Vollenhovia sakishimana

This species nests in the soil or rotten wood in forests. It is polygynous with an an average of 3.8 queens per nest. 

Identification
Terayama & Kinomura (1997) - Closely resembles Vollenhovia emeryi, but differs from the latter by the absence of a large brown spot on frons, having subparallel clypeal carinae, yellowish body color, and smaller body size (HL 0.52-0.55 mm and HW 0.43-0.45 mm in sakishimana workers; HL 0.55-0.59 mm and HW 0.50-0.54 mm in emeryi workers).

Distribution based on Regional Taxon Lists
Palaearctic Region: Japan.

Nomenclature

 *  sakishimana. Vollenhovia sakishimana Terayama & Kinomura, 1997: 5, figs. 5, 9 (w.q.) JAPAN.

Worker
Holotype. HL 0.54 mm; HW 0.45 mm; SL 0.33 mm; CI 83; SI 73; WL 0.66 mm; PL 0.24 mm; PH 0.28 mm; DPW 0.15 mm; TL 2.1 mm.

Head longer than wide, with subparallel sides and concave posterior margin in frontal view. Mandibles with 7 teeth; basalmost tooth minute. Clypeal carinae subparallel. Antennae with 12 segments; scape 0.61 x head length. Eyes 0.12 mm in diameter.

Alitrunk with largely straight dorsal margin of promesonotum in profile; metanotal groove not incised dorsally; dorsal margin of propodeum weakly convex; posterodorsal comer of propodeum with a small tooth and is as long as basal width in profile.

Petiole slightly higher than long. with convex dorsal margin in profile; anterodorsal comer dully angulate; posterodorsal comer convex, not forming angle. Subpetiolar process large, with rounded ventral margin; its thin lamellar wall 0.06 mm in height. Postpetiole as long as high. highest at midlength, with relatively strongly convex dorsal outline in protile; posterodorsal margin convex.

Head and dorsum of promesonotum shagreened and moderately punctated; unsculptured longitudinal band absent on promesonotal dorsum; mesopleura and lateral surfaces of propodeum coarsely punctated; petiole and postpetiole reticulate; sculpture on postpetiole weaker than that on petiole, and much shinier; gaster and legs smooth and subopaque.

Color: yellowish brown including mandibles, antennae and legs; frons without large brown spot.

Queen
Paratype. HL 0.60 mm; HW 0.55 mm; SL 0.38 mm; CI 92; SI 69; WL 0.90 mm; PL 0.28 mm; PH 0.33 mm; DPW 0.20 mm; TL 2.6 mm(one measured).

Head slightly longer than wide. with weakly concave posterior margin; eyes 0.17 mm in diameter; ocelli forming obtuse triangle.

Alitrunk 0.53 mm in maximum dorsal width; mesonotal dorsum weakly shagreened and moderately punctated, without unsculptured longitudinal band medially; posterodorsal corner of propodeum with distinct tooth in profile.

Petiole higher than long, with convex dorsal outline in profile. Subpetiolar process large and high, with relatively strongly convex ventral margin. Postpetiole highest at midlength, with convex dorsal outline in profile; posterodorsal margin convex.

Color: yellowish brown; ocellar triangle blackish brown; frons without large brown spot.

Variation. Five paratype workers with the following measurements and indices: HL 0.50-0.53 mm; HW 0.46-0.48 mm; SL 0.31-0.33 mm; CI 88-93; SI 67-68; WL 0.68-0.70 mm; PL 0.24-0.25 mm: PH 0.28-0.30 mm; DPW 0.15-0.16 mm; TL 2.0-2.1 mm.

The subpetiolar process of the Ogasawara and Yonaguni specimens are somewhat smaller than that of the Iriomote and Ishigaki specimens. In some paratype specimens the basalmost tooth of the mandibles is obscure and the propodeal tooth is much shorter than that of the holotype.

Type Material
Holotype. Worker, Iriomote-jima, Okinawa Pref., 28.III.1991, M. Terayama leg. Paratypes. 8 workers, same data as holotype; 1 female, 1 worker, Ohtomi, Iriomote-jima, Okinawa Pref., 6.VIII.1985, K. Yamauchi leg., 1 female, 3 workers, Yoshino, Ishigaki-jima. Okinawa Pref., 16.VIII.1985, K. Yamauchi leg.

Type depository. The holotype and some paratypes are deposited in the Museum of Nature and Human Activities, Hyogo, and the other paratypes are in the National Institute of Agro-Environmental Sciences, Tsukuba, and National Science Museum, Tokyo.

Etymology
The specific epithet refers to the type locality.

Determination Clarifications
This new species corresponds to Vollenhovia sp. 5 (“Sakishima-umematsuari” in Japanese name) in Terayama and Yamauchi (1992) and V. sp. B in Onoyama (1976).

References based on Global Ant Biodiversity Informatics

 * 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.; Kinomura, K. 1997. Taxonomic studies of Japanese Formicidae, part 3. Genus Vollenhovia Mayr. Nature & Human Activities 2:1-8.
 * 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.; Ikudome, S.; Terayama, M. 1999. Identification guide to the Aculeata of the Nansei Islands, Japan. Sapporo: Hokkaido University Press, xii + 831 pp. pp138-317.