Syscia humicola

Found on the floor of broad-leaved forest. Colonies include several tens of workers. Rare. (Japanese Ant Image Database)

Distribution based on Regional Taxon Lists
Palaearctic Region: Japan.

Nomenclature

 *  humicola. Cerapachys humicola Ogata, 1983: 132, figs. 1-13 (w.q.m.) JAPAN.
 * Combination in Syscia: Borowiec, M.L. 2016: 224.
 * Status as species: Bolton, 1995b: 143; Imai, et al. 2003: 210.

Description
Worker: HW 0.44-0.48 mm, HL 0.52-0.62 mm, 0.24-0.26 mm, WL 0.74-0.82 mm, petiolar node L 0.25-0.30 mm, postpetiolar node L 0.35-0.44 mm, mm, TL 2.79-3.10 mm. n. sp. CI 73-85, SL 0.92-0.31 mm, ML 0.25-0.30 mm, petiolar node W postpetiolar node W 0.35-0.45 Head rectangular, subparallel-sided; posterior margin slightly concave in full face view; posterior corner forming right angle. Occipital carina distinct, surrounding occipital foramen squarely. Eye absent. Frontal area with raised carinae in the middle contiguously; lateral corner with small process anteriorly. Clypeus depressed ; anterior margin straight. Antenna ll-segmented ; antenna1 scape clavate, short, as long as 7 following segments together; second segment small, received in hollow of scape; apical segment large, bulbous, as long as 5 preceding segments together. Mandible subtriangular, with edentate masticatory border and acute apex. Palp formula of maxillary 2-, labial 2-segmented. Trunk rigid, parallel-sided ; dorsal surface flat, without suture ; pronotum anteriorly rounded in dorsal view, without margination ; propodeum truncate posteriorly, with weakly marginate declivity. Metasternal process distinct. Petiolar and postpetiolar nodes as broad as long. Petiolar node parallelsided, narrower than trunk ; subpetiolar process triangular. Postpetiolar node trapezoidal, broadest at posterior border which is broader than trunk. First gastric segment large, about 1.5 x as long as postpetiolar node. Legs short; middle leg with pectinate tibia1 spur, as in fore and hind legs. Body surface opaque, with fine reticulation. Hairs short, pale yellow, suberect or decumbent. Color reddish brown.

Ergatoid queen: HW 0.48-0.50 mm, HL 0.56-0.66 mm, CI 76-86, SL 0.30-0.31 mm, ML 0.25-0.31 mm, WL 0.80-0.92 mm, petiolar node L 0.29-0.31 mm, petiolar node W 0.30-0.33 mm, postpetiolar node L 0.43-0.50 mm, postpetiolar node W 0.44-0.50 mm, TL 3.13-3.53 mm. Body form and proportions like those of worker, but slightly larger in size. Eyes present but variable, with one pigmented spot to about 35 facets (diameter 0.13 mm). Anteromedian ocellus present or absent; if present, situated in the l/5 of HL from posterior margin of head. Paired posterior ocelli absent in specimens examined. Sculpture, pilosity and coloration as in worker.

Male : HW 0.56-0.60 mm, HL 0.50-0.60 mm, CI 100-112, SL 0.19-0.20 mm, ML 0. 18-O. 21 mm, WL 0.96-l. 00 mm, petiolar node L 0.24-0.25 mm, petiolar node W 0.23-o. 25 mm, postpetiolar node L 0.29-o. 31 mm, postpetiolar node W 0.31-o. 34 mm, TL 1.80-l. 90 mm, fore wing L 2.06-2.16 mm. Head, excluding eyes, slightly narrower than trunk ; vertex depressed, forming flat area. Occipital carina distinct as in worker. Eye large, about 0.24mm in greatest diameter. Frontal area as in worker, but carinae less raised and separated more widely; anterolateral corner without process. Clypeus broad ; anterior margin rounded. Antenna 12-segmented ; scape thick, short, as long as 3 following segments together; third antenna1 segment smallest, l/2 as long as fourth segment; apical segment large, longer than 2 preceding segments together. Mandible developed, subtriangular, as in worker. Palp formula of maxillary 4-, labial 2-segmented. Trunk rigid ; mesoscutum with distinct notauli ; propodeal declivity slightly concave, without margination. Petiole and postpetiole like those of worker, but with more rounded corners. First gastric segment large, 1.5 x as long as postpetiolar node. Fore wing with reduced veins; r-m and m-cu cross veins absent; stigma large and distinct. Legs long; tibia1 spurs of fore, middle and hind legs as in worker. Subgenital plate with two distinct projections apically. Genitalia retractile; basal ring broader than long, somewhat heavily screlotized ventrally ; paramere rounded apically in lateral view, ventral surface concave at apical l/3 of its length ; volsella with large digitus and small cuspis ; digitus with sensillae on outer surface ; both partly visible through ventral concavity of paramere in lateral view. Aedeagal plate subtriangular ; apex acute, directed downward and curved outside. Body surface with small punctures, which are abundant on head, scutum and scutellum; interspaces smooth and shining. Pilosity as in worker, but sparser. Body black, legs and antenna lighter. - Ogata (1983)

(Korean individuals, short description) Body length c.a 2.5mm, bright orange ground color. Body entirely punctate and densely covered with short yellowish hair. Head longer than width, occipital margin deeply concave. Compound eye absent. Antennal scape club-shaped, very short. Antennal funiculus relatively thick. Antenal clypeal margin straight, not concave. Mandible small, triangular-shaped. Pronotal humeral angle absent in dorsal view. Dorsum of thorax distinctly flat without any remarkable sutures or grooves in profile view. Legs short, tibial spur enlarged. Propodeal slope steep. Petiole square-shaped, dorsum of petiolar node flat in profile view. Subpetiolar process anteriorly present and distinct. - Dong (2017)

References based on Global Ant Biodiversity Informatics

 * 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.
 * Guénard B., and R. R. Dunn. 2012. A checklist of the ants of China. Zootaxa 3558: 1-77.
 * Kawahara Y., S. Hosoyamada, and S. Yamane. 1999. Ant fauna of the Terayama Station for Education and Research on Nature, Kagoshima University. Bulletin of the Faculty of Education, Kagoshima University. Natural Science 50: 147-156.
 * 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, D.P. Ryu, J.H. Kim. 1995. Ants of Chindo island in Korea (Hymenoptera; Formicidae). The Korean Journal of Systematic Zoology 11(1): 101-113.
 * Kim, Byung-Jin, Ky-Gyong Kim, Dong-Pyo Ryu and Joong-Hyon Kim. 1995. The Korean Journal of Systematic Zoology. 11(1):101-113.
 * Ogata K. 1983. The ant genus Cerapachys F. Smith of Japan, with description of a new species (Hymenoptera, Formicidae). Esakia 20:131-137.
 * 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.
 * Teruyama. M. 1988. Ant fauna of Saitama Prefecture, Japan. ARI Reports of the Myrmecologists Society (Japan) 16: 4-13
 * Yamane S., Y. Harada, and K. Eguchi. 2013. Classification and ecology of ants. Natural history of ants in Southern Kyushu. 200 pages