, chapter 1 in How many species of Ants in Amami Islands? Pp. 92-132.
 * Yamane S., S. Ikudome, and M. Terayama. 1999. Identification guide to the Aculeata of the Nansei Islands, Japan. Sapporo: Hokkaido University Press, xii + 831 pp. pp, 138-317.
 * Yamane S., Y. Harada, and K. Eguchi. 2013. Classification and ecology of ants. Natural history of ants in Southern Kyushu. 200 pages
 * Yamane S.; Ikudome, S.; Terayama, M. 1999. Identification guide to the Aculeata of the Nansei Islands, Japan. Sapporo: Hokkaido University Press, xii + 831 pp. pp138-317.
 * Yamazaki Y., S. Yamane, T. Hishida, T. Kuwahara, and N. Inoue. 2009. Ant fauna on the grounds of the Kashima-Jingu Shrine, Ibaraki, Central Japan (Hymenoptera, Formicidae). Bull. Ibaraki Nat. Mus. 12: 5-14.
 * Yoshitomi H., and S. Matsuno. 2012. List of species of Hymenoptera and Diptera in Matsuyama City, Ehime Prefecture, Shikoku, Japan. pp. 167-176. In: Committee for Surveys of Natural Environment of Matsuyama City (Chief Editor: Kazuo ISHIKAWA) (ed.) Checklist of the Wild Animals, Fungi, and Plants of Matsuyama City, 2012. Published by the Department of Environment, Matsuyama City, 404 pp.