Acropyga nipponensis

A. nipponensis can survive in a wide range of habitats, occurring in both rainforests and temperate forests. It has been collected along creek beds and in soil under stones or rotting wood. This species has been found in trophobiotic association with the mealybug in Japan, with the mealybug living in the ants' nests and the ants feeding on the mealybugs' honeydew (Terayama, 1985, 1986; LaPolla, 2004).

Identification
LaPolla (2004) - Worker: 11 segmented antennae; mandible broad, with 5 teeth, basal tooth enlarged and rectangular, apically truncated; HW: < 0.5 mm. Queen: As in worker with modifications expected for caste. Male: 12 segmented antennae; parameres extremely thin and long; mandible with 4 teeth; basal tooth as in worker though less pronounced. Compare with Acropyga butteli and Acropyga inezae.

The primary means of separating workers of A. nipponensis from Acropyga butteli is by differences in head width < 0.5 mm in the former, > 0.5 mm in the latter). Examination reveals distinct morphometric differences between the two species. Queen morphology also suggests that the two species are not conspecific. An A. nipponensis queen measured had a total length of 2.85 mm versus an A. butteli queen with a total length of 4.02 mm.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Borneo, Indonesia, Malaysia, Philippines. Oriental Region: Taiwan. Palaearctic Region: China, Japan.

From LaPolla (2004): This species has been recorded as far north as temperate regions of Japan, south and west to China and Indonesia.

Nomenclature

 * . Acropyga (Atopodon) nipponensis Terayama, 1985b: 287, figs. 14-18 (w.) JAPAN.
 * LaPolla, 2004a: 39 (q.m.).
 * Status as species: Morisita, et al. 1991: 15; Bolton, 1995b: 57; Terayama, Fellowes & Zhou, 2002: 30 (redescription); Imai, et al. 2003: 83; LaPolla, 2004a: 39 (redescription); Pfeiffer, et al. 2011: 36; Ran & Zhou, 2011: 66; Guénard & Dunn, 2012: 27.
 * Senior synonym of jiangxiensis: LaPolla, 2004a: 39.
 * jiangxiensis. Acropyga (Atopodon) jiangxiensis Wang, C. & Wu, 1992a: 226, figs. 1-4 (w.m.) CHINA (Jiangxi).
 * Status as species: Wu, J. & Wang, 1995: 128; Bolton, 1995b: 57; Terayama, Fellowes & Zhou, 2002: 29 (redescription).
 * Junior synonym of nipponensis: LaPolla, 2004a: 39.

LaPolla (2004) - The male described in this study as A. nipponensis is associated with workers of the species originally described as A. jiangxiensis, a species now treated as a junior synonym. This male is clearly different from A. butteli and Acropyga inezae males. The paratype worker of A. jiangxiensis examined cannot be separated from workers of A. nipponensis and they are therefore considered to be conspecific. The two characters cited by Terayama et al. (2002) as separating A. nipponensis and A. jiangxiensis are suspect, for both are difficult to interpret with such a small sample size. Slight shape changes in the posterior margin and the dorsum of the propodeum were used to warrant recognition of two species, but here I treat those morphological differences as simply intraspecific variation. As male specimens are collected from across the range of A. nipponensis the status of this species should be reexamined.

Worker
LaPolla (2004) - (n=5): TL: 1.97-2.05; HW: 0.457-0.487; HL: 0.576-0.597; SL: 0.391-0.417; ML: 0.436-0.532; GL: 0.878-0.944; CI: 76.55-83.97; SI: 80.29-89.72.

Head: light brownish-yellow; covered in a dense layer of short, appressed hairs; head longer than broad; posterior margin entire to slightly concave medially; 11 segmented, incrassate antennae; scape fails to reach posterior margin by about half the length of pedicel; clypeus broad, with appressed to erect hairs on surface; anterior clypeal margin uneven coming to three points, a medial and 2 lateral points; mandible broad, with 5 teeth; basal tooth enlarged and rectangular, apically truncated; anterior clypeal margin and inner mandibular margin nearly parallel. Mesosoma: light brownish-yellow; in lateral view, with short shelf before rising sharply toward mesonotum; pronotum with appressed hairs, long erect hairs posteriorly; mesonotum slightly higher than propodeum, covered in a layer of appressed to erect hairs; metanotal area distinct; propodeum gently rounded, with appressed hairs dorsally; declivity steep. Gaster: petiole thick and erect, reaching height of anterior portion of propodeal spiracle; gaster light brownish-yellow with dense layer of appressed hairs, with scattered erect hairs throughout.

Queen
LaPolla (2004) - (n=1): TL: 2.85; HW: 0.604; HL: 0.688; SL: 0.528; ML: 0.882; GL: 1.3; CI: 90.42; SI: 87.42. As in worker with modifications expected for caste.

Male
LaPolla (2004) - Head: brownish-yellow, darker toward apex around 3 prominent ocelli; head longer than broad; covered in a thick layer of appressed hairs; eyes large, breaking outline of head in full frontal view; 12 segmented, incrassate antennae; scape surpasses posterior margin by about length of the pedicel; clypeus broad, slightly convex medially, with scattered erect hairs; mandible with 4 teeth, the basal as in worker, though less distinct; inner mandibular margin and anterior clypeal margin nearly parallel. Mesosoma: unfortunately the mesosoma of the single examined male specimen was too badly distorted to be described properly. Gaster: brownish-yellow; covered in a thick layer of appressed hairs with scattered erect hairs throughout. Genitalia: in lateral view, parameres long and very thin, each tapering to a pointed apex; cuspi bent slightly toward digiti; cuspi apices with short, peg-like teeth; digiti straight and long, about 2 times as long as cuspi; digiti with apices rounded, each with short peg-like teeth midlength where cuspi bends toward them.

Measurements: not completed as specimen was too badly distorted to be measured properly.

Type Material
Acropyga nipponensis Terayama, 1985: 287 (w.). 1 holotype worker, JAPAN: Noboritachi, Mikura-jima Is., Tokyo (K. Masuko) [not examined]. Terayama et al., 2002: 30, description and key.

Acropyga jiangxiensis Wang and Wu, 1992: 226 (w.m.). 1 holotype worker, CHINA: Jiangxi Provin., Fenyi Co., Dagang Mt. (c. Wang) [not examined]; 1 worker paratype, 1 male paratype, same locality as holotype (CFRB) [examined]. NEW SYNONYM. Terayama et al., 2002: 29, description and key.

References based on Global Ant Biodiversity Informatics

 * CSIRO Collection
 * Chen Y., C.-W. Luo, H. W Li, Z. H. Xu, Y. J. Liu, and S. J. Zhao. 2011. The investigation of soil ant resources on the West slope of Mt Ailao. Hubei Agricultural Sciences 50(7): 1356-1359.
 * 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.
 * Fukumoto S. and Sk. Yamane. 2015. Records of ants from Uke–jima, Amami Islands, Japan (Hymenoptera,  Formicidae). Nature of Kagoshima 41: 195–197.
 * Guénard B., and R. R. Dunn. 2012. A checklist of the ants of China. Zootaxa 3558: 1-77.
 * Hosoichi S., M. Yoshimura, Y. Kuboki, and K. Ogata. 2007. Ants from Yakushima Island, Kagoshima Prefecture. Ari 30: 47-54.
 * Hosoishi S., M. Yoshimura, Y. Kuboki, and K. Ogata. 2007. Ants from Yakushima Island, Kagoshima Prefecture. Ari 30: 47-54.
 * LaPolla J.S. 2004. Acropyga (Hymenoptera: Formicidae) of the world. Contributions of the American Entomological Institute 33(3): 1-130.
 * Li Qiao, Chen You-qing, Guo Xiao, Duan Yan, Chen Yan-lin, and Xu Zheng-hui. 2007. Diversity of ants in differents habitats in Yuanmou arid-hot valley, Yunnan. Journal of Fujian College of Forestry 27(3): 272-277.
 * Pfeiffer M.; Mezger, D.; Hosoishi, S.; Bakhtiar, E. Y.; Kohout, R. J. 2011. The Formicidae of Borneo (Insecta: Hymenoptera): a preliminary species list. Asian Myrmecology 4:9-58
 * Ran H., and S. Y. Zhou. 2011. Checklist of Chinese Ants: the Formicomorph Subfamilies (Hymenoptera: Formicidae) (I). Journal of Guangxi Normal University: Natural Science Edition. 29(3): 65-73.
 * Terayama M. 1985. Two new species of the genus Acropyga (Hymenoptera, Formicidae) from Taiwan and Japan. Kontyû 53: 284-289.
 * 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., 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 S. Kubota. 2002. Ants of Tokyo, Japan. ARI 26: 1-32.
 * Terayama M.; Fellowes, J. R.; Zhou, S. 2002. The East Asian species of the ant genus Acropyga Roger, 1862 (Hymenoptera: Formicidae: Formicinae). Edaphologia 70:21-32.
 * Terayama, M., J. R. Fellowes and Zhou S.-Y. 2002. The East Asian species of the ant genus Acropyga Roger, 1862 (Hymenoptera: Formicidae: Formicinae). Edaphologia 70: 21-32
 * Wu Z. W., X. D. Bi, X. He, Z. X. Lu, L. J. Wei, and Y. Q Chen. 2015. Impact of continuous fire disturbance on ground-dwelling ant communities in arid-hot valleys of Panzhihua, Sichuan. Journal of Yunnan University 37(3): 467-474.
 * 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.
 * Zhang N. N., Y. Q. Chen, Z. X. Lu, W. Zhang, and K. L. Li. 2013. Species diversity, community structure difference and indicator species of leaf-litter ants in rubber plantations and secondary natural forests in Yunnan, southwestern China. Acta Entomologica Sinica 56(11): 1314-1323.